基于不同碱金属/碱土金属催化方式的纤维素热解特性研究

Converting biomass into biofuels first involves breaking down solid polymers, in particular cellulose, which are long chains of glucose that constitute up to 60% of biomass into small fragments. Many systemic experiments have been carried out by other researchers about pyrolysis of cellulose. However, it's difficult to obtain nascent char, molten cellulose (intermediary cellulose) and primary volatile at the same time due to the limitation of various pyrolysis reactors. According to the review of literatures, there is no report about the influence of alkali and alkaline earth metal（AAEM） on the intermediary cellulose during pyrolysis. The experiments design of the study is introduced as follows. Different factor including temperature, heating rate and holding time will be consided in pyrolysis experiments. Ionic liquid is used to dissolve the cellulose and synthetic cellulose with specify content of AAEM can be obtained with the assistance of the supersaturated AAEM solution. Primary reaction products can be analysed quantitatively from cellulose pyrolysis in wire mesh reactor. It will promote understanding on the mechanism of primary and secondary reaction during cellulose pyrolysis. The influence of AAEM catalysis on primary products distribution during cellulose pyrolysis will be investigated. The objective of this study is to provide a basis for building more descriptive models of the evolution of chemical species during fast pyrolysis in practical reactor systems.

聚合物分解是生物质转换为生物燃料的首要过程，构成生物质的主要聚合物是纤维素。受反应器和实验条件的限制，已有针对纤维素热解特性的实验研究难以同时获得其热解反应的一次产物，包括热解过程中形成的初生焦、中间态纤维素及挥发份，尤其是有关碱金属/碱土金属（AAEM）的催化作用对中间态纤维素组分分布影响的研究尚属空白。 本项目将利用能最小化二次反应的金属网反应器，针对纤维素热解的典型一次产物进行定量分析，在此过程中综合考虑热解温度、升温速率、停留时间等因素对上述产物的影响；利用离子液体纤维素再生技术，合成具有特定AAEM含量的纤维素样品，通过在金属网反应器中不同催化方式的热解实验，探讨AAEM对纤维素热解典型一次产物分布的影响规律；本项目研究成果将有助于认识实际生物质热解过程中纤维素的反应路径、优化生物质热解性能，对改善其产物分布提供理论依据。

生物质作为唯一一种碳基新能源，能够缓解化石能源相关的能源短缺和环境污染。纤维素是木质纤维素三组分之一，其热解机理的揭示对于生物质热转化的工业应用至关重要。在前人的研究中，大量的二次反应阻碍了机理的揭示，而本项目利用最小化二次反应的金属网反应器，成功获得了纤维素热解的一次产物（初生焦、中间态纤维素、初生焦油），并对一次产物进行了充分的分析和表征。其中，针对中间态纤维素产量小、所含脱水糖类分析难的特点，本项目首次将苯甲酰氯衍生化耦合HP-LC的分析方法应用于脱水糖的定量分析，取得了很好的表现。定量分析的结果揭示了脱水糖从焦向焦油中转移的规律。此外，本项目探究了碱金属/碱土金属（AAEM）对于纤维素热解的催化作用，揭示了不同温度下，碱金属和碱土金属对于纤维素的不同催化效果。最终，本项目提出了纤维素热解和AAEM的催化机理路线，为生物质的工业化应用提供了重要的理论依据，有助于实际生物质热解过程中工艺条件的优化。