107-01-7Relevant articles and documents
Opitz et al.
, p. C3 (1974)
Supramolecular origins of product selectivity for methanol-to-olefin catalysis on HSAPO-34
Song,Fu,Haw
, p. 4749 - 4754 (2001)
Ethylene selectivity in methanol-to-olefin (MTO) catalysis is related to the number of methyl groups on benzene rings trapped in the nanocages of the preferred catalyst HSAPO-34. By correlating the time evolutions of the catalysts' 13C NMR spectra and the volatile product distribution following abrupt cessation of methanol flow, we discovered that (in the absence of other adsorbates) propene is favored by methylbenzenes with four to six methyl groups but ethylene is predominant from those with two or three methyl groups. We substantially increased ethylene selectivity by operating at lower methanol partial pressures or higher temperatures, either of which reduces the steady-state average methyl substitution. As a step toward a kinetic analysis of the MTO reaction on HSAPO-34, we treated each nanocage with a methylbenzene molecule as a supramolecule capable of unimolecular dissociation into ethylene or propene and a less highly substituted methylbenzene. Addition of a water molecule to a nanocage containing a methylbenzene produces a distinct supramolecule with unique properties. Indeed, co-feeding water with methanol significantly increased the average number of methyl groups per ring at steady state relative to identical conditions without additional water, and also increased ethylene selectivity, apparently through transition state shape selectivity.
The Gas-Phase Elimination Kinetics of 2-Hydroxy-2-Methylbutyric Acid and 2-Ethyl-2-Hydroxybutyric Acid
Chuchani, Gabriel,Martin, Ignacio,Rotinov, Alexandra
, p. 849 - 854 (1995)
The elimination kinetics of the title compounds have been examined over the temperature range of 270 - 320 deg C and pressure range of 19 - 117 torr.The reactions, carried out in seasoned vessels, with the free-radical suppressor toluene always present, are homogeneous, unimolecular, and follow a first-order rate law.The products of 2-hydroxy-2-methylbutyric acid are 2-butanone, CO, and H2O; while of 2-ethyl-2-hydroxybutyric acid are 3-pentanone, CO, and H2O.The rate coeffcient is expressed by the following Arrhenius equation: for 2-hydroxy-2-methylbutyric acid, log k1(s-1) = (12.87 +/- 0.19) - (171.2 +/- 2.1) kJ mol-1 (2.303 RT)-1; and for 2-ethyl-2-hydroxybutyric acid, log k1(s-1) = (12.13 +/- 0.34) - (159.4 +/- 3.7) kJ mol-1 (2.303 RT)-1.Augmentation of alkyl bulkiness at the 2-position of the 2-hydroxycarboxylic acids showed an increase in the rate of dehydration.The electron release of alkyl groups, rather than steric acceleration, appears to enhance the pyrolysis decomposition of these substrates.These reactions are believed to proceed through a semi-polar five-membered cyclic transition type of mechanism.
Highly Selective MTO Reaction over a Nanosized ZSM-5 Zeolite Modified by Fe via the Low-Temperature Dielectric Barrier Discharge Plasma Method
Bai, Xuefeng,Bukina, Z. M.,Kolesnichenko, N. V.,Li, Yuzong,Maximov, A. L.,Su, Xiaofang,Wang, Wei,Wang, Yongchao,Wu, Wei
, p. 137 - 148 (2020)
Nanosized ZSM-5 zeolites were synthesized via in situ seed-induced hydrothermal method, and samples modified with an Fe promoter were prepared by the traditional wet impregnation-thermal decomposition and dielectric barrier discharge plasma (DBD) methods, respectively. The catalytic performance was studied by the methanol-to-olefin (MTO) reaction. The results showed that the acidity of the catalysts, the dispersity of the Fe promoter, and the interaction degree with the ZSM-5 zeolite are closely related to product selectivity in the MTO reaction. Compared with the Fe-NZ5 sample prepared by the traditional impregnation-calcination method, the FeD-NZ5 samples prepared by the DBD method demonstrated the higher selectivity of C2—C4 light olefins and the lower coke deposition during long-term evaluation (100 hr), which can be attributed to the weaker acid strength, more uniform Fe promoter dispersion, and strong interaction with the ZSM-5 zeolite.
Oxygen scrambling and stereochemistry during the trifluoroethanolysis of optically active 2-butyl 4-bromobenzenesulfonate
Dietze, Paul E.,Wojciechowski, Marek
, p. 5240 - 5244 (1990)
It is shown that during the trifluoroethanolysis of 2-butyl 4-bromobenzenesulfonate, containing 18O in the nonbridging oxygens, scrambling of the oxygen label occurs. When enantiomerically enriched 2-butyl 4-bromobenzenesulfonate is subjected to the same solvolysis conditions, racemization of the starting ester is not observed. Therefore if an ion-pair intermediate is involved in the trifluoroethanolysis reaction, the ion pair has a sufficient lifetime to permit rotation of the anion leading to oxygen scrambling. However, rotation of the cation, which would lead to racemization, does not occur. The possibility that the oxygen scrambling may be a concerted reaction and not involve an ion-pair intermediate is discussed.
