关键词: X型沸石, 侧链烷基化反应, 沸石表面酸、碱中心, 苯乙烯, 甲醇, 甲苯

Abstract: The relations of the acid-base properties of X-type Zeolite to the side-chain alkylation of toluene with methanol have been studied by TPD, IR, TPSR and other methods. The alkylation mechanism has also been discussed. The results showed that methanol initially decomposed into HCHO on the strong base sites of zeolite, subsequently, HCHO reacted with toluene, which was on the acid sites, and produced styrene. The catalytic activity of the alkylation is mainly dependent on the number of the strong base sites on the zeolite but the excess of strong base sites may lead to the further decomposition of HCHO into CO which is unfavourable to the formation of styrene.The number and strength of acid-base on zeolite can be adjusted by alkali-cation exchange and by impregnation in H₃BO₃and KOH. Therefore it affected on the catalytic activity.Asatisfactory yield of styrene is obtained on a KX(H₃BO₃/KOH) zeolite sample which was impregnated with the mixed solution of H₃BO₃and KOH (molar ratio=1:1), and the high activity is attributed to the proper number of strong base sites in the zeolite sample.

Key words: X-type zeolite. Side-chain alkylation, Acid-base sites of zeoli-te surface, Styrene, Methanol, Toluene