Al含量对Pt-SO2-4 /ZrO2-Al2O3固体超强酸催化

通过向SO^2-₄ /ZrO₂催化剂中同时引入适量的Pt和Al₂O₃, 制备出了具有较高催化性能和稳定性的Pt-SO^2-₄ /ZrO₂-Al₂O₃型固体超强酸催化剂. 以正戊烷异构化反应为探针, 考察了Al含量对催化剂性能的影响; 并采用X射线衍射(XRD)、比表面积测定(BET)、红外(IR)光谱、程序升温还原(TPR)、热重-差热分析(TG-DTA)和氨-程序升温脱附(NH₃-TPD)手段对催化剂进行了表征. 结果表明, Al能够提高ZrO₂的晶化温度, 抑制硫的分解, 增加催化剂的比表面积, 增强硫氧键的结合, 提高催化剂的还原性能, 增加催化剂的酸强度和酸总量. 当Al₂O₃含量(质量分数, w)为5.0%时, Pt-SO^2-₄ /ZrO₂-Al₂O₃固体超强酸催化剂的催化活性最好, 在100 h内异戊烷收率可稳定在52.0%以上, 选择性在98.2%以上.

Effect of Al Content on the n-Pentane Isomerization of the Solid Superacid Pt-SO2-4 /ZrO2-Al2O3

Highly active and stable Pt-SO^2-₄ /ZrO₂-Al₂O₃ solid superacid catalysts were prepared by simultaneously introducing appropriate amounts of Pt and Al2O3 into a SO^2-₄ /ZrO₂ catalyst. The effect of Al content on the performance of the catalysts was studied using n-pentane isomerization as a probe reaction and the catalysts were characterized by X-ray diffraction (XRD), specific surface area measurements (BET), infrared (IR) spectroscopy, temperature-programmed reduction (TPR), thermogravimetry-differential thermal analysis (TG-DTA), and NH₃ temperature-programmed desorption (NH₃-TPD). The results show that Al can increase the crystallization temperature of ZrO₂ and inhibit the decomposition of sulfur. Al can also increase the surface area of the catalyst, strengthen the combination between S and O, improve the redox performance of the catalyst and increase the acid strength and the acidity of the catalyst. The catalytic activity of the Pt-SO^2-₄ /ZrO₂-Al₂O₃ solid superacid catalyst with a Al₂O₃ mass fraction of 5.0% was found to be the best. The isopentane yield was stable above 52.0% and the selectivity was higher than 98.2% within 100 h.