二步法合成笼状大孔/介孔三维有序Cs_2O-Sb_2O_5/SiO_2

Two-steps synthesis of mesoporous Cs_2O-Sb_2O_5/SiO_2 with three-dimensionally ordered cage-like macropores

以聚氯乙烯（PS）胶晶束为模板,正硅酸乙酯（TEOS）为硅源,采用原位溶胶凝胶-水热法负载活性组分Cs2O-Sb2O5,制备出具有笼状大孔的介孔Cs2O-Sb2O5/SiO2材料。用透射电镜（TEM）、扫描电镜（SEM）、物理吸附与化学吸附（N2-TPD、CO2-TPD和NH3-TPD）以及X衍射（XRD）等手段对样品进行表征。结果表明,该材料呈3DOM笼状结构,大孔孔径约150 nm,孔壁有介孔存在,介孔孔径主要集中在5 nm。以BJH方法计算,在P/P0=0.9919时测得孔容积为约2.98 cm3.g-1,BET方法测得比表面积约为103.5m2.g-1,制得的催化剂具有酸碱双中心,碱强度为150℃和443℃,碱量为1.0~1.2 mmo.lg-1。酸强度为200℃,酸量为0.51~0.55 mmo.lg-1。以醋酸甲酯与甲醛在固定床反应器上合成丙烯酸甲酯为探针反应,对所合成的催化剂进行考察,得到丙烯酸甲酯的收率在50~55%,与相同活性组分的介孔催化剂相比,笼状大孔/介孔催化剂由于空间形貌决定其催化活性、选择性、重复使用及抗积碳等性能显著提高。

Mesoporous Cs2O-Sb2O5/SiO2 material with cage-like macropores assembled by using tetraethoxysilane（TEOS） as a silica source,polystyrene colloidal crystal used as template,and in-situ Sol-Gel and impregnation method was applied to load Cs2O-Sb2O5active component.The obtained materials were fully charaterized by SEM,TEM,N2physical adsorption,chemisorption（NH3-TPD,CO2-TPD）,and XRD.Results showed that the material was the one with 3DOM cage-like structure in which the macroporous pore size was about 150 nm,and discovered that mesopores did exist in the pore wall.Mesoporous pore size was comparatively centralized around 5 nm.Calculated by means of BJH,the pore volume was recorded at about 2.98 cm3·g-1 when P/P0=0.991 9;Through BET method,surface area was recorded at about 103.5 m2·g-1,the loaded active component showed acid-base bifunctional property with base strengths at 150 ℃ and 443 ℃,base amount at 1.0～1.2 mmol·g-1,and acid strength was recorded at 200 ℃,base amount at 0.51～0.55 mmol·g-1.The catalytic was tested by a probe reaction in which methyl acrylate was synthesiz from methyl acetate.The yield of methyl acrylate was recorded at 50～55%,the ester yield was still stable even after the catalyst was repeatedly used for 8 times,and no phenomenon of apparent carbon deposit was detected.