Indium-containing catalysts for oxidative dehydrogenation of organic compounds

For the first time, a method was developed for introducing indium into Mg-Al hydrotalcites—precursors of oxide catalysts for oxidative dehydrogenation of alkanes. Samples of oxide catalysts were synthesized that contained indium oxide and also oxides of magnesium, aluminum, chromium, vanadium, molybdenum, and niobium in various combinations. The catalytic properties of the produced catalysts were studied in the oxidative dehydrogenation of ethane, propane, and isobutane. It was established that the introduction of indium into catalysts increases the selectivity and the yields of desired products. New hydroxo salts with a layered structure of the hydrotalcite type were synthesized: [Al_{1 ? n} In _n Mg _m (OH)_{3 + 2m ? 1}][(NO₃) · nH₂O] and quaternary magnesium indium chromium aluminum hydroxonitrate of the composition [Al_0.5In_0.5Cr_0.5Mg_2.5(OH)_8.5][(NO₃) · nH₂O]; these salts were found to be isostructural. The obtained compounds were studied as catalyst precursors.     

Gallium-containing catalysts for oxidative dehydrogenation of organic compounds

A method was developed for introducing gallium into Mg-Al hydrotalcites—precursors of oxide catalysts for oxidative dehydrogenation of alkanes. Samples of oxide catalysts were synthesized that contained gallium oxide and also oxides of magnesium, aluminum, chromium, vanadium, molybdenum, and niobium in various combinations. The catalytic properties of the produced catalysts were studied in the oxidative dehydrogenation of ethane, propane, isobutane, and hexane. It was established that the addition of gallium to catalysts increases the ethylene and propylene yields in the oxidative dehydrogenation of ethane and propane. New hydroxo salts with a layered structure of the hydrotalcite type were synthesized: ternary magnesium gallium aluminum hydroxonitrate of variable composition [Al_{1 ? n} Ga _n Mg _m (OH)_{3 + 2m ? 1}][NO₃ · nH₂O] and quaternary magnesium gallium chromium aluminum hydroxonitrate of the composition [AlGaCrMg_1.8(OH)_11.6][NO₃ · nH₂O]; these salts were found to be isostructural.     

Copper-containing catalysts for the oxidative dehydrogenation of organic compounds

A method of doping magnesium aluminum hydrotalcites, which are precursors for oxidative dehydrogenation oxide catalysts of various compositions, with copper(II) was developed, and copper(II)-containing oxide catalyst samples were synthesized. The catalytic properties of these catalysts were studied in the oxidative dehydrogenation of ethane, propane, and hexane. The conversion of ethane into ethylene on the copper-containing catalysts was established to proceed with high selectivities (90?C97%) and at low temperatures (400?C450°C).     

Tungsten-containing catalysts for oxidative dehydrogenation of hydrocarbons

Methods for introducing tungsten into the precursors of oxide catalysts for oxidative dehydrogenation (OD) were developed. Tungsten-containing samples of oxide catalysts of various compositions were synthesized and their catalytic properties in OD of ethane were studied. The introduction of tungsten into the catalysts increased the yield of ethylene in all cases. In the series of tungsten-containing catalysts, the ethylene yield increased in the following order of the catalysis: Mg-Al-V-Mo-W-O < Mg-Al-Ni-V-Mo-W-O < Mg-Al-Fe-V-Mo-W < Mg-Al-Cr-V-Mo-W-O.     

Modification of VPO catalysts for oxidative dehydrogenation of ethane

Based on the previously discussed hypothesis concerning the mechanism of conversion of paraffins, we have modified the structure of VPO catalysts by developing the (220) plane of VOHPO₄·0.5H₂O and introducing a bismuth additive. We have shown that this leads to an increase in the P/V ratio on the surface, an increase in the number of Lewis centers and the strength of such centers, and a change in the ratio of Lewis centers to Brönsted centers. The change in the surface characteristics of the samples, in accordance with the hypotheses, improves their properties in oxidative dehydrogenation of ethane, increasing the catalytic activity and the yield of the target product ethylene.     

