- The e- + 1,3-Butadiene 1,3-Butadiene- Equilibrium in n-Hexane
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The rate constants for attachment of excess electrons to 1,3-butadiene (ka) and detachment from the butadiene anoin (kd) in n-hexane are reported.The equilibrium constant, Keq = ka/kd, increases rapidly with pressure and decreases as the temperature increases.At -7 deg C attachment is observed at 1 bar.At high pressures the attachment rate is diffusion controlled.The activation energy for detachment is about 21 kcal/mol; detachment is facilitated by the large entropy of activation.The reaction volumes for attachment range from -181 cm3/mol at 400 bar to -122 cm3/mol at 1500 bar and are largely attributed to the electrostriction volume of the butadiene anion (Δel).Values of Δel) calculated by a model, which includes a glassy shell of solvent molecules around the ion, are in agreement with experimental reaction volumes.The analysis indicates the partial molar volume of the electron in hexane is small and probably negative.It is shown that the entropies of reaction are closely related to the partial molar volumes of reaction.
- Holroyd, Richard A.,Schwarz, Harold A.,Stradowska, Elizabeth,Ninomiya, Shiro,Itoh, Kengo,Nishikawa, Masaru
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- Preadsorbed oxygen atoms affect the product distribution and kinetics of acetylene cyclization to benzene on Pd(111): A laser-induced thermal desorption/fourier transform mass spectrometry study
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The study presented here focuses on determining the role of oxygen as a modifier on Pd(111) and its effects on the cyclization of acetylene to benzene. Laser-induced thermal desorption/Fourier transform mass spectrometry (LITD/FTMS) is used as a sensitive tool for measuring the in situ kinetics of benzene formation from acetylene on O/Pd(111). Low exposure of acetylene on O/Pd(111) leads to the anticipated formation of benzene and 1,3-butadiene. Though there is no evidence of furan formation on the surface, oxidation products, such as CO and H2O, are observed. An enhancement in the yield of benzene has been observed with increasing oxygen preexposure. Our evidence suggests that this enhancement is caused by oxygen-island compression of acetylene molecules into bare patches of Pd, which effectively increases the local coverage of acetylene in those regions. Isothermal kinetic studies of 1.1 langmuirs of acetylene on a 50% saturated layer of O on Pd(111) (from a 0.25 langmuir exposure of O2 at 250 K) yield an Ea of 37.8 ± 3 kJ/mol using initial rates (and 36.2 ± 3 kJ/mol using a pseudo-first-order model). Both the activation energy and preexponential factor from a 50% saturation coverage of oxygen on Pd(111) correspond to the values expected for twice the acetylene exposure on a clean surface. The apparent contradiction between increased benzene yields and activation barrier for the O/Pd system can be rationalized by the compensation effect, where a more tightly bound reactant can lead to a greater entropy of activation.
- Caldwell, Tracy E.,Abdelrehim, Ihab M.,Land, Donald P.
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- Hydrocarbon Activation by Gas-Phase Lanthanide Cations: Interaction of Pr+, Eu+, and Gd+ with Small Alkanes, Cycloalkanes, and Alkenes
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We describe ion beam studies of the interaction of gas-phase lanthanide ions, praseodymium (Pr+), europium (Eu+), and gadolinium (Gd+), with small alkanes, cycloalkanes, alkenes, and several oxygen-containing compounds.Only Gd+ is seen to activate C-H and C-C bonds of alkanes.The ground-state electronic configuration of Gd+ (4f75d16s1) is different from those of Pr+ (4f36s1) and Eu+ (4f76s1), leading to the conclusion that the f electrons play little part in the metal ion reactivity.Gd+ can be thought of as having two valence electrons, and indeed it reacts similarly to Sc+ and the other group 3 metal ions Y+ and La+, yielding products corresponding to elimination of hydrogen, alkanes, and alkenes.The elimination of neutral alkenes in the reaction of Gd+ with alkanes results in the formation of metal dialkyl or hydrido-alkyl complexes.This finding leads to estimates for the sum of two Gd+ ? bond dissociation energies of between 110 and 130 kcal/mol.Gd+ and Pr+ react readily with alkenes, yielding mostly dehydrogenation products along with smaller amounts of C-C bond cleavage products.Reactions of Gd+ and Pr+ with oxyen-containing species such as nitric oxide, formaldehyde, acetaldehyde, and acetone yield primarily the metal oxide ions and provide a lower limit for D(M+-O) of 179 kcal/mol, in good agreement with literature values of D(Pr+-O) = 188.4 +/- 5.2 kcal/mol and D(Gd+-O) = 181.0 +/- 4.4 kcal/mol.In keeping with the strong metal ? bonds, Gd+ is also seen to readily react with formaldehyde to eliminate CO and form GdH2+.
- Schilling, J. Bruce,Beauchamp, J. L.
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- Effect of CH2Br2-Addition upon Direct Oxidative Dehydrogenation of Butane into 1,3-Butadiene over Fe-Sb-O Composite Catalyst
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Effect of CH2Br2-addition upon direct oxidative dehydrogenation of butane into 1,3-butadiene has been investigated in a conventional flow apparatus.The activity and selectivity of Fe-Sb-O catalyst were much improved by the addition of CH2Br2 to butane in the mole ratio, CH2Br2/n-C4H10, of 0.03 to 0.10 at temperatures near 450 deg C.
- Saitoh, Hitoshi,Satoh, Satoshi,Sodesawa, Toshiaki,Nozaki, Fumio
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- Tin-Assisted Fully Exposed Platinum Clusters Stabilized on Defect-Rich Graphene for Dehydrogenation Reaction
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Tin-assisted fully exposed Pt clusters are fabricated on the core-shell nanodiamond@graphene (ND@G) hybrid support (a-PtSn/ND@G). The obtained atomically dispersed Pt clusters, with an average Pt atom number of 3, were anchored over the ND@G support by the assistance of Sn atoms as a partition agent and through the Pt-C bond between Pt clusters and defect-rich graphene nanoshell. The atomically dispersed Pt clusters guaranteed a full metal availability to the reactants, a high thermal stability, and an optimized adsorption/desorption behavior. It inhibits the side reactions and enhances catalytic performance in direct dehydrogenation of n-butane at a low temperature of 450 °C, leading to >98% selectivity toward olefin products, and the turnover frequency (TOF) of a-PtSn/ND@G is ~3.9 times higher than that of the traditional Pt3Sn alloy catalyst supported on Al2O3 (Pt3Sn/Al2O3).
- Zhang, Jiayun,Deng, Yuchen,Cai, Xiangbin,Chen, Yunlei,Peng, Mi,Jia, Zhimin,Jiang, Zheng,Ren, Pengju,Yao, Siyu,Xie, Jinglin,Xiao, Dequan,Wen, Xiaodong,Wang, Ning,Liu, Hongyang,Ma, Ding
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- Decomposition of 2-methylfuran. Experimental and modeling study
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The thermal reactions of 2-methylfuran were studied behind reflected shock waves in a pressurized driver single pulse shock tube over the temperature range 1100-1400 K and with overall densities of approx. 3 × 10-5 mol/cm3. A large number of products resulting from unimolecular cleavage of the ring and consecutive free radical reactions were obtained under shock heating. The unimolecular decomposition is initiated by two parallel channels: (1) 1,2-hydrogen atom migration from C(5) to C(4) and (2) a methyl group migration from C(2) to C(3) in the ring. Each channel is followed by two parallel modes of ring cleavage. In the first channel, breaking the O - C(2) and the C(4) - C(5) bonds in the ring yields CO and different isomers of C4H6, whereas breaking of the O - C(2) and the C(3) - C(4) bonds yields CH2CO and two isomers C3H4. In the second channel, breaking the O - C(5), and C(2) - C(3) bonds in the ring yields again CO and isomers of C4H6, whereas in the second mode O - C(5), C(2) - C(3), and C(3) - C(4) are broken to yield CO, C2H2, and C2H4. The four C4H6 isomers in decreasing order of abundance were 1,3-butadiene, 1-butyne, 1,2-butadiene, and 2-butyne. The major decomposition product is carbon monoxide. The rate constant for its overall formation is estimated to be kCO = 1015.88 exp(-78.3 × 103/RT) s-1, where R is expressed in units of cal/(K mol). Other products that were found in the postshock samples in decreasing order of abundance were C4H4, C2H2, CH4, p-C3H4, C2H6, C2H4, a-C3H4, C6H6, C4H4O, C3H6, and C4H2. The total decomposition of 2-methylfuran in terms of a first order rate constant is given by ktotal = 1014.78 exp(-71.8 × 103/RT) s-1. This rate and the production rate of carbon monoxide are slightly higher than the ones found in the decomposition of furan. An oxygen-carbon mass balance among the decomposition products was obtained. A reaction scheme composed of 36 species and some 100 elementary reactions accounts for the product distribution over the temperature range covered in this study. First order Arrhenius rate parameters for the formation of the various reaction products are given, a reaction scheme is suggested, and results of computer simulation and sensitivity analysis are shown. Differences and similarities in the reactions of furan and 2-methylfuran are discussed.
- Lifshitz,Tamburu,Shashua
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- IR laser-induced thermolysis of silacyclopent-3-ene: Extrusion of silylene and chemical vapour deposition of polycarbosilane phases via reactions of silylene, buta-1,3-diene and methylene
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Infrared laser-induced (SF6) photosensitized decomposition and infrared laser multiphoton decomposition of silacyclopent-3-ene occur as extrusion of silylene, yielding butadiene as a major gaseous product and affording chemical vapour deposition of solid saturated polycarbosilane films. The involvement of H2Si:, H2C: and buta-1,3-diene in the formation of the films is revealed through quantification of the gaseous products and identification of H2Si: and H2C: by laser induced fluorescence.
- Pola, Josef,Urbanová, Markéta,Díaz, Luis,Santos, Magna,Bastl, Zdenek,?ubrt, Jan
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- Ion and radical rearrangements as a probe of the mechanism of a surface reaction : The desulfurization of cyclopropylmethanethiol and 3-butene-1-thiol on Mo(110)
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Rearrangement reactions were used to probe the transient intermediates in thiol desulfurization induced by Mo(110) by studying cyclopropylmethanethiol and 3-butene-1-thiol. Thiolate intermediates were identified in both cases using vibrational spectroscopy, which indicates facile S-H bond scission on Mo(110). Heterolytic C-S bond scission, leading to a cationic intermediate, is excluded based on the lack of rearrangement products in the reactions of 3-butene-1-thiolate and the absence of cyclobutane or cyclobutene in the reaction of cyclopropylmethyl thiolate on Mo(110). Hydrogenolysis without rearrangement is the primary pathway for both thiols investigated. The lack of rearrangement in the 3-butene-1-thiolate indicates that C-S bond scission and C-H bond formation occur nearly simultaneously. Evidence for the radical pathway is obtained from the production of 1,3-butadiene formed via the rearrangement of cyclopropylmethyl group following C-S bond scission in the cyclopropylmethyl thiolate and by related studies of cyclopropylmethyl bromide. The investigation of the cyclopropylmethyl bromide also demonstrates that trapping of the cyclopropylmethyl radical is favored over selective β-dehydrogenation. This is the first study in which radical rearrangements have been used to obtain detailed information about the nature of extremely short-lived reactions in a surface process.
- Wiegand,Napier,Friend,Uvdal
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- ZnTa-TUD-1 as an easily prepared, highly efficient catalyst for the selective conversion of ethanol to 1,3-butadiene
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High performances in the conversion of ethanol to 1,3-butadiene were achieved with a Zn(ii) and Ta(v) catalyst supported on TUD-1, a mesoporous silica. The selectivity reached 73% after 3 h at 94% conversion. At an increased ethanol flow, the initial productivity increased to 2.45 g1,3-BD gcat-1 h-1, which remained stable for 60 h on stream, making it the most productive catalyst according to the literature. Preliminary characterization suggests that its morphological and acid properties contribute to these exceptional performances.
