QIBEBT-IR  > 绿色化学催化团队
半纤维素催化转化为糠醛的绿色制备过程研究
高红玲
Thesis Advisor王海松
2015-06
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline化学工程
Keyword半纤维素 糠醛 Zsm-5 有机溶剂
Abstract随着环境污染、能源紧缺、气候变暖等问题的日益严峻,人们的视野开始转向绿色的环保原料---生物质。但作为木材最广泛的利用方式制浆造纸,其大部分半纤维素以废液的形式被燃烧或排掉。所以,将半纤维素提取出来用于生产具有高附加值的化学品,对提高生物质利用的经济性及促进造纸行业的转型升级具有重要意义。本文以溶解浆厂阔叶木水热提取液半纤维素和化纤厂碱抽提液半纤维素为原料,开展催化转化为糠醛的绿色制备过程研究。针对溶解浆厂水热抽取液半纤维素难以利用,液体酸腐蚀及污染环境等问题,设计了以固体酸ZSM-5为催化剂制备糠醛的工艺过程研究。通过实验得出制备糠醛的最佳实验条件:反应温度190 ºC,1.0 g ZSM-5,反应时间3 h,15 mL阔叶木水热提取液,30 mL甲苯,1.05 g NaCl。此时,得到最大糠醛产率(82.43%)和木糖转化率(96.84%)。而在相同实验条件下,以木单糖溶液为原料,糠醛的得率仅为51.60%,说明在以固体酸为催化剂制备糠醛的过程中,与木单糖相比,阔叶木水热提取液半纤维素更适合作为原料。ZSM-5催化剂的重复使用及结构表征说明,ZSM-5具有一定的活性和结构稳定性,在此体系中重复使用五次之后,糠醛的得率仍高达67.11%,适用于半纤维素催化转化为糠醛。本文还研究了以化纤厂阔叶木浆粕碱抽提液半纤维素为原料,利用ZSM-5水解制备糠醛。通过正交实验得出影响糠醛产率因素的顺序为:反应温度>催化剂用量>反应时间,得出糠醛生产的最优水平组合:反应温度180 ºC,反应时间2 h,催化剂用量1.5 g。对糠醛产率最大影响因素--反应温度进行优化,并考察无机盐和甲苯的加入对糠醛产率的影响。结果表明,在180 ºC,30 mL甲苯,不加无机盐的最优条件下反应2 h,糠醛产率最高为40.18%,这主要是因为化纤厂碱抽提半纤维素相对分子量较大,难以一步催化水解为糠醛。进一步研究了酶解两步法制备糠醛。研究结果表明,在木聚糖酶用量0.5 mL/g,反应温度50 ºC,反应时间18 h,水解为低聚木糖后,再生产糠醛,糠醛的产率可达74.68%,有效提高固体酸催化水解高分子量半纤维素制备糠醛的产率。针对溶解浆厂水热抽取液半纤维素难以利用,液体酸腐蚀及污染环境等问题,设计了以固体酸ZSM-5为催化剂制备糠醛的工艺过程研究。通过实验得出制备糠醛的最佳实验条件:反应温度190 ºC,1.0 g ZSM-5,反应时间3 h,15 mL阔叶木水热提取液,30 mL甲苯,1.05 g NaCl。此时,得到最大糠醛产率(82.43%)和木糖转化率(96.84%)。而在相同实验条件下,以木单糖溶液为原料,糠醛的得率仅为51.60%,说明在以固体酸为催化剂制备糠醛的过程中,与木单糖相比,阔叶木水热提取液半纤维素更适合作为原料。ZSM-5催化剂的重复使用及结构表征说明,ZSM-5具有一定的活性和结构稳定性,在此体系中重复使用五次之后,糠醛的得率仍高达67.11%,适用于半纤维素催化转化为糠醛。本文还研究了以化纤厂阔叶木浆粕碱抽提液半纤维素为原料,利用ZSM-5水解制备糠醛。通过正交实验得出影响糠醛产率因素的顺序为:反应温度>催化剂用量>反应时间,得出糠醛生产的最优水平组合:反应温度180 ºC,反应时间2 h,催化剂用量1.5 g。对糠醛产率最大影响因素--反应温度进行优化,并考察无机盐和甲苯的加入对糠醛产率的影响。结果表明,在180 ºC,30 mL甲苯,不加无机盐的最优条件下反应2 h,糠醛产率最高为40.18%,这主要是因为化纤厂碱抽提半纤维素相对分子量较大,难以一步催化水解为糠醛。进一步研究了酶解两步法制备糠醛。研究结果表明,在木聚糖酶用量0.5 mL/g,反应温度50 ºC,反应时间18 h,水解为低聚木糖后,再生产糠醛,糠醛的产率可达74.68%,有效提高固体酸催化水解高分子量半纤维素制备糠醛的产率。
Other AbstractWith increasing concern about global warming and dwindling fossil-oil supplies, attention is turning to “green processes that use sustainable and environmentally friendly feedstock--biomass. Most of hemicellulose in waste aqueous solutions are burned or thrown away in pulp and paper industry which is the most widely use of wood. Therefore, it would be not only economically beneficial to improve biomass utilization, but also greatly significant to promote the transformation and upgrading of the pulp and paper industry if the extracted hemicellulose could be converted into high-value chemicals. In the present work, two types of hemicellulose solutions were used as the feedstock, including the hot water extracted hemicellulose