
Effect of nitric acid peptizator on the performance of a MCM22 zeolite catalyst
YU HaiQing; LI JianWei; SUN XiaoYan; LI YingXia; CHEN BiaoHua
Journal of Beijing University of Chemical Technology ›› 2008, Vol. 35 ›› Issue (4) : 24-28.
Effect of nitric acid peptizator on the performance of a MCM22 zeolite catalyst
A series of MCM-22 zeolite catalyst samples have been prepared with nitric acid as peptizator using an extrusion molding method. The zeolites were characterized by means of particle strength tests, TG-DTA, N2 adsorptiondesorption measurements, and mercury intrusion porosimetry. The effects of varying the amount of the peptizator on the physical properties of MCM-22 catalyst were investigated. The results showed that with increasing nitric acid dosage, the mechanical strength of the zeolite catalyst increased at first and then decreased, with the maximum catalyst strength being obtained at a dosage of 10 mass percent nitric acid. The specific surface area and total acid were enhanced by adding the appropriate amount of nitric acid. Taking the alkylation of benzene with propylene as a model reaction, the catalytic performances of the MCM-22 zeolite catalysts prepared in this work were evaluated by means of a semi-continuous gas-liquid reactor and a liquid-liquid continuous reactor. The experimental results showed that when the nitric acid dosage was less than 20 mass percent, the activity of MCM-22 zeolite increased with increasing nitric acid dosage. The selectivity to cumene reached a maximum value when the nitric acid dosage was 10 mass percent.
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