Effect of acid-metal balance of bifunctional Pt/Beta catalysts on vapor phase hydrodeoxygenation of m-cresol.

• HDO of m-cresol was studied at 250 °C and 1 atm on Pt/Beta with varying BAS/Pt. • Increasing BAS density increases diffusion constraints of m-cresol and products. • Increasing BAS/Pt ratio reduces both the reaction rate and TOF of HDO. • Products distribution varies due to the combined effects of BAS/Pt and diffusion. • A low BAS/Pt is beneficial for improving stability by reducing coke deposition. Metal/zeolite bifunctional catalysts have been widely explored for hydrodeoxygenation (HDO) of phenolics. However, the effect of acid-metal balance is not clearly understood because it is difficult to decouple this from other effects. In this work, a series of 1 wt.% Pt/Beta catalysts with different Brønsted acid site (BAS) to surface Pt ratios (BAS/Pt) were prepared by varying only the density of BAS, and tested in HDO of m-cresol at 250 °C and atmospheric pressure. Increasing BAS density increases intra-crystallite diffusion constraints of m-cresol/products due to strong chemisorption on BAS, and therefore slows their transportation through BASs toward the Pt sites inside the micropores of zeolite. As a result, both the reaction rate and turnover frequency of HDO are reduced with increasing BAS/Pt ratio. Increasing BAS/Pt ratio increases the yield of ring contraction products but reduces the yields of methylcyclohexane and methylcyclohexanone, because of the increased acid functionality and diffusion constraints of intermediates. A low BAS/Pt ratio is beneficial for improving catalytic stability by reducing coke deposition. [ABSTRACT FROM AUTHOR]