Alkali Promoter Synergism in Selective Oxidation - M. M. BHASIN AND C. D. HENDRIX




Alkali metal promoters have played a key role in improving selectivity and activity to desired oxidation products in a wide variety of commercial selective oxidations, for example, ethylene to ethylene oxide, benzene and butane to maleic anhydride as well as dehydrogenation of ethylbenzene to styrene. To date the literature in catalysis has searched and discovered optimum catalysts for such reactions by laboriously varying one-variable at-a-time. This assumes there is no interaction between the two variables, i.e., the effects of each promoter on catalytic performance is independent of the concentration of each promoter. It will be shown that through the use of statistically designed experiments in 3 or more alkali promoters and/or catalyst composition variables, synergistic action between such promoters was discovered for selective oxidation of ethylene to ethylene oxide. Synergism or synergistic action means that the combined action of promoter A with promoter B (over an unpromoted catalyst) results in an enhancement of efficiency and/or activity beyond that could have been achieved by either promoter acting alone. High precision mathematical models developed will be presented along with their experimental confirmation. Methodology of statistical designed experiments that led to discovery of such synergism will also be highlighted.