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Study On The Catalyst For The Partial Oxidation Of Methane To Oxygenous Compound

Posted on:2013-02-23Degree:MasterType:Thesis
Country:ChinaCandidate:L LiuFull Text:PDF
GTID:2211330371954549Subject:Chemical Engineering
Abstract/Summary:PDF Full Text Request
At present, the researches of oxidation of methane to methanol are mainly proceeded in gas-solid phase or gas-liquid phase reaction system. However, the former reaction are generally in harsh conditions of high temperature and high pressure, which causes problems such as carbon deposition, deactivation of catalysts, and deep oxidation of products. In the liquid phase reaction, often using fuming sulfuric acid or trifluoroacetic acid as solution, which makes products and catalysts difficulty to recycle, and the reaction kettle are corroded badly. Due to these drawbacks, the two systems are not applicable to industrial applications.Through summarizing former research findings, the article raises the PW12-PMo12-NaVO3 three-component as catalyst system and dilute sulfuric acid as solution, and then proportion of three components and reaction operating conditions are studied in homogeneous and heterogeneous systems respectively.Firstly, in gas-liquid reaction system, the pH=1 dilute sulfuric acid was demonstrated to be the optimum solution by comparing acetic acid with dilute sulfuric acid in different pH-value. Meanwhile, the amount and ratio of PW12-PMo12-NaVO3 components and process conditions were discussed and optimized. The experimental results show the optimum conditions as follows:mole ratio of catalyst components was:n(PMo12):n(PW12):n(NaVO3)=1:1.5:3, catalyst concentration was 7.83mmol/L, stirring speed was 300 rpm, the reaction temperature was 220℃, the pressure was 3.5MPa, the methane flow was 120ml/min, the air flow was 180ml/min, and the highest CH4% was 1.47% in that condition.On the basis of research in gas-liquid system, silica in 20-40 mesh size was selected as a carrier to support the PMo12-PW12-NaVO3 three components, the solution was the pH=1 dilute sulfuric acid, and the mole ratio of catalyst components was still 1:1.5:3. The preparation conditions of catalyst were discussed and process conditions were researched preliminarily. The optimum conditions are as follows:optimal load ratio was 13.37%(PMo12-3.75%, PW12-8.87%, NaVO3-0.75%), the amount of catalyst was 10g, the activation temperature was 350℃, the activation time was 4h, the reaction temperature was 210℃, and conversion of CH4 was 1.01%.
Keywords/Search Tags:methane, silica, heteropoly acid, sodium metavanadate, catalytic oxidation
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