采用共沉淀法合成了铜铬类水滑石(CuCr-HTLc)和铜铝类水滑石(CuAl-HTLc),借助XRD、IR及N2吸附-脱附等方法对其进行了表征。并将合成的两种催化剂分别应用于苯甲醛与甲醇反应生成安息香甲醚反应中进行活性评价。结果表明,当合成体系中,二价金属离子M^2+与三价金属离子M^3+物质的量之比为2/1,共沉淀pH值分别控制在4.3±0.2和4.9±0.2时,可合成得到CuCr-HTLc和CuAl-HTLc。二者相比,前者具有较好的晶型、极窄的孔径分布、较高的比表面积。当反应温度为50℃、反应时间为90 min时,CuCr-HTLc催化苯甲醛与甲醇反应的苯甲醛转化率为89.56%,安息香甲醚选择性接近100%;而采用CuAl-HTLc催化剂时,苯甲醛转化率为61.49%,安息香甲醚选择性接近100%。因此,对于催化苯甲醛与甲醇生成安息香醚的反应,CuCr-HTLc优于CuAl-HTLc。
The CuCr-HTLc and CuAl-HTLc were synthesized by co-precipitation method and characterized by XRD, FT-IR and N2-adsorption/desorption measurements. The catalytic reaction of benzaldehyde and methanol to prepare benzion methyl ether was performed to evaluate the catalytic activites of CuCr-HTLc and CuAl-HTLc. The result showed that CuCr-HTLc and CuAl-HTLc were obtained when the mole ratio of M^2+/M^3+ in synthesis system was 2/1 and final values of pH were controlled at 4. 3 ±0. 2 and 4. 9 ± 0. 2, respectively. Compared with CuAl-HTLc, CuCr-HTLc possessed better crystalline shape, bigger specific surface area, narrower pore structure. Under the conditions of 50~C and 90 min the highest conversion 89.56% of benzaldehyde in the catalytic reaction of benzaldehyde and methanol over CuCr-HTLc could be reached, with the benzoin methyl ether selectivity of nearly 100%, while the highest conversion of benzaldehyde over CuAl-HTLc was only 61.49%, with the benzoin methyl ether selectivity of nearly 100%, indicating that the CuCr-HTLc performanced better than CuAl-HTLc in catalytic reaction of preparing benzoin methyl ether.