Catalytic fast pyrolysis of biomass over core-shell HZSM-5@silicalite-1 in a bench-scale two-stage fluidized-bed/fixed-bed reactor

In order to inhibit the coke formation on the external surface of HZSM-5 during catalytic fast pyrolysis (CFP) of biomass, core-shell structured HZSM-5@silicalite-1 zeolite catalysts were hydrothermally synthesized through the growth of silicalite-1 along the surface of a commercial HZSM-5. The catalyst characterization results indicate that silicalite-1 outer shell layer was successfully formed on the HZSM-5 core particles. Silicalite-1 coating was proved to be effective to reduce the external acidity as well as keep the internal acidity and channel patency of core HZSM-5 by catalytic probe reactions. The catalytic performances of HZSM-5@silicalite-1 samples in CFP of biomass were investigated using a bench-scale continuous feeding two-stage fluidized-bed/fixed-bed combination reactor. The results show that the productions of olefins and BTX were promoted (especially BTX), while the formations of catalyst coke and PAHs were significantly inhibited after silicalite-1 coating.