葡萄糖制取5-羟甲基糠醛的催化剂制备及其性能研究毕业论文_化学工程与工艺毕业论文

葡萄糖制取5-羟甲基糠醛的催化剂制备及其性能研究毕业论文

2021-04-27更新

摘 要

5-羟甲基糠醛(5-Hydroxymethylfurfural, HMF)作为一种多功能的平台化合物,主要是利用木质纤维素通过降解与脱水反应生成。由HMF出发,可以合成一系列化学品和新型的高分子材料,包括医药、树脂类塑料、柴油燃料添加物等。因此,HMF被认为是一种介于生物质能源和石油化工产品之间的桥梁。

本文设计了以五氧化二铌为异构化催化剂和糖基固体酸为脱水催化剂组成的双固体催化剂体系,催化葡萄糖转化为HMF。通过两步法制备了糖基固体酸GTS-2系列,并对其结构和性能进行了分析。主要研究结果如下:

(1)以葡萄糖为碳源,浓硫酸提供磺酸基,经过不完全碳化和酸化两步,合成了GTS-2系列,通过改变两步法中的碳化温度,制备了GTS-2系列。在700℃下制备了最优化条件下的羰基催化剂GTS-2-700, GTS-2-700的磺酸基含量为0.7mmol/g、羧基含量为0.8 mmol/g,从GTS-2系列的催化活性结果可知,碳化温度越高,疏水性越强,HMF的产率越高,GTS-2-700 gt; GTS-2-550 gt; GTS-2-400 gt; GTS-2-250。

(2)通过在最佳温度下引入致孔剂,合成了GTS-2-700-Na2SO4系列,在葡萄糖:Na2SO4=1:1.5的条件下制备了最优化的催化剂GTS-2-700-Na2SO4-3。GTS-2-700-Na2SO4-3是一种具有多稠芳环结构,表面为无序多环碳层排列的无定型结构的疏水性材料,表面含有磺酸根、羧酸根和酚羟基三种酸性官能团,其含量分别为1.1,0.8,1.4mmol/g。

(3)采用BET、XRD、SEM、FTIR、酸度滴定和接触角测定手段对其结构和性能进行表征发现:糖基催化剂GTS-2系列均为无序的多环碳层排列,有多稠芳环,呈无定型结构,表面含有-SO3H、-COOH和-OH三种酸性官能团;糖基固体酸GTS-2系列催化剂表面的疏水性随制备温度升高而增强。

(4)从GTS-2-700-Na2SO4系列的催化活性结果可知,在最优温度下,Na2SO4 与葡萄糖质量比越高,疏水性越强,孔结构越好,水合副产物越少,HMF的产率越高,GTS-2-700-Na2SO4-3gt;GTS-2-700-Na2SO4-2gt;GTS-2-700-Na2SO4-4gt;GTS-2-700-Na2SO4-1。

(5)在HMF最佳合成工艺条件下,以Nb2O5和GTS-2-700- Na2SO4-3为催化体系,催化葡萄糖合成HMF。即反应温度为195 ℃,反应时间为5 h,催化剂用量为葡萄糖质量的5 wt%,Nb2O5和GTS-2-700- Na2SO4-3配料比为1:1时,葡萄糖转化率为100%,HMF产率为74%。

关键词葡萄糖; 5-羟甲基糠醛;异构化反应;脱水反应;

Catalyst preparation and performance research for glucose prepare 5-Hydroxymethylfurfural

ABSTRACT

5-Hydroxymethylfurfural (HMF) is a versatile platform compound, which is usually generated through degradation and dehydration reaction from lignocellulose.Starting from HMF,we can synthesize a serious of chemicals and new polymer materials, including pharmaceutical,plastic resins and diesel fuel additives etc. HMF is thus considered as a bridge between biomass energy and petrochemical.

Under the guidance of multi-scale coupling mechanism, this paper designs a new reaction system of double soild catalysts and biphasic solvents for converting glucose into HMF. Double solid catalyst system is composed of niobium pentoxide for isomerization and sugar-based solid acid catalyst for dehydration,and biphasic solvent system consists of saturated salt water and tetrahydrofuran.Sugar-based solid acid catalysts(GTS-2series)were prepared by two-step method,respectively,and their structure and performance were analyzed.By single factor experiments,process conditions of HMF synthesis were investigated.The main results were as follows:

(1)Glucose is used as the carbon source, sulfuric acid provide a sulfonic acid group, after incomplete carbonization and acidification steps, synthesized GTS-2 series, by changing the two-step process of carbonization temperature, prepared GTS-2 series. Prepared at 700 ℃ carbonyl catalyst GTS-2-700 under optimal conditions, GTS-2-700 sulfonic acid group content of 0.7mmol / g, a carboxyl group content of 0.8 mmol / g, catalytic from GTS-2 series activity results, carbonization temperature is higher, the stronger the hydrophobicity, the higher the yield of HMF, GTS-2-700gt; GTS-2-550gt; GTS-2-400gt; GTS-2-250.

(2)We introduced porogens at an optimum temperature, synthesized Series GTS-2-700-Na2SO4, The optimized catalyst GTS-2-700-Na2SO4-3 was prepared under glucose: Na2SO4 = 1: 1.5 conditions. GTS-2-700-Na2SO4-3 is a condensed aromatic ring having a multi-structure, the surface of the carbon layer arrangement disordered polycyclic hydrophobic material of amorphous structure, the surface containing sulfonate, carboxylate and acidic phenolic hydroxyl group of three functional group, which contents were 1.1,0.8,1.4mmol / g.

(3)By BET, XRD, SEM, FTIR, ph titration and contact Angle measurement methods on the structure and properties were characterized found that sugar base catalyst and GTS-2series is disorderly polycyclic carbon layer is arranged, how thick aromatic ring in the amorphous structure, surface containing -SO3H, -COOH and -OH three kinds of acidic functional groups;Hydrophobic with the preparation temperature on the surface of the catalyst increased.

(4) We can know from the result of the catalytic activity of the series of GTS-2-700-Na2SO4, at the optimal temperature,The mass ratio of Na2SO4 and glucose was higher, the hydrophobicity was stronger, the pore structure was better, the hydration byproducts was less, HMF yield was higher,GTS-2-700-Na2SO4-3gt;GTS-2-700-Na2SO4-2gt;GTS-2-700-Na2SO4-4gt;GTS-2-700-Na2SO4-1.

(5) Under the optimum conditions of composing HMF, Nb2O5 and GTS-2-700- Na2SO4-3 was used as catalytic system, to catalytic glucose to synthesis HMF. That reaction temperature was 195 ℃, the reaction time was 5 h, the amount of catalyst was 5 wt% of glucose quality, Nb2O5 and GTS-2-700- Na2SO4-3 ingredient ratio was 1: 1, The conversion of glucose was 100%, The yield of HMF was 74%.

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