沸石的表面酸、碱性与甲醇、甲苯侧链烷基化反应

以TPD和质谱检测的TPSR、IR及微型反应器等手段探讨了X型沸石的表面酸、碱性质对甲醇、甲苯侧链烷基化反应的作用及可能的反应历程。

Relationiship Between the Acid-Base Properties of Zeolite Surface and the Activity of Side-Chain Alkylation of Toluene with Methanol

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 H3BO3 and KOH. Therefore it affected on the catalytic activity.A satisfactory yield of styrene is obtained on a KX(H3BO3/KOH) zeolite sample which was impregnated with the mixed solution of H3BO3 and KOH (molar ratio=1:1), and the high activity is attributed to the proper number of strong base sites in the zeolite sample.