不同方法制备钯基催化剂对直接合成过氧化氢性能的影响

发布时间：2018-09-02 06:24

【摘要】：采用紫外线光催化法、沉积-沉淀法、反相胶束法和浸渍法分别制备了催化剂Pd/TiO_2-UV、Pd/TiO_2-CD、Pd@TiO_2、Pd/TiO_2-JZ,利用一氧化碳-脉冲、氮气吸附/脱附曲线、氢气程序升温还原(H2-TPR)、X射线衍射(XRD)对催化剂进行了表征分析,并测定了各催化剂对直接合成过氧化氢性能的影响。结果表明,Pd/TiO_2-UV和Pd/TiO_2-CD催化剂催化氢氧直接合成过氧化氢的活性明显高于Pd@TiO_2和Pd/TiO_2-JZ催化剂,反应0.5 h时单位质量钯合成过氧化氢的产率分别达到1 631.4 mmol/(g·h)和852.3 mmol/(g·h),这是由于催化剂上活性金属钯的颗粒尺寸较小、分散度较大、提供的活性位点较多,有利于更多的反应物分子在活性位上的吸附与活化,提高其合成过氧化氢的活性。其中Pd/TiO_2-UV催化剂具有最高的催化活性,这是由于该催化剂上氧化钯含量较少,形成的钯-氧化钯界线较长,导致该催化剂上钯-氧化钯位点的数量更多,提供反应物氢气解离吸附和氧气非解离吸附的活性位点也就越多,催化活性也就越高。
[Abstract]:The catalyst Pd/TiO_2-UV,Pd/TiO_2-CD,Pd@TiO_2,Pd/TiO_2-JZ, was prepared by UV photocatalytic method, deposition-precipitation method, reverse micelle method and impregnation method, respectively. The carbon monoxide pulse and nitrogen adsorption / desorption curves were used to prepare the catalyst. Hydrogen temperature programmed reduction (H2-TPR) X-ray diffraction (XRD) was used to characterize the catalysts and the effects of the catalysts on the direct synthesis of hydrogen peroxide were determined. The results showed that the catalytic activity of PD / TiO2-UV and Pd/TiO_2-CD catalysts for the direct synthesis of hydrogen peroxide was significantly higher than that for Pd@TiO_2 and Pd/TiO_2-JZ catalysts. The yield of hydrogen peroxide was 1 631.4 mmol/ (g h) and 852.3 mmol/ (g h), respectively at the reaction time of 0. 5 h, which was due to the smaller particle size, higher dispersion and more active sites of active palladium on the catalyst. It is beneficial to the adsorption and activation of more reactant molecules on the active site and to improve the activity of hydrogen peroxide synthesis. The Pd/TiO_2-UV catalyst has the highest catalytic activity, which is due to the lower content of palladium oxide on the catalyst and the longer Palladium oxide boundary, which results in more palladium oxide sites on the catalyst. The more active sites that provide hydrogen dissociation adsorption and oxygen non-dissociation adsorption, the higher the catalytic activity.
【作者单位】：贵州大学化学与化工学院;贵州省绿色化工与清洁能源技术重点实验室;
【基金】：国家自然科学基金项目(21366008),黔科合JZ字[2014]2008号
【分类号】：O643.36;TQ123.6

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