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将一系列负载型硅钨酸催化剂用于甘油脱水制丙烯醛反应中.表征结果表明,最终所得催化剂具有高的热稳定性、大的孔径、强的L酸位和大的比表面积.X射线光电子能谱中清晰地出现归属于W(W 4f=35.8 eV),Al(Al 2p=74.9 eV)和Zr(Zr 3d=182.8 eV)元素的谱峰.在SiW_(20)-Al/Zr_(10)催化剂上丙烯醛选择性最高,为87.3%,此时甘油转化率为97%.由于高浓度L酸位的存在,显著降低了催化剂表面积碳量,因而该催化剂即使反应40 h之后仍具有较高地催化生成丙烯醛的活性和选择性.响应面方法表明,在以下优化条件下反应甘油转化率和丙烯醛选择性分别达87.7%和97.0%:催化剂用量0.5wt%,进料甘油浓度10 wt%,反应温度300 ℃.传质限制评估结果显示,当颗粒尺寸d_P<20μm时,反应不存在内外扩散限制.综上可见,强L酸催化剂有望用于甘油脱水制丙烯醛反应中
A series of supported silicotungstic acid catalysts were used in the dehydration of glycerol to acrolein.The characterization results show that the resulting catalyst has high thermal stability, large pore size, strong L acid sites and large specific surface area.X-ray The spectral peaks attributed to the elements W (W 4f = 35.8 eV), Al (Al 2p = 74.9 eV) and Zr (Zr 3d = 182.8 eV) clearly appear in the photoelectron spectra. 10) The catalyst had the highest acrolein selectivity of 87.3% with a glycerol conversion of 97%. Due to the high concentration of L acid sites, the amount of carbon on the surface of the catalyst was significantly reduced, The results showed that the conversion of glycerol and the selectivity of acrolein reached 87.7% and 97.0% respectively under the following optimum conditions: 0.5wt% of catalyst and 10wt% of feed glycerin wt% and the reaction temperature is 300 ℃ .The results of mass transfer restriction assessment show that there is no internal and external diffusion limitation when the particle size d_P <20μm.In conclusion, the strong L acid catalyst is expected to be used in the dehydration of glycerol to acrolein