106-99-0Relevant articles and documents
The e- + 1,3-Butadiene 1,3-Butadiene- Equilibrium in n-Hexane
Holroyd, Richard A.,Schwarz, Harold A.,Stradowska, Elizabeth,Ninomiya, Shiro,Itoh, Kengo,Nishikawa, Masaru
, p. 7142 - 7146 (1994)
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.
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Williams,Hurd
, p. 122 (1940)
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Effect of CH2Br2-Addition upon Direct Oxidative Dehydrogenation of Butane into 1,3-Butadiene over Fe-Sb-O Composite Catalyst
Saitoh, Hitoshi,Satoh, Satoshi,Sodesawa, Toshiaki,Nozaki, Fumio
, p. 3649 - 3650 (1986)
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.
Tin-Assisted Fully Exposed Platinum Clusters Stabilized on Defect-Rich Graphene for Dehydrogenation Reaction
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
, p. 5998 - 6005 (2019)
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).
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
Pola, Josef,Urbanová, Markéta,Díaz, Luis,Santos, Magna,Bastl, Zdenek,?ubrt, Jan
, p. 202 - 208 (2000)
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.
ZnTa-TUD-1 as an easily prepared, highly efficient catalyst for the selective conversion of ethanol to 1,3-butadiene
Pomalaza,Vofo,Capron,Dumeignil
, p. 3203 - 3209 (2018)
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.
Generation and Reaction of Vinyl Groups on a Cu(100) Surface
Yang, Michael X.,Eng, Joseph,Kash, Phillip W.,Flynn, George W.,Bent, Brian E.,et al.
, p. 12431 - 12439 (1996)
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.
Improving 1,3-butadiene yield by Cs promotion in ethanol conversion
Patil, Pratap T.,Liu, Dapeng,Liu, Yan,Chang, Jie,Borgna, Armando
, p. 67 - 74 (2017)
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.
Rates of Reactions of Cyclopropane, Cyclobutane, Cyclopentene, and Cyclohexene in the Presence of Boron Trichloride
Lewis, D. K.,Bergmann, J.,Manjoney, R.,Paddock, R.,Kalra, B. L.
, p. 4112 - 4116 (1984)
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.
Comyns, A. E.,Lucas, H. J.
, p. 4341 - 4344 (1957)
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Sasaki et al.
, p. 605 (1976)
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Bimetallic Zn and Hf on silica catalysts for the conversion of ethanol to 1,3-butadiene
De Baerdemaeker, Trees,Feyen, Mathias,Müller, Ulrich,Yilmaz, Bilge,Xiao, Feng-Shou,Zhang, Weiping,Yokoi, Toshiyuki,Bao, Xinhe,Gies, Hermann,De Vos, Dirk E.
, p. 3393 - 3397 (2015)
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.
Effect of Preparation Method and CuO Promotion in the Conversion of Ethanol into 1,3-Butadiene over SiO2–MgO Catalysts
Angelici, Carlo,Velthoen, Marjolein E. Z.,Weckhuysen, Bert M.,Bruijnincx, Pieter C. A.
, p. 2505 - 2515 (2014)
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.
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
Zhang-Lin, Y.,Forissier, M.,Vedrine, J. C.,Volta, J. C.
, p. 267 - 275 (1994)
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.
Ethanol/acetaldehyde conversion into butadiene over sol-gel ZrO2-SiO2 catalysts doped with ZnO
Xu, Yuchao,Liu, Zongzhang,Han, Zheng,Zhang, Minhua
, p. 7140 - 7149 (2017)
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.
Improving the synthesis of Zn-Ta-TUD-1 for the Lebedev process using the Design of Experiments methodology
Pomalaza, Guillaume,Capron, Micka?l,Dumeignil, Franck
, (2020)
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.
Oxidative dehydrogenation of n-butane on nano-carbon catalysts having graphitic structures
Jang, Da Young,Jang, Hyung Gyu,Kim, Gye Ryung,Kim, Geon-Joong
, p. 1145 - 1156 (2011)
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.
Kinetic study of the mechanism of the low-temperature pyrolysis of vinyl bromide
Laws,Hayley,Anthony,Roscoe
, p. 1830 - 1837 (2001)
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.
Single-Collision Gas-Surface Vibrational Energy Transfer in a Reacting System
Kelley, D. F.,Kasai, T.,Rabinovitch, B. S.
, p. 1100 - 1103 (1981)
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.
Laser-Induced Reactions of Hexafluorobenzene and Selected Hydride Compounds
Koga, Yoshinori,Chen, Ruth,Keehn, Philip M.
, p. 306 - 311 (1987)
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.
Insight in the relationship between magnetism of stoichiometric spinel ferrites and their catalytic activity
Chen, Kezheng,Liu, Chunting,Ma, Ji
, (2020)
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.
Reaktive Arsen-Heterocyclen. II. 3-Arsolene als Arsiniden-Quelle
Schenk, Wolfdieter A.,Stubbe, Michael
, p. C4 - C6 (1993)
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.
Recurring Chains Following Addition of Atomic Hydrogen to Acetylene
Callear, Anthony B.,Smith, Geoffrey Benedict
, p. 3229 - 3237 (1986)
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.
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Hiraoka,Srinivasan
, p. 2720 (1968)
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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
Zeyss, Sabine,Wendt, Gerhard,Hallmeier, Karl-Heinz,Szargan, Ruediger,Lippold, Gerd
, p. 3273 - 3279 (1996)
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).
Impact of composition and structural parameters on the catalytic activity of MFI type titanosilicalites
Bruk, Lev,Chernyshev, Vladimir,Khramov, Evgeny,Kravchenko, Galina,Kustov, Aleksander,Kustov, Leonid,Kuz'Micheva, Galina,Markova, Ekaterina,Pastukhova, Zhanna,Pirutko, Larisa
, p. 3439 - 3451 (2022/03/14)
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.
Effect of Steam–Air Treatment of Alumina–Chromia Dehydrogenation Catalysts on Their Physicochemical and Catalytic Characteristics
Nazimov,Klimov,Saiko,Noskov
, p. 1283 - 1291 (2021/12/29)
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.
Understanding Ta as an Efficient Promoter of MgO–SiO2 Catalyst for Conversion of the Ethanol–Acetaldehyde Mixture into 1,3-Butadiene
Gao, Qiang,Jiang, Angjiong,Jiang, Haoxi,Yang, Guochao,wang, Lingtao
, (2021/10/27)
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.]
