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Lewis acid-catalyzed carbohydrate Preparation of 5 - (hydroxymethyl) furfural

Author: TianYuKui
Tutor: GuoQingXiang
School: University of Science and Technology of China
Course: Organic Chemistry
Keywords: Glucose Fructose Lewis acid Dehydration 5 - (hydroxymethyl) furfural Ionic liquid
CLC: TQ251.11
Type: Master's thesis
Year: 2011
Downloads: 135
Quote: 1
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Abstract

With the rapid growth of fossil energy consumption and fossil fuel resources, limited storage, renewable and clean energy development and application of widely recognized and valued. In a variety of renewable resources, biomass-based carbohydrate is a great potential for carbon-based alternative energy and sustainable development of chemical raw materials. Dehydrated carbohydrates, biomass-based solution of 5 - (hydroxymethyl) furan-formaldehyde is considered to be connected to the petrochemical industry and raw material industry bridge. Therefore, carbohydrates dehydration Preparation of 5 - (hydroxymethyl) furfural and in-depth research has been widely carried out. This study aimed to develop a biomass-based carbohydrate dehydration Preparation of 5 - (hydroxymethyl) furfural new ways to make the reaction more environmentally greener, while making it more in line with commercial requirements, and thus be more widely used. Biomass-based carbohydrate dehydration Preparation of 5 - (hydroxymethyl) furfural the main raw material for the glucose and fructose. With respect to glucose, fructose as starting materials Preparation of 5 - (hydroxymethyl) furan-formaldehyde becomes simple. Fructose molecule through intramolecular dehydration that get direct part 5 - (hydroxymethyl) furfural. Reaction with solid acid catalyst used, a Lewis acid, organic acid and an inorganic acid. However, glucose as a raw material preparation of 5 - (hydroxymethyl) furan-formaldehyde is relatively difficult, the reaction glucopyranose first through isomerization of fructose is converted into furan, and then through the catalytic dehydration to form 5 - (hydroxymethyl) furaldehyde. Which glucopyranose fructose is converted into furan-type reaction rate-determining step. Lewis acid was found in the ionic liquid CrCl2 efficient catalytic conversion of glucose to 5 - (hydroxymethyl) furfural. Based on the previous studies, in this paper the author systematically studied in ionic liquids, Lewis acid catalyzed dehydration of glucose and fructose Preparation of 5 - (hydroxymethyl) furfural factor. Lewis acid structure through different catalytic effect on the findings of a study CrCln and SnCln both can efficiently catalyzed conversion of glucose to 5 - (hydroxymethyl) furfural. Fructose as raw material in the 5 - (hydroxymethyl) furan-formaldehyde reaction, the Lewis acid catalyst is more acidic, the catalyst the better, to give 5 - (hydroxymethyl) furfural yield is higher. Lanthanide metal chloride in the reaction showed good catalytic activity and product selectivity. Also studied the structure of ionic liquids on the catalytic reaction. Imidazolium ionic liquids in conversion of glucose to 5 - (hydroxymethyl) furan showing the reaction of formaldehyde in an odd-even effect. Branched chain carbon atoms with respect to an odd number of ionic liquid, branched chain carbon atoms and an ionic liquid is even more conducive to 5 - (hydroxymethyl) furan generation of formaldehyde. In the fructose conversion of 5 - (hydroxymethyl) furan-formaldehyde reaction, the ionic liquid, the shorter the length of branched-chain alkyl group of 5 - (hydroxymethyl) furfural yield is higher. In the ionic liquid Preparation of 1 - methyl - 3 - ethyl imidazole ([C2MIM] Br) in, SnCl2 catalyze glucose to 5 - (hydroxymethyl) furan-formaldehyde yield was 65%, ErCl3 can catalyze fructose to give 5 - (hydroxymethyl) furan yield of 90% formaldehyde. Compared to the homogeneous reaction, heterogeneous catalytic reaction in favor of continuous production, the catalyst and reduce the cost of repeated recycling. Therefore, the author catalysts for homogeneous catalysis shortcomings, has conducted a heterogeneous catalyst carbohydrates Preparation of 5 - (hydroxymethyl) furan Formaldehyde. To prepare the catalytic fructose 5 - (hydroxymethyl) furan-formaldehyde research, the solid acid catalyst to obtain a wide range of applications, such as an acidic ion resin, a heteropoly acid. However, the solid acid catalyst of glucose Preparation of 5 - (hydroxymethyl) furfural research, is relatively small. This article, the author tried different metal atoms doped MCM-41 mesoporous molecular sieves to catalyze glucose and fructose to prepare 5 - (hydroxymethyl) furfural. Reaction was found, in addition to Sn-MCM-41 can efficiently catalyzed glucose and fructose system take 5 - (hydroxymethyl) furfural, other mesoporous molecular sieves are not catalyze the reaction. At 110 ° C for 6h conditions, mesoporous molecular sieve catalyst Sn-MCM-41 can catalyze glucose get 51% 5 - (hydroxymethyl) furfural, get 63% fructose catalyzed 5 - (hydroxymethyl) furfural. After the reaction, the catalyst by filtration and can be directly separated. After filtration of the catalyst through the water and washed several times with ethanol, and then through 550 ° C to activate the firing repeatedly, the catalyst activity does not occur significantly reduced.

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