Europium oxide containing catalysts for oxidative dehydrogenation of alkanes

A method is developed to incorporate europium into Mg–Al hydrotalcites, which are precursors for oxide catalysts of oxidative dehydrogenation (ODH) of alkanes; samples of oxide catalysts are prepared, where europium oxide and gallium, magnesium, aluminum, chromium, vanadium, molybdenum, and niobium oxides are contained in various combinations. The catalytic properties of these catalysts in the reactions of ethane, propane, and butane ODH are studied. The incorporation of europium into some of our studied multicomponent catalysts enhances the reaction selectivity and increases yields of desired products.     

Phosphated ceria,selective catalysts for oxidative dehydrogenation of isobutane

The oxidative dehydrogenation (ODH) of isobutane over pure ceria and phosphated ceria catalysts, containing two different amounts of phosphorus, was examined at temperatures ranging from 450 to 610 °C. The catalysts were characterized using nitrogen adsorption, DRX, SEM, EDX, XPS and TPR techniques. Adding phosphorus to ceria and increasing the phosphorus content results in a modification of the physicochemical characteristics of the catalyst, the redox ability of the catalytic material being strongly diminished. At the same time, by adding phosphorus to ceria and increasing the phosphorus content, a decrease of the catalytic activity accompanied by an important increase of the selectivity for isobutene, mainly at the expense of carbon oxides, was observed. A compensation effect in catalysis was also observed for the isobutane conversion on this series of catalysts.     

Niobium phosphates as new highly selective catalysts for the oxidative dehydrogenation of ethane

Several niobium phosphate phases have been prepared, fully characterized and tested as catalysts for the selective oxidation of ethane to ethylene. Three distinct niobium phosphate catalysts were prepared, and each was comprised predominantly of a different bulk phase, namely Nb(2)P(4)O(15), NbOPO(4) and Nb(1.91)P(2.82)O(12). All of the niobium phosphate catalysts showed high selectivity towards ethylene, but the best catalyst was Nb(1.91)P(2.82)O(12), which was produced from the reduction of niobium oxide phosphate (NbOPO(4)) by hydrogen. It was particularly selective for ethylene, giving ca. 95% selectivity at 5% conversion, decreasing to ca. 90% at 15% conversion, and only produced low levels of carbon oxides. It was also determined that the only primary product from ethane oxidation over this catalyst was ethylene. Catalyst activity also increased with time-on-line, and this behaviour was ascribed to an increase of the concentration of the Nb(1.91)P(2.82)O(12) phase, as partially transformed NbOPO(4), formed during preparation, was converted to Nb(1.91)P(2.82)O(12) during use. Catalysts with predominant phases of Nb(2)P(4)O(15) and NbOPO(4) also showed appreciable activity and selectivities to ethylene with values around 75% and 85% respectively at 5% ethane conversion. The presence of phosphorous is required to achieve high ethylene selectivity, as orthorhombic and monoclinic Nb(2)O(5) catalysts showed similar activity, but displayed selectivities to ethylene that were <20% under the same reaction conditions. To the best of our knowledge, this is the first time that niobium phosphates have been shown to be highly selective catalysts for the oxidation of ethane to ethylene, and demonstrates that they are worthy candidates for further study.     

Highly efficient VOx/SBA-15 mesoporous catalysts for oxidative dehydrogenation of propane

Highly dispersed vanadia species on SBA-15 mesoporous silica have been found to exhibit a highly efficient catalytic performance for the oxidative dehydrogenation (ODH) of propane to light olefins (propene + ethylene).     

Kinetic studies of unsteady-state oxidative dehydrogenation of n-butylenes over oxide catalysts

Kinetic studies of unsteady- and steady-state oxidative dehydrogenation of n-butylenes indicate that in unsteady-state conditions the diffusion of oxygen ions out of the catalyst bulk plays a significant part. The parameters of the unsteady-state kinetic model have been numerically calculated.

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The selective oxidative dehydrogenation of ethane over hydrothermally synthesised MoVTeNb catalysts

Mo-V-Te-Nb metal oxide catalysts prepared by hydrothermal synthesis and heat-treated in N2 at high temperatures (600-700 degrees C) show high activity and selectivity for the oxidative dehydrogenation of ethane to ethene. Yields of ethene of 75% have been obtained at 400 degrees C on the best catalysts.     

