不同类型分子筛对甲缩醛的催化性能

Studies on Catalytic Properties of Different Types of Molecular Sieves for Synthesis of Methylal

在间歇反应方式下 ,研究了以甲醛和甲醇为原料合成甲缩醛反应所需的催化剂 .在3 0℃ ,醛醇摩尔比为 1∶ 2 ,加入 5% (质量分数 )的催化剂条件下 ,考察了 HY,HM,Hβ,γ-Al2 O3 和 HZSM-5等催化剂对该合成反应的催化效果 ,从中优选出 HZSM-5.进一步对不同硅铝比和不同交换度的 HZSM-5进行评价 .实验结果表明 ,硅铝比为 3 8,交换 4次的HZSM-5分子筛对该合成反应具有良好的催化作用 ,甲醛的转化率为 45% ,甲缩醛的选择性达 99% .该催化剂经 2 0次重复使用 ,甲醛的转化率、甲缩醛的选择性无明显变化 。

The synthesis of methylal from methanol and methanal over different types of molecular sieves was studied. A batch reactor was employed. In a molar ratio of 1∶2 of methanal to methanol and in the presence of 5%(mass fraction) the catalyst, five sorts of catalysts (HZSM-5, HY, HM, Hβ and \{γ-Al 2O 3)\} were tested at 30 ℃, among them, HZSM-5 showed the best catalytic activity. HZSM-5 with 38∶1 of Si to Al and 4 of exchange degree was extremely effective for this reaction. The conversion rate of mathanal was 45% and the selectivity of methylal was 99%, both the conversion rate and the selectivity were reproducible after the catalyst was reused for 20 times.