Molybdenum oxide catalyst, dehydrogenation

Methanol undergoes reactions that are typical of alcohols as a chemical class (3). Dehydrogenation and oxidative dehydrogenation to formaldehyde over silver or molybdenum oxide catalysts are of particular industrial importance. 

K. Chen, S. Xie, A.T. Bell, and E. Iglesia, Alkali effects of molybdenum oxide catalysts for the oxidative dehydrogenation of propane, J. Catal. 195, 244-252 (2000). 

A. Christodoulakis, E. Heracleous, A.A. Lemonidou and S. Boghosian, An operando Raman study of structure and reactivity of alumina-supported molybdenum oxide catalysts for the oxidative dehydrogenation of ethane, J. 

Aldehydes can be prepared by the dehydrogenation of a primary alcohol. Formaldehyde results from the dehydrogenation of methanol at high temperatures with an iron oxide-molybdenum oxide catalyst ... 

K. Chen, S. Xie, A.T. Bell and E. Iglesia, Structure and properties of oxidative dehydrogenation catalysts based on M0O3/AI2O3, J. Catal, 198(2), 232-242, 2001. H.C. Hu and l.E. Wachs, Catalytic properties of supported molybdenum oxide catalysts In situ Raman and methanol oxidation studies, J. Phys. Chem., 99(27), 10911-10922, 1995. 

Chiistodoulakis, A., Heracleous, E., Lemonidou, A., etal (2006). An Operando Raman Study of Structure and Reactivity of Alumina-supported Molybdenum Oxide Catalysts for the Oxidative Dehydrogenation of Ethane, J. Catal., 242, pp. 16-25. 

Burch, R. and Swarnakar, R. Oxidative dehydrogenation of ethane on vanadium-molybdenum oxide and vanadium-niobium-molybdenum oxide catalysts. Appl. Catal 1991, 70, 129. 

Styrene, the best known representatives of the aromatic olefin class, is readily obtained by cometathesis reaction of stilbene with ethene in the presence of alumina-supported molybdenum oxide catalysts. In a two-step process [27] stilbene is first produced from toluene by catalytic dehydrogenative coupling over Pb0/Al203, followed by codisproportionation to styrene, with ethene, over M0O3/AI2O3 ... 

Chen, K., Iglesia, E., and Bell, A. T. Isotopic tracer studies of reaction pathways for propane oxidative dehydrogenation on molybdenum oxide catalysts. J. Phys. Chem. B 105, 646-653 (2000). 

Tsilomelekis, G., Christodoulakis, A., and Boghosian, S. Support effects on structure and activity of molybdenum oxide catalysts for the oxidative dehydrogenation of ethane. Catal Today 127,139-147 (2007). 

The reaction scheme is rather complex also in the case of the oxidation of o-xylene (41a, 87a), of the oxidative dehydrogenation of n-butenes over bismuth-molybdenum catalyst (87b), or of ethylbenzene on aluminum oxide catalysts (87c), in the hydrogenolysis of glucose (87d) over Ni-kieselguhr or of n-butane on a nickel on silica catalyst (87e), and in the hydrogenation of succinimide in isopropyl alcohol on Ni-Al2Oa catalyst (87f) or of acetophenone on Rh-Al203 catalyst (87g). Decomposition of n-and sec-butyl acetates on synthetic zeolites accompanied by the isomerization of the formed butenes has also been the subject of a kinetic study (87h). 

Formaldehyde, produced by dehydrogenation of methanol, is used almost exclusively in die syndiesis of phenolic resins (Fig. 7.2). Iron oxide, molybdenum oxide, or silver catalysts are typically used for preparing formaldehyde. Air is a safe source of oxygen for this oxidation process. 

In the middle thirties the reactions of naphtha and certain compounds known to be present in naphtha were being studied in university and industrial laboratories. One of the problems was to find a catalyst that was capable of synthesizing an aromatic from a paraffin. It was reasoned that the hydrogenation-dehydrogenation oxide-type catalysts such as molybdenum oxide and chromium might possess suitable activity at temperatures well below those employed in thermal reforming. 

In order to probe the enhanced transport in Def-MCM41, we compared the catalytic performance of various molybdenum oxide/mesoporous material catalysts for ethylbenzene dehydrogenation reaction in Table 2. 

Ethylbenzene dehydrogenation is generally catalyzed by a potassium-promoted iron oxide catalyst. The most widely used catalysts are composed of iron oxide, potassium carbonate, and various metal oxide promoters. Examples of metal oxide promoters include chromium oxide, cerium oxide, molybdenum oxide, and vanadium oxide. " The potassium component substantially increases catalyst activity relative to an unpromoted iron oxide catalyst. Potassium has been shown to provide other benefits. In particular, it reduces the formation of carbonaceous deposits on the catalyst surface, which prolongs catalyst life. 

Alumina catalysts activated by additions of dehydrogenating catalysts, e.g., nickel oxide, copper oxide or sulfide, zinc oxide or sulfide, cobalt selenide, zinc phosphate, cadmium tungstate, mixtures of the oxides of zinc and tungsten, of cadmium and molybdenum, etc., are claimed to be superior in the formation of acetaldehyde from mixtures of steam and acetylene at 350° to 400° C.l-la Zinc oxide catalysts may be activated in a similar way by the addition of small amounts of molybdates or molybdic acid, and are effective at 300° to 350° C.121b... 

The other component necessary for the preparation of novolacs is methanal that is produced by catalytic dehydrogenation of methanol as shown in equation 6. Typical catalysts are a combination of iron oxide and molybdenum oxide or silver [30],... 

Propane Dehydrogenation over Supported Molybdenum Catalysts. The combined energy-dispersive (ED)-XAFS, UV-Vis, and Raman represents a powerful device that couples three spectroscopic techniques in one reactor, which probes the same part of a metal oxide catalyst under true reaction conditions and is capable of delivering subsecond time resolution. A scheme of the setup is given in Figure 32. 

Koc, S. N., Gurdag, G., Geissler, S., Guraya, M., Orbay, M., and Muhler, M. The oxidative dehydrogenation of propane over potassium-promoted molybdenum oxide/ sol-gel zirconia catalysts. J. Mol Catal A Chem. 225,197-202 (2005). 

---