采用等体积浸渍法制备了不同金属离子（Mⁿ⁺）改性的系列氟化镁基催化剂（M/MgF₂），考察了其在高温气相条件下催化转化2-氯-1，1，1，2-四氟丙烷（HCFC-244bb）合成新一代环保制冷剂2，3，3，3-四氟丙烯（HFO-1234yf）的反应性能。实验结果表明，单一氟化镁上同时存在脱HF、脱HCl 2种反应过程，但前者为主反应，脱HF生成副产物2-氯-3，3，3-三氟丙烯（HCFO-1233xf）的选择性达87.7%，目标脱HCl产物HFO-1234yf选择性不足10%。Al³⁺改性后，催化剂活性显著增加，但脱HF选择性也随之增大（约90%）。3% Fe/MgF₂、3% Zr/MgF₂催化剂上HFO-1234yf选择性有所提高，但不足20%。碱金属K⁺、Cs⁺的添加可大幅提高催化剂的脱HCl选择性，分别为76.4%和86.6%，但催化剂活性低于未改性MgF₂催化剂。采用N₂物理吸附、NH₃-TPD等表征手段对催化剂结构、表面酸性进行表征，并将其与催化反应性能进行关联，结果表明，催化剂表面酸性的减弱有利于反应向选择性脱HCl方向移动。

A series of magnesium fluoride-based catalysts (M/MgF₂) modified by different metal ions (Mⁿ⁺) are prepared by equal volume impregnation method and their catalytic performances are investigated in the gas-phase catalytic dehydrochlorination of 1,1,1,2-tetrafluoro-2-chloropropane (HCFC-244bb) to make 2,3,3,3-tetrafluoropropylene (HFO-1234yf),a new generation of environment-friendly refrigerant.It is found that both dehydrofluorination and dehydrochlorination reactions occur on the pure MgF₂ catalyst,with dehydrofluorination as the main reaction.More importantly,the dehydrochlorination selectivity to HFO-1234yf is only 8.8%,and the selectivity to 2-chloro-3,3,3-trifluropropylene (HCFO-1233xf) is as high as 87.7%.The catalyst modified by Al³⁺exhibits higher activity,however,the un-expected dehydrofluorination selectivity to HCFO-1233xf increases to around 90% over the catalyst modified by Al³⁺,although.The dehydrochlorination selectivity to HFO-1234yf over 3%Fe/MgF₂ or 3%Zr/MgF₂ catalysts increases,but still less than 20%.High dehydrochlorination selectivity can be achieved over the MgF₂ catalysts modified by K or Cs halides,reaching 76.4% and 86.6% respectively,however,the activities of these catalysts are lower than the pure MgF₂ catalyst.The structure and surface acidity of prepared catalysts are characterized by means of XRD,NH₃-TPD and N₂ physical adsorption measurements,which are then correlated with catalytic performance.The results show that decreasing the surface acidity of catalyst can benefit the dehydrochlorination of HCFC-244bb.

贾兆华(1992-),男,硕士生,研究方向为含氟化学品合成,1542320290@qq.com