| The reaction of the aromatic phenol gas adjacent depth catalytic alkylation was one of the major production methods for the production of2,6-dimethyl phenol and2,3,6-trimethylphenol. This thesis with the m-cresol, phenol, mixed cresol and methanol as raw materials, studied systematically the reaction mechanisms, thermodynamics, catalysts and the reaction conditions.This paper first comprehensive acid-base catalytic mechanism proposed the way of the aromatic phenol gas adjacent depth catalytic alkylation, and thermodynamic analysis of the main side reaction. It is expect to provide theoretical guidance of the catalyst screening and optimization of process conditions.In this paper, followed by the catalysts of the aromatic phenol gas adjacent depth catalytic alkylation were studied.Firstly, Fe-Cr-Si-K composite oxide catalyst as the based catalyst, and a series of the different metal iron composite oxide catalyst were prepared by the Coprecipitation method. Under the same conditions, evaluation of the impact of metal types (Me=Cu、Zn、Ti、V、 Mn、Co、Ni、Zr、Mg、Al、In、Sn、Ge、Sb) on the reaction of alkylation of m-cresol to2,3,6-trimethylphenol and the phenol gas adjacent depth catalytic alkylation of the production of2,6-dimethyl phenol. The results showed that activity of the Fe-Cr-Si-K-In catalyst was the best.Furthermore, Fe-Cr-Si-K composite oxide catalyst as the based catalyst, and the source of iron, Fe/In molar ratio, precipitation temperature, precipitate the end of pH value, and calcinations temperature in the process of preparation of catalyst and other conditions were optimized. The results showed that:under the conditions of preparation of catalyst of iron nitrate as a source of iron, Fe/In molar ratio was100/3.45,25%of the ammonia as the precipitant, precipitation temperature was65℃, precipitate the end of pH value was9.0, the calcinations temperatures was550℃, in which the catalyst showed the highest depth of ortho catalytic properties.Another Fe-Cr-Si-K-In composite oxide catalysts were characterized using the X-ray diffraction(XRD), BET surface area, pore volume and pore size distribution(BET), temperature-programmed ammonia desorption(NH3-TPD), temperature-programmed hydrogen reduction(H2-TPR) and other characterization methods. The catalyst function-properties relationship was discussed.The characterization results showed that:source of iron used in the catalyst preparation process will directly affect the catalytic activity, and the main reason of catalytic activity decreased was that part of the Fe2O3was reduced to Fe3O4. To a certain extent, indium exist that can inhibit the phase transition process. Compared to the calcinations temperatures with precipitation temperature, precipitate the end of pH has a greater impact on the catalytic performance. It through catalyst specific surface area and acidity to influence the catalytic activity. The results showed that:the presence of acid in which is not a great amount of moderate-intensity and strong acid sites was favorable.Finally, the reaction process of the aromatic phenol gas adjacent depth catalytic alkylation was studied.With Fe-Cr-Si-K-In composite oxide catalyst as the catalyst optimized process conditions, we studied the influence of reaction temperature, liquid hourly space velocity and material ratio on the aromatic phenol with methanol gas adjacent depth catalytic alkylation reaction. In the reaction of alkylation of m-cresol to2,3,6-trimethylphenol, the optimal conditions were:reaction temperature was330℃, LHSV was0.72h-1-1.54h-1and o-cresol/methanol/water mole ratio was1:5:5. Under the optimum conditions, the conversion of o-cresol was up to99.45%, the selectivity of2,3,6-Trimethylphenol was95.82%. While, in the phenol gas adjacent depth catalytic alkylation of the production of2,6-dimethyl phenol, the conversion of phenol was up to92.46%, the selectivity of2,6-dimethyl was85.16%, when phenol/methanol/water mole ratio was1:5:1, reaction temperature was350-370℃and LHSV was1.2h-1. |
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