Hydrogenation catalyst, gold

Fig. 9 Dependence of catalytic activity of MgO-supported catalysts containing cationic gold and (except in the most active catalyst) gold clusters for ethene hydrogenation at 760 Torr and 353 K (reactive mixture of He, ethene, and H2—ethene partial pressure, r ethene. 40 Torr Phydrogen. 160 Torr the balance He). Note the nonlinearity of the scale at the top [53]...

A. Ueda, andM. Haruta, Nitric oxide reduction with hydrogen, carbon monoxide, and hydrocarbons over gold catalysts. Gold Bull. 32, 3-11 (1999). 

In contrast to PGM catalysts, gold nanocatalysts are generally more active for CO oxidation than for H2 oxidation. In addition, gold catalysts are almost insensitive to CO2, and their activity is enhanced by moisture, the products of the two reactions. Gold catalysts are therefore strong candidates for the selective oxidation of CO in H2-rich gases [2, 35, 38,46, 52, 53,101,157,159, 183-200], a reaction needed to produce pure hydrogen for fuel cells. 

Table 3 Results of acrolein hydrogenation over gold and silver CHSG catalysts.

Modifiers can be added to metal catalysts to improve their selectivity and reactivity. These modifiers can be electron acceptors or donors. Alkali metals, for example, are added to increase the bond energy of adsorbed carbon monoxide. Some modifiers enhance selectivity by stabilizing higher oxidation states of metals. Modifiers can also promote desired catalytic reactivity by initiating electronic effects in addition to structural modification of the catalysts. Gold, for example, enhances the catalytic activity of palladium for the oxidation of hydrogen (5). Metal catalysts used in industrial processes have been reviewed by Mouilijn et al. (6). 

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