不同分子筛负载Pd催化剂催化苯加氢烷基化制备环己基苯

以不同分子筛为载体，采用浸渍方法制备了一系列Pd/分子筛催化剂，采用XRD、NH3-TPD、BET和SEM表征方法对不同分子筛进行表征，并考察了低温下不同分子筛酸性和孔结构对Pd/分子筛催化剂催化苯加氢烷基化制备环己基苯(CHB)性能的影响。结果表明：苯加氢烷基化反应的催化性能受不同分子筛酸量和孔结构的影响，以小孔道、高酸量的HZSM-5、H-IM-5分子筛和大孔道、低酸量H-RZM的分子筛为酸性组元的Pd/分子筛催化剂，苯转化率(<16%)和环己基苯选择性较低(<45%)；以大孔道、适中酸量的HBETA和HMCM-49 分子筛为酸性组元的Pd/分子筛催化剂，苯转化率和环己基苯选择性明显提高，可分别达36.61%、62.85%和34.69%、71.55%；HY分子筛具有较开阔的孔道、较高酸量，Pd/HY催化苯加氢烷基化反应的苯转化率(48.63%)和环己基苯选择性最高(82.94%)，是较为合适的低温苯加氢烷基化反应的酸性组元。

Benzene Hydroalkylation to Cyclohexylbenzene over Different Zeolites Supported Pd Catalysts

Bifunctional Pd catalysts supported on different zeolites were prepared by the impregnation method. Effects of the acidity and pore channel structure of zeolites on the performance in the hydroalkylation of benzene to cyclohexylbenzene (CHB) were investigated in detail at low temperature. Characterization methods such as XRD, NH3-TPD, BET and SEM were well applied. Results indicate that catalysts with relatively small pore channel and large acidity amount, like HZSM-5 and H-IM-5, and the catalysts with large size pore and low acidity content, like H RZM all work poor, with low benzene conversion (<16%) and CHB selectivity (<45%). Yet, those catalysts with amplified pore channel and moderate amount of acid sites, like HBETA and HMCM-49, exhibit relatively high conversion (36.61% and 34.69%, respectively) and selectivity (62.85% and 71.55%, respectively) in the hydroalkylation reaction to cyclohexylbenzene. Therefore, it is concluded that HY zeolite with more wide pore channels and larger acidity amount is the most suitable catalyst carrier, of the highest benzene conversion (48.63%) and CHB selectivity (82.94%).