Optimization of Catalytic Upgrading of Pyrolysis Products

Biofuel production is an attractive alternative to conventional fossil fuel, effectively solving problems like resource depletion and greenhouse gas emission. Use of solid feedstock and organic wastes to produce biofuel is seen as a promising route from the economical and sustainability point of view. Pyrolysis is one of the possible thermochemical methods to convert solid biomasses to valuable liquid and gas products. However, the bio-oil obtained from pyrolysis can be used as biofuel only after an upgrading step. In facts, raw bio-oil contains various oxygenated organic compounds, which make it instable, and has high average molecular weight, high viscosity, and low heating value. A suitable method for upgrading bio-oil is catalytic cracking of the pyrolysis products. Catalytic upgrading converts high molecular weight compounds of the bio-oil into lower-weight molecules. This work investigated the slow pyrolysis and in-situ catalytic cracking of chicken manure in a lab-scale fixed bed reactor. The application to chicken manure is of upmost practical interest, since the pyrolysis process would provide an environmentally safe manner for solving the current problems about disposal of this waste. The catalyst considered was pellet-extruded zeolites (zsm-5). In order to study the effect of influential factors (temperature and catalyst to biomass ratio) on the obtained products, experimental design techniques were used. The process was investigated in both the absence and presence of the in-situ catalyst. The results were statistically analyzed and the influential factors were optimized with the aim of obtaining products with higher quality and heating value. The results can give a clue on how to compromise between the quality of the two potentially valuable products of pyrolysis process (bio-oil and biogas) and the energy requirement of the process.