摘要
分别以Na2 WO4和H2 WO4为钨源,以正硅酸四乙酯为硅源直接合成了W SBA 15介孔分子筛样品,并用小角XRD ,N2吸附,FT IR ,UV Vis,SEM和XRF等手段对合成的分子筛进行了表征.结果表明,只用P12 3(EO2 0 PO70 EO2 0 )为模板剂时,分子筛中钨的含量只是投料量的一半;而以P12 3和十六烷基三甲基溴化铵为混合模板剂时,钨能有效地掺杂到SBA 15分子筛中.当原料中的Si/W摩尔比为4 0时,W SBA 15分子筛中的钨物种以高度分散状态存在,且以H2 WO4为钨源比以Na2 WO4为钨源更易将钨掺杂到SBA 15介孔分子筛中.W SBA
Tungsten-containing mesoporous molecular sieves W-SBA-15 were synthesized under conventional hydrothermal conditions in strong acidic solution using Na2WO4 or H2WO4 as tungsten source and tetraethyl orthosilicate as silicon source. The molecular sieves were characterized by means of small angle XRD, N-2 adsorption, FT-IR, UV-Vis, SEM and XRF. When only P123 (EO20PO70EO20) was used as structure directing agent, the tungsten content in W-SBA-15 was half that in gel solution. While the mixture of P123 and cetyltrimethylammonium bromide was used as template, the tungsten in gel solution can be effectively incorporated into W-SBA-15. H2WO4 was more effective as tungsten source than Na2WO4. When the Si/W ratio was 40 in gel solution, the tungsten species in W-SBA-15 were highly dispersed. The W-SBA-15 materials had a high catalytic activity for epoxidation of cyclohexene.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2005年第5期412-416,共5页
