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Study on the Preparation of Platinum-Acidic Ionic Liquid Bifunctional Catalyst and the Catalytic Synthesis of P-Aminophenol

Author: CuiYongMei
Tutor: WangYanJi
School: Hebei University of Technology
Course: Chemical processes
Keywords: P-aminophenol Nitrobenzene Acidic Ionic Liquids Pt nanoparticles Bifunctional catalyst
CLC: O643.32
Type: PhD thesis
Year: 2009
Downloads: 423
Quote: 2
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Abstract


P-aminophenol (PAP) is an important intermediate for organic synthesis, is widely used in medicine, dyes, rubber, photographic and other fields. In this paper, nitrobenzene as feedstock by catalytic hydrogenation synthesis the aminophenol process the use of sulfuric acid solution, through the design of new catalysts consisting of platinum metal and acidic ionic liquid, developed a new environmentally friendly synthesis of p-aminophenol processes. Using a two-step synthesis of a novel quaternary ammonium type Brφnsted acidic ionic liquid N, N, N-tri-methyl-N-sulfo-butyl hydrogen sulfate and ammonium ([HSO 3 -BN (CH < sub> 3 ) 3 ] HSO 4 ), FTIR, NMR, ESI-MS and elemental analysis method to determine the structure of the ionic liquid and the of phenyl hydroxylamine rearrangement reaction has good catalytic activity; On this basis, the use of sol - gel prepared immobilized ionic liquid catalyst [HSO 3 -bN (CH 3 ) 3 ] HSO 4 -SiO 2 , under optimum conditions, phenyl hydroxylamine conversion rate 100%, p-aminophenol selectivity of 60.5%. Designed and prepared by the supported platinum catalyst (hydrogenation activity bit) and acidic ionic liquid (rearrangement of the active site) constitutes a new type of highly efficient dual-function solid - liquid catalyst system Pt / SiO 2 [HSO 3 -bN (CH 3 ) 3 ] HSO 4 ; studied Pt / the SiO 2 < / sub> amount of catalyst, the concentration of ionic liquid, the reaction medium, additives and reaction conditions on the catalytic nitrobenzene hydrogenation synthesis the influence of aminophenol performance. Determine the best match of the amount of platinum catalyst and the ionic liquid concentration: Pt / SiO for 2 amount of 5% by weight of the ionic liquid concentration of 22.5wt%; under optimized conditions, nitrobenzene conversion rate of 96.6 % of the amino phenol selectivity of 81.4%, higher than the sulfuric acid system; ionic liquid-specific nature of the quaternary ammonium salt increases the solubility of nitrobenzene, and to improve the performance of the reaction; characterization of the structure of ionic liquid recovered after the reaction, proved to have good stability. The Pt / SiO , recovered 2 catalyst and acidic ionic liquid catalytic system composed recycled three times, no significant decline in activity. Acidic ionic liquid [HSO 3 -bN (CH 3 ) 3 ] HSO 4 , established at the same time get uniformly dispersed Pt nanoparticles and metals and acid active centers bifunctional catalyst; and its structure was characterized by TEM, UV-Vis, FTIR, XPS, XRD and so on. Preparation of Pt nanoparticles uniformly dispersed in the ionic liquid, particle size of approximately 3 nm, has a face-centered cubic phase structure, can be long-term (more than 4 months) remained stable dispersion state. Directly prepared by the platinum nanoparticles and acidic ionic liquid consisting of Pt-[HSO , 3 -BN (CH 3 ) 3 ] HSO 4 contemplated the homogeneous dual function catalyst; ScS alcohol / water ratio, the reflux time and the type of alcohol and other preparation conditions, and platinum nanoparticles content of the ionic liquid concentration, temperature, hydrogen partial pressure of the reaction The conditions on the hydrogenation of nitrobenzene synthesis of the aminophenol performance impact. Optimization to determine the suitability of the preparation conditions and reaction conditions, the nitrobenzene conversion was 99.3%, the aminophenol yield of 77.5%; the acidic ionic liquid is found not only play a role of an acid catalyst, but also as a protective agent, stabilizer dispersant can effectively prevent the agglomeration of the Pt nanoparticles. By sol - gel, impregnation and bonding legitimate platinum - immobilized ionic liquid catalyst was prepared by Pt-ionic liquid / SiO 2 immobilized bifunctional catalyst. Sol - gel method embedding the ionic liquid on silica gel to obtain Pt-[HSO 3 -bN (CH 3 ) 3 ] HSO 4 / SiO 2 bifunctional catalyst was investigated platinum solid load, preparation temperature, the amount of ethanol and gel aging time of preparation conditions on the performance of catalytic reaction, Under optimized conditions, the nitrobenzene conversion rate of 66.7%, 28.8% yield of p-aminophenol. Platinum and ionic liquid load, use sequential impregnation method and prepared by impregnation the Pt [HSO 3 -bmim] HSO 4 / SiO , 2 bifunctional catalyst. Loading, drying, reduction methods of preparation conditions on the performance of catalytic reaction. Optimized conditions, the nitrobenzene conversion rate of 68.6%, 41.4% yield of p-aminophenol. Synthesized and characterized a novel Brφnsted acidic ionic liquid 1 - vinyl-3 - sulfobutyl imidazole hydrogen sulfate salt ([HSO 3 -bvim] HSO 4 ), and mercapto functional groups of the silica surface with chemically fixed in the acidic ionic liquid was prepared by free radical chain transfer reaction [the HSO 3 -bvim] HSO 4 / SiO 2 solid acid catalyst, platinum metal by chemical reduction method load on the solid acid catalyst, to obtain Pt-[the HSO 3 -bvim] HSO / SiO 2 bifunctional catalyst. The reaction performance of the bi-functional catalyst is lower, mainly due to the less is bonded to the silica surface, the number of ionic liquids and the steric hindrance effect caused. But due to the chemical bonds cooperation with, its stability was significantly higher than the sol - gel method and catalyst prepared by impregnation.

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalytic reaction
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