Study On The Effect Of Char On Biomass Fast Pyrolysis

Biomass is considered only renewable carbon source which can replace fossil fuels in some degree. Biomass liquefaction is one of the most promising direction. Bio-oil catalytic upgranding is becoming a hot area of current research. Because of complex structure characteristics and internal metal elements, catalytic properties of biochar was discovered and understood. In addition, it cannot be ignored in the process of understanding the interaction between volatile and chars in fast pyrolysis. So understanding of interaction between biochar and volatile is important for understanding fast pyrolysis and developing the technology of upgranding of bio-oil.Cotton stalk char, corn stalk char were used as a catalyst for in-situ catalytic pyrolysis experiment. The temperature in the catalytic area and biochar adjust the yields of fluid production and gas together in the biochar catalytic pyrolysis experiment; The increasing temperature decrease fluid production and promote gas yields growth; Biochar added will expand the trend. Increased temperature of catalytic area promote acetic acid, hydroxyacetone and other straight chain ketones growth(the acetic acid increase a little in corn stalk series). However, acetic acid and hydroxyacetone continuously cracke over biochar while eyclopentanones are relatively stable even a little increase. Increased temperature of catalytic area promote phenols growth even some inhibitory effect. However, the phenols increase significantly under biochar catalysis. In addition, Temperature and biochar promote phenols with oxygenous and unsaturated branched chain to converting into phenols with saturated alkane branched chain on various degrees.Biochars with acid wash and Na, K, Mg, Fe impregnated were used as a catalyst for in-situ catalytic pyrolysis experiment. Metal and biochar characteristics(pore structure characteristics and surface chemical properties) play a important role on enrichment of phenols and cracking of acids; but there were some variances between Cotton stalk and corn stalk. The yield of hydroxyacetone decrease and eyclopentanones increase under catalysts because of the combined effect of both impregnated metal and biochar characteristics. Catalysis promote yields of H2, CH4 and CO, CO2 and C2H6 growth, and the Fe significantly effect on the growth of the hydrogen. Biochar characteristics and metal elements are important influencing factors on the volatiles catalytic cracking and reforming.Cotton stalk char promotes sugars cracking(yields of monosaccharide increase in C-FeCl3) and promote ketones growth(where eyclopentanones is dominating) in cellulose pyrolysis. In addition, it promote 5-Hydroxymethyl Furfural to converting into Furfural and 5-Methyl Furfural. Cotton stalk char promote ketones, alcohols and eyclopentanones growth in hemicellulose pyrolysis; The increase of alcohol is mainly related to the metal elements.