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Tandem Catalysis for Hydrogenation of CO and CO2 to Lower Olefins with Bifunctional Catalysts Composed of Spinel Oxide and SAPO-34
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-07-06 , DOI: 10.1021/acscatal.0c01579
Xiaoliang Liu 1 , Mengheng Wang 1 , Haoren Yin 1 , Jingting Hu 1 , Kang Cheng 1 , Jincan Kang 1 , Qinghong Zhang 1 , Ye Wang 1
Affiliation  

Transformation of syngas (H2/CO) and hydrogenation of CO2 into lower olefins are attractive routes for chemical utilization of various carbon resources and CO2, but both suffer from limited product selectivity. Tandem catalysis that integrates the activation of CO or CO2 to an intermediate and the subsequent controllable C–C bond formation to form lower olefins offers a promising approach. Here, we report the hydrogenation of both CO and CO2 over bifunctional catalysts composed of a spinel binary metal oxide and SAPO-34. ZnAl2O4/SAPO-34 and ZnGa2O4/SAPO-34 are found to be highly selective for the synthesis of lower olefins from both CO and CO2. Our studies reveal that the oxygen vacancy site on metal oxides plays a pivotal role in the adsorption and activation of CO or CO2, while the −Zn–O– domain accounts for H2 activation. We demonstrate that methanol and dimethyl ether formed on metal oxide are the reaction intermediates, which are subsequently converted to lower olefins by the Brønsted acid sites in zeolite. The hydrogenation of CO and CO2 on metal oxide surfaces proceeds via the same formate and methoxide species. We elucidate that the water–gas shift reaction on oxide surfaces is responsible for CO2 formation during syngas conversion. The cofeeding of CO2 in syngas offers a useful strategy to inhibit CO2 formation.

中文翻译:

尖晶石氧化物和SAPO-34组成的双功能催化剂串联催化加氢合成CO和CO 2为低级烯烃

合成气(H 2 / CO)的转化和CO 2加氢成低级烯烃是各种碳资源和CO 2的化学利用的有吸引力的途径,但是两者都具有有限的产物选择性。串联催化将CO或CO 2的活化结合到中间体中,随后可控的C–C键形成形成低级烯烃,这提供了一种有前途的方法。在这里,我们报告了由尖晶石二元金属氧化物和SAPO-34组成的双功能催化剂对CO和CO 2的加氢作用。ZnAl 2 O 4 / SAPO-34和ZnGa 2 O 4发现/ SAPO-34对从CO和CO 2合成低级烯烃具有高度选择性。我们的研究表明,金属氧化物上的氧空位在CO或CO 2的吸附和活化中起着关键作用,而-Zn–O–结构域占H 2活化的原因。我们证明,在金属氧化物上形成的甲醇和二甲醚是反应中间体,它们随后通过沸石中的布朗斯台德酸位点转化为低级烯烃。金属氧化物表面上的CO和CO 2的氢化通过相同的甲酸盐和甲醇盐进行。我们阐明了氧化物表面的水煤气变换反应是造成CO 2的原因合成气转化过程中形成。合成气中CO 2的共同进料提供了抑制CO 2形成的有用策略。
更新日期:2020-08-08
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