Thermal Decomposition of Allylic Sulfinic Acids: Confirmation of a Retro-ene Mechanism
King, Malcolm D.,Sue, Rodney E.,White, Rodney H.,Young, David J.
, p. 1797 - 1798 (1993)
The acidolysis of trialkyltin allylic sulfinates yields the corresponding sulfinic acids which undergo a first-order thermal decomposition with γ-syn substitution as predicted for a retro-ene mechanism.
Olefin oligomerization via new and efficient Br?nsted acidic ionic liquid catalyst systems
Wang, Guoqin,Song, Heyuan,Li, Ruiyun,Li, Zhen,Chen, Jing
, p. 1110 - 1120 (2018)
Olefin oligomerization reaction catalyzed by new catalyst systems (a Br?nsted-acidic ionic liquid as the main catalyst and tricaprylylmethylammonium chloride as the co-catalyst) has been investigated. The synthesized Br?nsted acidic ionic liquids were characterized by Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV), 1H nuclear magnetic resonance (NMR), and 13C NMR to analyze their structures and acidities. The influence of different ionic liquids, ionic liquid loading, different co-catalysts, catalyst ratios (mole ratio of ionic liquid to co-catalyst), reaction time, pressure, temperature, solvent, source of reactants, and the recycling of catalyst systems was studied. Among the synthesized ionic liquids, 1-(4-sulfonic acid)butyl-3-hexylimidazolium hydrogen sulfate ([HIMBs]HSO4) exhibited the best catalytic activity under the tested reaction conditions. The conversion of isobutene and selectivity of trimers were 83.21% and 35.80%, respectively, at the optimum reaction conditions. Furthermore, the catalyst system can be easily separated and reused; a feasible reaction mechanism is proposed on the basis of the distribution of experimental products.
Fast and Selective Semihydrogenation of Alkynes by Palladium Nanoparticles Sandwiched in Metal–Organic Frameworks
Choe, Kwanghak,Li, Guodong,Qiu, Xueying,Ri, Myonghak,Shi, Xinghua,Tang, Zhiyong,Wang, Hui,Wang, Yinglong,Xue, Guangxin,Yuan, Yi,Zhao, Wenshi,Zheng, Fengbin
, p. 3650 - 3657 (2020)
The semihydrogenation of alkynes into alkenes rather than alkanes is of great importance in the chemical industry. Unfortunately, state-of-the-art heterogeneous catalysts hardly achieve high turnover frequencies (TOFs) simultaneously with almost full conversion, excellent selectivity, and good stability. Here, we used metal–organic frameworks (MOFs) containing Zr metal nodes (“UiO”) with tunable wettability and electron-withdrawing ability as activity accelerators for the semihydrogenation of alkynes catalyzed by sandwiched palladium nanoparticles (Pd NPs). Impressively, the porous hydrophobic UiO support not only leads to an enrichment of phenylacetylene around the Pd NPs but also renders the Pd surfaces more electron-deficient, which leads to a remarkable catalysis performance, including an exceptionally high TOF of 13835 h?1, 100 % phenylacetylene conversion 93.1 % selectivity towards styrene, and no activity decay after successive catalytic cycles. The strategy of using molecularly tailored supports is universal for boosting the selective semihydrogenation of various terminal and internal alkynes.
PROPERTIES OF MAGNESIUM OXIDES PREPARED FROM VARIOUS SALTS AND THEIR CATALYTIC ACTIVITY IN 1-BUTENE ISOMERIZATION.
Matsuda,Tanabe,Hayashi,Sasaki,Miura,Sugiyama
, p. 990 - 994 (1982)
The basicity, one-electron donor property, and surface area were examined on the magnesium oxide catalysts prepared from six different kinds of magnesium salts. Magnesium oxide prepared from magnesium nitrate, oxalate, and acetate exhibited strong basicity and relatively large surface area and, on the other hand, MgO prepared from magnesium chloride, carbonate and sulfate had relatively weak basicity and small surface area. Number of one-electron donor centers hardly changed in the variety of magnesium oxides, except the one prepared from magnesium chloride. Isomerization of 1-butene was carried out on the six kinds of catalysts at 30 degree C. The magnesium oxides prepared from nitrate, oxalate, and acetate salts (group A) exhibited isomerization activity and the ones from chloride, sulfate, and carbonate (group B) did not entirely.
