【作者】 张波；

【导师】 仲兆平；

【作者基本信息】 东南大学 ， 环境工程， 2016， 博士

【摘要】 生物质能的推广利用有助于缓解日益严重的能源与环境问题,在众多的生物质能源化开发途径中,催化快速热解(catalytic fast pyrolysis,CFP)制油技术具备良好的前景。但是,CFP所得生物油存在缺氢多氧的显著问题,需要开展针对性改善研究。本论文从生物质原料、HZSM-5催化剂、热解反应器和工艺、初级生物油等多方面对CFP制油技术进行全面系统的优化研究,提高生物油中烃类相对含量,降低含氧量。在原料方面创新性地开展了玉米秸秆和多氢原料高密度聚乙烯(high-density polyethylene,HDPE)催化共热解的研究,提高了烃类在产物中的相对含量,为从生物质原料源头补氢建立了理论基础。玉米秸秆和HDPE在催化共热解过程中存在显著的协同作用,会促进烃类生成。当热解温度为750℃时,可冷凝挥发性有机产物产率达到最大。当玉米秸秆/HDPE质量比大于1.0时,产物中芳香烃相对含量变化不明显;当玉米秸秆/HDPE质量比小于1.0时,芳香烃相对含量随着玉米秸秆/HDPE质量比的减小而稳步增加。在催化剂方面提出了 HZSM-5分子筛抗结焦改性调控的新方法。首先利用水热处理对HZSM-5催化剂进行脱氧效果优化研究:发现随着水热处理温度的提高,可冷凝挥发性有机产物产率不断降低,且水热处理的HZSM-5催化剂使得玉米秸秆热解气中C02和烃类含量明显提高,能够提高脱氧效果,且水热处理温度越高,催化脱氧效果越好。接着对HZSM-5催化剂进行了预结焦和再生处理,试验结果表明,对HZSM-5催化剂进行适当的预结焦,可以降低焦的产率,提高生物油的品质。在热解反应器和工艺方面率先开发了玉米秸秆微波辅助加热催化快速热解(microwave-assisted catalytic fast pyrolysis,MACFP)制油新技术。首先研究了 MACFP双级热解制油技术,考察了关键工况参数对产物分布和生物油品质的影响。结果表明反应温度为500℃时热解制油效果最佳,此外催化剂用量的提高会降低生物油产率并提高其品质。研究结果还显示MACFP双级热解制油的效果优于单级热解。以此为基础,进一步将外表面经过Si02化学气相沉积改性的抗结焦HZSM-5催化剂应用于玉米秸秆MACFP双级热解制油技术,降低了过程中催化剂的结焦量和生物油中含氧化合物的相对含量,进一步提高了生物油中烃类的相对含量。最后在初级生物油方面首次通过"初级生物油乙醚萃取——乙醚可溶物(ether-soluble fraction,ES)微波加热催化酯化"的组分分离提质和"初级生物油链式氧化催化脱氧——电催化温和加氢——催化裂解制烃"的进一步脱氧补氢精炼这两条技术路线对生物油进行了品质提升研究。在第1条技术路线中,乙醚萃取所得ES的物理和化学性质均得到有效改善,有助于提高生物油的品质。ES微波加热催化酯化试验中,微波加热条件下酸类转化效果远优于传统加热方式,微波加热催化酯化后ES中酸类的种类和总相对含量明显降低,而酯类的种类和相对含量则均有提高。在第2条技术路线中,经Zn粉脱氧提质的生物油含氧量下降23.92%,酸类、醇类和糖类化合物的相对含量有所降低,而酯类、羰基类和酚类化合物的相对含量则升高;电催化温和加氢之后的生物油中酸类、酯类、羰基类、酚类、糖类和呋喃类化合物的相对含量均有所降低,而醇类的相对含量则大幅度上升;催化裂解制烃时,产物中芳香烃、烯烃以及总化学品的碳产率随着原料有效氢碳比的增加而增加。论文还对有效氢碳比的定义进行了修正,在修正时综合考虑了原料宏观元素组成和结构特征。更多还原

