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采用等体积浸渍法制备了活性炭负载Pd催化剂(Pd/C),通过正交实验研究了活性炭的种类、催化剂的制备条件等对活性炭负载钯催化剂上CO氧化性能的影响,得到了最优的制备条件。并通过N2吸附、程序升温脱附(TPD)、程序升温还原(H2-TPR)和透射电镜(TEM)等对催化剂进行了表征。正交实验极差分析表明制备各因素对催化剂氧化CO活性影响的次序为:还原剂>活性炭>还原剂用量>还原温度>还原溶pH值。催化剂表征结果表明活性炭的比表面积和孔径分布不是决定Pd/C催化剂性能的关键因素,活性炭的种类、表面组成和性质对催化剂的性能有显著的影响。其中椰壳炭(AC1)表面羧基的活性较高,同时具有较强的表面碱性,有利于活性金属Pd在载体表面的分散,并提高了Pd与载体之间的相互作用,从而使催化剂具有较高的CO氧化性能。提高Pd的担载量,可显著提高催化剂稳定性。以乙二醇作为还原剂,在pH=10,还原温度为60℃的条件下所制备的0.5%Pd/AC催化剂,在反应温度20℃时连续反应120 h仍可保持CO的全转化。
The active carbon supported Pd catalyst (Pd / C) was prepared by the same volume impregnation method. The effects of the type of activated carbon, the preparation conditions of the catalyst on the oxidation performance of CO on the activated carbon loaded palladium catalyst were studied by orthogonal experiments. The optimum conditions were obtained condition. The catalysts were characterized by N2 adsorption, TPD, H2-TPR and TEM. The range analysis of orthogonal experiment shows that the order of the influence of preparation factors on the activity of CO oxidation is as follows: reducing agent> activated carbon> the amount of reducing agent> reducing temperature> reducing solution pH value. The results of catalyst characterization show that the specific surface area and pore size distribution of activated carbon are not the key factors to determine the properties of Pd / C catalyst. The type, surface composition and properties of activated carbon have a significant influence on the performance of the catalyst. Among them, the activity of carboxyl groups on the surface of coconut shell charcoal (AC1) is high, and at the same time, it has a strong surface alkalinity, which facilitates the dispersion of the active metal Pd on the surface of the support and increases the interaction between Pd and the support so that the catalyst has Higher CO oxidation performance. Increasing the amount of Pd supported can significantly improve the stability of the catalyst. With 0.5% Pd / AC catalyst prepared by using ethylene glycol as reductant and pH = 10, the reduction temperature is 60 ℃, the complete conversion of CO can be maintained when the reaction temperature is 20 ℃ for 120 h.