气固相法合成Ti-ZSM-5催化苯酚羟基化的研究

HYDROXYLATION OF PHENOL CATALYZED BY TI-ZSM-5 PREPPARED FROM THE GAS-SOLID ISOMORPHOUS SUBSTITUTION

钛硅分子筛对以 30 %H2 O2 为氧化剂的苯酚羟基化反应具有良好的催化活性 ,反应可同时生成邻苯二酚 (CAT)和对苯二酚 (HQ)。本文利用TiCl4 气固相法制得Ti -ZSM - 5分子筛作为苯酚 /H2 O2 羟基化反应的催化剂 ,详细考察了溶剂种类、催化剂用量、苯酚 /H2 O2 摩尔比、反应温度、反应时间以及反应助剂对Ti-ZSM - 5催化苯酚羟基化反应性能的影响。结果表明 ,水是苯酚羟基化反应最理想的溶剂 ;改变其它反应条件 ,对苯酚羟基化反应选择性影响不大 ,可稳定在～ 98% ,且邻苯二酚 /对苯二酚摩尔比为～ 0 .85,但对苯酚转化率和H2 O2 有效利用率却有较大的影响 ,在适当反应条件下 ,H2 O2 有效利用率可达 74 .9%。添加助剂醋酸可提高Ti-ZSM -

Ti-Si molecular sieves have an outstanding catalytic property using 30% H 2O 2 as oxidant for the hydroxylation of phenol, in which catechol(CAT) and hydroquinol(HQ) can be obtained concurrently. In this article, the hydroxylation of phenol/H 2O 2 system catalyzed by Ti-ZSM-5, which were prepared from the TiCl 4 gas-solid isomorphous substitution, has been studied. The effects of solvent species, Ti-ZSM-5 amount, phenol/H 2O 2 molar ratio, reactiontemperature, time and additives on the hydroxylation were investigated. The results showed that water was the best solvent for the phenol hydroxylation catalyzed by Ti-ZSM-5. Changing other reaction conditions, the selectivities of hydroxylation had a little change, being ～98%, and CAT/HQ molar ratio being ～0.85, but both phenol conversion and H 2O 2 utility changed significantly. Under the optimum conditions, the utilization ratio of H 2O 2 can reach 75mol%. The addition of HAc can promote the catalytic efficiency of Ti-ZSM-5.