- Pomalaza,Vofo,Capron,Dumeignil
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- Vacuum-Ultraviolet (147.0 and 123.6 nm) Photolysis of trans- and cis-1,2-Dimethylcyclopropanes
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The photochemical decompositions of trans- and cis-1,2-dimethylcyclopropanes were investigated at 147.0 and 123.6 nm with standard rare gas resonance lamps.The observed products in the scavenged photolysis system were hydrogen, propylene, acetylene, ethylene, 1,3-butadiene, trans- or cis-2-butenes, pentadienes, allene, methylacetylene, and 1,2-butadiene, listed in decreasing importance.Quantum yields for each of the products were determined in experiments performed in both the presence and the absence of additives.Nitric oxide and oxygen were employed as radical scavengers, whereas hydrogen sulfide and hydrogen iodide were used as radical interceptors.Four radical species were identified and quantified, including methyl, vinyl, allyl, and a mixed C4H7 system.In both systems, ten primary processes have been proposed and the quantum efficiencies assigned for each primary reaction channel.The quantum efficiency for the methylene elimination channel ranged between 0.07 to 0.10 for both systems at both wavelengths. trans-1,2-Dimethylcyclopropane led exclusively to the trans-2-butene, whereas the cis- produced only the cis-2-butene.
- Pendleton, Tanis S.,Kaplan, Michael,Doepker, Richard D.
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- Generation and Reaction of Vinyl Groups on a Cu(100) Surface
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The adsorption and reactions of vinyl bromide and vinyl iodide on a Cu(100) surface have been studied by temperature-programmed desorption in conjunction with near-edge X-ray absorption fine structure (NEXAFS) and work function change measurements.Vinyl bromide adsorbs molecularly on the surface at 100 K.The polarization dependence of the ?*C=C resonance indicates that the molecules lie with their ? bond within 28 +/- 5 deg of parallel to the surface.Upon heating, both vinyl bromide and vinyl iodide decompose to generate surface vinyl groups, which adopt a tilted orientation on the surface.Both the molecular halides and the surface vinyl groups show a splitting of the ?*C=C NEXAFS resonance due to the inequivalence of the carbon atoms in these species.The position of the ?*C-C shape resonances for these species indicates little change (0.05 Angstroem) in C=C bond length due to adsorption and dissociation to form vinyl groups.Chemical displacement studies show that the C-Br bond cleavage in vinyl bromide occurs at 160 K.This dissociation temperature is confirmed by complementary NEXAFS and work function change measurement results.At 250 K, vinyl groups couple to yield 1,3-butadiene with 100percent selectivity.
- Yang, Michael X.,Eng, Joseph,Kash, Phillip W.,Flynn, George W.,Bent, Brian E.,et al.
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- Improving 1,3-butadiene yield by Cs promotion in ethanol conversion
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Gas phase conversion of ethanol into butadiene was studied over silica-supported ZnO, ZrO2 and ZnO-ZrO2 catalysts in a fixed-bed reactor. Surface active sites were characterised using a variety of techniques including temperature-programmed desorption (TPD) of NH3 and CO2 as well as Fourier transform infrared (FTIR) spectroscopy of adsorbed pyridine. An increased concentration of acid and base sites was found in the following order: ZnO?2?2. In addition, new acid and base sites were generated when alkaline metal promoters were introduced. Typical reaction products for all catalysts include acetaldehyde, butadiene, ethylene, propylene, butenes, diethyl ether and C4 oxygenates. Compared to single oxide supported catalysts, a remarkable acid-base synergetic effect was observed on the binary oxides supported catalysts with or without alkali metal modification. The improved catalytic activity and selectivity can be attributed to the right balance between acid and base sites, minimising dehydration to ethylene while promoting dehydrogenation to acetaldehyde. Furthermore, the existence of acid-base pairs with the appropriate configuration and strength promotes the aldol condensation and Meerwein-Ponndorf-Verley (MPV) reduction efficiently.
- Patil, Pratap T.,Liu, Dapeng,Liu, Yan,Chang, Jie,Borgna, Armando
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- ISOMERIZATION OF BUTYNES TO 1,3-BUTADIENE OVER SOLID BASE CATALYSTS
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1-Butyne and 2-butyne underwent isomerization to 1,3-butadiene over CaO, SrO, MgO, La2O3, ThO2 and ZrO2 catalysts below 100 deg C.Among these catalysts, the CaO catalyst exhibited the highest activity, and was active even at 30 deg C.
- Sato, Kenji,Hattori, Hideshi
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- Rates of Reactions of Cyclopropane, Cyclobutane, Cyclopentene, and Cyclohexene in the Presence of Boron Trichloride
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Cyclopropane (CP), cyclobutane, cyclopentene, and cyclohexene were heated, with added BCl3, in a static reactor to 628-748 K.The latter three were also heated with BCl3 to 939-1435 K in a single-pulse shock tube; a shock tube study of CP with BCl3 was reported earlier.In the static reactor CP isomerization to propene was greatly accelerated by BCl3 as previously reported, but none of the other reactants appeared to be affected by the catalyst.In the shock tube the BCl3 also appeared to have no effect on the primary decomposition reactions studied, but some changes in rates of side product formation were noted.Mechanistic implications of the high degree of specificity, shown by BCl3 toward reactions of cyclic hydrocarbons, are offered.
- Lewis, D. K.,Bergmann, J.,Manjoney, R.,Paddock, R.,Kalra, B. L.
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- Detection of Steady State Multiplicity during Dimethyl Ether Conversion Catalyzed by ZnO/γ-Al2O3 Composite: Effect of Coke and Hydrogen Peroxide
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Abstract: The heterogeneous catalytic conversion of dimethyl ether (DME) to 1,3-butadiene and butylenes in the presence of a ZnO/γ-Al2O3 catalyst in a wide range of temperatures, feed space velocities, and reactant concentrations has been studied. It has been found that temperature regions of 380–420 and 440–480°C, which are conventionally designated as low-temperature and high-temperature regions, differ in the laws governing the occurrence of the process associated with the specificity of coking of the catalyst surface and a redistribution of the surface concentration of Br?nsted and Lewis acid sites. A hypothesis of a change of the catalytic process mechanism upon the transition of the reaction into the high-temperature region has been put forward and confirmed by the occurrence of a hysteresis detected in this temperature range. The effect of hydrogen peroxide on the hysteresis parameters and the steady state stability during DME conversion has been shown.
- Maksimov, A. L.,Talyshinskii, R. M.,Tret’yakov, V. F.
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- Kinetic Features and Lattice-oxygen Participation in Propene Oxidation over Bi-Mo Oxide and some Mo Oxide Catalysts
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The rates of propene conversion in the absence of oxygen have been compared with those in the presence of oxygen at the same propene pressures.Over Bi-Mo oxides which are mainly composed of the β- or γ-phase, the rates for propenal formation were 3.5-4.5 times bigger in the presence of oxygen than in the absence of oxygen.In contrast, some Mo-containing oxide catalysts such as MoO3, Co-Mo(1/1), Co-Te-Mo (1/1/1) and other Bi-Mo oxides exhibit little or no difference in the rates of propenal formation in the presence or absence of oxygen.In the case of but-1-ene and (E)-but-2-ene oxidation, both rates were nearly the same even on β- and γ-phase Bi-Mo oxides.Such a sensitive effect of oxygenon propenal formation formatin over β- and γ-phase oxides seems to originate from an appreciable increase of active sites owing to a reoxidation step.Using 18O tracer studies in propene oxidation, the extents of lattice-oxygen participation were determined over various Mo oxide catalysts.The number of active sites for propene oxidation was found to be closely related to the extent of lattice-oxygen participation.A modified redox mechanism was proposed on the basis of a different active site model for the reduction and reoxidation steps.The kinetic features were discussed using this model.
- Ono, Takehiko,Nakajo, Takahiko,Hironaka, Tatsuo
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- Pronounced Catalytic Activity and Selectivity of MgO-SiO2-Na2O for Synthesis of Buta-1,3-diene from Ethanol
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MgO-SiO2 (molar ratio = 1:1) prepared from ethyl orthosilicate and magnesium nitrate and promoted with 0.1 wtpercent Na2O exhibited a high catalytic activity (100percent) and selectivity (87percent) for formation of buta-1,3-diene at 350 deg C.
- Ohnishi, Ryuichiro,Akimoto, Takao,Tanabe, Kozo
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- Bimetallic Zn and Hf on silica catalysts for the conversion of ethanol to 1,3-butadiene
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Silica-supported catalysts for the conversion of ethanol to 1,3-butadiene were investigated. The combination of Hf(IV) and Zn(II) resulted in a stable, active, and selective catalyst in which the Zn(II) effectively suppressed the dehydration activity of Hf(IV); the catalyst preparation method plays a crucial role. Using the crystalline Zn-silicate hemimorphite as an alternative Zn(II) source proved to be even more successful in suppressing ethanol dehydration.
- De Baerdemaeker, Trees,Feyen, Mathias,Müller, Ulrich,Yilmaz, Bilge,Xiao, Feng-Shou,Zhang, Weiping,Yokoi, Toshiyuki,Bao, Xinhe,Gies, Hermann,De Vos, Dirk E.
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- Kinetics of Pyrolysis of Furan
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The kinetics of pyrolysis of furan vapour diluted in argon have been studied behind reflected shock waves in a shock tube both by time-resolved infrared CO2 laser absorption spectrometry and by single pulse shock techniques of product analysis over the temperature range 1100-1700 K, at pressures of ca. 20 atm and at uniform residence times of ca. 300 μs.The rate of overall disappearance of furan, as measured by absorption spectrometry, was found to be first order in furan concentration, with a rate constant of koverall = 1015.3+/-0.3 exp-1/RT>s-1 in agreement with a previous determination by Lifshitz et al. (A.Lifshitz, M.Bidani and S.Bidani, J.Phys.Chem., 1986, 90, 5373).Principal products were carbon monoxide, C3H4 (propyne and allene) and acetylene.Ketene was identified in the products by FTIR spectroscopy.A detailed chemical reaction model for the pyrolysis was developed and shown to give good predictions of the concentration profiles of furan and the major products.Modelling and thermochemical considerations led to the postulate that the initiation of pyrolysis takes place by C-O bond scission to a biradical which can undergo decomposition, via parallel reaction paths, to the observed products.
- Organ, Phillip P.,Mackie, John C.
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- Effect of Preparation Method and CuO Promotion in the Conversion of Ethanol into 1,3-Butadiene over SiO2–MgO Catalysts
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Silica–magnesia (Si/Mg=1:1) catalysts were studied in the one-pot conversion of ethanol to butadiene. The catalyst synthesis method was found to greatly influence morphology and performance, with materials prepared through wet-kneading performing best both in terms of ethanol conversion and butadiene yield. Detailed characterization of the catalysts synthesized through co-precipitation or wet-kneading allowed correlation of activity and selectivity with morphology, textural properties, crystallinity, and acidity/basicity. The higher yields achieved with the wet-kneaded catalysts were attributed to a morphology consisting of SiO2spheres embedded in a thin layer of MgO. The particle size of the SiO2catalysts also influenced performance, with catalysts with smaller SiO2spheres showing higher activity. Temperature-programmed desorption (TPD) measurements showed that best butadiene yields were obtained with SiO2–MgO catalysts characterized by an intermediate amount of acidic and basic sites. A Hammett indicator study showed the catalysts’ pKavalue to be inversely correlated with the amount of dehydration by-products formed. Butadiene yields could be further improved by the addition of 1 wt % of CuO as promoter to give butadiene yields and selectivities as high as 40 % and 53 %, respectively. The copper promoter boosts the production of the acetaldehyde intermediate changing the rate-determining step of the process. TEM-energy-dispersive X-ray (EDX) analyses showed CuO to be present on both the SiO2and MgO components. UV/Vis spectra of promoted catalysts in turn pointed at the presence of cluster-like CuO species, which are proposed to be responsible for the increased butadiene production.
