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用沉积-沉淀法制备了CrOx-Y2O3催化剂,考察焙烧气氛及温度对1,1,1-三氟-2-氯乙烷(HCFC-133a)气相氟化合成1,1,1,2-四氟乙烷(HFC-134a)催化性能的影响.采用拉曼光谱、X射线粉末衍射(XRD)等表征手段观察了催化剂中铬物种价态的变化情况.结果表明,先氮气后空气中不同温度(T)焙烧的催化剂(NAT),随着空气中焙烧温度的升高,Cr物种由CrO3向YCrO4、YCrO3转变.500℃焙烧的NA500催化剂虽然活性低于直接在空气中350℃焙烧的催化剂(A350),然而前者的反应稳定性明显高于后者.这归因于YCrO4物种在氟化过程中生成的活性物种既不易流失并且表面不容易结炭.
The CrOx-Y2O3 catalyst was prepared by deposition-precipitation method. The effects of calcination atmosphere and temperature on the fluorination of 1,1,1-trifluoro-2-chloroethane (HCFC-133a) to 1,1,1,2-tetra (HFC-134a) .The catalytic performance of chromium species in the catalyst was investigated by Raman spectroscopy, X-ray powder diffraction (XRD) and other characterization methods.The results showed that the first nitrogen in the air at different temperatures (T) calcined catalyst (NAT), Cr species changed from CrO3 to YCrO4 and YCrO3 with the increase of calcination temperature in air.The activity of NA500 calcined at 500 ℃ was lower than that of calcined at 350 ℃ A350), however, the stability of the former was obviously higher than that of the latter, which was attributed to the fact that the active species produced by the YCrO4 species during fluorination was not easily lost and the surface was not easily carbonized.