Effect of K and Ca elements on transient light hydrocarbons and oxygen-containing gases during biomass fast pyrolysis

doi:10.11949/j.issn.0438-1157.20160032

Abstract

Abstract:

K and Ca elements in the biomass are in the form of inorganic and organic matter. AAEM species affect the chain scission and depolymerization process during the biomass pyrolysis of lignin, cellulose and hemicellulose molecules. To a certain extent, it affects the formation and transformation of biomass pyrolysis gas. In the process of pyrolysis reaction, the intermediate transient product has a very important significance for the formation of final product during the pyrolysis reaction. In this paper, biomass (rice husk) was treated with acid washing, and then the directional load of K, Ca elements, respectively. By using Py-GC/MS in the pyrolysis temperature of 500—900℃, the experimental study on rapid pyrolysis of biomass was carried out. By gas chromatography mass spectrometry (GC/MS), a semi quantitative analysis was made on the types and contents of light hydrocarbons and oxygen-containing species. It explained the effect of K and Ca elements on the transient light hydrocarbons and oxygen-containing species during biomass fast pyrolysis and the formed mechanism transformation of pyrolysis gas phase. At low temperature (≤600℃), fast pyrolysis instantaneous gas products of H-form, K-loaded and Ca-loaded biomass were mainly CO, CO₂ and CH₄. K and Ca elements promoted the generation of CO and CO₂. However, at high temperature (≥700℃), C₃H₆ became the main transient gas products. Ca element had a certain promotion effect on the formation of C₃ (C₃H₆), while K element inhibited the generation of C₃H₆.

Key words: biomass, fast pyrolysis, K, Ca, transient product

摘要：

K、Ca元素以无机态和有机态的形式赋存于生物质内，影响着生物质热解过程中木质素、纤维素及半纤维素分子的断链及解聚过程，进而一定程度地影响着生物质热解气相产物形成与转化。热解反应过程中中间瞬态产物作为气体合成的中间产物对于热解反应最终气相产物的形成具有极为重要的研究意义。将生物质（稻壳）进行了酸洗处理，再定向负载K、Ca元素，利用Py-GC/MS在500~900℃热解温度下，对生物质原料进行了快速热解的实验研究。利用气相色谱质谱仪（GC/MS）对进样延迟时间为20 s时生物质快速热解瞬态轻烃及含氧气态组分的种类及含量进行了在线半定量分析，从而进一步表征了K和Ca元素对生物质快速热解气相组分的影响以及热解反应过程中气相中间产物的形成转化机制。研究结果表明：低温条件下（≤600℃），H-form、K-loaded和Ca-loaded生物质快速热解瞬态气体产物以CO、CO₂、CH₄为主，K与Ca元素促进了生物质热解CO与CO₂的生成。高温条件下（≥700℃），C₃H₆成为20 s瞬态热解过程的主要气相产物，Ca元素对C₃（C₃H₆）等物质的形成具有一定的促进作用，而K元素一定程度上抑制了C₃H₆的生成。

关键词: 生物质, 快速热解, 钾, 钙, 瞬态产物

CLC Number:

X382.1

FENG Dongdong, ZHAO Yijun, ZHANG Yu, QIAN Juan, SUN Shaozeng. Effect of K and Ca elements on transient light hydrocarbons and oxygen-containing gases during biomass fast pyrolysis[J]. CIESC Journal, 2016, 67(7): 2970-2978.

冯冬冬, 赵义军, 张宇, 钱娟, 孙绍增. K和Ca元素对生物质快速热解瞬态轻烃及含氧气体的影响[J]. 化工学报, 2016, 67(7): 2970-2978.

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