The Setup Of A Microcalorimetric Device And Its Application In The Research Of Metal Catalysis

In the heterogeneous catalysis and gas/solid systems, the measurement of differential heat of adsorption is essential in understanding the nature of gas-solid interactions and the properties of catalyst surfaces. In this dissertation, a microcalorimetric device for the accurate measurements of differential heat of adsorption on the surfaces of catalysts was designed and built. A special all-metal vessel for the measurement of differential heat of adsorption on metal catalysts, which can be operated under the condition of high vacuum and wide temperature range, and a sample treatment cell, where the sample is treated in-situ under the ultrahigh pure gas, were designed and constructed. In order to check the reliability of microcalorimetric system, the measurements of differential heat of adsorption such as H₂ on Pt/SiO₂ and γ-Mo₂N were carried out. The results are in excellent agreement with those published in the literature. The error analysis of the experimental data showed that the relative errors for the measurement of adsorption heat were within 4%.Microcalorimetry was employed to study the adsorption characteristics of N₂H₄ as well as its decomposition products and intermediate on Ir based catalysts with different indium contents (1.8%, 10.8% and 22.1%) and supports (Al₂O₃, SiO₂), in order to elucidate the changes in surface structure and the reaction process of hydrazine decomposition on highly loaded Ir/Al₂O₃ catalysts. It was found that the strong interaction of indium and Al₂O₃ led to the higher dispersion of iridium on Ir/Al₂O₃ catalysts. Moreover, the interaction of Ir-Al₂O₃, as well as the defect sites of iridium particles resulted in strong H₂ adsorption sites on highly...