Experimental Research On Biomass Pyrolysis And Tar Catalytic Cracking In A Fixed Bed

As a clean and renewable resource, biomass is a new way to resolve the problem of fossil energy shortage and environment pollution. Not only can biomass pyrolysis technology convert low-quality biomass to high-quality liquid fuel or gas, but also some valuable chemical materials have been paid great attentions during these years. This paper focused on the mechanism about tar in the process of biomass pyrolysis technology, and porous particles performed on the catalytic cracking of biomass tar.First of all, four typical kinds of biomass were chosen to be conducted in a vertical fixed bed reactor. the influence of pyrolysis condition on tar production from biomass materials,such as pyrolysis temperature and residence time, was studied. By Comparing study of cellulose and lignin content in the raw different type of biomass, higher cellulose content results in a higher yield of tar. While the higher content of lignin, the higher the yield of char produced. The tar yield is highest at 600℃. Pyrolysis gas residence time at high temperature was also an important factor. The longer the stay, the lower the yield of tar.The tar catalytic cracking experiment of the sample was conducted using porous silica (porous, low catalytic performance), activity Al₂O₃ (porous, high catalytic performance), zeolite (porous, high catalytic properties ), compared with non-porous Al₂O₃ particles melt and quartz sand. The results show that the order of tar reduction is : zeolite > activated alumina > activated alumina melt> porous silica> silica sand, and with the increase of the catalyst bed height, the ratio of tar cracking was increased.Finally, the main components of biomass pyrolysis tar was analyzed by GC-MS. The results show that the residence time played an important role in the reduction of tar by using porous with low catalytic particles, which resulted in an reduction of polycyclic aromatic compounds in the tar. While the role of porous particle with high catalytic activity reduced the tar by chemical catalysis because the small molecules tar, such as phenol and phenol derivatives, and some medium-sized molecules were reduced, but the content of polycyclic aromatic hydrocarbons were increased.