| In modern industrial production and national economic development, acid catalyst plays an important role in catalysis, in recent years, In view of the problems of long-term use of liquid acid catalyst technology, people have carried out extensive research work to find alternative for liquid acid catalyst. Solid acid is easily separated from liquid phase reaction system, anti-corrosion equipment, simple post-processing, less pollutant emissions, good thermal stability, can be used in high temperature range, expand the thermodynamics on possible acid catalytic reaction of application scope, solid acids turn to be a catalytic research hot spot. Many remarkable research results have been reported, significantly speed up the replace of liquid acid catalyst technology in chemical industry process. But the density of existing strong acid, distribution of acid species and the stability of the reaction medium are still the bottleneck problem in practical. Around these problems we carried out a series of system research, developed a new kind of liquid sulphur trioxide sulfonation method, 25 new type of solid acids were prepared and studied them in the preparation of biodiesel, the catalytic activity of small molecule reactions such as esterification. Innovative achievements are obtained. The main contents are as follows:1:In view of the shortcomings of low acid density of carbon-based solid acid presently, Using sulfur trioxide sulfonation method,21 types of sulfonated carbon-based materials were sulfonated under the low temperature, carbon-based solid acid were prepared with 10-50% higher acid density than other sulfonating methods. The highest sulfonic acid content is 5.4 mmol g-1,0.6 mmol g-1 higher than reported of the highest amount of carbon-based solid in the literature. The efficient sulfonating ability liquid sulphur trioxide mainly comes from the sulfonation process of free radicals.2:The preparated solid acid has good catalytic activity and high stability in beckmann rearrangement reaction (BR), and condensation reaction of ethylene glycol with benzaldehyde (CPE), esterification of oleic acid (EOM) and hydrolysis of methyl epoxy ethane (HPO). Among them, the yield of methyl oleate under the CMFDU-14-SO3H solid acid catalyst of esterification of methanol with oleic acid can get 98%. 23%higher than the same solid acid catalyst in the literature. The carbon-based solid acid prepared by this new method will go further on the road of replacement of liquid homogeneous catalyst.3:In view of the low utilization of solid acid active sites.3D graphene compounds was prepared, then sulfonated using sulfur trioxide sulfonation method, got 3D graphene solid acid, which has sulfonic acid content as high as 4.0 mmol g"1. 3D graphene solid acid with 3D structure possesses advantages such as strong mechanical strength and rapid electronic transmission ability, adsorpting reagents in a small range like enzyme, reactant contact with functional groups fully, and more, the carbon structure of graphene in the catalytic reaction is good at electronic transfer. Due to the three-dimensional porous structure and excellent intrinsic properties of graphene, and sulfur trioxide sulfonation method,3D graphene solid acid catalyst with stable structure has a excellent performance at esterification of cyclohexanol, esterification of oleic acid and the hydrolysis reaction of epoxy ethane, These results show that the catalyst has good catalytic activity,3D graphene solid acid provides a new train of thought for later design of catalyst preparation.4:In view of the inorganic molecular sieve acid has a low number of strong acid sites, using sulfur trioxide as sulfonation method, silicon material represented by sulfonated SBA-15 with high acid density was prepared under the low temperature. Whose sulfonic acid content is 1.9 mmol g-1, The solid acid has 0.9 mmol g-1 higher amount of acid than other sulfonated method on the preparation of silicon-based solid acid, the prepared solid acid has good catalytic activity, high stability, good catalytic performance, the applicability of the liquid sulfur trioxide sulfonation method covers from carbon to silicon materials, sulfur trioxide sulfonation method gives more choice for the green solid acid catalyst materials.5:For catalytic reaction of oleic acid esterification, it can be analyzed the reactants are obvious hydrophobic organic compounds, solid acid materials must also have a hydrophobic surface suitable for the catalysis, and a larger specific surface area, the high amount of acid is crucial. According to these characteristics, we design and prepare Styrene-Divinyl benzene material, prepared it to be a solid acid using sulfur trioxide sulfonating method. The sulfonic acid amount is 6 mmol g-1. Then applicate solid acid to the esterification of oleic acid, the results showed that the catalyst for the synthesis of biodiesel has good catalytic activity, oleic acid had a very good conversion even after five cycles, at low temperature (65 ℃), the proportion of methanol to oleic acid are smaller (5:1), compared with the conventional solid acid, catalyst activity improved greatly (95%), and the stability and the amount of acid have also been greatly enhanced. This provides a new road for the biological fuel oil successfully.6:The preparation of nano porous N-doped carbon fiber was as follows:a simple homogeneous precipitation reaction between DTPA and aluminium salt, then calcinate. Carbon solid acid was prepared through simple solvent heat treatment of sulfuric acid or sulphur trioxide sulfonation of N-doped carbon fiber. Lots of sulfuric groups grafted on the surface of N-doped porous carbon materials (proton acid content as high as 1.8 mmol g-1). In acetal reaction of benzene formaldehyde with glycol, the conversion is high over solid acid, and can maintain the same catalytic activity after multiple recycles. The conversion is still as high as 99.0%. Carbon fiber solid acid prepared by using the method of sulfur trioxide sulfonation has sulfonic group content as high as 2.5 mmol g-1. This simple method of preparing a large number of nano porous nitrogen-doped carbon fiber offers a new industrial synthetic route, this material will show excellent peformance in acid catalysis. |
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