Study On Influence Of Additives On Biomass Pyrolysis

Energy sources is the base of human survival and development. Biomass energy is one of the most important renewable energies. Conversion biomass to high qulity gas and liquid fuels based on pyrolysis technology is of great significance to relax energy tension and environmental pollution of our country and raising peasant's income and to realize sustainable development of national economy.In this study, pyrolysis experiments by conventional and microwave heating were conducted for fir,pine,cotton stalk sawdust. The effects of temperature,particle of material,microwave power on yield of pyrolysis production and gas composition and evolving time of three biomasses pyrolysis were investigated.It highlights the effects of the eight inorganic additives (NaOH,Na₂CO₃,Na₂SiO₃,NaCl,TiO₂,HZSM-5,H₃PO₄,Fe₂(SO₄)₃)on the yield of pyrolysis production and evolving time and distribution of gas and liquid products and moisture of liquid water.With enactment temperature rising, slow pyrolysis of three kinds of biomass become more complete. With microwave power increasing, solid yields decrease and gas and liquid yields increase for fir pyrolysis,while liquid yields are greater than gas yields invariably.Eight additives all reduce the liquid yields of the three kinds of biomass in slow and microwave pyrolysis; larger heating speed leads to more gas yields and more effective calalytic role of the additives.Generally speaking, additives make the first drop of liquid appearing time shorter in microwave pyrilysis and the temperature corresponding to the appearance of the first liquid drop decrease,especially for those basic and acidic additives.It was found that gas product from three kinds of biomass pyrolysis consists mainly of H₂, C_H4, CO, CO₂. Most additives have made the molar fraction of H₂, CH₄ and CO increase and those of CO₂ decrease, thus enhancing content of combustible gas of gas product. HZSM-5 increases H₂ yield and H3PO4 decreases CO₂ yield to a great extent.Larger heating speed is advantageous for enhancing content of combustible gas of gas product,so is by microwave heating.The effects of additives on composition of liquid product is notable.The enrichment components of liquid are Furfural, Cyclopentenone, Butyrolactone, Phenol, 2-methoxy-, levoglucosan, d-Allose, Pentanal, Phenol,2-Butene-1,4-diol, D-Mannoheptulose. Almost all three biomasses pyrolysis products contain Furfural and Phenol, 2-methoxy-.Each additive have specific enrichment component. Synergetic effect of additives and heating manners can result in the enrichment of some components. The solid residue mainly contains residual carbon.