碱土金属对ZrO_2-Al_2O_3及其负载Pd-Rh密偶催化剂的影响(英文)

Effects of Alkaline Earth Metal on Performance of ZrO_2-Al_2O_3 Support and Pd-Rh Close-Coupled Catalyst

采用胶溶法制备了一系列碱土金属改性的ZrO2-Al2O3,并以其为载体采用等体积浸渍法制备了Pd-Rh密偶催化剂.采用低温N2吸附-脱附、X射线衍射(XRD)、氨气程序升温脱附(NH3-TPD)对载体样品进行了表征.结果表明,碱土金属的添加增大了ZrO2-Al2O3的比表面积,Sr-Zr-Al样品经1000°C焙烧5h后具有最大的比表面积,为164m2·g-1.对催化剂进行了H2程序升温还原(H2-TPR)、X射线光电子能谱(XPS)和活性表征,考察了催化剂对C3H8的转化活性.测试结果表明,添加碱土金属能有效提高催化剂上丙烷的转化活性.

A series of alumina supports stabilized by alkaline earth metals and zirconia were prepared by the peptizing method. Pd-Rh close-coupled catalysts supported on modified alumina were prepared by the impregnation method. The supports were characterized by low temperature nitrogen adsorption-desorption method, X-ray diffraction （XRD）, and NH3-temperature programmed desorption （NH3-TPD）. For the catalysts, H2-temperature programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS） were carried out. We also carried out catalytic activity tests for C3H8 conversion. Results show that the addition of alkaline earth metals increases the surface area of the supports and the surface area of Sr-Zr-Al reaches 164 m2·g-1 after calcination at 1000 °C for 5 h. The introduction of alkaline earth metals into the ZrO2-Al2O3 supports also improves their catalytic activity toward propane oxidation and the activities of the Pd-Rh catalysts containing alkaline earth metals are higher than that of the catalyst prepared with a ZrO2-Al2O3 support.