Pd/AlF3 Catalysts for Catalytic Dehydrofluorination of 1,1,1,3,3-Pentafluoropropane

A series of Pd/AlF3 catalysts was prepared by an impregnation method and tested for vapor-phase dehy- drofluorination of 1,1,1,3,3-pentafluoropropane（HFC-245fa） to synthesize 1,3,3,3-tetrafluoropropene（HFO-1234ze）. The highest activity was obtained over Pd/AIF3 catalyst containing 1.0%（mass fraction） of Pd, with an HFC-245fa conversion of 79.5% and an HFO-1234ze selectivity of 99.4% after the reaction at 300 ℃ for 100 h. The reactivity was related to the surface acidity, as AlF3 provided active sites for the reaction. With the addition of Pd, the catalyst stability could be significantly improved. Raman spectroscopic and thermal-gravimetric analysis results reveal that there was less carbon deposit on spent Pd/AlF3 catalyst surface because Pd could effectively pyrolyse it. Thus, Pd/AlF3 catalysts were bi-functional for dehydrofluorination of HFC-245fa.

气相催化合成CF_3I的催化剂载体研究

CHF3和碘在金属盐催化下合成三氟碘甲烷(CF3I),研究了载体对CHF3催化合成转化率和CF3I选择性的影响,发现多孔氟化铝(PAF)作为载体时,反应转化率为17.5%,对CF3I的选择性高,达到62.9%,反应前后催化剂的BET比表面积测试和等离子发射光谱(ICP)分析发现,活性炭作为载体的催化剂反应后比表面积降低,活性物流失达到45%;而PAF作为载体的催化剂,活性物流失程度较低,高温裂解CHF3的实验表明,PAF能够促进CHF3的裂解和CF2卡宾的岐化。

镁、钐和锆对AlF_3催化剂的乙炔气相氢氟化反应性能的影响

研究了Mg、Sm和Zr助剂对AlF_3催化剂的乙炔气相氢氟化合成氟乙烯反应性能的影响。通过XRD、NH_3-TPD和拉曼光谱对催化剂进行了表征。结果表明,添加Zr既能保持C_2H_2的高转化率,提高氟乙烯选择性,同时能降低积炭选择性;加入Mg或Sm助剂,均使C_2H_2转化率下降,Mg大幅度降低积炭选择性,Sm提高了氟乙烯选择性。助剂的加入,改变了催化剂表面酸性位的数量和性能,是影响催化剂性能的主要因素。