- Angelici, Carlo,Velthoen, Marjolein E. Z.,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.
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- Stable Mono- and Dinuclear Organosilver Complexes
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A series of mononuclear and dinuclear complexes of silver(I), supported by an N-heterocyclic carbene and bound to sp3-, sp2-, and sp-hybridized carbanions, has been synthesized. Synthetic routes include transmetalation from organozinc, organomagnesium, and organosilicon reagents, as well as the deprotonation of a terminal alkyne. These complexes exhibit greater thermal stability than typical organosilver reagents, permitting spectroscopic and structural characterization. The carbanion-bridged disilver cations feature three-center, two-electron bonding with short Ag···Ag distances. A mononuclear vinylsilver complex releases organic homocoupling products upon thermal decomposition, while mononuclear alkylsilver complexes exhibit nucleophilic behavior, for example, inserting CO2 to form silver carboxylates.
- Tate, Brandon K.,Jordan, Abraham J.,Bacsa, John,Sadighi, Joseph P.
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- On the Mechanism of n-Butane Oxidation to Maleic Anhydride on VPO Catalysts. II. Study of the Evolution of the VPO Catalysts under n-Butane, Butadiene, and Furan Oxidation Conditions
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The evolution of the VOPO4 phases and of (VO)2P2O7 and the activated VPO catalyst has been studied by XRD, 31P MAS-NMR, laser Raman spectroscopy, and electron spin resonance after the oxidation of butane, butadiene, and furan.With the exception of δ VOPO4, which partly changes to αII VOPO4, almost no evolution of the bulk structure has been observed.It is concluded that the mechanism of butane oxidation on the VPO catalyst implies principally the participation of a limited number of superficial layers of the structure.Catalytic properties depend on the redox properties of a limited number of V5+ ensembles on the (VO)2P2O7 matrix.A proposal for the mechanism of n-butane oxidation which implies an alkoxide route is presented.
- Zhang-Lin, Y.,Forissier, M.,Vedrine, J. C.,Volta, J. C.
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- Surface Reactions of Oxygen Ions. 4. Oxidation of Alkenes by O3- on MgO
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Surface reactions between simple alkenes and O3- ions on MgO were observed at 25 deg C.Following the reaction of ethylene or propylene with O3-, CO2 and CH4 were detected as major products upon heating the sample.The reaction of cis-2-butene with O3- resulted in the formation of butadiene and oxygen-containing organic compounds, as well as CO2 and CH4.Thermal desorption patterns and infrared spectra of surface complexes suggest that carboxylate ions are intermediates in the formation of CO2 and CH4 and peroxy radicals are intermediates in the formation of oxygen-containing organic molecules.
- Takita, Yusaku,Iwamoto, Masakazu,Lunsford, Jack H.
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- Ethanol/acetaldehyde conversion into butadiene over sol-gel ZrO2-SiO2 catalysts doped with ZnO
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ZnO promoted ZrO2-SiO2 catalysts synthesized by a sol-gel method were investigated in the two-step ethanol transforming to 1,3-butadiene process. The influence of promoters and the preparation method of the catalysts on the catalytic performance were studied in detail and the reaction conditions were optimized. The as-prepared catalysts were characterized by BET, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Resonance (FT-IR), X-ray photoelectron spectroscopy (XPS), FT-IR spectroscopy of adsorbed pyridine (Py-IR) and temperature-programmed desorption of NH3 (NH3-TPD). ZnO added ZrO2-SiO2 catalysts show the best catalytic activity and the catalysts prepared by the hybrid sol-gel method were superior to those prepared by the sol-gel coupled with impregnation method. The addition of promoters in the ZrO2-SiO2 system decreased the total acidity and lowered the selectivity to dehydration products. The best performance with ethanol/acetaldehyde conversion of 40.7% and 1,3-butadiene selectivity of 83.3% was reached at 310 °C, ethanol/acetaldehyde mole ratio of 3.5 and WHSV of 1.4 h-1 using a 0.5 wt% ZnO doped ZrO2-SiO2 catalyst.
- Xu, Yuchao,Liu, Zongzhang,Han, Zheng,Zhang, Minhua
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- Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene over a Multicomponent Bismuth Molybdate Catalyst: Influence of C3–C4 Hydrocarbons
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Abstract: The influence of light hydrocarbons, such as n-butane, isobutane, propylene, cis- and trans-2-butenes, and isobutene on the oxidative dehydrogenation of 1-butene to 1,3-butadiene over BiMoKNiCoFePOx/SiO2catalyst has been studied using a gas flow reactor. The inhibition effect of the listed hydrocarbons on the target reaction increased in the order of n-butane ~ isobutane propylene 2-butenes isobutene. In addition, in contrast to 1-butene, isobutene has shown significant contribution to coke formation. It was suggested, that the coke formation and therefore the rate of the catalyst regeneration exercise a significant influence on the efficiency of 1-butene transformation into 1,3-butadiene in the concurrent presence of other hydrocarbons. Graphical Abstract: [Figure not available: see fulltext.]
- Sobolev, Vladimir I.,Koltunov, Konstantin Yu.,Zenkovets, Galina A.
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- Improving the synthesis of Zn-Ta-TUD-1 for the Lebedev process using the Design of Experiments methodology
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The synthesis method of a zinc-tantalum catalyst supported on three-dimensional mesoporous silica with high specific surface area was studied. Its activity in the conversion of ethanol to butadiene was optimized using the Design of Experiment approach. A Plackett-Burman screening design identified the important preparation parameters, notably the ratio of Zn to Ta. It was subsequently optimized using the Response Surface Methodology, affording a highly active catalyst.
- Pomalaza, Guillaume,Capron, Micka?l,Dumeignil, Franck
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- Shock tube measurements of the rate constant for the reaction cyclohexene → ethylene + 1,3-butadiene
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The rate constant for the reaction cyclohexene → ethylene + 1,3-butadiene was determined by monitoring the formation of ethylene during the pyrolysis of cyclohexene behind reflected shock waves. Ethylene mole-fraction time-histories were measured using direct laser absorption at 10.532 μm. Experiments were performed between 950-1300 K and 0.8-3.7 atm. Measurements do not indicate any pressure dependence at these conditions. The data are best-fit by an Arrhenius expression k [s-1] = 4.84 × 1014 exp (-31 900 [K]/T) with uncertainties of ±19-36%, depending on the temperature. This appears to be the most accurate determination to date of the rate constant for cyclohexene decomposition.
- Stranic, Ivo,Davidson, David F.,Hanson, Ronald K.
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- Oxidative dehydrogenation of n-butane on nano-carbon catalysts having graphitic structures
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The catalytic activity of well-nanostructured carbon, for example glassy carbon spheres, SWCNT, graphene, and graphite, has been demonstrated in the oxidative dehydrogenation (ODH) of butane to obtain olefins. The catalytic performance of the carbon samples was stable, with prolonged reaction time. The proportion of butenes in the product decreased as the reaction temperature increased, whereas selectivity for ethene and propene increased with increasing temperature. Pd-containing carbon nanofibers (CNF) had superior selectivity for butadiene formation than Pd free CNF catalyst. Carbon with graphitic structures was highly selective for propylene and butenes without severe combustion in ODH of butane.
- Jang, Da Young,Jang, Hyung Gyu,Kim, Gye Ryung,Kim, Geon-Joong
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- Kinetics of the thermal isomerizations of gaseous vinylcyclopropane and vinylcyclobutane
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Rate constants for the thermal isomerizations of vinylcyclopropane to cyclopentene have been measured over a wide temperature range, 577-1054 K, in a static reactor and a single-pulse shock tube; they are well represented by log(A, s-1) = 14.3 and Ea = 51.7 kcal/mol. This activation energy is higher than two previously reported values by some 2 kcal/mol; rate constants at high temperatures are about a factor of 2 larger than calculated from the Arrhenius parameters derived from the earlier low-temperature data. The thermal decomposition and isomerization reactions of vinylcyclobutane to give ethene plus 1,3-butadiene and cyclohexene have also been followed in shock-tube kinetic studies at 839-965 K. Combining the new rate constants with those from two lower-temperature studies gives the following: for the total consumption of vinylcyclobutane, log(A, s-1) = 14.5 and Ea = 49.3 kcal/mol; for production of ethene and butadiene, log(A, s-1) = 14.5 and Ea = 49.8 kcal/mol; and for isomerization to cyclohexene, log(A, s-1) = 13.4 and Ea = 47.5 kcal/mol. These values are close to previously reported Arrhenius parameters based on lower temperature static-reactor kinetic investigations. The diradical transition structure for the vinylcyclobutane to cyclohexene isomerization appears to be strain free, while the transition structure for the vinylcyclopropane to cyclopentene conversion retains some 4.6 ± 0.9 kcal/mol of ring strain and torsional strain energy.
- Lewis, David K.,Charney, Donald J.,Kalra, Bansi L.,Plate, Ann-Marie,Woodard, M. Heather,Cianciosi, Steven J.,Baldwin, John E.
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- Kinetic study of the mechanism of the low-temperature pyrolysis of vinyl bromide
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The pyrolysis of vinyl bromide has been examined in the temperature range 637-733 K and at pressures from 6 to 86 kPa. The yields of the major hydrocarbon products, C2H2, C2H4, and 1,3-C4H6, are second order in vinyl bromide over the entire range of temperatures investigated. At the higher temperatures, initiation by molecular elimination of HBr dominates, while at lower temperatures a free radical initiation channel becomes increasingly important. Our data for the overall process leading to HBr fit the relation ln(k) = (30.7 ± 4.8) - ((26.6 ± 3.3) x 103)/T, with the rate constant in the units L mol-1 s-1, indicating an activation energy of 220 kJ mol-1 ± 12% for the HBr elimination. A simple Arrhenius extrapolation is close to previous results at temperatures from 800 to over 2000 K. The combination of our data and the earlier measurements of the HBr elimination is reasonably represented by ln(k) = 37 - (3 × 104)/T. Our data suggest that the free radical pathway is disproportionation rather than unimolecular cleavage of the C-Br bond, a situation analogous to that in the low-temperature thermal decomposition of ethylene. Kinetic analysis indicates that the activation energy of this new free radical initiation channel is approximately 150 kJ mol-1, much less than the C-Br bond energy.
- Laws,Hayley,Anthony,Roscoe
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- Single-Collision Gas-Surface Vibrational Energy Transfer in a Reacting System
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Gas-surface vibrational energy accomodation in a rective system has been studied under single-collision conditions.The reaction system is the isomerization of cyclobutene to 1,3-butadiene.Both seasoned pyrex and silica surfaces were used over the temperature ranges 400-775 and 500-975 K, respectively.Strong collider behavior was observed below ca. 425 K.The vibrational energy accomodation coefficient was found to decrease with rise of temperature from ca. 1.0 to 0.2, while the relative collisional efficiency β1 declined from ca. 1.0 to 0.008.A stochastic model was used to fit the data.
- Kelley, D. F.,Kasai, T.,Rabinovitch, B. S.
