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.