Construction of Acid-Base Synergetic Sites on Mg-bearing BEA Zeolites Triggers the Unexpected Low-Temperature Alkylation of Phenol

Novel Mg-bearing BEA zeolites are synthesized to simultaneously endow significantly enhanced basicity without compromising acidity over the zeolite framework. Serving as efficient solid acid-base bifunctional catalysts, they achieve the liquid-phase selective methylation of phenol with methanol to produce o- and p-cresol (o/p=2) under mild conditions. The method is readily extendable to the alkylation of phenols with various alcohols. Stereo-and regioselectivity (>95% for p-product) was attained on the alkylation of phenol with bulky tert-butyl alcohol, rendering the first acid-base cooperative shape-selective catalysis relying on the basicity of zeolites. A preliminary mechanistic analysis reveals that the remarkable activity and shape-selectivity come from the superior special acidic-basic synergetic catalytic sites on the uniform microporous channels of the BEA zeolite.