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- Dehydrogenation of 1-butene with CO2 over VOx supported catalysts
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Butadiene (BD) is an important intermediate in chemical industry and is obtained predominantly from fossil sources. In the future new and sustainable BD sources and synthesis routes might be required to meet the rising demands for this compound. Here, the synthesis of BD from 1-butene in the presence of CO2 was studied using supported vanadium oxide as active compound. Among the tested supports SBA-15 was shown to be the most effective one and a maximum BD yield of 39 % could be achieved. The VOx/SBA-15 catalysts were characterized by complementary methods to obtain insight about the effect of catalyst synthesis and vanadium loadings on the formation of VOx surface structures as well as the catalytic performance. CO2 has a positive impact on the reaction. Coking was considered to be the main reason for the catalyst deactivation and the decreasing BD yield with increasing time on stream.
- Bartling, S.,Eckelt, R.,Iffl?nder, K.,Kreyenschulte, C.,Lund, H.,Steinfeldt, N.,Wotzka, A.
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- Laser-Induced Reactions of Hexafluorobenzene and Selected Hydride Compounds
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Infrared-laser-induced reactions between C6F6 and general hydrides R-H (R = H, D, CH3, HCC, H2C=CH, and Cl) were studied by irradiating C6F6 at 1027 cm-1 in C6F6/R-H mixtures.In general, two competitive pathways involving C-F bond cleavage in C6F6 were observed as follows: (1) C6F6 + R-H C6F5H + R-F and (2) C6F6 + R-H C6F5R + HF.C6F6 decomposition also took place to a minor extent depending on the mole fraction of C6F6 and gave rise to C2F4 and C2H2.From infrared and GC/MS analysis of the product mixtures after 20-200 pulses, C6F5H was observed in all reactions except that involving D2.When D2 was used C6F5D was the major product.C6F5H was the major product in the reactions involving H2 and C2H2.In the reaction with C2H4, C6F5H was the major product derived from C6F6 though C2H2 was the major product of the reaction.The large amount of C2H2 seems to be derived from an additional sensitized decomposition of C2H4.C6F5H was present in minor amounts in the reaction with CH4 and HCl.Besides C6F5H, other monosubstituted products derived from C6F6 were also formed, generally within 20-100 pulses.Thus, C6F5CH3, C6F5CH=CH2, C6F5CCH, and C6F5Cl were produced, respectively, in the reaction of C6F6 with CH4, C2H4, C2H2, and HCl.In the first and last cases these products were the major ones observed.The results are discussed mechanistically in terms of the initial formation of the C6F5. radical and synthetically in terms of the utility of obtaining selective-laser-induced reduction of C6F6.
- Koga, Yoshinori,Chen, Ruth,Keehn, Philip M.
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- Insight in the relationship between magnetism of stoichiometric spinel ferrites and their catalytic activity
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In this work, spinel ferrites were chosen as prototype systems for oxidative dehydrogenation of 1-butene to address the long-standing issue that whether there is a correlation between catalytic and magnetic properties of magnetic catalysts. Under zero magnetic field, the conversion was the largest for NiFe2O4 (74.5 mol%) and the least for ZnFe2O4 (12.6 mol%), with no quantative relationship between magnetism and catalytic activity. In contrast, under a magnetic field of 1603 Oe, the largest and least conversion values changed to 86.6 and 13.5 mol% for MgFe2O4 and ZnFe2O4, respectively, and these values exhibited an inverse Gauss relation with initial susceptibility.
- Chen, Kezheng,Liu, Chunting,Ma, Ji
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- Reaktive Arsen-Heterocyclen. II. 3-Arsolene als Arsiniden-Quelle
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Gas phase pyrolysis (500-600 deg C, 1 s) of 1-phenyl-3-arsolene, 1-phenyl-3-methyl-3-arsolene, and 1-phenyl-3,4-dimethyl-3-arsolene gives polymeric (PhAs)x and its corresponding diene.Upon increasing the temperature, further decomposition to elemental arsenic and a mixture of aromatic hydrocarbons can be observed.If the pyrolysis is carried out with a large excess of butadiene or dimethylbutadiene, significant amounts of phenylarsinidene transfer products are formed.
- Schenk, Wolfdieter A.,Stubbe, Michael
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- Recurring Chains Following Addition of Atomic Hydrogen to Acetylene
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The C2H3 radical was prepared by attachment of H atoms to C2H2.Complex chain reactions ensue: C2H3 + H2 -> C2H4 + H; C2H3 + C2H2 -> C4H5; C4H5 + H2 -> C4H6 (1,3-butadiene) + H; C4H5 + C2H2 -> C6H6 + H (cis addition); C4H5 + C2H2 -> C6H7 (trans addition); C6H7 + H2 -> C6H8 (trans-1,3,5-hexatriene) + H; C6H7 + C2H2 -> C8H9 (leading to higher members).Relative coefficients are derived from product ratios, and the system has been closely matched with a model scheme.The products of the mutual termination reaction of two C2H3 radicals have been investigated.
- Callear, Anthony B.,Smith, Geoffrey Benedict
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- Dehydration of 2,3-butanediol over zeolite catalysts
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2,3-Butanediol as a product of biomass processing is a cheap alternative raw material for synthesis of methyl ethyl ketone (MEK) and butadiene-1,3. The catalytic activity of Al- and Zr-containing BEA zeolites and an alumina-based catalyst in 2,3-butanediol dehydration has been investigated. It has been shown that the presence of Br?nsted (H-BEA) or Lewis (Al2O3) sites leads to the selective formation of MEK and the combination of two types of sites (Zr-BEA) facilitates the formation of heavy products of condensation.
- Nikitina,Sushkevich,Ivanova
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- Morphological control of inverted MgO-SiO2 composite catalysts for efficient conversion of ethanol to 1,3-butadiene
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In this work, three novel MgO-SiO2 composite catalysts with inverted structure have been synthesized via a facile and scalable strategy by means of the incipient wetness impregnation of the silica sol onto MgO precursors with different morphologies, and evaluated for the one-step conversion of ethanol to 1,3-butadiene. The prepared flower-like MgO-SiO2 composite catalysts exhibited highly enhanced catalytic activity than those catalysts synthesized from MgO precursors with nanodisks and nanosheets morphologies. Characterization results based on XRD, FT-IR, UV–vis, BET, CO2-TPD, NH3-TPD, ethanol-TPD, and 29Si MAS NMR revealed that unique layered flower-like architectures may facilitate the formation of interfacial Mg-O-Si chemical bond in binary MgO-SiO2 composite catalysts which are mainly responsible for the superior activity. This study presents a new strategy to design and develop the catalyst for efficient conversion of bio-ethanol to 1,3-butadiene by morphological control of MgO-SiO2 bifunctional catalysts.
- Li, Shenxiao,Men, Yong,Wang, Jinguo,Liu, Shuang,Wang, Xuefei,Ji, Fei,Chai, Shanshan,Song, Qiaoling
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- Influence of zirconium phosphate on the properties of (VO)2P2O7 catalysts for the selective oxidation of n-butane to maleic anhydride
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The effect of zirconium phosphate on the catalytic, textural and structural properties of (VO)2P2O7 catalysts has been studied. Catalysts with different P/V and Zr/V ratios were prepared using different preparation methods and characterized by thermoanalytical and texture measurements, X-ray diffraction (XRD), potentiometric titration, FTIR, X-ray absorption [X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS)] and laser Raman spectroscopy. The n-butane conversion and the maxima of maleic anhydride (MA) yield shift to lower reaction temperatures on modification of (VO)2P2O7 with zirconium phosphate. There is no correlation between catalytic and textural properties of the modified catalysts. The zirconium phosphate modification causes a partial amorphization of the (VO)2P2O7 catalysts and leads to an enhancement of the VOPO4 microdomains (α1-, β-VOPO4 and amorphous VOPO4).
- Zeyss, Sabine,Wendt, Gerhard,Hallmeier, Karl-Heinz,Szargan, Ruediger,Lippold, Gerd
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- Decomposition of 4,4-Dimethylpent-1-ene in the Presence of Oxygen between 400 and 500 deg C: Oxidation Chemistry of Allyl Radicals
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The decomposition of 4,4-dimethylpent-1-ene (DMP) in the presence of O2 has been used as a source of allyl radicals over the temperature range 400-500 deg C.The reaction has been studied in both KCl-coated (peroxy species destroyed at the surface) and aged boric-acid-coated vessels (peroxy species preserved), and the basic mechanism shown to be: (1) (2).Previous studies have shown that 99percent of the t-butyl radicals undergo reaction (2), so that the system is an excellent source of allyl and HO2 radicals.A full product analysis has carried out over a wide range of mixture composition and associated mechanistic aspects discussed.It is shown that allyl radicals are unreactive towards both DMP and O2 and that they react mainly in radical-radical processes. (3) (8) (18).Values of k8/k18 = 0.37, 0.38 and 0.42 are obtained at 400, 440 and 480 deg C, respectively.From a reasonably reliable estimate of and , values of k8 = (3.3 +/- 0.9) * 1E9 and k18 = (7.4 +/- 2.4) * 1E9 dm3 mol-1 s-1 are obtained at 480 deg C.No previous estimates of these rate constants are available in the literature.Values of k4 have been determined and when combined with independent data at higher temperatures give log(A4/s-1) = 14.19 +/- 0.25 and E4 = 255.5 +/- 5.3 kJ mol-1 over the range 400-1025 deg C.DMP -> (CH3)2C=CH2 + CH3CH=CH2 (4).A value of K11 = (2.5 +/- 1) * 1E2 dm3 mol-1 s-1 has been obtained at 480 deg C and shown to be consistent with the reaction's high endothermicity. (11)
- Lodhi, Zulfiqar H.,Walker, Raymond W.
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- Impact of composition and structural parameters on the catalytic activity of MFI type titanosilicalites
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Titanosilicalite of the MFI type was obtained via a hydrothermal method. Its initial and annealed at 75 °C (TS-1P(75)) and 500 °C (TS-1P(500)) forms were studied by X-ray powder diffraction (PXRD), X-ray absorption spectroscopy (XAS-method), Fourier-transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), temperature-programmed ammonia desorption (TPD NH3), and pyridine adsorption (Py). The full-profile Rietveld method allowed us to observe the presence of the organic template tetrapropylammonium hydroxide (TPAOH) in the framework voids, as well as to determine the silicate module (Si/Ti = 73.5) and the distribution of Ti4+ ions over the MFI-type structure sites (Ti atoms replace Si ones in two positions: T1 and T6). The coordination numbers of titanium (CNTi = 4.6 for TS-1P and TS-1P(75), CNTi = 3.8 for TS-1P(500)) were established by the XAS-method. The catalytic activity of titanosilicalites was found in the reactions of nitrous oxide decomposition (the maximal decomposition rate is demonstrated for the TS-1P(75) sample), allyl chloride epoxidation to epichlorohydrin (the best combination of all indicators was exhibited for the TS-1P sample) and propane conversion (maximum propane conversion, and butadiene and propylene selectivity were observed in both TS-1P(75) and TS-1P(500) samples). Mechanisms for the catalytic processes are proposed. The relationship between the catalytic properties and the composition (Si/Ti), Ti4+ ion distribution over the MFI-type structure sites, the local environment of titanium ions, and the number of acid sites in the titanosilicalites are discussed.
- Bruk, Lev,Chernyshev, Vladimir,Khramov, Evgeny,Kravchenko, Galina,Kustov, Aleksander,Kustov, Leonid,Kuz'Micheva, Galina,Markova, Ekaterina,Pastukhova, Zhanna,Pirutko, Larisa
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p. 3439 - 3451
(2022/03/14)
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- Oxidative dehydrogenation of n-butene to buta-1,3-diene with novel iron oxide-based catalyst: Effect of iron oxide crystalline structure
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We investigate the effect of the crystalline structure of iron oxide catalysts on oxidative dehydrogenation (ODH) of n-butene. ODH reactions of n-butene were carried out with a fixed-bed flow reactor at 450 °C under a but-1-ene (1-C4H8) or cis-but-2-ene (cis-2-C4H8)(mL/min)/O2(mL/min) flow ratio of 5/2.5. Of the various iron oxide-based catalysts (α-, β-, γ-, ε-Fe2O3, Fe3O4, ZnFe2O4), ε-Fe2O3 showed the highest ODH activity. To the best of our knowledge, ε-Fe2O3 has never been used for the ODH of n-butene. Moreover, the catalytic performance of ε-Fe2O3 was improved by adding SiO2, which is related to the maintenance of its structure and improves its redox property. A high BD selectivity of 65 % and BD yield of 18 % were then obtained for 4 h without deactivation. This catalyst can be applied to the ODH of cis-2-C4H8 and is proposed as the noble high catalytic performance catalyst for the ODH of n-butene.
