Ding Ya-Long, Wang Hua-Qin, Xiang Mei, Yu Pei, Li Rong-Qiang, Ke Qing-Ping
College of Chemistry and Pharmaceutical Engineering, Huanghuai University, Zhumadian, China.
School of Chemical Engineering and Materials, Changzhou Institute of Technology, Changzhou, China.
Front Chem. 2020 Sep 25;8:790. doi: 10.3389/fchem.2020.00790. eCollection 2020.
With the demand of energy and re-utilization of wastes, the renewable lignocellulosic biomass, has attracted increasing and significant attention for alleviating the growing energy crisis and environment problems. As main components of lignocellulosic biomass, lignin, cellulose, and hemicellulose are connected by hydrogen bond to form a compact skeleton structure, resulting the trenchant condition of biomass pyrolysis. Also, pyrolysis products of above three main constituents contain a large amount of oxygenates that cause low heating value, high corrosiveness, high viscosity, and instability. Meanwhile, zeolites are of considerable significance to the conversion of lignocellulosic biomass to desirable chemical products on account of fine shape selectivity and moderate acid sites and strength. Among numerous zeolites, ZSM-5-based catalysts have been most extensively studied, and the acidity and porosity of ZSM-5 can be tuned by changing the content of Si or Al in zeolite. Beyond that, doping of other metal elements, such as Mn, Co, Ni, Ga, Ce, Pt, into ZSM-5 is also an efficient way to regulate the strength and density of acid sites in zeolite precisely. This review focused on the recent investigation of Ni-modified microporous ZSM-5 used in catalytic pyrolysis of lignin and cellulose. The application of metal-modified hierarchical ZSM-5 is also covered.
随着能源需求以及废弃物的再利用，可再生木质纤维素生物质因缓解日益严重的能源危机和环境问题而受到越来越多的关注。作为木质纤维素生物质的主要成分，木质素、纤维素和半纤维素通过氢键相连形成紧密的骨架结构，导致生物质热解条件苛刻。此外，上述三种主要成分的热解产物含有大量含氧化合物，导致低热值、高腐蚀性、高粘度和不稳定性。同时，由于具有良好的形状选择性以及适度的酸位点和强度，沸石对于将木质纤维素生物质转化为理想的化学产品具有重要意义。在众多沸石中，基于ZSM-5的催化剂得到了最广泛的研究，并且ZSM-5的酸度和孔隙率可以通过改变沸石中Si或铝或铝的含量来调节。除此之外，将其他金属元素，如锰、钴、镍、镓、铈、铂，掺杂到ZSM-5中也是精确调节沸石中酸位点强度和密度的有效方法。本综述重点关注了镍改性微孔ZSM-5在木质素和纤维素催化热解中的最新研究进展。还涵盖了金属改性分级ZSM-5的应用。
