Investigations On Bio-Fuels Production From Crop Straws By Pyrolysis

Biomass energy is a kind of environmental friendly and renewable energy sources. Crop straw is a kind of important biomass resources and its energy-oriented utilization has great significance. The investigations on bio-fuels production from crop straws by pyrolysis were carried out in this paper.The effects of material types, heating rates and pretreatments on the crop straws pyrolysis properties and the release regulars of the products were investigated by thermogravimetric analysis (TG) coupled with Fourier transform infared spectrometry (FTIR), and the kinetic parameters were calculated by Distributed Activation Energy Model (DAEM). The results showed that the pyrolysis processes of wheat straw, cotton straw, sorghum straw and maize straw and the product compositions were similar. The activation energy of the four straws calculated by DAEM was slight different. The release of volatiles was promoted and the maximum concentration of the main products CO2, CO and CH4and its corresponding temperature increased with the increasing heating rates. Pretreatments had major effects on the product generation and the activation energy of wheat straw. On the man-made reaction equipment, the influence of demineralization pretreatments on the wheat straw pyrolysis product yields and compositions was studied. Using molten salt32wt%Li2CO3-33wt%Na2CO3-K2CO3as the biomass pyrolysis catalyst, heat carrier and dispersing agent, the effects of material types, pyrolysis temperatures, feeding rates and carrier gas flow rates on the crop straws pyrolysis process were investigated. The results indicated that the gaseous product yields of wheat straw were increased while the liquid product yields were decreased by demineralization treatments. Water and base leaching could advance the formation of H2and acid leaching was in favor of the production of CH4. The product yields and composition distributions of wheat straw were affected by the pyrolysis conditions in molten salt. The gaseous products of the four straws pyrolysis in molten salt mainly consisted of H2, CO2and CH4. The main compositions of bio-oil were oxygenated compounds. Pretreatment of material was conducted, which, to a certain degree, could improve the quality of bio-oil.This research provides a certain reference for a further understanding of biomass pyrolysis mechanism and the desired bio-fuels production.