- Kiyokawa, Takayasu,Ikenaga, Naoki
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- CATALYTIC CONVERSION OF ETHANOL TO 1-/2-BUTENES
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Simple and economical conversion of aqueous ethanol feed streams into butenes by a single step method using transition metal oxides on a silica supports under preselected processing conditions. By directly producing a C4-rich olefin mixture from an ethanol containing stream various advantages are presented including, but not limited to, significant cost reduction in capital expenses and operational expenses.
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Paragraph 0013-0022; 0026-0046
(2021/06/11)
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- METHOD FOR PRERARING BUTADIENE
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The present invention relates to a method for producing butadiene, comprising butenes, steam and oxygen (O). 2 The method according to S10, wherein the mixed gas stream comprising the inert diluent gas and inert diluent 1 gas is fed to the first reactor (step S). The catalyst of claim 1, wherein the mixed gas stream is passed through a catalytic bed containing MoBi or more selected from the group consisting of a ferritic and 1-series metal oxide catalyst in the first reactor. S20. The reaction product stream is fed into the reactor 2. The 2-series metal oxide catalyst in a MnCe-th reactor passes through a catalyst layer, and includes a step (S30) of removing the oxygen compound contained in the reaction product stream, wherein the operating temperature of the first reactor 1 150 is 250, and the operating temperature of the first reactor 550 °C is 350 °C 2.
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Paragraph 0088-0131
(2021/10/17)
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- Chemoenzymatic Buta-1,3-diene Synthesis from Syngas Using Biological Decarboxylative Claisen Condensation and Zeolite-Based Dehydration
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A method for producing buta-1,3-diene (1,3-BD) by an amalgamation of chemical and biological approaches with syngas as the carbon source is proposed. Syngas is converted to the central intermediate, acetyl-CoA, by microorganisms through a tetrahydrofolate metabolism pathway. Acetyl-CoA is subsequently converted to malonyl-CoA using a carbonyl donor in the presence of a carboxylase enzyme. A decarboxylative Claisen condensation of malonyl-CoA and acetaldehyde ensues in the presence of acyltransferases to form 3-hydroxybutyryl-CoA, which is subsequently reduced by aldehyde reductase to give butane-1,3-diol (1,3-BDO). An ensuing dehydration step converts 1,3-BDO to 1,3-BD in the presence of a chemical dehydrating reagent.
- Balasubramaniam, Sivaraman,Badle, Sneh,Badgujar, Swati,Veetil, Vinod P.,Rangaswamy, Vidhya
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p. 705 - 711
(2020/12/01)
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- Selective production of 1,3-butadiene from 1,3-butanediol over Y2Zr2O7 catalyst
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The vapor-phase dehydration of 1,3-butanediol (1,3-BDO) to produce 1,3-butadiene (BD) was evaluated over yttrium zirconate, which was prepared through a hydrothermal aging process. 1,3-BDO was initially dehydrated to three unsaturated alcohols, namely 3-buten-2-ol, 3-buten-1-ol, and 2-buten-1-ol, followed by the further dehydration to BD. The catalytic activity of yttrium zirconate was greatly dependent on the calcination temperature. Also, the reaction temperature was one of the important factors to produce BD efficiently. The selectivity to BD was increased with increasing reaction temperature up to 375°C, while coke formation resulted in catalyst deactivation together with by-product formation at higher temperatures. Yttrium zirconate catalyst calcined at 900°C showed a high BD yield of 95% at 375°C and 10 hr on stream.
- Matsuda, Asami,Matsumura, Yoshitaka,Sato, Satoshi,Yamada, Yasuhiro
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p. 1651 - 1658
(2021/07/21)
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- SUPPORTED TANTALUM CATALYST FOR THE PRODUCTION OF 1,3-BUTADIENE
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The invention relates to a process for the production of 1,3-butadiene from a feed comprising ethanol and acetaldehyde in the presence of a supported tantalum catalyst obtainable by aqueous impregnation of the support with a water-soluble tantalum precursor. Furthermore, the present invention relates to a process for the production of a supported tantalum catalyst, and the supported tantalum catalyst. Finally, the invention relates to the use of the supported tantalum catalyst for the production of 1,3-butadiene from a feed comprising ethanol and acetaldehyde to increase one or both of selectivity and yield of the reaction.
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Page/Page column 14-17
(2021/04/03)
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- Understanding Ta as an Efficient Promoter of MgO–SiO2 Catalyst for Conversion of the Ethanol–Acetaldehyde Mixture into 1,3-Butadiene
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In this work, Ta was firstly reported as an efficient promoter of MgO–SiO2 for the conversion of ethanol and acetaldehyde to 1,3-butadiene. The doping of Ta into MgO–SiO2 forms Ta–O–Si bonds and generates more strong Lewis acid sites, which not only promote the aldol condensation reaction but also significantly facilitate the Meerwein–Ponndorf–Verley reduction, the total conversion around 80% which drops to 65% after 24?h. In addition, the catalyst showed desirable stability in 24?h long-term stability evaluation, the selectivity remained stable at 80%. Graphic Abstract: [Figure not available: see fulltext.]
- Gao, Qiang,Jiang, Angjiong,Jiang, Haoxi,Yang, Guochao,wang, Lingtao
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- Effect of Steam–Air Treatment of Alumina–Chromia Dehydrogenation Catalysts on Their Physicochemical and Catalytic Characteristics
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The effect of calcined alumina–chromia catalyst containing 13 wt.% Cr with additions of Na+ and Zr4+ in an air–water vapor atmosphere (from 0 to 80 vol % water vapor) at 750°С and a pressure of 1 bar on the physicochemical properties of the catalyst and its activity in n-butane dehydrogenation was evaluated. The steam treatment led to a slight decrease in the specific surface area (by up to 10%), partial decomposition of Cr(VI) compounds (up to 60%), and Cr2O3 crystallization. The catalytic activity decreased with an increase in the water vapor:air ratio. Low water vapor concentration (10 vol %) favored a remarkable decrease in the amount of the coke formed (by 60%) without considerably affecting alkene yield. Thus, the introduction of water vapor into the calcination atmosphere allowed control of the Cr(VI) amount and catalyst selectivity.
- Nazimov,Klimov,Saiko,Noskov
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p. 1283 - 1291
(2021/12/29)
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- CATALYTIC HYDROCARBON DEHYDROGENATION
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A catalyst for dehydrogenation of hydrocarbons includes a support including zirconium oxide and Linde type L zeolite (L-zeolite). A concentration of the zirconium oxide in the catalyst is in a range of from 0.1 weight percent (wt. %) to 20 wt. %. The catalyst includes from 5 wt. % to 15 wt. % of an alkali metal or alkaline earth metal. The catalyst includes from 0.1 wt. % to 10 wt. % of tin. The catalyst includes from 0.1 wt. % to 8 wt. % of a platinum group metal. The alkali metal or alkaline earth metal, tin, and platinum group metal are disposed on the support.
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Paragraph 0059; 0060; 0124; 0125
(2021/03/13)
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- Pt/TS-1 catalysts: Effect of the platinum loading method on the dehydrogenation of n-butane
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A series of catalysts in which platinum was supported on the crystalline pure titanium silicalite (TS-1) were prepared using two different loading methods, namely, an ethylene glycol (EG) reduction method and the conventional incipient wetness impregnation (IM) technique. Various characterization techniques were used to study the effect of the loading method on the physicochemical and morphological properties of the prepared catalysts. Also the effect of the platinum-loading method on the dehydrogenation of n-butane was investigated in a fixed-bed reactor. The results show that the EG method favors the formation of a more-concentrated Pt dispersion, which results in much better catalytic activities for the selective formation of butenes and butadiene (> 97 %). This phenomenon is interpreted by carrying out density functional theory (DFT) calculations with focus on the relationship between the coverage of n-butane on Pt surface and the activation barrier for the first C[sbnd]H bond cleavage.
- Shao, Mingyuan,Hu, Chaoquan,Xu, Xuebing,Song, Yang,Zhu, Qingshan
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- Selective Butene Formation in Direct Ethanol-to-C3+-Olefin Valorization over Zn-Y/Beta and Single-Atom Alloy Composite Catalysts Using in Situ-Generated Hydrogen
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The selective production of C3+olefins from renewable feedstocks, especially via C1and C2platform chemicals, is a critical challenge for obtaining economically viable low-carbon middle-distillate transportation fuels (i.e., jet and diesel). Here, we report a multifunctional catalyst system composed of Zn-Y/Beta and “single-atom” alloy (SAA) Pt-Cu/Al2O3, which selectively catalyzes ethanol-to-olefin (C3+, ETO) valorization in the absence of cofed hydrogen, forming butenes as the primary olefin products. Beta zeolites containing predominately isolated Zn and Y metal sites catalyze ethanol upgrading steps (588 K, 3.1 kPa ethanol, ambient pressure) regardless of cofed hydrogen partial pressure (0-98.3 kPa H2), forming butadiene as the primary product (60% selectivity at an 87% conversion). The Zn-Y/Beta catalyst possesses site-isolated Zn and Y Lewis acid sites (at ~7 wt % Y) and Br?nsted acidic Y sites, the latter of which have been previously uncharacterized. A secondary bed of SAA Pt-Cu/Al2O3selectively hydrogenates butadiene to butene isomers at a consistent reaction temperature using hydrogen generatedin situfrom ethanol to butadiene (ETB) conversion. This unique hydrogenation reactivity at near-stoichiometric hydrogen and butadiene partial pressures is not observed over monometallic Pt or Cu catalysts, highlighting these operating conditions as a critical SAA catalyst application area for conjugated diene selective hydrogenation at high reaction temperatures (>573 K) and low H2/diene ratios (e.g., 1:1). Single-bed steady-state selective hydrogenation rates, associated apparent hydrogen and butadiene reaction orders, and density functional theory (DFT) calculations of the Horiuti-Polanyi reaction mechanisms indicate that the unique butadiene selective hydrogenation reactivity over SAA Pt-Cu/Al2O3reflects lower hydrogen scission barriers relative to monometallic Cu surfaces and limited butene binding energies relative to monometallic Pt surfaces. DFT calculations further indicate the preferential desorption of butene isomers over SAA Pt-Cu(111) and Cu(111) surfaces, while Pt(111) surfaces favor subsequent butene hydrogenation reactions to form butane over butene desorption events. Under operating conditions without hydrogen cofeeding, this combination of Zn-Y/Beta and SAA Pt-Cu catalysts can selectively form butenes (65% butenes, 78% C3+selectivity at 94% conversion) and avoid butane formation using onlyin situ-generated hydrogen, avoiding costly hydrogen cofeeding requirements that hinder many renewable energy processes.
