(219h) Hierarchical Zeolite Composite Catalyst from the Aerosol-assisted Encapsulation of ZSM-5in Ordered MCM-41 Microspheres

Despite the high activity of zeolites for the cracking of hydrocarbon molecules, its rapid deactivation due to coke deposition remains a drawback. These microporous zeolites also need to be embedded in meso/macro porous supports to improve heat and mass transport within a fixed bed reactor as well as reduce the pressure drop across the reactor. By dispersing zeolites within the matrix of mesoporous silica such as MCM-41, the MCM-41 can serve as a protective coating by acting as a sacrificial material for coke deposition and will also enable improved transfer of reactants to the zeolites. We report new findings in the use of an aerosol-assisted synthesis technique to incorporate ZSM-5 zeolites into the matrix of spherical MCM-41 nanoparticles. In this work, pre-synthesized ZSM-5 was introduced into silica precursor solution and aerosolized through a furnace using N2 as carrier gas. Detailed characterization of the synthesized catalysts using electron microscopy (SEM and TEM), BET analysis and X-ray diffraction (XRD) confirmed the encapsulation of the ZSM-5 within the MCM-41 matrix. To determine the accessibility of reactants to the encapsulated ZSM-5 through the pores of MCM-41, we performed the catalytic reduction of 4-nitrophenol to 4-aminophenol over encapsulated Ni/ZSM-5. We have also shown the efficacy of this composite catalyst towards improving the catalytic pyrolysis and upgrading of miscanthus x gigantus biomass to liquid fuels. The mesoporous matrix of the MCM-41 can also serve as support for metal catalysts leading to the coupling of multi-stage cracking and upgrading reactions into one catalytic system. These properties have immense implications for hydrocarbon processing and the production of sustainable fuels.