生物质非原位催化快速热解制取高芳香烃及烯烃含量生物油的机理研究

Biomass fast pyrolysis for bio-oil production technology has a wide application prospect. However, its extensive application as hydrocarbon fuel is restricted because bio-oil has undesirable properties such as a high oxygen content, instability, etc. Therefore, to produce bio-oil with high yield of aromatic and olefin hydrocarbons, making its properties similar to those of hydrocarbon fuel is a key problem to be solved urgently. Ex-situ catalytic fast pyrolysis is proposed for increasing yield of aromatic and olefin hydrocarbons of bio-oil and its mechanisms and effects will be investigated. Biomass catalytic fast pyrolysis experiments will be carried out in self-developed fluidized bed reactor for bio-oil production. ZSM-5 and CaO catalysts will be used together and the ZSM-5 catalyst will be modified. The suitable catalysts will be screened. Biomass ex-situ catalytic fast pyrolysis will be researched in order to analyze product regulation mechanism. Optimal parameters of biomass ex-situ catalytic fast pyrolysis will be determined. The kinetic model will be proposed and effect of pyrolysis parameters on pyrolysis product regulation will be deduced. Effect of hydrogen to carbon effective ratio on improving bio-oil quality will be investigated. In situ Fourier Transform Infrared Spectrometer will be used to monitor adsorption of pyrolysis vapor on the surface of the catalyst and structure changes of components of the pyrolysis vapor. In this way, catalytic reaction mechanism and possible deactivation mechanism of the catalyst can be investigated in molecular level. Chemical reaction mechanism of bio-oil during storage will be analyzed by data analytical method of metabonomics. This research will lay a theoretical foundation for production and application of bio-oil.

生物质快速热裂解制取生物油技术具有广阔的应用前景。然而，由于生物油含氧量高、化学稳定性差等缺点，限制了其作为碳氢燃料广泛使用，因此，制取高芳香烃及烯烃含量生物油，使其类似碳氢燃料的特性是亟待解决的关键问题。本项目提出研究生物质非原位催化快速热解方法对提高生物油中芳香烃及烯烃含量的机理及效果。利用流化床反应器进行非原位催化快速热解制取生物油试验。采用沸石和氧化钙催化剂联用、催化剂改性方法筛选出合适的催化剂。开展生物质非原位催化快速热解产物调控的机理分析，获得优化工艺条件，建立反应动力学模型，推断热解产物的调控机理。探讨改变原料有效氢碳比对改善催化热解生物油品质的促进作用。采用原位傅立叶变换红外光谱仪监测热裂解蒸气在催化剂表面的吸附及组成变化，从分子水平上探讨催化反应机理及催化剂可能的失活机制。运用代谢组学数据处理方法分析生物油在储存过程中发生的化学反应机理。为生物油的生产与应用奠定理论基础。

针对生物油含氧量高、化学稳定性差等问题，本项目提出研究生物质非原位催化快速热解方法对提高生物油中芳香烃及烯烃含量的机理及效果。取得的主要成果如下：1）明确了ZSM-5与CaO催化剂对生物质催化快速热解芳香烃选择性的调控机制。使用ZSM-5后，玉米秸秆催化热裂解主要产物中出现了甲苯、茚、萘、二甲基萘等烃类。在温度为550℃时，烃类选择性达到最高，为29.24%。在4 wt.%的铁改性ZSM-5作用下，芳香烃选择性最高，为38.28%。CaO 具有减少酸性馏分的潜力。2）阐明了生物质及其组分催化快速热裂解产物调控规律。微晶纤维素催化热裂解的活化能从214.32 kJ/mol降低到187.47 kJ/mol。使用8 wt.%镍改性ZSM-5时，半纤维素催化热裂解产物的芳香烃选择性最高，为54%。微晶纤维素、半纤维素、木质素和水稻秸秆催化热裂解的单环芳香烃的产率分别为 62.93、79.78、67.02 和 77.38 mg/g。3）明确了有效氢碳比对生物质-废旧轮胎共热裂解烃类选择性的促进作用。水稻秸秆与废旧轮胎在较佳有效氢碳比（0.441）下，使用ZSM-5时，共热裂解单环芳烃和烯烃的相对含量分别为22.92%和 49.42%。自由基理论表明生物质作为激活体引发废旧轮胎分解，废旧轮胎作为氢供体促进生物质的分解并增加烃类产物的相对含量。4）明晰杨木木屑非原位催化热裂解过程中催化剂失活机理和再生效果。制备了Fe负载多级孔ZSM-5催化剂，热重-原位红外光谱分析表明挥发物释放特征和FTIR光谱与热裂解行为一致。双金属Fe-Ni/ZSM-5在累积生物质与催化剂的质量比为4时催化剂失活程度很大，碳氢化合物产率从22.9%降至3.61%。由于理化性质的可逆变化，再生后催化剂在芳香烃制备中仍保持较高的活性。5）利用小型流化床热裂解装置，研究了稻壳热裂解温度、催化剂用量和催化剂放置位置对生物油理化特性的影响。随着热裂解温度升高，生物油的含水率和酸碱度变化规律一致，先降低后升高，而其灰分、热值、固含量和粘度呈先升高后降低的趋势。催化热裂解温度为500℃，生物油热值为22.16 MJ/kg。6）运用代谢组学方法分析生物油储存稳定性的机理。为生物油的生产与应用奠定理论基础。