高比表面积Cr_2O_3-α-AlF_3催化剂的制备和应用(英文)

Preparation and Application of a Cr_2O_3-α-AlF_3 Catalyst with a High Specific Surface Area

采用炭硬模板法制备了高比表面积Cr_2O_3-α-AIF_3催化剂.该催化剂的合成过程主要包括三步:(1)将一定浓度的蔗糖溶液浸渍到Cr_2O_3-γ-Al_2O_3中,然后经过热处理,使得蔗糖分解为炭;(2)将含炭的Cr_2O_3-γ-Al_2O_3固体在400℃用HF气体进行完全氟化;(3)在高温下利用燃烧法除去炭硬模板.对所制备的催化剂进行了X射线衍射(XRD),氮气吸脱附曲线,氨气程序升温脱附(NH_3-TPD),透射电镜(TEM),扫描电镜(SEM)和X射线能量散射(EDX)技术表征.结果表明,氟化过程对Cr_2O_3-α-AIF_3催化剂比表面积有重要影响,在最佳实验条件下,能够得到比表面积为115 m^2·g^(-1)的催化剂.此催化剂对催化裂解二氟乙烷(HFC-152a)制备氟乙烯(VF)的催化活性明显高于直接氟化制备的Cr_2O_3-α-AIF_3催化剂,这是因为高比表面积的Cr_2O_3-α-AIF_3催化剂具有较大的酸量.

A high specific surface area Cr_2O_3-α-AIF_3 catalyst was prepared using a carbon hard template method.The synthesis procedure consisted of three consecutive steps：（1） the impregnation of a sucrose （C_（12）H_（22）O_（11）） aqueous solution with Cr_2O_3-γ-Al_2O_3 and subsequent thermal treatment;（2） the thermal treatment of the obtained solid with HF,C@Cr_2O_3-γ-AI_2O_3 can be completely transformed into C@Cr_2O_3-γ-AIF_3 at 400℃with hydrogen fluoride;（3） the removal of the carbon template in C@Cr_2O_3-γ-AIF_3 upon high temperature combustion giving the high surface area Cr_2O_3-γ-AIF_3（115 m^2·g^（-1））.The catalysts were characterized by X-ray diffraction（XRD）,N_2 physisorption,ammonia temperature-programmed desorption（NH_3-TPD）,transmission electron microscopy（TEM）,scanning electron microscopy（SEM）,and energy dispersion X-ray（EDX） techniques.We found that the fluorination process was crucial for the resulting Cr_2O_3-α-AIF_3 with a high specific surface area of 115 m^2·g^（-1） under optimal conditions.The Cr_2O_3-α-AIF_3 catalyst with a high specific surface area was more active for the decomposition of 1,1-difluoroethane than the catalyst prepared by the direct fluorination of Cr_2O_3-γ-Al_2O_3, because it contained a higher amount of acid sites.