Efficient Conversion of m-Cresol to Aromatics on a Bifunctional Pt/HBeta Catalyst

The catalytic conversion of meta-cresol (3-methylphenol) was investigated over HBeta, Pt/SiO2, and Pt/HBeta catalysts at 400 degrees C and atmospheric pressure. The acid sites of zeolite HBeta catalyze methyl transfer reactions (isomerization and transalkylation), yielding cresol isomers (para- and ortho-cresol), dimethylphenol (xylenol) isomers, and phenol. Pt alone catalyzes hydrodeoxygenation and hydrogenation reactions, leading to toluene as the major product and methylcyclohexane as the minor product. Bifunctional Pt/HBeta catalyzes both methyl transfer reactions and hydrodeoxygenation reactions at the same time, producing toluene, benzene, and xylenes. The Pt/HBeta catalyst is about 10 times more active than the Pt/SiO2 catalyst toward hydrodeoxygenation, with a turnover frequency (on the basis of Pt only) 3 times higher, highlighting the significant role of acid sites in the metal-catalyzed hydrodeoxygenation reactions of phenolics. While Pt/HBeta and Pt/SiO2 exhibit similar rates of coke formation, the former has a higher stability than the latter under the same reaction condition's.