derived from hardwood in a dissolving pulp mill and the alkali extracted hemicellulose from a chemical fiber factory, for the study of furfural production.More efficient process for the production of furfural was designed and investigated to solve those issues as reported previously, like the hemicellulose underutilization, liquid acid corrosion and environment pollution. The maximum furfural yield of 82.43% and xylose conversion of 96.84% were achieved at 190 ºC for 3 h with 1.0 g ZSM-5, 1.05 g NaCl, 15 mL hot water extracted solution, and 30 mL toluene. However, the furfural yield was just 51.60% when the same concentration of pure xylose solution was used under the same conditions. Hemicellulose solution derived from hard wood was more suitable for furfural production. Under the optimized conditions, furfural yield was still up to 67.11% even after the fifth reuse of catalyst (ZSM-5). Catalyst recycling study and structural characterization showed that ZSM-5 had a certain activity and structure stability. It was applicable to furfural production.Hemicellulose from hardwood alkali extraction liquid was also used as material for furfural production catalyzed by ZSM-5. The result of orthogonal test showed that the influence of different experimental conditions on furfural yield was: reaction temperature> catalyst dosage> reaction time. The optimal conditions for furfural production were 180 ºC, 2 h, 1.5 g ZSM-5. Reaction temperature, the biggest influence factor, as well as the dosage of inorganic salt and organic solvent were further optimized. Under the optimal conditions of 180 ºC, 30 mL toluene, and 2 h, furfural yield was just 40.18%. It was difficult to produce furfural in one step because the molecular weight of alkali extraction hemicellulose was bigger. Therefore, alkali extraction hemicellulose was hydrolyzed by enzyme (xylanase dosage 0.50 mL/g, 50ºC, 18 h) prior to ZSM-5 hydrolysis for furfural formation. The maximum furfural yield of 74.68% was achieved under the best reaction conditions. Therefore, before ZSM-5 hydrolysis, the furfural yield was effectively improved by enzyme pretreatment of hemicellulose with high molecular weight.
Department绿色化学催化团队
Subject Area化学工程
Date Available2016-01-01
Subtype硕士 ; 学位论文
Language中文
Document Type学位论文
Identifierhttp://ir.qibebt.ac.cn/handle/337004/8092
Collection绿色化学催化团队
Affiliation中国科学院青岛生物能源与过程研究所
Recommended Citation
GB/T 7714
高红玲. 半纤维素催化转化为糠醛的绿色制备过程研究[D]. 北京. 中国科学院研究生院,2015.
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