Synthesis of the hierarchical Fe-substituted porous HBeta zeolite and the exploration of its catalytic performance

Abstract

A series of hierarchical isomorphically Fe-substituted porous beta zeolites (BEAs) was synthesised in a one-step process via soft-template approach (nFe-HBeta, n = Fe/Al) and a series of Ni-based catalysts (10Ni/nFe-HBeta) was prepared by equal volume impregnation. The results showed that the nFe-HBeta zeolites possessed a sheet-like structure with a high crystallinity and numerous porous channels. The introduction of the heterogeneous iron atoms can reduce the degree of order of the mesoporous phase and decrease the size of the zeolite particles and the number of moderate and strong acidic sites. For the 10Ni/nFe-HBeta catalyst, a synergistic effect existed between the framework iron and NiO species, which can enhance the interaction between the active Ni and HBeta support, increase the dispersion of the active metal Ni, and reduce the NiO particle size. In the ethanol steam reforming (ESR) reaction, Fe introduction can inhibit the ethanol dehydration reaction through the shielding of acidic sites and could promote the steam reforming reaction of CO and CH4, effectively improving the H2 selectivity. Among the Fe-containing catalysts, 10Ni/0.15Fe-HBeta showed a H2 selectivity of up to 72.15% and an ethanol conversion rate of 99.6% at 500°C, while the amount of coke deposition was only 4.3% after a 12 h reaction.