- Allard, Lawrence F.,Assary, Rajeev S.,Cordon, Michael J.,Krause, Theodore R.,Kropf, A. Jeremy,Li, Zhenglong,Lin, Fan,Liu, Dongxia,Miller, Jeffrey T.,Purdy, Stephen C.,Unocic, Kinga A.,Wang, Huamin,Wegener, Evan C.,Yang, Ce,Zhang, Junyan,Zhou, Mingxia
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p. 7193 - 7209
(2021/06/30)
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- Zeolitic catalytic conversion of alcohols to olefins
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A catalyst composition for converting an alcohol to olefins, the catalyst composition comprising the following components: (a) beta zeolite; (b) at least one element selected from the group consisting of zinc, magnesium, calcium, strontium, sodium, and potassium; and (c) at least one element selected from the group consisting of hafnium, yttrium, zirconium, tantalum, niobium, and tin; wherein the components (b) and (c) are independently within or on a surface of said beta zeolite. The catalyst may also further include component (d), which is copper or silver. Also described herein is a method for converting an alcohol to one or more olefinic compounds, the method comprising contacting the alcohol with a catalyst at a temperature of at least 100° C. and up to 500° C. to result in the alcohol being converted to the one or more olefinic compounds.
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Page/Page column 11; 12
(2021/07/08)
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- Nickel-catalyzed reductive 1,3-diene formation from the cross-coupling of vinyl bromides
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Facile construction of 1,3-dienes building upon cross-electrophile coupling of two open-chain vinyl halides is disclosed in this work, showing moderate chemoselectivities between the terminal bromoalkenes and internal vinyl bromides. The present method is mild and tolerates a range of functional groups and can be applied to the total synthesis of a tobacco fragrance solanone.
- Sha, Yunfei,Liu, Jiandong,Wang, Liang,Liang, Demin,Wu, Da,Gong, Hegui
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supporting information
p. 4887 - 4890
(2021/06/16)
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- Vapor-phase dehydration of 1,4-butanediol to 1,3-butadiene over Y2Zr2O7 catalyst
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Vapor-phase catalytic dehydration of 1,4-butanediol (1,4-BDO) was investigated over Y2O3-ZrO2 catalysts. In the dehydration, 1,3-butadiene (BD) together with 3-buten-1-ol (3B1OL), tetrahydrofuran, and propylene was produced depending on the reaction conditions. In the dehydration over Y2O3-ZrO2 catalysts with different Y contents at 325°C, Y2Zr2O7 with an equimolar ratio of Y/Zr showed high selectivity to 3B1OL, an intermediate to BD. In the dehydration at 360°C, a BD yield higher than 90% was achieved over the Y2Zr2O7 calcined at 700°C throughout 10 h. In the dehydration of 3B1OL over Y2Zr2O7, however, the catalytic activity affected by the calcination temperature is roughly proportional to the specific surface area of the sample. The highest activity of Y2Zr2O7 calcined at 700 °C for the BD formation from 1,4-BDO is explained by the trade-off relation in the activities for the first-step dehydration of 1,4-BDO to 3B1OL and for the second-step dehydration of 3B1OL to BD. The higher reactivity of 3B1OL than saturated alcohols such as 1-butanol and 2-butanol suggests that the C=C double bond of 3B1OL induces an attractive interaction to anchor the catalyst surface and promotes the dehydration. A probable mechanism for the one-step dehydration of 1,4-BDO to BD was discussed.
- Matsuda, Asami,Matsumura, Yoshitaka,Sato, Satoshi,Yamada, Yasuhiro
-
-
- Synthesis of Butadiene from Formaldehyde and Propylene on Cesium Salts of Silicotungstic Heteropoly Acid
-
Abstract: A one-stage gas-phase synthesis of butadiene from formaldehyde and propylene on silica-supported cesium salts of silicotungstic heteropoly acid was realized for the first time. The physicochemical properties of the catalysts were studied by X-ray fluorescence analysis, low-temperature nitrogen adsorption, XRD, SEM, Raman spectroscopy, and NH3–TPD. The coke deposits were studied by the TGA–DTA method. Analysis of the catalytic properties showed that an increase in the concentration of cesium atoms in CsxH4–xSiW12O40/SiO2 (x = 0–3) has a beneficial effect on the endurance of the catalyst but is accompanied by a decrease in activity and butadiene selectivity. In the case of CsH3SiW12O40/SiO2, the butadiene selectivity was 51 mol %. [Figure not available: see fulltext.]
- Dobryakova, I. V.,Ivanova, I. I.,Kasyanov, I. A.,Matveeva, О. D.,Nikiforov, A. I.,Ponomareva, О.А.,Shkuropatov, A. V.
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p. 916 - 924
(2021/08/16)
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- Direct Evidence on the Mechanism of Methane Conversion under Non-oxidative Conditions over Iron-modified Silica: The Role of Propargyl Radicals Unveiled
-
Radical-mediated gas-phase reactions play an important role in the conversion of methane under non-oxidative conditions into olefins and aromatics over iron-modified silica catalysts. Herein, we use operando photoelectron photoion coincidence spectroscopy to disentangle the elusive C2+ radical intermediates participating in the complex gas-phase reaction network. Our experiments pinpoint different C2-C5 radical species that allow for a stepwise growth of the hydrocarbon chains. Propargyl radicals (H2C?C≡C?H) are identified as essential precursors for the formation of aromatics, which then contribute to the formation of heavier hydrocarbon products via hydrogen abstraction–acetylene addition routes (HACA mechanism). These results provide comprehensive mechanistic insights that are relevant for the development of methane valorization processes.
- ?ot, Petr,Hemberger, Patrick,Pan, Zeyou,Paunovi?, Vladimir,Puente-Urbina, Allen,van Bokhoven, Jeroen Anton
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supporting information
p. 24002 - 24007
(2021/10/01)
-
- DEPOLYMERIZATION OF OLIGOMERS AND POLYMERS COMPRISING CYCLOBUTANE UNITS
-
Methods of polymer and/or oligomer depolymerization are described herein which, in some embodiments, enable facile polymer and/or oligomer decomposition under mild, non-energy intensive conditions. Briefly, a method of depolymerization comprises providing a reaction mixture comprising a transition metal catalyst, and a polymer or oligomer having a backbone including cyclobutane units, and decomposing the polymer or oligomer to provide diene monomer or alkene monomer.
- -
-
Paragraph 0033; 0034
(2021/08/06)
-
- SINGLE-STAGE METHOD OF BUTADIENE PRODUCTION
-
The invention relates to a gas-phase synthesis of butadiene from ethanol or from a mixture of ethanol and acetaldehyde. The method of production includes conversion of ethanol or a mixture of ethanol with acetaldehyde in the presence of a catalyst, wherein the reaction is carried out in the presence of a solid catalyst with a mesoporous Zr-containing zeolite having a BEA type structure and at least one metal in a zero oxidation state selected from the group: silver, copper and gold. The claimed method is suitable for carrying out the reaction under continuous flow conditions in the reactor with a fixed bed of catalyst. The invention makes possible to achieve a high yield of butadiene with high selectivity to butadiene and high stability of the catalyst.
- -
-
Paragraph 0039-0042
(2020/11/24)
-
- Catalyst for reaction for preparing 1,3-butadiene from ethanol, preparation and applications thereof
-
The invention relates to a catalyst for a reaction for preparing 1,3-butadiene from ethanol, a preparation method and applications thereof. The catalyst is an MFI type molecular sieve, which has a nanosheet layer structure, contains two transition metals X and Y and an alkaline earth metal Z, and is formed by cross growth of nanosheet layers, wherein the thickness of the nanosheet layer is 2-50 nm, the metal component X of the catalyst is one or more than two selected from transition metal elements Zn, Ni, Fe, Cu and Ag, the component Y of the catalyst is one or more than two selected from acidic or alkaline metals Zr, Y, Hf, La, Ce, Sn and Ta, and the metal elements are loaded on a molecular sieve carrier in a post-treatment manner. The invention provides a catalyst for preparing 1,3-butadiene by stably and efficiently catalyzing ethanol conversion, a preparation method and applications thereof, wherein the catalyst has obvious industrial application value in a process for preparing butadiene from ethanol.
- -
-
Paragraph 0040-0095
(2020/06/17)
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- METHOD FOR PREPARING 1,3-BUTADIENE
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One embodiment of the present application provides a method for preparing 1,3-butadiene, the method comprising the steps of: introducing a reactant containing butene and oxygen into a first reactor and performing an oxidative dehydrogenation process in the first reactor; and introducing oxygen and a first product formed through the first reactor into a second reactor connected in series with the first reactor, wherein the first product formed through the first reactor includes 1,3-butadiene, a light component, and a heavy component, and removing the heavy component from the second reactor.(AA) O2 inputCOPYRIGHT KIPO 2020
- -
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Paragraph 0069; 0072-0075
(2020/05/15)
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- N,N,O-Coordinated tricarbonylrhenium precatalysts for the aerobic deoxydehydration of diols and polyols
-
Rhenium complexes are well known catalysts for the deoxydehydration (DODH) of vicinal diols (glycols). In this work, we report on the DODH of diols and biomass-derived polyols using L4Re(CO)3as precatalyst (L4Re(CO)3= tricarbonylrhenium 2,4-di-tert-butyl-6-(((2-(dimethylamino)ethyl)(methyl)amino)methyl)phenolate). The DODH reaction was optimized using 2 mol% of L4Re(CO)3as precatalyst and 3-octanol as both reductant and solvent under aerobic conditions, generating the active high-valent rhenium speciesin situ. Both diol and biomass-based polyol substrates could be applied in this system to form the corresponding olefins with moderate to high yield. Typical features of this aerobic DODH system include a low tendency for the isomerization of aliphatic external olefin products to internal olefins, a high butadiene selectivity in the DODH of erythritol, the preferential formation of 2-vinylfuran from sugar substrates, and an overall low precatalyst loading. Several of these features indicate the formation of an active species that is different from the species formed in DODH by rhenium-trioxo catalysts. Overall, the bench-top stable and synthetically easily accessible, low-valent NNO-rhenium complex L4Re(CO)3represents an interesting alternative to high-valent rhenium catalysts in DODH chemistry.
- Klein Gebbink, Robertus J. M.,Li, Jing,Lutz, Martin
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p. 3782 - 3788
(2020/06/22)
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- Highly active and durable WO3/Al2O3catalysts for gas-phase dehydration of polyols
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Gas-phase glycerol dehydration over WO3/Al2O3catalysts was investigated. WO3loading on γ-Al2O3significantly affected the yield of acrolein and the catalyst with 20 wt% WO3loading showed the highest activity. The WO3/Al2O3catalyst with 20 wt% WO3loading showed higher activity and durability than the other supported WO3catalysts and zeolites. The number of Br?nsted acid sites and mesopores of the WO3/Al2O3catalyst did not decrease after the reaction, suggesting that glycerol has continuous access to Br?nsted acid sites inside the mesopores of WO3/Al2O3, thereby sustaining a high rate of formation of acrolein. Dehydration under O2flow further increased the durability of the WO3/Al2O3catalyst, enabling the sustainable formation of acrolein. In addition, the WO3/Al2O3catalyst with 20 wt% WO3loading showed high activity for the dehydration of various polyols to afford the corresponding products in high yield.
