Dissertation > Industrial Technology > Chemical Industry > Basic Organic Chemistry Industry > The production of aromatic compounds > Phenols, aromatic alcohols and their derivatives > Phenols and their derivatives > Benzene series phenol

Hydroxylation of Benzene to Phenol over Organic Molybdovanadophosphoric Heteropolyacid Salt Catalysts

Author XuWenJun
Tutor ZhuWeiDong;ZhangFuMin
School Zhejiang Normal University
Course Physical and chemical
Keywords Direct Hydroxylation of Benzene Organic salts of heteropolyacids Keggin Phase transfer Ionic liquids
CLC TQ243.12
Type Master's thesis
Year 2011
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Phenol is an important chemical raw materials, and its industrial production, mainly through indirect synthesis of complex synthetic routes, the consumption of raw materials, environmental pollution is serious shortcomings. Therefore, from the point of view of the environmental and economic considerations, the research and development of new technology has become one of the most challenging issues in the chemical production of the one-step oxidation of benzene to phenol. H2O2 as an environmentally friendly, clean-oxidants in the direct oxidation of benzene to phenol was received extensive attention from researchers. Vanadium-containing heteropoly acid has been applied under different reaction conditions, in the hydroxylation of benzene. But have been reported in the catalyst, the hydroxylation of benzene to phenol production is still low. Research and problems, the work is expected to develop a heteropoly acid-based with phase transfer properties of efficient catalyst in the hydroxylation of benzene with hydrogen peroxide in the preparation of phenol reaction. Hydroxylation of benzene into the target reaction, through the modification of the nitrogen heterocyclic amines and chain amines molybdovanadophosphoric heteropoly acid catalyst reaction evaluation, screening out the best catalyst. On this basis, further optimization molybdovanadophosphoric heteropoly acid catalysts of vanadium atoms and an organic amine cation, a number of substituted, optimized through experiments to determine the optimum reaction conditions, and then a catalytic reaction kinetics study, the last of the acidic ion The liquid reaction medium the benzene hydroxylation reaction Preliminary. Specific studies mainly following sections: 1) Heterocyclic organic amine modified the Keggin structure molybdovanadophosphoric heteropoly acid, organic amine salt catalyst prepared using FT-IR, UV-vis and TG-DTA on its characterization. The optimal reaction conditions, Chemically Modified molybdovanadophosphoric heteropoly acid exhibit high catalytic activity in the hydroxylation of benzene, phenol was 28.1%, significantly better than pure molybdenum vanadium phosphorus heteropolyacids H4PMo11VO40. 2) select different carbon chain length organic amine molybdovanadophosphoric of heteropoly acid weak base strong acid reaction, and prepared a series of long-chain molybdovanadophosphoric heteropoly organic amine salt. Compare the performance of the catalyst in benzene and hydrogen peroxide to phenol hydroxylation reaction, the heteropolyacids molybdovanadophosphoric triethylamine salt {[(C2H5) 3NH]} [PMo11VO40] - ([TEA] 4-PMo11V,) the highest activity. As the solvent to a mixture of glacial acetic acid and acetonitrile (1:1 by volume), 0.2 g [of TEA] 4-PMo11V catalyst and 1 ml of benzene, 3.5ml 30wt% H202 solution, and the reaction temperature was 60 ℃, reaction time, 8H, under the reaction conditions, the selectivity of phenol with a yield of 32.3% of phenol, 88.2%. Heteropoly acid organic amine salt catalyst in the organic components of the hydroxylation of benzene a significant role in promoting the reaction, which is mainly the electronic interaction between the organic component heteropolyanion and heteropolyacids of the \behavior. Heteropoly acid amine salt of the organic chain, and \3) the the TEA] 4-PMo11V (?) Cui agent hydroxylation of benzene to phenol catalyzed reaction kinetics study reaction kinetic order of benzene and hydrogen peroxide to 1, the activation energy of the reaction 93.3kJ · mol-1. 4) synthesis of a series of Bronsted acid ionic liquid at room temperature, the use of FT-IR and TG-DTG and other means to characterize the structure and thermal stability of the ionic liquid. The temperature of the thermal decomposition of the ionic liquid is higher than 573K. Such ionic liquids as solvents, [TEA] 4-PMo11V catalyst as the oxidant, H202, to explore, to development and to provide a basis for the hydroxylation of benzene with hydrogen peroxide to phenol process of benzene to phenol hydroxylation reaction.

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