【Abstract】 The development of biomass energy is beneficial for alleviating increasingly serious energy and environmental problems.A wide array of methods has been researched for the utilization of biomass energy,and one of the most attractive ways is catalytic fast pyrolysis(CFP)technology for the production of liquid fuels(termed bio-oil).However,hydrogenation and deoxygenation are needed for the generated bio-oil,and foundational research should be conducted.In order to promote the hydrocarbon production in biomass CFP process,a comprehensive systematic optimization research is carried out form the aspects of biomass feedstock,HZSM-5 catalyst,pyrolysis reactor and process,and primary bio-oil in this thesis.Catalytic fast co-pyrolysis of corn stover and high-density polyethylene(HDPE)was carried out to increase the relative content of hydrocarbons in pyrolysis vapors.The results illustrated that there was a remarkable synergistic effect between corn stover and HDPE,resulting in a promotion for hydrocarbon production.Besides,the highest yield of pyrolysis vapors was achieved at the reaction temperature of 750℃.When the mass ratio of corn stover to HDPE was above 1.0,the relative content of aromatic hydrocarbons remained virtually constant,and then increased with decreasing mass ratio of corn stover to HDPE when this mass ratio was below 1.0.Fresh HZSM-5 catalyst was hydrothermally treated,and catalytic upgrading of corn stover fast pyrolysis vapors with fresh and hydrothermally treated HZSM-5 catalysts was studied.Hydrothermal treatment caused a reduction in the yield of pyrolysis vapors,and HZSM-5 catalyst with higher hydrothermal treatment temperature resulted in a higher relative content of carbon dioxide and hydrocarbons.On the other hand,the increase of hydrothermal treatment temperature was also conducive to the decrease of oxygen content in the organic pyrolysis vapors.Results also showed that pre-coking was a good method to minimize coke yield and induce the formation of target products.A novel technology of two-step microwave-assisted catalytic fast pyrolysis(MACFP)of corn stover for bio-oil production using microwave absorbent and HZSM-5 catalyst was investigated.The results showed that the optimum MACFP temperature was 500℃,and the increase of catalyst-to-biomass ratio reduced the bio-oil yield and promoted the bio-oil quality.In addition,compared to one-step MACFP,two-step MACFP could reduce the use of HZSM-5 catalyst and improve the bio-oil quality.Also,SiO2-chemical vapor deposition modified HZSM-5 was applied in MACFP process,leading to the decrease in coke yield and relative content of oxygenates and increase in relative content of hydrocarbons in the bio-oil.The primary bio-oil was also upgraded in this thesis using two technical routes.In the first technical route,primary bio-oil was first extracted by ether,and then microwave-assisted catalytic esterification of ether-soluble(ES)fraction was conducted.Experimental results showed that ES had a better quality compared to crude bio-oil,and the relative content of acids in ES decreased dramatically while that of esters increased after microwave-assisted catalytic esterification.Meanwhile,microwave heating resulted in a better effect in contrast with conventional heating method.In the second technical route,primary bio-oil was upgraded using looped-oxide catalysis technique first,and after upgrading the oxygen content in bio-oil reduced significantly,and the relative contents of acids,alcohols and sugars decreased while those of esters,carbonyls and phenols increased.Then the upgraded bio-oil was further refined using electrocatalytic hydrogenation(ECH)technique,and after ECH,the relative contents of acids,esters,carbonyls,phenols and furans decreased while the relative content of alcohols increased significantly.Finally,catalytic cracking of the generated bio-oil was carried out to produce hydrocarbons,and the carbon yield of aromatics,olefins and total chemicals increased with the increase in hydrogen to carbon effective ratio.In this thesis,the definition of hydrogen to carbon effective ratio was improved,which combined the macro level element compositions and structural features in the feedstocks.更多还原