Infrared studies of the interaction between dihydroxybenzenes and their ethers with the surfaces of γ‐Al2O3, MoS2 and a CoMo/γ‐Al2O3 catalyst

Abstract

AbstractHydroquinone and resorcinol are strongly chemisorbed on alumina by their oxygen atoms and form a flat adsorption mode. Catechol may be chemisorbed, but very weakly in a flat mode on molybdenum sulfide. On alumina it is adsorbed in an inclined mode through the oxygen atoms. For the CoMo/Al2O3 catalyst an inclined mode is preferred at lower temperatures although a flat mode may be competitive at higher temperatures.The monomethyl ethers are chemisorbed through the phenyl oxygen. The mode of adsorption for the ring is probably flat for the meta and para compounds and inclined for the ortho compound. The ortho compound shows demethoxylation at 250°C followed with the para compound 300°C. Steric constraints evidently hinder to a part adsorption of the ortho compound on the catalyst surface.The dimethyl ethers are chemisorbed in a flat mode on the supports. The adsorbed compounds react by demethylation on the alumina type supports with the para compound reacting at the lowest temperature, around 200°C, and the meta compound only at the highest temperature used, 300°C. The ortho compound has an intermediate reactivity.Adsorption of all ethers on molybdenum sulfide is very weak.