Leaching Char with Acidic Aqueous Phase from Biomass Pyrolysis: Removal of Alkali and Alkaline-Earth Metallic Species and Uptakes of Water-Soluble Organics
Leaching Char with Acidic Aqueous Phase from Biomass Pyrolysis: Removal of Alkali and Alkaline-Earth Metallic Species and Uptakes of Water-Soluble Organics
复制标题
DOI：
10.1021/acs.energyfuels.1c01889
复制
发表时间：
2021-07
期刊：
影响因子：
5.3
通讯作者：
Tianlong Liu;Xiangpeng Gao;Alireza Z. Mofrad;Shinji Kudo;Shusaku Asano;J. Hayashi
中科院分区：
文献类型：
--
作者：
Tianlong Liu;Xiangpeng Gao;Alireza Z. Mofrad;Shinji Kudo;Shusaku Asano;J. Hayashi
通常需要从生物质和/或其热解衍生的炭中去除碱金属和碱土金属（AAEM）物质以减轻其燃烧期间的灰分相关问题。用热解产生的酸性水相（AP）浸出生物质是一种很有前途的策略，但遇到了几个问题，包括脱水后湿生物质中的高水分含量和生物质中有机碳的损失。在这里，我们提出了一个新的过程，浸炭与热解AP的AAEM物种的去除和水溶性有机物的焦炭的吸收。在450 °C下，在螺旋钻反应器中对小麦秸秆热解产生的焦炭和热解AP进行时间依赖性浸出，液固质量比为20。结果表明，大部分K、Mg和Ca在第一个小时内浸出。热解AP中的非酸性化合物对K的浸出有一定的阻碍作用，但对Mg和Ca的浸出没有影响。除丙酮醇外，其他有机化合物（例如，糠醛和酚类化合物）在第一个小时内迅速降解，在1-2小时内变慢，然后达到平衡。密度泛函理论（DFT）的计算结果表明，这些有机化合物和焦炭之间的相互作用的化学吸附的存在。在优化的浸出时间（1小时）的重复浸出运行表明，热解AP是足够的从同一个运行中浸出的焦炭，实现去除率为10.63.7wt%的K，10.43.7wt%的Mg，和10.60.7wt%的Ca。经过多次浸取后，浸出液中只剩下2，3-丁二酮、丙酮醇、2（5 H）-呋喃酮和剩余的乙酸4种有机物，简化了热解AP的组成。用热解AP浸出炭而不是麦草提供了显著的优点，包括脱水后湿固体中的水分含量降低，有机碳的损失可以忽略不计，以及酚类化合物的捕获增强。
The removal of alkali and alkaline-earth metallic (AAEM) species from biomass and/or its pyrolysis-derived char is often required to mitigate ash-related issues during their combustion. Leaching of biomass with an acidic aqueous phase (AP) produced from its pyrolysis is a promising strategy but encounters several issues, including high moisture content in wet biomass after dewatering and loss of organic carbon from biomass. Here, we propose a new process that leaches char with pyrolytic AP for the removal of AAEM species from and the uptakes of water-soluble organics by char. The char and pyrolytic AP produced from the pyrolysis of wheat straw at 450 °C in an auger reactor were subjected to time-dependent leaching at a liquid-to-solid mass ratio of 20. The results demonstrate that the majority of K, Mg, and Ca are leached within the first hour. Nonacidic compounds in the pyrolytic AP slightly hinder the leaching of K but have no impacts on that of Mg and Ca. Except for acetol, the uptakes of other organic compounds (e.g., furfural and phenolic compounds) by char are rapid in the first hour, become slower in 1–2 h, and then reach equilibrium. The results from density functional theory (DFT) calculations suggest the presence of chemisorption for the interactions between these organic compounds and char. Repeated leaching runs at the optimized leaching time (1 h) suggest that the pyrolytic AP is sufficient for leaching the char from the same run, achieving removal rates of ∼63.7 wt % for K, ∼43.7 wt % for Mg, and ∼60.7 wt % for Ca. After repeated leaching, there are only four organic compounds, including 2,3-butanedione, acetol, 2(5H)-furanone, and the remaining acetic acid, left in the leachate, simplifying the compositions of the pyrolytic AP. Leaching the char, instead of wheat straw, with the pyrolytic AP offers significant advantages, including the reduced moisture content in the wet solid after dewatering, negligible loss of organic carbon, and enhanced capture of phenolic compounds.