Hydrocarbons surface science

The catalysts with the simplest compositions are pure metals, and the metals that have the simplest and most uniform surface stmctures are single crystals. Researchers have done many experiments with metal single crystals in ultrahigh vacuum chambers so that unimpeded beams of particles and radiation can be used to probe them. These surface science experiments have led to fundamental understanding of the stmctures of simple adsorbed species, such as CO, H, and small hydrocarbons, and the mechanisms of their reactions (42) they indicate that catalytic activity is often sensitive to small changes in surface stmcture. For example, paraffin hydrogenolysis reactions take place rapidly on steps and kinks of platinum surfaces but only very slowly on flat planes however, hydrogenation of olefins takes place at approximately the same rate on each kind of surface site. 

Catalysis and Surface Science Developments in Chemicals from Methanol, Hydrotreating of Hydrocarbons, Catalyst Preparation, Monomers and Polymers, Photocatalysis and Photovoltaics, edited by Heinz Heinemann and Gabor A. Somorjai... 

Surface science studies have generated much insight into how hydrocarbons react on the surfaces of platinum single crystals. We refer to Somorjai [G.A. Somor-jai. Introduction to Surface Chemistry and Catalysis (1994), Wiley, New York] for a detailed overview. Also, the reactions of hydrocarbons on acidic sites of alumina or on zeolites have been studied in great detail [H. van Bekkum, E.M. Flanigan and J.C. Jansen (Eds.), Introduction to Zeolite Science and Practice (1991), Elsevier, Amsterdam],... 

CO oxidation and the reaction between CO -t NO have been extensively studied. Much less is known about hydrocarbon oxidation, and the role of hydrocarbons in reducing NO is only beginning to be explored. Surface science studies with reactions on well-defined single-crystal surfaces have contributed significantly to our understanding, for an overview see B.E. Nieuwenhuys, Adv. Catal. 44 (1999) 259. 

Fetzer, J. C., The Production of Large Polycyclic Aromatic Hydrocarbons During Catalytic Hydrocracking, in Catalysts in Petroleum Refining and Petrochemical Industries, 1996. Kuwait, Studies in Surface Science and Catalysis, Elsevier. 100 pp. 263-271. 

Frei, H. (1997). Highly selective photochemical and dark oxidation of hydrocarbons by 02 in zeolites. In Studies in Surface Science and Catalysis. 3rd World Congress on Oxidation Catalysis, Grasselli, R.K., Oyama, S.T., Gaffney, A.M. and Lyons, J.E. (eds), Vol. 110, pp. 1041-1050. Elsevier Science, New York... 

Figure 4.11 Different types of selectivity in zeolite catalysts. (Reprinted from Introduction to Zeolite Science and Practice, Studies in Surface Science and Catalysis, Vol. 137, I.E. Maxwell, W.J.H. Stork, Introduction to Zeolite Science and Practice, Studies in Surface Science and Catalysis, Vol. 137, Hydrocarbon Processing with Zeolites, pp. 747-819. Copyright 2001. With permission from Elsevier.)...

The results presented above demonstrate that one could obtain fundamental information concerning the structure, oxidation state and reactivities of a model K/NiO/Ni(100) catalyst by using a combination of advanced surface science techniques. The experimentd approaches described here could in principle be applied to other model catalysts which are of importance in the selective oxidation of hydrocarbons. These results also demonstrate that it is very important to use a variety of surface techniques to obtain complementary results. 

An economical process for the low-temperature non-oxidative coupling of methane to give higher hydrocarbons would be commercially attractive. Direct observation of surface intermediates would be valuable in improving the efficiency of the process. The reaction has been characterized on ruthenium single-crystal surfaces by surface science techniques including HREELS 32) and references cited therein). 

The chemisorption and reaction of hydrogen and hydrocarbon fragments on catalytically active transition metal surfaces has received a great deal of attention due to the commercial importance of hydrocarbon formation reactions (1-15). The methanation reaction on nickel has been studied by a variety of surface science techniques. Yates, et al. (1), and others, have concluded that the following steps must occur on Ni(lll) ... 

One area in which such surface science strategies have proved to be remarkably successful in following rather complex surface catalytic reactions has been in the area of hydrocarbon conversion catalysis [1-3], initially focusing on reforming [4-10] and hydrogenation [11,12] reactions. This work demonstrated, for example, that hydrocarbons could undergo drastic transformations on noble metal surfaces, such as the conversion of ethylene into strongly bound, but relatively uiu-eactive ethylidyne species on Pt(lll) [13-23]. 

Tjandra S, Zaera F (1996) A surface science study of the hydrogenation and dehydrogenation steps in the interconversion of cyclic hydrocarbons on Ni(lOO). J Catal 164 82... 

Rostrup-Nielsen, I.R., Christensen, T.S., and Dybkjaer, I. Steam reforming of liquid hydrocarbons. Studies in Surface Science and Catalysis, 1998, 113, 81. 

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