- Aihara, Takeshi,Asazuma, Katsuya,Miura, Hiroki,Shishido, Tetsuya
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p. 37538 - 37544
(2020/10/19)
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- Ethanol Conversion to Butadiene over Isolated Zinc and Yttrium Sites Grafted onto Dealuminated Beta Zeolite
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Zinc and Yttrium single sites were introduced into the silanol nests of dealuminated BEA zeolite to produce Zn-DeAlBEA and Y-DeAlBEA. These materials were then investigated for the conversion of ethanol to 1,3-butadiene. Zn-DeAlBEA was found to be highly active for ethanol dehydrogenation to acetaldehyde and exhibited low activity for 1,3-butadiene generation. By contrast, Y-DeAlBEA was highly active for 1,3-butadiene formation but exhibited no activity for ethanol dehydrogenation. The formation of 1,3-butadine over Y-DeAlBEA and Zn-DeAlBEA does not occur via aldol condensation of acetaldehyde but, rather, by concerted reaction of coadsorbed acetaldehyde and ethanol. The active centers for this process are Si-O-Y(OH)-O-Si or Si-O-Zn-O-Si-O groups closely associated with adjacent silanol groups. The active sites in Y-DeAlBEA are 70 times more active than the Y sites supported on silica, for which the Y site is similar to that in Y-SiO2 but which lacks adjacent hydroxyl groups, and are 7 times more active than the active sites in Zn-DeAlBEA. We propose that C-C bond coupling in Y-DeAlBEA proceeds via the reaction of coadsorbed acetaldehyde and ethanol to form crotyl alcohol and water. The dehydration of crotyl alcohol to 1,3-butadiene is facile and occurs over the mildly Br?nsted acidic Si-OH groups present in the silanol nest of DeAlBEA. The catalysts reported here are notably more active than those previously reported for both the direct conversion of ethanol to 1,3-butadiene or the formation of this product by the reaction of ethanol and acetaldehyde.
- Qi, Liang,Zhang, Yanfei,Conrad, Matthew A.,Russell, Christopher K.,Miller, Jeffrey,Bell, Alexis T.
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supporting information
p. 14674 - 14687
(2020/10/13)
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- Oxidative dehydrogenation of n-butane to butadiene catalyzed by new mesoporous mixed oxides NiO-(beta-Bi2O3)-Bi2SiO5/SBA-15 system
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NiO-beta-Bi2O3-Bi2SiO5/SBA-15 catalysts, containing 10?20 wt% Ni and 10?30 wt% Bi loaded as metal weight on mesoporous SiO2 support (SBA-15), were utilized for the oxidative dehydrogenation of n-butane to butadiene, comparing from the viewpoint of Bi oxide phase and combination balance with Ni oxide and the support. Bi2SiO5 and beta-Bi2O3 phases change depending on Ni/Bi ratio. “Reverse core-shell” structure with uniform mesoporosity catalytically active for the oxidative dehydrogenation of n-butane to butadiene was successfully synthesized with semi-dry conversion method. The shell was formed as Bi2SiO5/SBA-15 by partially dissolving an array of silanol inside SBA-15 mesopores with impregnated bismuth nitrate. The Bi2SiO5 of the shell was increased by co-impregnated nickel nitrate. The layered core faced to mesopore was formed as catalytically active NiO/beta-Bi2O3 on the shell. The degrees of formation Bi2SiO5 and beta-Bi2O3 reflected in the butadiene selectivity through changing the reducibility and dispersion properties. The catalyst with moderate loading of 20 wt% Ni and 10 wt% Bi exhibited a high advantage in the n-butane conversion: 30 % and butadiene selectivity: 49 % at 450 °C compared to the less and excess loaded catalysts. The catalytic performance of other mesoporous silica support catalysts also changed differently depending on Bi2SiO5 and beta-Bi2O3 phases.
- Aitani, A. M.,Alasiri, H.,Asaoka, S.,Tanimu, G.
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- MESOPOROUS SILICA SUPPORTED CATALYST FOR OXIDATIVE DEHYDROGENATION
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Oxidative dehydrogenation catalysts comprising bismuth and nickel oxides impregnated on mesoporous silica supports such as SBA-15 and mesoporous silica foam. Methods of preparing and characterizing the catalysts as well as processes for oxidatively dehydrogenating n-butane to butadiene using the catalysts are also described. The disclosed catalysts demonstrate higher n-butane conversion and butadiene selectivity than catalysts supported by conventional silica.
- -
-
Paragraph 0035; 0052; 0122-0127
(2020/07/07)
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- Synthesis of 1,3-Butadiene from 1-Butanol on a Porous Ceramic [Fe,Cr]/γ-Al2O3(K,Ce)/α-Al2O3 Catalytic Converter
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Abstract: —A two-stage method was developed for the synthesis of 1,3-butadiene by dehydration of 1-butanol to a mixture of butenes on γ-Al2O3 granules prepared by self-propagating high-temperature synthesis (SHS) followed by dehydrogenation of the butene fraction to 1,3-butadiene using a porous ceramic catalytic SHS converter [Fe,Cr]/γ-Al2O3(K,Ce)/α-Al2O3. The dehydration of 1-butanol to the butene mixture proceeded almost completely at ~100percent selectivity on γ-Al2O3 granules obtained by SHS at 300°C, which is 50 degrees lower than on industrial gamma-alumina granules. The use of an original hybrid catalytic membrane reactor (HCMR) with selective removal of hydrogen from the reaction zone led to a ~1.3-fold increase in the yield of 1,3-butadiene at ultrapure hydrogen extraction of up to 16 mol percent of the total amount of the hydrogen product. The catalytic activity of the system did not decrease after 20 h of experiment, in contrast to its activity in the industrial process, where catalyst regeneration is performed every 8–15 min.
- Dumeignil, F.,Fedotov, A. S.,Heyte, S.,Marinova, M.,Moiseev, I. I.,Paul, S.,Simon, P.,Tsodikov, M. V.,Uvarov, V. I.
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p. 390 - 404
(2020/07/03)
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- The influence of zinc loadings on the selectivity control of bio-ethanol transformation over MgO-SiO2 catalysts
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Catalytic transformation of ethanol has been studied over a series of MgO-SiO2 composite catalysts with different ZnO loadings. Vast differences in product selectivity are obtained by varying ZnO loadings in enabling the control over product distribution. Our results reveal that MgO-SiO2 composite catalysts with low ZnO loadings tend to show an enhanced efficiency for C[sbnd]C bond coupling and exceptionally high selectivity to 1,3-butadiene whereas the high ZnO loadings favor the formation of acetaldehyde via dehydrogenation. Thorough analysis of characterization results via XRD, BET, IR, TPD, and 29Si MAS NMR indicates that ZnO loading influences the extent of MgO and SiO2 interaction during preparation, and the surface acid-base chemistry, which were both found to correlate with the catalytic performance. This study proposes that the Mg[sbnd]O[sbnd]Si interfacial structure formed by the strong MgO and SiO2 interaction at low ZnO loadings is of prime importance for the formation of 1,3-butadiene, benefiting from the desirable properties of balanced dehydrogenation and C[sbnd]C bond coupling while excess ZnO loadings destroy the Mg[sbnd]O[sbnd]Si interfacial bonds over the MgO-SiO2 composite catalysts, which are the key structures required for C[sbnd]C bond growth.
- Liu, Shuang,Men, Yong,Song, Qiaoling,Wang, Jinguo,Wang, Xuefei,Yang, Mei
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-
- Properties and activity of Zn-Ta-TUD-1 in the Lebedev process
-
A zinc and tantalum-containing mesoporous silica catalyst highly active and selective in the Lebedev process has been prepared using the one-pot TUD-1 methodology. Selectivity towards butadiene reached 60-70%, making Zn-Ta-TUD-1 one of the best performing catalysts in the literature. To rationalize these results and establish a structure-activity relationship, a series of similar catalysts was prepared and characterized. Nitrogen physisorption, XPS, ICP-AES, XRD, TEM, UV-vis spectroscopy, TGA NH3-TPD, H2-TPR and FT-IR techniques were used. The most active samples were found to possess a large specific surface area and highly dispersed metal oxide phase incorporated within the mesoporous silica matrix. In combination with catalytic testing, characterization also showed a direct correlation between the number of Lewis acid sites and butadiene yield, confirming the structure-activity relationship theory prevalent for the Lebedev process. Deactivation of Zn-Ta-TUD-1 was also studied using the same techniques to characterize the properties of spent catalysts. It was found that the accumulation of heavy carbonaceous species caused a reduction of specific surface area and pore size coinciding with the observed loss in activity. Nevertheless, the pores of TUD-1 were large enough to avoid total pore blockage and a high selectivity could be maintained for 72 hours.
- Pomalaza, Guillaume,Simon, Pardis,Addad, Ahmed,Capron, Micka?l,Dumeignil, Franck
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supporting information
p. 2558 - 2574
(2020/05/13)
-
- CATALYST, DEVICE FOR MANUFACTURING CONJUGATED DIENE, AND METHOD FOR MANUFACTURING CONJUGATED DIENE
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A catalyst for synthesizing a conjugated diene from a raw material including an alcohol, which includes at least Ce and Zn as metal elements constituting the catalyst. An apparatus for producing a conjugated diene, including: a reaction tube (1) provided with the catalyst; a supply means for supplying a raw material gas containing the raw material into the reaction tube (1); and an outlet means for releasing a product from the reaction tube (1). A method for producing a conjugated diene, including contacting a raw material gas containing a raw material with the catalyst to obtain a conjugated diene. The amount of the raw material is preferably 10 to 50% by volume (in terms of gas volume) with respect to 100% by volume (in terms of gas volume) of the raw material gas.
- -
-
Paragraph 0119-0120
(2020/07/14)
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- MgO?SiO2 Catalysts for the Ethanol to Butadiene Reaction: The Effect of Lewis Acid Promoters
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MgO?SiO2 samples, having the composition of natural talc (NT), were obtained by co-precipitation (CP) and wet kneading (WK) methods. The materials were used as catalysts of the ethanol-to-1,3-butadiene reaction. ZnO, Ga2O3 and In2O3 were tested as promoters. The catalyst WK gave the highest 1,3-Butadiene (BD) yield among the non-promoted catalysts because of the high specific surface area and strong basicity. Results suggested that over the neat WK catalyst the acetaldehyde coupling to crotonaldehyde was the rate-determining process step. Formation of crotyl alcohol intermediate was substantiated to proceed by the hydrogen transfer reaction between crotonaldehyde and ethanol. The crotyl alcohol intermediate becomes dehydrated to BD or, in a disproportionation side reaction, it forms crotonaldehyde and butanol. The promoter was found to increase the surface concentration of the reactant and reaction intermediates, thereby increases the rates of conversion and BD formation. The order of promoting efficiency was Zn>In>Ga.
- Szabó, Blanka,Novodárszki, Gyula,Pászti, Zoltán,Domján, Attila,Valyon, József,Hancsók, Jen?,Barthos, Róbert
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p. 5686 - 5696
(2020/09/22)
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- Conversion of ethanol to 1,3-butadiene over high-performance Mg-ZrO: X/MFI nanosheet catalysts via the two-step method
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Mg-Zr/MFI nanosheet (NS) catalysts were prepared by a wet impregnation method for ethanol conversion to 1,3-butadiene (1,3-BD) via the two-step method in a dual fixed bed reaction system. Compared with Zr catalysts loaded on MFI(micro) or commercial SiO2, 16%Zr/MFI(NS) gave the better performance, with 42.3% 1,3-BD selectivity and 60.5% total conversion of ethanol and acetaldehyde. Introducing 1.2 wt% Mg to 16%Zr/MFI(NS) improved the 1,3-BD selectivity to 54.7% at the expense of a 6% drop in the catalytic activity. Reaction conditions imposed remarkable influence on the reaction results. When the reaction was conducted at 350 °C, a WHSV of 1.44 h-1 and a 2 : 1 ratio of ethanol to acetaldehyde, the 1,3-BD selectivity reached 74.6% with 41.5% total conversion. Such high performance over 1.2%Mg-16%Zr/MFI(NS) was maintained well in a 7 day (168 h) run without deactivation. The catalysts were characterized by XRD, N2 adsorption, UV-Vis, Raman, and infra-red spectroscopy, NH3-TPD, TEM and TG. The results showed that the Zr species on MFI(NS) are well distributed with the highest dispersion as compared with the microporous MFI and SiO2 supported Zr catalysts. The Zr species preferentially occupied the silanol nests of MFI(NS) and eliminated the Br?nsted acid sites at 4 wt% Zr loading, and afforded abundant Lewis acid sites in the form of Zr(OH)(OSi)3 when the Zr loading was increased to 16 wt%. As a base site, Mg is inactive for MPVO reduction but slightly active for the aldol condensation of acetaldehyde, both of which are much inferior to that of the Lewis acid sites. The 1.2%Mg-16%Zr/MFI(NS) catalyst with hierarchical structures of meso- and micro-pores, abundant weak Lewis acid sites but nearly no Br?nsted acid sites is competent for the two-step ethanol to 1,3-BD conversion process with high activity, selectivity and stability.
