金属基磺酸型固体酸催化剂催化纤维素降解制备5-羟甲基糠醛的研究

发布时间：2018-08-03 11:38

【摘要】：近年来,化石能源的过度使用使得环境污染和能源短缺问题日益严重,人类对于新能源的需求越来越迫切。生物质由于其具有来源广泛、储量丰富等优点,被认为是最有前途的可再生资源之一。生物质资源的开发利用可以降低化石能源的消耗,有利于社会经济的可持续发展。纤维素是最为丰富的生物质资源,以纤维素为原料,可以得到重要的平台化合物5-羟甲基糠醛(HMF),进而可以转化为多种化学品。本论文设计并合成了多种负载型双酸性固体酸催化剂,并将其用于催化纤维素降解制备5-羟甲基糠醛。利用红外光谱、拉曼光谱、X射线衍射、N2吸附-脱附、扫描电镜、透射电镜等多种表征手段对催化剂的组成和结构进行了分析,并对纤维素降解制备HMF的反应条件进行了优化。首先合成了介孔分子筛MSNP并对其进行了磺酸化改性,然后以其为载体,以咪唑型离子液体为媒介,引入CrCl3,制备了具有双重酸性的[pmim]CrCl4-MSNP-SO3H催化剂。将此催化剂用于纤维素降解制备HMF的实验,考察了催化剂的用量、纤维素的初始浓度、反应温度和时间对HMF产率的影响。结果发现当[pmim]CrCl4-MSNP-SO3H用量为0.05 g,纤维素初始量为0.01 g,反应温度为160oC,反应时间为140 min时,HMF产率可达39.1%。该体系具有较好的稳定性,循环使用4次而没有明显的活性损失。为了进一步提高HMF的产率,合成了三种介孔分子筛MSNP、MCM-41和SBA-15,利用嫁接法负载了含有布朗斯特酸性的吡啶型离子液体[PPy-SO3H]Cl,并引入了CrCl3,得到了具有布朗斯特酸和路易斯酸双重酸性的催化剂。实验发现,催化剂的载体对其催化活性有较大影响,其中以MSNP为载体时活性最佳。随后,以[PPy-SO3H]CrCl4-MSNP为催化剂,探究了催化剂的用量、纤维素的初始浓度、反应温度和时间对HMF产率的影响。其中当纤维素初始量为0.01 g,催化剂用量为0.05 g,反应温度为130oC,反应时间为120 min时,HMF产率高达61.5%。此外,该体系循环使用6次时仍然具有较好的活性。以葡萄糖和磺基水杨酸为原料,水热法制备了含有磺酸基的碳微球CM-SO3H,并利用浸渍法负载了多种金属氯化物,得到了具有双重酸性的碳基固体酸催化剂MClx-CM-SO3H。探究了不同金属氯化物对纤维素降解制备HMF的影响,发现负载CrCl3时活性最佳。随后对催化剂的用量、纤维素的初始浓度、反应温度和时间对催化活性的影响进行了考察,结果发现,以0.01 g纤维素为反应底物,加入0.05gCrCl3-CM-SO3H(负载量为40wt%),在140oC反应120 min,HMF产率可达66.7%。此外,该体系具有一定的耐水性。
[Abstract]:In recent years, the problem of environmental pollution and energy shortage is becoming more and more serious due to the excessive use of fossil energy, and the demand for new energy is becoming more and more urgent. Biomass is considered to be one of the most promising renewable resources because of its wide range of sources and abundant reserves. The exploitation and utilization of biomass resources can reduce the consumption of fossil energy and contribute to the sustainable development of social economy. Cellulose is the most abundant biomass resource. With cellulose as the raw material, the important platform compound 5-hydroxymethylfurfural (HMF), can be transformed into many chemicals. In this paper, several supported double acid solid acid catalysts were designed and synthesized, which were used to catalyze the degradation of cellulose to 5 hydroxymethyl furfural. The composition and structure of the catalyst were analyzed by means of infrared spectroscopy, Raman spectroscopy, X-ray diffraction (XRD) N _ 2 adsorption and desorption, scanning electron microscopy (SEM) and transmission electron microscope (TEM), and the reaction conditions for the preparation of HMF by cellulose degradation were optimized. Mesoporous molecular sieve MSNP was synthesized and modified with sulfonic acid. Then the [pmim] CrCl4-MSNP-SO3H catalyst with double acidity was prepared by introducing CrCl3 into the imidazole ionic liquid as the carrier. The effects of the amount of catalyst, the initial concentration of cellulose, the reaction temperature and time on the yield of HMF were investigated. The results showed that when the dosage of [pmim] CrCl4-MSNP-SO3H was 0. 05 g, the initial amount of cellulose was 0. 01 g, the reaction temperature was 160 OC and the reaction time was 140 min, the yield of HMF could reach 39. 1%. The system has good stability and is recycled for 4 times without obvious loss of activity. In order to further improve the yield of HMF, Three kinds of mesoporous molecular sieve MSNPN MCM-41 and SBA-15 were synthesized. The pyridine ionic liquid [PPy-SO3H] Cl containing Brownst acid was supported by grafting method, and CrCl3 was introduced. The catalyst with the double acidity of Brownstearic acid and Lewis acid was obtained. It was found that the support of the catalyst had great influence on its catalytic activity, and the best one was when MSNP was used as the carrier. Then, using [PPy-SO3H] CrCl4-MSNP as catalyst, the effects of the amount of catalyst, initial concentration of cellulose, reaction temperature and time on the yield of HMF were investigated. When the initial amount of cellulose was 0.01 g, the amount of catalyst was 0.05 g, the reaction temperature was 130 OC and the reaction time was 120 min, the yield of HMF reached 61.5%. In addition, the system still has good activity when it is recycled for 6 times. Carbon microspheres containing sulfonic groups were prepared by hydrothermal method from glucose and sulfosalicylic acid, and various metal chlorides were loaded by impregnation method. The double acidic carbon-based solid acid catalyst MClx-CM-SO3H was obtained. The effects of different metal chlorides on the preparation of HMF by cellulose degradation were investigated. It was found that the activity of CrCl3 was the best when loaded. The effects of the amount of catalyst, the initial concentration of cellulose, the reaction temperature and time on the catalytic activity were investigated. It was found that the yield of 0.05gCrCl3-CM-SO3H could reach 66.7% at 120 min after 140oC reaction with 0.01g cellulose as substrate and 40 wt% loading. In addition, the system has a certain water resistance.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ251.11

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