摘要
将 Ru Cl3· x H2 O和 Zn Cl2 与 Na OH共沉淀 ,再用适量的 Na OH溶解部分 Zn,制备了以 Ru为活性组分、Zn为助剂的苯选择加氢制环己烯的催化剂 .研究了 Zn含量、碱溶用 Na OH浓度、温度等因素对活性与选择性的影响 ,并用 XRD、SEM、BET比表面积、孔径分布等测试手段对催化剂进行表征 .结果表明 ,Zn含量为 5 %左右时 ,苯的转化率可保持在 6 5 %左右 ,且环己烯的收率较高 .碱溶用 Na OH浓度宜控制在 2 %～ 4 % .沉淀时的反应温度 6 0℃左右较好 .XRD表明 ,活性组分 Ru和 Zn均被还原 ,并形成了 Ru- Zn固溶体 ,Ru微晶粒径为 3～ 5nm,经 SEM可以观察到 Ru微晶呈高分散 .BET比表面积 30～ 4 0 m2 /g,催化剂最可几孔径分布范围 30～ 70nm.与一般沉淀法相比 。
A Ru\|Zn catalyst was prepared by precipitation method which involves RuCl\-3· x H\-2O and ZnCl\-2 co\|precipitation with NaOH and then dissolved with NaOH to exclude the excess Zn to form the porous structure of the catalyst. The effect of Zn content, NaOH concentration and precipitation temperature on the activity and selectivity to cyclohexene were studied. The catalyst was characterized by means of XRD, SEM, BET surface area measurement etc. It was concluded that as Zn content of the catalyst is about 5% benzene conversion is suitable and cyclohexene yield is high. A proper NaOH concentration for dissolving the excess Zn is 2%~4%. And the precipitation temperature should be near 60 ℃. XRD shows that Ru and Zn in the catalyst exist in metal state and form the solid solution, Ru crystallite size is 3~5 nm. High dispersion of Ru can be seen by SEM. The specific surface area of the catalyst is 30~40 m\+2/g and the range of the pore size distribution is 30~70 nm. By comparison of this method with the general precipitation, the Ru\|Zn catalyst enhanced the selectivity to cyclohexene due to its pore structure caused by alkali dissolving again.
出处
《分子催化》
EI
CAS
CSCD
北大核心
2002年第5期349-354,共6页
Journal of Molecular Catalysis(China)
基金
河南省教育厅自然科学基金资助项目
关键词
苯
选择加氢
Ru-Zn催化剂
沉淀法
碱溶
制备
表征
钌
锌
环己烯
Selective hydrogenation of benzene
Ru\|Zn catalyst
Precipitation
Alkali dissolving
Preparation
Characterization
