Bifunctional Catalysis Principles of Petroleum Reforming

We must first differentiate metal-support interactions that undoubtedly occur when a metal particle is placed on a support that has distinctly either acidic or basic character from true bifunctional catalysis. Such interactions have been shown to introduce delicate but significant alteration to the organisation of the metal s valence electrons, and these have important catalytic consequences but reactions that are affected are still metal-catalysed, and should not be regarded as instances of 

Aromatic molecules are now not so acceptable as components of ICE fuel, due to the carcinogenic behaviour of benzene, although they are still wanted by the petrochemical industry. Other additives including tetraethyl-lead and oxygenated molecules (alcohols, ethers) have been approved from time-to-time as anti-knock or octane-rating enhancers, but each has its disadvantages or environmental hazards as well, and none is totally free from objection. Palladium has sometimes been used with platinum to control carbon formation. 

Other alkanes have not however been neglected. n-Pentane has been less studied, perhaps because the more limited scope of its reactions, and, although the Cs ring is strain-free, n-pentane is less easily cyclised than n-hexane, and indeed n-heptane cyclises even more effectively (see Table 14.1). neoHexane (2,2-dimethylbutane) has three types of C—C bond, the reactivities of which differ, while 2,2,3,3-tetramethylbutane has only two types of C—C bond, the breaking of which gives either two molecules of wobutane or methane - -trimethylbutane. These have been usefully employed to characterise catalysts, and the different reactivities of C—C bond in other branched alkanes have also been examined (Section 14.2.4). 

TABLE 14.1. Product Selectivities for the Reactions of n-Alkanes with Hydrogen over Platinnm Catalysts (T = 603 K, Ph 16 kPa) 

NMR (MASNMR) (Section 14.3). Of course, without gas-chromatography almost nothing could have been achieved. 

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