金属离子负载凹凸棒土催化碱抽提木质素制备芳香醛的研究

摘要：木质素是自然界中含量仅次于纤维素的天然高分子生物质，是一种取之不尽用之不竭的天然资源。将木质纤维素类物质通过有效分解途径转变为生物能源或生物质基化学品是解决能源危机及实现化学品原料绿色化的有效途径。本文采用稻草秸秆为主要原料，通过碱法蒸煮、酸析等步骤，制备碱抽提木质素，用于制备芳香醛化合物。分别采用FeCl3、、、、对凹凸棒土进行改性，催化碱抽提木质素降解，以对羟基苯甲醛、香草醛及丁香醛的总产量为指标，比较催化剂的催化效果，进而选出较好的催化剂。实验结果表明：所选催化剂中，FeCl3改性凹土的催化剂催化效果最好，在160℃、180r/min和0.5MPa的O2的反应条件下，6 g碱抽提木质素原料在反应120min时芳香醛的总产量最多，为0.1651g，其中对羟基苯甲醛的产量为0.07505g，香草醛的产量为0.08651g，丁香醛的产量为0.003489g；得率分别为：2.27%、2.62%、0.11%，总得率为5.00%。70308

毕业论文关键词：稻草、碱法抽提、酸析木素、凹凸棒土、催化氧化降解、芳香醛

Abstract: The content of lignin ranks only second to cellulose in biomass and it is a kind of inexhaustible natural resources. With the depleting of fossil resources together with the increasing concern about global warming and environmental pollution, biomass is considered as ideal and promising alternatives for the production of fuels and chemicals. In this paper, the straw stalks was used as the main raw material and extraction lignin preparation was conducted through the steps of cooking, acid precipitation for the preparation of aromatic aldehyde compounds. The attapulgite was modified by 、、、、 respectively and used as catalyst in catalytic oxidative degradation of alkali extraction lignin, with p-hydroxybenzaldehyde, vanilla aldehyde and lilac aldehyde production as an index. The best catalyst was selected. Experimental results showed that among the several kinds of catalysts, modified catalyst showed the best catalytic effects under the reaction conditions of 160 ℃, 180 r/min, 0.5 MPa O2 and 0.1651 g aromatic aldehydes was prepared from 6 g alkali extraction lignin. P-hydroxybenzaldehyde was 0.07505 g, vanillin was 0.08651 g, lilac aldehyde was 0.003489 g, with the yield of 2.27%, 2.62%, 0.11%, respectively. The yield of total aromatic aldehydes was 5.00 %.

Keywords: rice straw；alkali extraction；acid precipitation lignin；attapulgite，catalytic oxidation degradation，aromatic aldehyde

1 绪论 4

1.1 木质素的利用 4

1.2 凹凸棒土的基本情况 4

2 实验材料与方法 5

2.1 实验材料与设备 5

2.2 实验方法与步骤 5

2.2.1 碱抽提木质素的制备及木质素含量测定 5

2.2.2 金属离子负载凹凸棒土催化剂的制备 7

2.2.3 碱抽提木质素催化氧化制备芳香醛 8

2.2.4 HPLC检测 9

3 结果与讨论 10

结论 19

参考文献 20

致谢 21

1 绪论

1.1 木质素的利用

随着石油资源的短缺，利用可再生的生物质制备燃料和化学品已成为当前的一个研究热点。木质纤维素资源因为产量大且可再生是一种优良的生物精炼底物，木质纤维素的生物精炼应当包括三种组分：纤维素，半纤维素和木质素。木质素作为一种工业废弃物一直未能得到高效利用。制浆造纸工业每年要从植物中分离出大约1.4亿吨纤维，同时得到5000万吨左右的木质素副产品[1]。金属离子负载凹凸棒土催化碱抽提木质素制备芳香醛的研究:http://www.751com.cn/huaxue/lunwen_79563.html