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Hay,Coull,Emmett
, p. 2809 (1949)
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Evans,Braithwaite,Field
, p. 534 (1940)
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Davis
, p. 64 (1929)
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Pitts et al.
, p. 6370 (1957)
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The Isomerization of Cyclopropane over Reduced Molybdena-Alumina Catalysts
Oliveros,Perez Zurita,Scott,Goldwasser,Goldwasser,Rondon,Houalla,Hercules
, p. 485 - 489 (1997)
The isomerization and metathesis of cyclopropane were carried out over a series of reduced molybdena-alumina catalysts (1.7-13 wt%Mo). The distribution of Mo oxidation states was determined by XPS. The average Mo oxidation state estimated from XPS agreed with that obtained by measuring the O2 consumption on reoxidation for a given catalyst. A good correlation was found between the catalytic activity for the isomerization reaction and the relative intensity of the XPS peak attributed to paired double-bonded Mo (IV) species (as in MoO2). The results indicate a direct relationship between these Mo (IV) species and the coordinative unsaturated sites involved in the formation of metallocyclobutane. The latter is reportedly the intermediate required for the isomerization reaction to take place.
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Brinton,Volman
, p. 1394 (1951)
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Catalytic transformation of ethanol to methane and butene over NiO NPs supported over mesoporous SBA-15
Chatterjee, Sauvik,Bhaduri, Kushanava,Modak, Arindam,Selvaraj, Manickam,Bal, Rajaram,Chowdhury, Biswajit,Bhaumik, Asim
, (2021)
Hexagonally ordered mesoporous silica material SBA-15 with thick pore wall is an ideal catalytic support for immobilizing reactive tiny metal oxide nanoparticles (NPs) due to its large pore size, high specific surface area, excellent feasibility for the i
Appleby et al.
, p. 1809,1810 (1953)
Takagi et al.
, p. 838 (1972)
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Billheimer,Reid
, p. 4343 (1930)
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Activity of Supported Tungsten Oxide Catalysts for the Metathesis of Propene
Andreini, Amedeo,Mol, Johannes C.
, p. 1705 - 1714 (1985)
The activity of several supported tungsten oxide catalysts for the metathesis of propene has been studied under temperature-programmed conditions.WO3/TiO2 was found to be active at moderate temperatures; its activity passes through a maximum when the reaction temperature is decreased from 670 to 450 K.WO3/ZnO is less active and its activity as a function of the reaction temperature goes through a maximum under certain conditions.In contrast to these catalysts and to the earlier reported behaviour of the well known WO3/Al2O3 catalyst, the activity of the WO3/SiO2 catalyst steadily increases for reaction temperatures up to 860 K.In this respect the WO3/SiO2-Al2O3 catalyst behaves like the WO3/SiO2 catalyst and not like the WO3/Al2O3 catalyst.The acidity of the supports has been determined by means of a temperature-programmed desorption technique, using t-butylamine as the adsorbed species.The results of this work do not suggest a relationship between the acidity of the supports and the activity for metathesis.
Evans, W. J.,Engerer, S. C.,Neville, A. C.
, p. 331 - 333 (1978)
Preparation of low carbon olefins on a core-shell K-Fe5C2?ZSM-5 catalyst by Fischer-Tropsch synthesis
Liu, Yang,Liu, Yongjun,Shao, Wenli,Zhang, Chenyang,Zhang, Xueqin,Zheng, Yi,Zhou, Weixia
, p. 26451 - 26459 (2020)
In this study, a core-shell catalyst based on Fe5C2?ZSM-5 (ZSM-5 capped Fe5C2 as active phase) is prepared by the coating-carbonization method for Fischer-Tropsch synthesis (FTS). Further, the designed ZSM-5 zeolites are utilized to screen the low carbon hydrocarbons from the products generated on the iron carbide active centre, and for catalytic disassembly of the long-chain hydrocarbons into low carbon olefins. Prior to utilization, the physical-chemical properties of the prepared catalysts are systematically characterized by various techniques of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FT-IR), and scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) observations, in addition to the effects of coating-carbonization, molecular sieve coating amount, and K-doping on core-shell iron-based catalysts. Next, the performance of Fischer-Tropsch synthesis is investigated in a micro-fixed bed reactor. The results manifest that, comparing with Fe5C2 and a supported Fe/ZSM-5 catalyst prepared by the traditional impregnation method, the core-shell Fe5C2?ZSM-5 catalysts show higher CO conversion rate, reaction activity and selectivity to low-carbon olefins. Comparatively, the Fe5C2?ZSM-5C catalyst prepared by carbonization after the coating method exhibited more surface area, smaller average pore size, and more reactive active sites, resulting in the improvement of screening of high carbon hydrocarbons and the enhancement of selectivity to low carbon olefins, in comparison to those prepared by the carbonization-coating method. In conclusion, the K-doping catalyst had significantly improved the reactive activity of the core-shell Fe5C2?ZSM-5 catalyst and the selectivity to low carbon olefins, while the CO conversion on K-Fe5C2?ZSM-20C still remained good.
