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Acid-catalyzed fractionation of almond shells in γ-valerolactone/water
Biomass Conversion and Biorefinery ( IF 4 ) Pub Date : 2021-01-08 , DOI: 10.1007/s13399-020-01261-4
Arianna Corti , Esther Torrens , Daniel Montané

The fractionation of almond shells, an agro-industry residue available in some Mediterranean climate regions, was investigated using acid-catalyzed hydrolysis in γ-valerolactone (GVL)/water. A set of non-isothermal experiments at nominal temperatures of 120, 140, and 160 °C and sulfuric acid concentrations from 25 to 75 mM were developed using a constant 80% w/w GVL in water concentration and a reaction time of up to 120 min. GVL was an efficient medium and promoted solubilization of both lignin and hemicellulose, even at low temperature during the initial period of reactor heating, while cellulose conversion was limited. A temperature of 160 °C gave the highest extraction of lignin and hemicellulose, but recovery of hemicellulose carbohydrates was better below 140 °C. Sulfuric acid concentrations above 45 mM promoted excessive dehydration of xylose and glucose to furans and humins, which were recovered with lignin. A model was developed to describe the kinetics of lignin and hemicellulose solubilization. It distinguished three fractions of different reactivity in each polymer (lignin or hemicellulose): fast-reacting, slow-reacting, and unreactive. The amount of each fraction was correlated with acid concentration and reaction temperature. Activation energies and the other parameters in the model were obtained numerically by least-squares optimization using the data from the non-isothermal experiments. Activation energies for the fast-reacting and slow-reacting fractions of hemicellulose were 142 and 39.7 kJ mol−1, and for those of lignin 134 and 71.7 kJ mol−1, respectively. Acid concentration had a larger influence than temperature on establishing the amounts of slow-reacting hemicellulose and lignin, whereas temperature was the dominant variable concerning the fractions of non-reacting polymers.



中文翻译:

γ-戊内酯/水中杏仁壳的酸催化分馏

使用在γ-戊内酯(GVL)/水中的酸催化水解作用,研究了杏仁壳的分馏,杏仁壳是一些地中海气候区域中的一种农业工业残留物。使用恒定的80%w / w GVL的水浓度和高达120的反应时间,在120、140和160°C的标称温度和25至75 mM的硫酸浓度下进行了一组非等温实验分钟 GVL是一种有效的介质,即使在反应器加热初期,即使在低温下也能促进木质素和半纤维素的溶解,而纤维素转化率受到限制。温度为160°C时,木质素和半纤维素的提取率最高,但在140°C以下,半纤维素碳水化合物的回收率更高。高于45 mM的硫酸浓度会促进木糖和葡萄糖过度脱水成呋喃和腐殖质,木质素可将其回收。建立了描述木质素和半纤维素溶解动力学的模型。它区分了每种聚合物(木质素或半纤维素)中不同反应性的三个部分:快速反应,缓慢反应和不反应。各部分的量与酸浓度和反应温度相关。使用来自非等温实验的数据,通过最小二乘法优化,以数值方式获得模型中的活化能和其他参数。半纤维素的快反应和慢反应部分的活化能分别为142和39.7 kJ mol 建立了描述木质素和半纤维素溶解动力学的模型。它区分了每种聚合物(木质素或半纤维素)中不同反应性的三个部分:快速反应,缓慢反应和不反应。各部分的量与酸浓度和反应温度相关。使用来自非等温实验的数据,通过最小二乘法优化,以数值方式获得模型中的活化能和其他参数。半纤维素的快反应和慢反应部分的活化能分别为142和39.7 kJ mol 建立了描述木质素和半纤维素溶解动力学的模型。它区分了每种聚合物(木质素或半纤维素)中不同反应性的三个部分:快速反应,缓慢反应和不反应。各部分的量与酸浓度和反应温度相关。使用来自非等温实验的数据,通过最小二乘法优化,以数值方式获得模型中的活化能和其他参数。半纤维素的快反应和慢反应部分的活化能分别为142和39.7 kJ mol 各部分的量与酸浓度和反应温度相关。使用来自非等温实验的数据,通过最小二乘法优化,以数值方式获得模型中的活化能和其他参数。半纤维素的快反应和慢反应部分的活化能分别为142和39.7 kJ mol 各部分的量与酸浓度和反应温度相关。使用来自非等温实验的数据,通过最小二乘法优化,以数值方式获得模型中的活化能和其他参数。半纤维素的快反应和慢反应部分的活化能分别为142和39.7 kJ mol-1,以及对于木质素134和71.7 kJ mol -1。酸浓度对确定慢反应性半纤维素和木质素的量的影响大于温度,而温度是影响非反应性聚合物组分的主要变量。

更新日期:2021-01-10
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