Direct synthesis of dimethyl ether from CO2 and H2 over novel bifunctional catalysts containing CuO-ZnO-ZrO2 catalyst admixed with WOx/ZrO2 catalysts
Direct synthesis of dimethyl ether from CO2 and H2 over novel bifunctional catalysts containing CuO-ZnO-ZrO2 catalyst admixed with WOx/ZrO2 catalysts
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DOI：
10.1016/j.cej.2018.05.057
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发表时间：
2018-09-15
影响因子：
15.1
通讯作者：
Limtrakul, Jumras
中科院分区：
文献类型：
--
作者：
Witoon, Thongthai;Kidkhunthod, Pinit;Limtrakul, Jumras
考察了不同温度焙烧的WOx/ZrO 2催化剂与Cu-ZnO-ZrO 2催化剂混合后的CO2加氢制二甲醚（DME）反应性能。考察了反应温度、压力、空速等操作条件对反应的影响。焙烧温度对WOx/ZrO 2催化剂的物理化学性质和催化性能起着至关重要的作用。煅烧温度从600 ℃升高到800 ℃，钨的表面密度逐渐增加（2.82-4.82 W nm（-2）），同时酸中心的数量和强度也增加。在900 ℃下煅烧的WOx/ZrO 2催化剂显示出9.63 W nm（-2）的W表面密度，其高于W的理论单层表面覆盖率（类似于8 W nm（-2）），表明WOx物质的饱和覆盖率与小部分纳米晶WO 3共存。在1000 ℃煅烧温度下，由于BET比表面积急剧减小（约为5 m2 g-1），形成了单斜相ZrO 2、块状WO 3颗粒和ZrW 2 O 8相。在260 ℃、30巴和空速4333.33 mL g（cat）（-1）h（-1）的48 h试验期间，在900 ℃下煅烧的与WOx/ZrO 2催化剂混合的CuO-ZnO-ZrO 2催化剂表现出最高的DME时空产率271.2 g（DME）kg（cat）（-1）h（-1）。
The present work examined the performance of WOx/ZrO2 catalysts calcined at different temperatures admixed with a Cu-ZnO-ZrO2 catalyst for CO2-to-dimethyl ether (DME) hydrogenation. The effect of operating conditions including reaction temperature, pressure and space velocity was also investigated. The calcination temperature was found to play a crucial role on the physicochemical properties of the WOx/ZrO2 catalysts as well as their catalytic performance. Increasing calcination temperature from 600 to 800 degrees C led to a gradual increase of W surface density (2.82-4.82 W nm(-2)) which was accompanied by an increase of both quantity and strength of acid sites. The WOx/ZrO2 catalyst calcined at 900 degrees C showed W surface density of 9.63 W nm(-2) which was higher than theoretical monolayer surface coverage of W (similar to 8 W nm(-2)), indicating the saturation coverage of WOx species coexisted with a small portion of nanocrystalline WO3. At calcination temperature of 1000 degrees C, the monoclinic ZrO2, bulk WO3 particles and ZrW2O8 phase were formed because of a drastic reduction in BET surface area (similar to 5 m(2)g(-1)). The CuO-ZnO-ZrO2 catalyst admixed with WOx/ZrO2 catalyst calcined at 900 degrees C exhibited the highest space-time yield of DME of 271.2 g(DME) kg(cat)(-1) h(-1) during a 48-h test at 260 degrees C, 30 bars and a space velocity of 4333.33 mL g(cat)(-1) h(-1).