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Gilbert,Wallis
, p. 184,188 (1940)
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Towards a practical development of light-driven acceptorless alkane dehydrogenation
Chowdhury, Abhishek Dutta,Weding, Nico,Julis, Jennifer,Franke, Robert,Jackstell, Ralf,Beller, Matthias
, p. 6477 - 6481 (2014)
The efficient catalytic dehydrogenation of alkanes to olefins is one of the most investigated reactions in organic synthesis. In the coming years, an increased supply of shorter-chain alkanes from natural and shale gas will offer new opportunities for inexpensive carbon feedstock through such dehydrogenation processes. Existing methods for alkane dehydrogenation using heterogeneous catalysts require harsh reaction conditions and have a lack of selectivity, whereas homogeneous catalysis methods result in significant waste generation. A strong need exists for atom-efficient alkane dehydrogenations on a useful scale. Herein, we have developed improved acceptorless catalytic systems under optimal light transmittance conditions using trans-[Rh(PMe3) 2(CO)Cl] as the catalyst with different additives. Unprecedented catalyst turnover numbers are obtained for the dehydrogenation of cyclic and linear (from C4) alkanes and liquid organic hydrogen carriers. These reactions proceed with unique conversion, thereby providing a basis for practical alkane dehydrogenations.
Olefin Rearrangement Resulting from the Gas-Phase KrF Laser Photolysis of Cr(CO)6
Tumas, William,Gitlin, Barbara,Rosan, Alan M.,Yardley, James T.
, p. 55 - 59 (1982)
We have found that irradiation of Cr(CO)6-1-butene mixtures in the gas phase with a KrF laser (248 nm) results in the efficient (yield ca. 0.2) isomerisation of 1-butene to 2-butene, in marked contrast to results in solution.The primary photochemical yield is independent of 1-butene pressure and of Cr(CO)6 pressure over wide pressure ranges.Secondary photochemical processes are also found, the importance of which depends upon 1-butene pressure.We also report yields of species Cr(CO)m(PF3)6-m resulting from irradiation of Cr(CO)6-PF3 mixtures at 248 nm.At high dilution -3>, we find relative yields of 0.10, 0.14, 0.73, and 0.03 for Cr(CO)2(PF3)4, Cr(CO)3(PF3)3, Cr(CO)4(PF3)2, and Cr(CO)5PF3, respectively.These results suggest a high degree of transormation following optical excitation at 248 nm.We present a resonable kinetic model to explain the observed isomerization of butene in which a primary photofragment, probably Cr(CO)3 or Cr(CO)2, is the active species.
Vapor-phase dehydration of 1,4-butanediol to 1,3-butadiene over Y2Zr2O7 catalyst
Matsuda, Asami,Matsumura, Yoshitaka,Sato, Satoshi,Yamada, Yasuhiro
, (2021/09/16)
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.
Tuning supported Ni catalysts by varying zeolite Beta heteroatom composition: effects on ethylene adsorption and dimerization catalysis
Meloni, Michael,Runnebaum, Ron C.
, p. 3393 - 3401 (2021/06/06)
The influence of zeolite heteroatom composition on the electron density and catalytic activity of a supported Ni cation is examined. Ni-[X]-Beta catalysts, where X = Al, Ga, Fe, or dealuminated, were synthesized and characterized with probe molecule adsorption with FTIR spectroscopy and C2H4dimerization catalysis. It was observedviaCO adsorption that supported Ni cations were increasing in electron density in the order: [Fe] > [Ga] > [Al]. C2H4dimerization activity increased with increasing electron density of the Ni cation. Despite similarities in reported acid site strength, the acid sites on [Fe]-Beta in this work had significantly lower activity than those on [Ga]-Beta for the skeletal isomerization of linear butenes as well as C2H4dimerization. Introducing H2as a reactant resulted in a decrease in dimerization activity for Ni-[Al]-Beta and Ni-[Ga]-Beta but an increase for Ni-[Fe]-Beta. The selectivity and activity of Ni-[DeAl]-Beta changed dramatically with the introduction of H2, which subsequently converted all C2H4withca.100% selectivity towards C2H6(even with a lower space velocity relative to without H2). These results demonstrate the ability of heteroatom composition to tune catalysis by using C2H4dimerization catalysis as a test reaction with zeolite Beta supported Ni catalysts.
