负载型氟化钾催化的稻秆粉末的甲醇解

发布时间：2018-06-04 22:51

本文选题：稻秆 + 甲醇解　；参考：《中国矿业大学》2015年硕士论文

【摘要】：醇解是生物质清洁高效利用的一种有效手段,从醇解所得生物油中可以获取高附加值化学品。本研究以甲醇为介质,以三种不同载体的负载型氟化钾(KF/Al2O3、KF/Ca O和KF/沸石)为催化剂,分别在微波辅助和超临界条件下对稻秆粉末进行液化解聚,考察催化与非催化条件下的生物油收率(YL)和生物油组成,并进一步解析解聚机理。首先以YL为指标进行了催化剂的筛选和醇解条件的优化,发现三种载体KF的较优负载量均为20%,KF/Al2O3和KF/沸石的较优焙烧温度在500 o C,而KF/Ca O为600 o C。超临界条件下的较优反应温度为300 o C,微波条件下为75 o C,而两种条件下的较优反应时间均为30min,较优催化剂用量均为5%。微波辐射下,考察了逐级解聚和催化解聚的规律。研究表明,第一级甲醇解生物油的主要成分为甾醇。第二级和第三级醇解的主要成分均为邻苯二甲酸酯,且含量接近50%。催化甲醇解得到的生物油共检测到66种化合物,而非催化条件只检测到23种。负载型KF促进了酮、醚、酯和脂肪烃的生成。在KF/Al2O3催化下,生物油主要族组分为甾醇;在KF/Ca O催化下主要为酮,达到了65.7%;KF/沸石催化下则主要为呋喃衍生物。超临界条件,考察了不同温度下解聚、逐级解聚和催化解聚的规律。实验表明,生物油的族组分分布随反应温度显现出一定的规律性,一定范围内,升高温度有利于酮、醚和酚的形成。高于一定温度,部分小分子则会发生重聚反应。负载型KF催化下得到的生物油的YL和化合物种类均明显增加,其中KF/沸石催化下所得YL最高。反应温度在260 o C时,催化所得生物油共检测到82种化合物,主要成分为酯,三种载体的KF均促进了酮、醚和含硅化合物的生成。另外,KF/Al2O3、KF/Ca O也促进了酚的生成,KF/Al2O3、KF/沸石有利于酯的生成。反应温度为300 o C时,催化得到的生物油共检测到172种化合物,明显多于非催化得到的64种。KF/Al2O3和KF/Ca O催化下的主要组分为酮,KF/沸石催化下则为酚。三种载体的KF均促进了酮、醚和酚的生成。KF/沸石也促进了醇、酯和芳烃的生成。在第二级甲醇解中,KF/Ca O催化下的YL较非催化条件更高,生物油主要成分为酚,占63.4%。非催化条件下的主要产物为硅酸四甲酯和二硅酸六甲酯,前者相对含量占65.2%,推测含硅化合物为稻秆中的植硅体与超临界甲醇反应生成。负载型KF在微波甲醇解和超临界甲醇解中均表现出良好的催化性能,推测其在反应中促进CH3OH解离出亲核试剂CH3O-,从而进攻连接纤维素和半纤维素糖环之间或木质素芳环之间的C-O桥键,使其断裂生成更多的小分子化合物。
[Abstract]:Alcoholysis is an effective method for the clean and efficient utilization of biomass. High value-added chemicals can be obtained from the bio-oil obtained by alcoholysis. In this study, the rice stalk powder was liquefied and depolymerized under microwave assisted and supercritical conditions using three supported KF / Al _ 2O _ 3H _ f / Ca _ 2O and KF/ zeolites as catalysts using methanol as the medium. The yield of bio-oil (YL) and the composition of bio-oil under catalytic and non-catalytic conditions were investigated, and the mechanism of depolymerization was further analyzed. Firstly, the catalyst selection and alcoholysis conditions were optimized by using YL as the index. It was found that the optimum calcination temperature of KF / Al _ 2O _ 3 and KF/ zeolite was KF/Ca OC and 600oC respectively for KF / Al _ 2O _ 3 and KF/ zeolites. The optimum reaction temperature is 300 o C under supercritical condition, 75 o C under microwave condition, and the optimum reaction time is 30 min under both conditions, and the optimal amount of catalyst is 5%. The law of stepwise depolymerization and catalytic depolymerization was investigated under microwave radiation. The results showed that the main component of the first methanololysis bio-oil was sterol. The main components of the second and third alcoholysis are phthalate, and the content is close to 50%. A total of 66 compounds were detected in bio-oil obtained by catalytic methanol hydrolysis, but only 23 compounds were detected under non-catalytic conditions. Supported KF promotes the formation of ketones, ethers, esters and fatty hydrocarbons. Under the catalysis of KF/Al2O3, the main component of bio-oil is sterol, and the main component is ketone under the catalysis of KF/Ca O, and the furan derivative under the catalysis of 65.7KF / zeolite. Under supercritical conditions, the rules of depolymerization, stepwise depolymerization and catalytic depolymerization at different temperatures were investigated. The experimental results show that the distribution of group components of bio-oil shows certain regularity with reaction temperature, and in a certain range, increasing temperature is favorable to the formation of ketones, ethers and phenols. Above a certain temperature, some small molecules will reunite. The YL and compound types of bio-oil obtained by supported KF catalyst increased obviously, among which the YL obtained by KF/ zeolite was the highest. At the reaction temperature of 260 o C, 82 compounds were detected in the bio-oil. The main components were esters. KF of the three carriers promoted the formation of ketones, ethers and silicon-containing compounds. In addition, KF / Al _ 2O _ 3 / KF / Cao also promoted the formation of phenol. KF / Al _ 2O _ 3 / KF / zeolite was beneficial to the formation of esters. At the reaction temperature of 300o C, 172 compounds were detected in the bio-oil, which was obviously more than 64 kinds of uncatalyzed. KF / Al _ 2O _ 3 and KF/Ca _ O, the main component of which was phenol under the catalysis of ketone KF / zeolite. KF of the three carriers promoted ketone, and the formation of ether and phenol. KF / zeolite also promoted the formation of alcohols, esters and aromatics. In the second stage of methanol hydrolysis, the YL catalyzed by KF / Ca O was higher than that under non-catalytic conditions. The main component of bio-oil was phenol, accounting for 63.443%. The main products under uncatalyzed conditions were tetramethyl silicate and hexyl disilicate, whose relative content was 65.2. It was inferred that the silicon-containing compounds reacted with supercritical methanol in rice stalks. The supported KF exhibited good catalytic performance in microwave methanol hydrolysis and supercritical methanol hydrolysis. It is speculated that it can promote CH3OH dissociation of nucleophilic reagent CH3O-and attack the C-O bridge bond between cellulose and hemicellulose sugar ring or between lignin aromatic ring and make it break down to form more small molecular compounds.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE667

【共引文献】