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.     

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.     

Oxidative dehydrodimerization of aromatic hydrocarbons on oxide catalysts

It has been shown that in contrast to benzene, toluene can readily participate in reactions of oxidative coupling. The inertness of benzene is explained by the absence of mobile hydrogen atoms in -position with respect to the unsaturated bond.

---

, , . - .

     

Catalytic systems for oxidative chlorination of hydrocarbons Communication 3. Properties of catalysts containing copper salts on an aluminum oxide support

Russian Chemical Bulletin -     

Mechanism of dehydrocyclization of paraffinic hydrocarbons on chromium oxide catalysts

Conclusions Dehydrocyclization of normal paraffins to aromatic hydrocarbons on chromium oxide catalysts does not include the stage of the formation of intermediate cyclohexanes or their chemisorbed forms (complexes of the cyclohexanes with the catalyst).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2561–2562, November, 1969.     

Role of phase boundary in heterogeneous oxide catalysts for oxidative coupling of methane

Bi₂EO₅ (E=Si, Ge) catalysts in a metastable state have been found to possess a high activity for oxidative coupling of methane. It has been assumed that the intergrowth boundaries for the Bi₂EO₅ decomposition products, on which active catalytic sites may be located, play a specific role on the catalytic performance of the oxides.     

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.

---

- . , . .

     

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.     

Relation of chemical structure to reactivity in complete oxidation on oxide contact catalysts for open-chain hydrocarbons

It is shown that the relative reactivities of alkanes, alkenes, alkynes, and cyclopropane in complete oxidation decreases with increase in the energy of the bond broken in the rate-limiting step: for alkanes from ethane upwards this is a C-C bond, for unsaturated hydrocarbons it is the -type C-C bond, and for methane it is a C-H bond.     

Mechanism of oxidative dehydrodimerization of propylene over Bi?Sn oxide catalysts

The kinetics of oxidative dehydrodimerization of propylene has been studied and interpreted in terms of the Langmuir-Hinshelwood scheme. Diallyl is shown to be formed by interaction between the gaseous and adsorbed forms of olefin.

---

- . .

     

Catalytic decomposition of methylene chloride on oxidative carbon supported metal oxide catalysts

Several carbon supported chromium oxide catalysts were prepared by varying textural and surface properties of support and tested for methylene chloride oxidation. They were investigated by TGA and XPS. The difference in acidity and high valence of chromium led to difference in activity. This revised version was published online in June 2006 with corrections to the Cover Date.     

High-throughput selection for heterogeneous catalysts

A catalyst library of 80 samples with different mass ratios of rare earth elements, cobalt (Co), cerium (Ce), and indium (In), was prepared by impregnation of a fresh HZSM-5 zeolite support. A high-throughput detection setup, based on UV absorption spectroscopy, was developed for heterogeneous catalyst selection. The catalytic properties of the library were tested in the selective catalytic reduction of NO by methane at 673 K. Among the Co/Ce series, the catalyst with Co/Ce = 2:1 and Co/H-ZSM5 = 2.5% has shown remarkable efficiency (up to 78%). In the Ce/In series, the reactivity of the catalyst with the support composition of Ce/In = 1:1 and Ce/H-ZSM5 = 2.0% was < or = 88%. Our initial experiments definitely indicated that this simple and inexpensive multichannel setup can be applied for the selection of other heterogeneous catalysts. According to the variation of the UV light intensity, resulting from the absorption of the reactant or product, it was possible to monitor the relative quantity of reactants or products during a catalytic reaction.     

Study of the temperature-programmed oxidative degradation of hydrocarbons over Ce-based catalysts by evolved gas analysis

The catalytic behaviour of ceria, zirconia and ceria–zirconia mixed oxides in the temperature-programmed degradation of toluene and n-hexane was analysed by means of evolved gas analysis (mass spectrometry). Pure cerium oxide resulted the most active catalyst in the oxidation of both compounds. This fact revealed the crucial role of the surface oxygen species in the decomposition of this type of hydrocarbons. The low affinity of CeO₂ for H₂O and CO₂, the major oxidation products, may be also responsible for the observed highly active catalytic behaviour.