Oxidative dehydrogenation of alkylheteroaromatic compounds 1. Catalysts containing vanadium and molybdenum for the oxidative dehydrogenation of alkylpyridines

The dehydrogenation of a series of alkylpyrïdines has been studied on vanadium and molybdenum oxide-containing catalysts in the presence of oxygen of the air and sulfur dioxide gas. A dependence was shown of the catalytic and physicochemical properties of the catalysts indicated on their composition and method of preparation. The optimum catalyst composition and the conditions of carrying out the reaction to provide high activity and selectivity when making vinylpyridines were determined. The relative reactivity of the alkylpyridines investigated on dehydrogenation and further oxidation was determined.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 802–811, June, 1994. Original article submitted April 19, 1994.     

Magnesium iron aluminum hydroxosalts and oxide catalysts for oxidative dehydrogenation of alkanes and alcohols

Methods are developed for the synthesis of precursors for oxide catalysts containing iron hydroxocarbonate and magnesium aluminum hydroxocarbonate with hydrotalcite-type layered structure and decavanadate and paramolybdate ions in anionic interlayers. These precursors are used to synthesize oxide catalysts for oxidative dehydrogenation of alcohols and alkanes with high selectivity and good yields of the desired product in conversion of ethane to ethylene and alcohols to carbonyl compounds.     

Spectral studies of catalysts of oxidative dehydrogenation of dimethyl ether to dimethoxyethane

Spectral methods (diffuse reflectance infrared Fourier transform spectroscopy, EPR) are used to study the adsorption of dimethyl ether and oxygen on a catalyst of oxidative dehydrogenation of dimethyl ether to dimethoxyethane. The formation of O ₂ ^? superoxide paramagnetic species is revealed. A mechanism of the formation of dimethoxyethane is proposed.     

Studies on the oxidative dehydrogenation of propane to propene over Co-V-O catalysts

A series of Co-V-O catalysts were prepared and their catalytic performances for the oxidative dehydrogenation of propane to propene were investigated. It was found that the p-type catalysts showed higher catalytic behavior than the n-type catalyst.     

Application of catalysts for producing organic compounds from plant biomass

Experimental data on acid-base and oxidation-reduction catalysis in the conversion of wood carbohydrates and lignin to levoglucosenone, levulinic acid, aromatic aldehydes and other fine chemicals are presented and discussed.     

助剂P对Ni-Al-O催化剂乙烷氧化脱氢性能的影响

通过一锅水热法制备了一系列磷改性Ni-Al-O催化剂(P_x-Ni-Al-O),以O₂为氧化剂,评价了系列催化剂的乙烷氧化脱氢制乙烯性能。结果表明,助剂P的掺入不仅可以减小NiO晶粒的尺寸,还影响了Ni和Al之间的相互作用。在350～475℃的温度范围内,P改性Ni-Al-O催化剂上乙烯选择性均高于未改性的催化剂,且适量P的引入还可以提高乙烷转化率。当反应温度为475℃时,P_0.15-Ni-Al-O催化剂上乙烯选择性和收率分别为61.4%和31.9%。此外,P改性后的催化剂表现出较强的抗积碳性能,连续反应22 h不失活。     

助剂P对Ni-Al-O催化剂乙烷氧化脱氢性能的影响

通过一锅水热法制备了一系列磷改性Ni-Al-O催化剂(Px-Ni-Al-O),以O₂为氧化剂,评价了系列催化剂的乙烷氧化脱氢制乙烯性能。结果表明,助剂P的掺入不仅可以减小NiO晶粒的尺寸,还影响了Ni和Al之间的相互作用。在350~475℃的温度范围内,P改性Ni-Al-O催化剂上乙烯选择性均高于未改性的催化剂,且适量P的引入还可以提高乙烷转化率。当反应温度为475℃时,P_0.15-Ni-Al-O催化剂上乙烯选择性和收率分别为61.4%和31.9%。此外,P改性后的催化剂表现出较强的抗积碳性能,连续反应22 h不失活。     

Metal complex catalysts for oxidative demercaptanization of sulfur compounds in crude oil

Demercaptanization of sulfur compounds in crude oil in the presence of metal complex oxidation catalysts was studied. The adsorption capacities of the catalysts and industrial mercaptane scavengers were compared. The possibility of using these catalysts for the removal of light sulfur impurities in the field oil preparation was shown.