钙改性的Pd/CeO2-ZrO2-Al2O3催化剂催化甲醇裂解反应

采用共沉淀法制备了未改性的和Ca掺杂的CeO2-ZrO2-Al2O3样品,进一步用浸渍法制备了Pd/CeO2-ZrO2-Al2O3(Pd/CZA)和Pd/CeO2-ZrO2-Al2O3-CaO (Pd/CZACa)催化剂.运用X射线衍射、N2吸附-脱附、储氧量测定、CO化学吸附、NH3程序升温脱附、CO2程序升温脱附、...

Ca-Modified Pd/CeO2-ZrO2-Al2O3 Catalysts for Methanol Decomposition

CeO2-ZrO2-Al2O3 and CeO2-ZrO2-Al2O3-CaO supports were prepared by the coprecipitation method and were loaded with Pd by impregnation to form Pd/CeO2-ZrO2-Al2O3 (Pd/CZA) and Pd/CeO2-ZrO2-Al2O3-CaO (Pd/CZACa) catalysts. The catalysts were characterized by X-ray diffraction, low temperature N2 adsorption-desorption, oxygen storage capacity, CO chemisorption, NH3 temperature-programmed desorption (NH3-TPD), CO2 temperature-programmed desorption (CO2-TPD), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The catalyst activity for methanol decomposition showed that the Ca modification improved the low-temperature activity of the catalyst, which lowered the complete conversion temperature on 34 oC. NH3-TPD and CO2-TPD showed that the addition of Ca poisoned the acid sites of the support or increased the number of weak basic sites and therefore changed the adsorption-desorption equilibria of the adsorbed species. It also enhanced the metal-support interaction and increased the electronic surroundings of Pd sites, which maintained Pd in a partly oxidized (Pdδ+) state and consequently increased the activity for methanol decomposition according to H2-TPR and XPS measurements.