摘要
考察了纳米ZrO2 的制备方法及Al2 O3 和KOH助剂的添加对ZrO2 催化CO加氢合成异丁烯反应的影响 .纳米ZrO2 的制备方法对ZrO2 的物理性质和催化性能有较大的影响 .用超临界流体干燥法干燥并在流动N2 气氛中焙烧制得的ZrO2 催化剂对异丁烯具有较高的选择性 .Al2 O3 和KOH助剂表现出非常优良的助剂效应 ,在大幅度提高催化剂对i C4烃选择性的同时保持了和ZrO2 同样高的催化活性 .催化剂的酸碱性表征结果表明 ,酸碱性对催化剂的催化性能影响很大 。
The influence of the preparation methods of the nanosized ZrO2-based catalysts and the addition of Al2O3 and KOH promoters to ZrO2 on their catalytic properties for the direct synthesis of isobutene from CO hydrogenation was investigated. The results indicate that the physical properties and the catalytic performance of the nanosized ZrO2 are strongly influenced by the preparation methods. The ZrO2 catalyst that is dried by the supercritical fluid drying method then calcined in a flow of N-2 is the most selective to isobutene. Al2O3 and KOH show excellent promoting effects on ZrO2 and can remarkably enhance the i-C-4 selectivity (65.2%) in the total hydrocarbons, while surely maintaining the CO conversion at 20.9%, which is more than that over the pure ZrO2(18.9%). The acidic and basic properties of the Al2O3 and KOH promoted ZrO2-based catalysts were characterized by NH3-TPD and CO2-TPD. The results indicate that the catalyst performance depends strongly on the acid-base properties of the catalysts. Increasing the amounts of acid sites on ZrO2 can enhance the activity and promote the formation of linear C-4 hydrocarbons. However, the amounts of base sites are very important for the formation of i-C-4 hydrocarbons. With the increasing of the ratio of base sites to acid sites on the catalysts, the percentage of i-C-4 in the total C-4 hydrocarbons increases. A certain amount of Al2O3 and KOH added to ZrO2 enhances both the amount of acid and base sites on ZrO2, while maintaining an appropriate ratio of base sites to acid sites.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2002年第2期185-190,共6页
基金
清华大学基础研究基金
清华大学分析基金资助课题
关键词
纳米催化剂
二氧化锆
一氧化碳
加氢
异构合成
异丁烯
碱性
助剂
酸性
催化性能
nanosized catalyst
zirconium dioxide
carbon monoxide
hydrogenation
isosynthesis
isobutene
acid-base property
promoter
