(738c) ZSM-5 Coating on SiC Foam Support As a Composite Catalyst for Fast Microwave-Assisted Pyrolysis of Biomass

Fast microwave assisted pyrolysis has been developed as an alternative process to convert biomass into biofuels with the advantages of uniform internal heating and easy process control. ZSM-5 is a type of zeolite often used in the pyrolysis process as a catalyst for upgrading pyrolysis vapor to form aromatic compounds. Traditionally, ZSM-5 powders or pellets are either mixed with biomass feedstock for in-situ catalysis or randomly packed as a fixed bed for ex-situ catalysis. One major drawback of the first scheme is the difficulty of recycling catalyst from its mixture with ash; for the second scheme, the main drawbacks include a) the limited and uneven heat and mass transfer through the catalyst bed, and b) the requirement of external heat source for maintaining the high temperature. Therefore, this study proposes a composite catalyst of ZSM-5 coated on SiC foam support as a better scheme of incorporating ZSM-5 in the microwave assisted pyrolysis process. ZSM-5 as the catalyst layer is coated on to the foam support by hydrothermal synthesis. SiC is used as the support material because of its excellent microwave absorbing ability together with its high thermal conductivity, low expansion coefficient and superior chemical inertness. In this composite catalyst, SiC absorbs microwave and provides heat to the ZSM-5 coatings without cracking or undesirable chemical reactions. The foam structure allows improved heat and mass transfer, narrower residence time distribution, and thus better control of the catalytic reaction. In the presentation, the effects of foam support pore size, catalyst layer thickness, catalyst temperature, and reaction time on the performance of the proposed catalyst will be discussed.