- Li, Lin,Li, Xianquan,Pan, Xiaoli,Pang, Jifeng,Wang, Chan,Zhang, Tao,Zheng, Mingyuan
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p. 2852 - 2861
(2020/06/17)
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- METHOD AND CATALYST FOR THE PRODUCTION OF 1, 3-BUTADIENE FROM ETHANOL
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The present invention is concerned with a catalyst for the conversion of ethanol to 1,3-butadiene comprising a component A selected from the list consisting of zeolite, silicon dioxide, aluminium oxide, or any combination thereof; and a component Bcat comprising a mixed metal oxide, a catalyst precursor for the preparation of a catalyst for the conversion of ethanol to 1,3-butadiene comprising a component A selected from the list consisting of zeolite, silicon dioxide, aluminium oxide, or any combination thereof; and a component Bpre comprising a layered double hydroxide (LDH) as well as a process for the conversion of ethanol to 1,3-butadiene, in which said catalyst is used.
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Page/Page column 19; 20
(2020/08/28)
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- Conversion of ethanol to butadiene over mesoporous In2O3-promoted MgO-SiO2 catalysts
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Mesoporous MgO-SiO2 mixed oxide catalysts were prepared for the conversion of ethanol to 1,3-butadiene. Mesoporosity was obtained by using SBA-15 material as support for magnesia or by applying one-pot synthesis method wherein magnesia precurso
- Barthos, Róbert,Hancsók, Jen?,May, Zoltán,Novodárszki, Gyula,Szabó, Blanka,Valyon, József
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-
- Deoxygenation of Epoxides with Carbon Monoxide
-
The use of carbon monoxide as a direct reducing agent for the deoxygenation of terminal and internal epoxides to the respective olefins is presented. This reaction is homogeneously catalyzed by a carbonyl pincer-iridium(I) complex in combination with a Lewis acid co-catalyst to achieve a pre-activation of the epoxide substrate, as well as the elimination of CO2 from a γ-2-iridabutyrolactone intermediate. Especially terminal alkyl epoxides react smoothly and without significant isomerization to the internal olefins under CO atmosphere in benzene or toluene at 80–120 °C. Detailed investigations reveal a substrate-dependent change in the mechanism for the epoxide C?O bond activation between an oxidative addition under retention of the configuration and an SN2 reaction that leads to an inversion of the configuration.
- Maulbetsch, Theo,Jürgens, Eva,Kunz, Doris
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p. 10634 - 10640
(2020/07/30)
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- Intermetallic GaPd2 Thin Films for Selective Hydrogenation of Acetylene
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The preparation of single-phase and catalytically active GaPd2 coatings was accomplished via DC magnetron sputtering using an intermetallic sputter target. Thin and uniform layers were deposited on borosilicate glass, Si(111) and planar as well as micro-structured stainless steel foils. The specimens were examined regarding their phase composition, film morphology and microstructure. Thin films of different layer thickness were catalytically characterized in the semi-hydrogenation of acetylene, which was conducted at 473 K and a feed gas composition of 0.5 vol.percent C2H2, 5 vol.percent H2 as well as 50 vol.percent C2H4 in helium. Pre-reduction of the catalyst was found to be essential to enhance the catalytic selectivity. Sputtered GaPd2 showed a high selectivity of 73 percent for the hydrogenation to ethylene at conversion levels above 80 percent. The surface-specific activity was strongly increased to 8.97 molacetylene·(A0·h)–1 compared to bulk- or nanoscale GaPd2 (1.93 and 0.30 molacetylene·(A0·h)–1, respectively) caused by the high specific surface area of the thin films.
- Zimmermann, René R.,Siebert, Martin,Ibrahimkutty, Shyjumon,Dittmeyer, Roland,Armbrüster, Marc
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p. 1218 - 1226
(2020/06/09)
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- Single-reactor conversion of ethanol to 1-/2-butenes
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A simplified processes for producing desired chemicals such as butenes from feedstock mixtures containing ethanol. In one set of embodiments this is performed in a single step, wherein a feed containing ethanol in a gas phase is passed over an acidic metal oxide catalyst having a transition metal dispersion of at least 5% on a metal oxide support. The ethanol content of the feedstock mixture may vary from 10 to 100 percent of the feed and in those non-eat applications the ethanol feed may contain water.
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Page/Page column 9
(2020/06/03)
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- Borane-induced ring closure reaction of oligomethylene-linked bis-allenes
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The trimethylene-linked bis-allene 3a reacts with Piers' borane [HB(C6F5)2] by a hydroboration/allylboration sequence to generate the cyclization product 5a. Its pyridine adduct was isolated and characterized by X-ray diffraction. Compound 5a undergoes a typical frustrated Lewis pair 1,2-P/B alkene addition reaction with PPh3 to give the heterobicyclic bridged olefinic zwitterionic product 9a. The tetramethylene-linked bis-allene 3b and its phenylene annulated analogue 3c react with HB(C6F5)2 to give the analogous seven-membered ring products 5b,c under mild conditions. The cyclization product 5a undergoes a series of sequential allylboration reactions with two equivalents of allene followed by ring-closure to give the four-component coupling product 12a. It undergoes FLP addition to an exo-methylene group upon treatment with PPh3. Compound 12a is oxidatively converted to the boron-free alcohol.
- Tao, Xin,?koch, Karel,Daniliuc, Constantin G.,Kehr, Gerald,Erker, Gerhard
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p. 1542 - 1548
(2020/02/25)
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- New PtSn structured catalysts with ZnAl2O4 thin film for n-butane dehydrogenation reaction
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Starting from structured supports based on compact spheres coated with a thin and porous layer of ZnAl2O4, mono and bimetallic catalysts were prepared. These catalysts were applied for the n-butane dehydrogenation reaction to produce light olefins. The structured supports were synthesized by coating with: bohemite-nitrate purified method (BP) and citrate-nitrate method (C). From the characterization results, the existence of strong Pt-Sn interaction in both bimetallic catalysts with probable alloys formation was found. In the PtSn/Sp-Zn-C catalyst, where higher metallic Pt-Sn interactions were observed, most of its metallic particles have sizes between 1 and 1.5 nm, which indicates a good metallic dispersion. These properties led to a catalyst with the best catalytic behavior, thus showing high yields to butenes, and a very good stability. Moreover, the presence of a structured support improves the mass and heat transference in this reaction carried out at high temperature.
- de Miguel, Sergio,Ballarini, Adriana,Bocanegra, Sonia
-
-
- New ZnCe catalyst encapsulated in SBA-15 in the production of 1,3-butadiene from ethanol
-
ZnO-CeO2/SBA-15 catalysts were prepared by two kinds of solid-state grinding method and used for the production of 1,3-butadiene (1,3-BD) from ethanol. A mixture of SBA-15 (with or without organic template) and metal precursors were ground in solid-state. The obtained catalysts were characterized by TG, N2 adsorption-desorption, TEM, XRD, Py-FTIR and NH3-TPD techniques. Superior dispersion of metal oxides and more exposed acid sites were achieved on the catalyst 10Zn1Ce5-AS with the presence of organic template in SBA-15 during the solid-state grinding process. The catalytic performance was evaluated in a fixed-bed reactor and a 1,3-butadiene selectivity of as high as 45% is achieved. This is attributed to the coupling effect of Zn and Ce species in the mesopores of SBA-15, in which Zn promotes ethanol dehydrogenation and Ce enhances aldol-condensation, respectively. Additionally, solvent-free method inspires new catalyst synthesis strategy for the production of 1,3-butadiene from ethanol.
- Zhao, Yujun,Li, Sijia,Wang, Zheng,Wang, Shengnian,Wang, Shengping,Ma, Xinbin
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supporting information
p. 535 - 538
(2019/05/21)
-
- Olefin reaction in the catalyst and the olefin production
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PROBLEM TO BE SOLVED: To provide a catalyst for obtaining an olefin in high selectivity with a vicinal diol as a raw material.SOLUTION: A catalyst for olefination reaction for use in a reaction to produce an olefin by a reaction of a polyol, having two adjacent carbon atoms each having a hydroxy group, with hydrogen comprises: a carrier; at least one oxide selected from the group consisting of oxides of the group 6 elements and oxides of the group 7 elements supported on the carrier; and at least one metal selected from the group consisting of silver, iridium, and gold supported on the carrier.SELECTED DRAWING: None
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-
Paragraph 0145-0146; 0149
(2020/10/31)
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- METHODS OF PRODUCING 1,3-BUTADIENE FROM ETHYLENE AND SULFUR
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Methods, catalysts, and systems for the production of 1,3-butadiene from a reaction mixture including ethylene and gaseous sulfur are described.
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Paragraph 0058
(2019/03/05)
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- Catalysts for Selective Coupling of Olefins, and Methods of Making and Using Same
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The present invention relates in part to the unexpected discovery of novel complexes capable of catalyzing the selective dehydrogenative coupling of olefins. The invention further relates to the use of these complexes for the selective coupling of olefins.
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Paragraph 0160; 0166-0169
(2019/05/15)
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- A METHOD FOR MANUFACTURING 1,3-BUTADIENE USING A CATALYST ARTICLE COATED WITH METAL OXIDE
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An embodiment of the present invention provides a method for manufacturing 1,3-butadiene comprising steps of: (a) conducting an oxidative dehydrogenation of a mixture comprising n-butene, oxygen, nitrogen and steam in the presence of a catalyst molded article; and (b) purifying a product of the step (a) using an absorption solvent, wherein a ratio of the volume of oxygen to a total volume of oxygen and nitrogen in the step (a) is 20% or more. According to an aspect of the present invention it is possible to economically manufacture 1,3-butadiene in a high purity and a high yield.COPYRIGHT KIPO 2020
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Paragraph 0127-0130; 0137
(2020/01/02)
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- Production of 1,3-butadiene in one step catalytic dehydration of 2,3-butanediol
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Catalysts able to selectively dehydrate 2,3-butanediol into butadiene have been designed. These catalysts, based on rare-earth orthophosphates showed that 58% selectivity to butadiene could be obtained at total conversion at only 300 °C, and were relatively stable. While the deactivation could be delayed by addition of water to the gas feeds, it could not be avoided and a regeneration was necessary. This regeneration was achieved by a simple heat treatment under air for a few hours at 450 °C. All results showed that Lewis acid sites corresponding to the rare earth cations are involved in the dehydration of 2,3-butanediol into butadiene. This dehydration occurs with the intermediate formation of 3-buten-2ol, probably over acid-base concerted sites and the subsequent dehydration of 3BDOL to butadiene over weak Br?nsted acid sites. All types of sites appear present on the catalysts surface and distributed in a relatively optimal way.
- Nguyen,Matei-Rutkovska,Huchede,Jaillardon,Qingyi,Michel,Millet
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- CATALYST FOR OXIDATIVE DEHYDROGENATION AND METHOD OF PREPARING THE SAME
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The present invention relates to a catalyst for oxidative dehydrogenation and a method of preparing the same. More particularly, the present invention provides a catalyst for oxidative dehydrogenation allowing oxidative dehydrogenation reactivity to be secured while increasing a first pass yield, and a method of preparing the catalyst.
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Paragraph 0101-0107
(2019/07/04)
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