木质纤维素解聚平台分子催化合成航油技术的进展

摘要

航油作为一种重要的空中交通燃料,它的不可替代性和航空业碳减排的压力,迫使航空业对生物航油的需求不断加大.由于油脂原料的局限性,使得未来生物航油的原料将趋向多元化发展,逐渐延伸到糖、木质纤维素等原料.木质纤维素类生物质具有储量丰富、廉价易得的优势,以木质纤维素为原料制备航油的技术近年来得到了大力发展.然而木质纤维素组分中的碳链结构与航油分子的碳链结构不匹配,所以木质纤维素制备航油的技术关键在于如何以中间分子,如CO和H2小分子的费托合成路线以及糠醛、乙酰丙酸等木质纤维素解聚平台分子的合成路线,通过合适的催化反应合成长链正/异构烷烃(C8～C16).由于木质纤维素解聚平台分子保留了原料组分中的碳骨架以及多种功能官能团,比较容易通过合成方法来调控燃料的品质和特性,所以近年来有关木质纤维素解聚平台分子催化合成航油的技术途径及其催化工艺的报道不断涌现.为了充分认识此类航油技术的发展潜力,本文以糠醛、乙酰丙酸、多元醇等几种重要平台分子的碳链构建方式为线索总结了合成航油的各种技术途径和相应的催化工艺.并结合作者的研究工作,从技术应用性和化工过程实现的角度分析了各种技术途径的优缺点以及所面临的共性难题,同时对未来生物航油技术的发展进行了初步展望.%As an important air transportation fuel, aviation fuel is irreplaceable and faces the pressure of carbon emission reduction regulations in the aviation industry, which will significantly increase demand for aviation biofuel. Due to the limitation of grease raw materials, the feedstocks of aviation biofuel will tend to develop in a diversified way in the future, and gradually extend to sugar, lignocellulose and other raw materials. Lignocellulose biomass has the advantages of abundant reserves, low price and easy availability, and the technology of producing aviation fuel from lignocellulose feedstock has been greatly developed in recent years. However, the carbon-chain structure of lignocellulose components does not match that of aviation fuel molecules, so the key technology of preparing aviation fuel from lignocellulose depends on synthesis of long-chain normal/isoparaffins (C8-C16) by appropriate catalytic reaction with intermediate molecules, such as Fischer-Tropsch synthesis from CO and H2 small molecules and cascade catalysis routes from furfural, levulinic acid or other platform molecules. Because lignocellulose platform molecules retain the carbon skeleton and various functional groups that existed in the raw material components, it is easier to control the quality and characteristics of fuel by synthetic methods. In recent years, many reports about the catalytic technologies and conversion pathways of aviation fuel synthesis from lignocellulose platform molecules have been emerging. In order to fully understand the development potential of these aviation technologies, the review summarized various conversion pathways and corresponding catalytic technologies of aviation fuel synthesis by taking the carbon-chain construction methods of several important platform molecules such as furfural, levulinic acid and polyol as the backbone. Based on authors' research work, the advantages and disadvantages of various technical approaches and faced common problems are analyzed from the perspective of technical applicability and chemical process realization. Lastly, a preliminary prospect of the development of aviation biofuel technology is presented.