【摘要】 为研究烘焙与催化剂对生物质热解产物特性的耦合影响机制,该文选用HZSM-5催化剂,对不同温度（200、230、260、290℃）烘焙后的柏木进行热解试验。结果发现,将烘焙与HZSM-5催化剂联用后,随着烘焙温度的升高,催化热解后积碳量呈下降趋势,最高降低了62.6%;气体产物中CO的体积分数从53.69%降低至40.84%,H₂和CO2的体积分数分别增大了43.1%和35.04%,CH₄的体积分数整体变化不明显;液体产物中,酸类物质大幅减少,芳香烃类产物显著增多,酚类产物发生富集;结果表明,烘焙与HZSM-5催化剂的联用有效地改善了快速热解产物尤其是生物油的品质。但是也要指出,烘焙温度过高时,积碳量增多、芳香烃类产物减少,因此柏木适宜的烘焙温度应该选择在230²60℃之间。更多还原

【Abstract】 Fast pyrolysis of biomass is a promising technology for bio-energy because of its high liquid yield and low cost. The liquid product of fast pyrolysis is called bio-oil, which is complex mixtures of water and various organic compounds. Bio-oil has many advantages such as little sulfur and nitrogen content, highly potential values, readily stored and transported properties. However, the high acidity, low heating values and high oxygen and water contents in bio-oil limit its broaden applications. Catalytic pyrolysis and catalytic upgrading of pyrolysis vapors have been used to improve the quality of bio-oil. However, there is a crucial challenge: Rapid deactivation of catalyst caused by serious coking. The relevant studies have shown that catalyst deactivation has a direct relationship with the high content of oxygenated compounds in pyrolysis volatile caused by high oxygen content in biomass. In addition, thermal pretreatment of biomass, torrefaction, has been shown to improve the quality of bio-oil by lowering the oxygen content and enhancing the aromatic yield. So, in this paper, the couple effects of torrefaction and catalytic pyrolysis on characteristics of pyrolytic products of cedarwood have been investigated. Pretreament of cedarwood via torrefaction was performed in a tube furnace at varying reaction temperature（200, 230, 260, 290℃） with a residence time of 30 min. The torrefied cedarwood were characterized by elemental analysis and proximate analysis. The results showed that increasing torrefaction temperature caused the increase of carbon content from 48.16% to 54.3%, the oxygen content decreased from 44.33% to 35.65%. And the torrefied cedarwood product has a brown/black color, reduced volatile content and increased energy density: 21.25 MJ/kg（after 30 min reaction time at 290℃） versus 18.13MJ/kg for untreated cedarwood. Then the torrefied cedarwood were subsequently catalytically fast pyrolyzed over HZSM-5 in a vertical tubular reactor at 550 ℃with a residence time of 30 min. The gas products of pyrolysis were analyzed by chromatograph（GC）, and liquid products were analyzed by gas chromatography mass spectrometry（GC-MS）. Torrefaction caused deacetylation and decomposition of hemicellulose, cleavage of ester linkages and demethoxylation of lignin. And the experimental results show that after coupled torrefaction and catalytic pyrolysis, increasing the torrefaction temperature caused the coke yield decreased; the content of CO in gas product decreased from 53.69% to 40.84%, the content of H₂ and CO₂ increased by 43.1% and 35.04% respectively, and the content of CH₄ had no obvious change. As for liquid products, with the increasing of torrefaction temperature, the content of acid significantly deceased, aromatic yield increased, and enrichment of phenols. The result indicated that the couple effects between torrefaction and catalytic pyrolysis are very important for upgrading of bio-oil. However, severe torrefaction can lead the coke yield increased and aromatic yield reduced. So the optimal torrefaction condition of cedarwood is 230-260℃.更多还原