纳米二氧化锆催化剂上一氧化碳加氢合成异丁烯

 考察了纳米ZrO2的制备方法及Al2O3和KOH助剂的添加对ZrO2催化\r\nCO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\r\n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\r\n焙烧制得的ZrO2催化剂对异丁烯具有较高的选择性．Al2O3和KOH助剂表\r\n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\r\n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\r\n碱性对催化剂的催化性能影响很大，催化剂上适宜的酸碱数量和酸碱比\r\n例是影响其催化CO加氢合成异丁烯性能的非常重要的因素．

Synthesis of Isobutene from CO Hydrogenation over Nanosized Zirconium Dioxide-Based Catalysts

The influence of the preparation methods of the nanosized ZrO 2 based catalysts and the addition of Al 2O 3 and KOH promoters to ZrO 2 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 ZrO 2 are strongly influenced by the preparation methods. The ZrO 2 catalyst that is dried by the supercritical fluid drying method then calcined in a flow of N 2 is the most selective to isobutene. Al 2O 3 and KOH show excellent promoting effects on ZrO 2 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 ZrO 2 (18 9%). The acidic and basic properties of the Al 2O 3 and KOH promoted ZrO 2 based catalysts were characterized by NH 3 TPD and CO 2 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 ZrO 2 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 Al 2O 3 and KOH added to ZrO 2 enhances both the amount of acid and base sites on ZrO 2, while maintaining an appropriate ratio of base sites to acid sites.