Passivated Surface of High Aluminum Containing ZSM-5bySilicalite-1: Synthesis and Application in Dehydration Reaction

:methanol dehydration reaction is an essentialprocess to bridge the biomass conversion and chemicals. However,the undesired distribution of zeolite acidity hinders its excellentcatalytic performance. In this work, the technique of passivatingsurface acidity of a high aluminum containing ZSM-5 zeolite by thegrowth of the silicalite-1 layer under hydrothermal conditions ispresented. The samples passivated with a single-step or double-stepsilicalite-1 deposition were tested for the dehydration of methanolto dimethyl ether and compared to the parent ZSM-5 zeolite usinga bench-scale packed bed reactor operated at 160-240 degrees C underatmospheric pressure. The formation of an amorphous silica layerdetermines the decrease of the accessible micropore surfacedetermining the drop in conversion and selectivity of the catalystwith the passivating single-step silicalite-1 deposition with respect to the parent zeolite. In contrast, the catalyst with a double-stepsilicalite-1 deposition showed a conversion close to the parent ZSM-5 zeolite one but with an improved selectivity at hightemperature, due to the low coke formation and retention in the highly porous structure

Automated summary

The technique of passivating surface acidity of high aluminum containing ZSM-5 zeolite by growing a silicalite-1 layer under hydrothermal conditions was investigated for methanol dehydration reaction. It was found that the catalyst with a double-step silicalite-1 deposition showed similar conversion to the parent ZSM-5 zeolite but improved selectivity at high temperature due to reduced coke formation and retention in the highly porous structure.