Insights into surface properties of non-thermal RF plasmas treated Pd/TiO2 in acetylene hydrogenation

• RF plasma treatment enhances Pd dispersion and induces the SMSI at room temperature.
• Surface defects of Pd metal particles are produced with plasma treatments.
• Further thermal reduction treatment undermines the effects of plasma on Pd catalysts.
• The ratio of multiply bound intensity of CO-FTIR to linearly bound intensity is a strong indicator of the Pd/TiO2 performance.
• RF plasma treated Pd/TiO2 exhibits the excellent performance for acetylene hydrogenation.

Non-thermal RF plasma treated Pd/TiO2 catalysts with additional thermal reduction exhibits excellent performance for selective hydrogenation of acetylene. To explore the influence of RF plasma on surface properties of Pd/TiO2 catalyst and unravel the excellent performance of RF plasma treated Pd/TiO2 catalysts, in situ FTIR adsorption spectra of CO on RF plasmas treated, RF plasmas treated with additional thermal reduction and thermally reduced Pd/TiO2 catalysts were investigated and compared in this study. It was found that RF plasma treatment at much lower temperature can produce metal particles with more surface defects and induces strong metal–support interaction (SMSI) as compared to the thermal reduction treatment, which favors achievement of excellent catalysis performance. However, RF plasma treated catalysts exhibits relatively poor thermal stability at high temperature because further thermal reduction of plasma treated samples can reduce the number of surface defects, change the distribution of Pd(1 0 0) and Pd(1 1 1) planes and weaken the SMSI effect to some extent. C2H2- & C2H4-TPD results support the analysis results of in situ FTIR well. The reaction test results of selective hydrogenation of acetylene are in good agreement with the results of in situ FTIR, TPD and CO-chemisorption.

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