Vapor phase isomerization of O-xylene at high pressure

Abstract

High pressure reaction (180.7 psia) behavior of oxylene isomerization using packed bed reactor was studied under various reaction conditions. In comparison with low pressure reaction, high pressure operation under hydrogen atmosphere showed no deactivation and fixed low isomerization selectivity. Pretreatment conditions affected the reaction behavior. Steam treated mordenites, especially cobalt or nickel ion-exchanged mordenites, showed higher activity but lower isomerization selectivity than dry air calcined mordenites. Temperature Programmed Desorption (TPD) using ammonia showed that dry air calcined mordenites had stronger acid sites than steam treated mordenites. In combination with low pressure reaction high pressure reaction data was interpreted from the stand point of acidity and acid strength. Atmosphere had an effect on coke formation. From surface area data and the analysis of trimethylbenzene mechanism of coke formation under different atmospheres was proposed. Effect of temperature, space time, metal loading, metal type and comparison with other catalysts were investigated and discussed.