熔盐热裂解生物质制生物油

Bio-oil production from biomass pyrolysis in molten salt

摘要:

为探讨热裂解条件对熔盐中生物质热裂解制生物油的影响，在自行设计的反应器中，以摩尔比为7∶6的ZnCl2-KCl混合熔盐作为热裂解的热载体、催化剂和分散剂，考察了500 ℃时添加的金属盐和生物质原料的影响，并采用气相色谱-质谱仪 (GC-MS) 对生物油的主要组成进行了分析。结果表明：添加的金属盐显著影响热裂解产物得率，稀土金属盐显著提高生物油得率，降低生物油的含水率，添加摩尔分数为5.0％ LaCl3时生物油得率为32.0％，含水率为61.5％；水稻秸秆热裂解的生物油和焦炭得率较高，稻壳热裂解的气体得率较高；金属添加盐对生物油组成有较强的选择性，LiCl和FeCl2对生物质向小分子裂解具有较强的催化作用，而CrCl3、CaCl2和LaCl3对生物油二次裂解具有抑制作用。研究结果为熔盐热裂解生物质制生物油提供了参考。

Abstract:

In order to investigate the effects of pyrolysis conditions on bio-oil production from biomass in molten salt, experiments of biomass pyrolysis were carried out in a self-designed reactor in which the molten salt ZnCl2-KCl (with mole ratio 7/6) was selected as heat carrier, catalyst and dispersion agent. The effects of metal salt added into ZnCl2-KCl and biomass material on biomass pyrolysis were discussed, and the main compositions of bio-oil were determined by GC-MS. Metal salt added into molten salt could affect pyrolysis production yields remarkably. Lanthanon salt could enhance bio-oil yield and decrease water content in bio-oil, when mole fraction of 5.0% LaCl3 was added, bio-oil yield could reach up to 32.0%, and water content of bio-oil could reduce to 61.5%. The bio-oil and char yields were higher when rice straw was pyrolysed, while gas yield was higher when rice husk was used. Metal salts showed great selectivity on compositions of bio-oil. LiCl and FeCl2 promoted biomass to pyrolyse into smaller molecular weight compounds. CrCl3, CaCl2 and LaCl3 could restrain second pyrolysis of bio-oil. The research provided a scientific reference for production of bio-oil from biomass pyrolysis in molten salt.