负载铯催化剂上苯酚与甲醇醚化制苯甲醚

研究了不同酸碱中心、载体、前躯体和负载量对负载铯催化剂上苯酚与甲醇醚化制苯甲醚反应行为的影响。结果表明,碱性中心比酸性中心具有更高的苯甲醚选择性,碱性中心的阳离子影响催化剂的苯甲醚选择性。载体影响铯离子的电子结合能,从而影响催化剂的醚化活性;铯离子的电子结合能越低,催化剂醚化活性越低;载体影响催化剂强碱性位数量,从而影响苯甲醚选择性;强碱性位数量越多,副反应越容易发生,苯甲醚选择性越低。不同前躯体制备的Cs/Si O2由于表面相对铯原子数量不同而活性不同;Cs/Si O2的单层负载量为1.0 mmol/g,超过单层负载量后催化剂的平均活性显著下降。

Phenol etherification with methanol to anisole over supported Cs catalysts

The effect of acid and basic sites, support, cesium precursor and cesium loading on the performance of supported Cs catalysts in the etherification of phenol with methanol to anisole was investigated. The results illustrate that the cations of basic sites play an important role in the selective conversion of phenol to anisole; the basic sites give higher selectivity to anisole than the acid sites. The catalytic activity in phenol etherification decreases with the increase of the cesium ion binding energy, which is related to the support used. Moreover, the support also has an influence on the amount of strong basic sites, which is related to the selectivity to anisole; high amount of strong basic sites may promote the side reaction and decrease the selectivity to anisole. Cs/SiO₂ catalysts prepared with various precursors are different in the surface Cs/Si atomic ratio, which may also influence the catalytic activity in phenol etherification; if the cesium loading exceeds the monolayer dispersion of cesium on SiO₂, which is nearly 1.0 mmol/g, the average activity of Cs/SiO₂ in phenol etherification decreases greatly.