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Selective Conversion of Carbon Dioxide into Liquid Hydrocarbons and Long-Chain α-Olefins over Fe-Amorphous AlOx Bifunctional Catalysts
ACS Catalysis ( IF 12.9 ) Pub Date : 2020-08-12 , DOI: 10.1021/acscatal.0c02611
Muhammad Kashif Khan 1, 2 , Paresh Butolia 2 , Heuntae Jo 1 , Muhammad Irshad 2 , Daseul Han 3 , Kyung-Wan Nam 3 , Jaehoon Kim 1, 2, 4
Affiliation  

Considerable progress has been made in the conversion of carbon dioxide (CO2), which is highly thermodynamically stable, into liquid hydrocarbons using metal oxide/zeolite composite catalysts. Nevertheless, producing liquid hydrocarbons with a single catalyst without utilizing additional C–C coupling agents remains a formidable challenge. Herein, we report a bifunctional iron aluminum oxide (FeAlOx) catalyst that directly converts CO2 into C5+ hydrocarbons with an overall selectivity of 77.0% and CO2 conversion of 20.2% at a H2/CO2 ratio of 1:1. Notably, the selectivity for linear α-olefins (LAOs) was 52.4%, accounting for 78.4% of the total C4+ olefins. At a high H2/CO2 ratio of 3:1, the yield of C5+ hydrocarbons was 19.7%. The concept of crystalline-/amorphous-structured active sites in the single FeAlOx catalyst was proposed. The reducible magnetite (Fe3O4) phase, which contains surface oxygen vacancies, facilitated the reverse-water–gas-shift (RWGS) reaction to form CO via CO2 hydrogenation, and subsequent C–C coupling over Hägg iron carbide afforded lower olefins (C2–C4=). Long-chain LAOs were then formed on the surface of amorphous aluminum oxide (AlOx) via the readsorption of C2–C4=. In addition, the amorphous AlOx phase enhanced CO2 and H2 adsorption, which facilitated the formation of carbonate, bicarbonate, and formate species via the RWGS reaction and the subsequent formation of long-chain hydrocarbons via the Fischer–Tropsch reaction. The bifunctional FeAlOx catalyst showed excellent stability for up to 450 h on-stream, demonstrating its potential as a practical-scale catalyst for the conversion of CO2 into value-added liquid fuels and chemicals.

中文翻译:

Fe-非晶态AlO x双功能催化剂将二氧化碳选择性转化为液态烃和长链α-烯烃

使用金属氧化物/沸石复合催化剂将高度热力学稳定的二氧化碳(CO 2)转化为液态烃已取得了很大进展。然而,在不使用额外的C-C偶联剂的情况下,用单一催化剂生产液态烃仍然是一个巨大的挑战。本文中,我们报告了一种双功能的铁氧化铝(FeAlO x)催化剂,该催化剂以1的H 2 / CO 2比率将CO 2直接转化为C 5+烃,总选择性为77.0%,CO 2转化率为20.2%。。值得注意的是,线性α-烯烃(LAOs)的选择性为52.4%,占总C的78.4%4+烯烃。在3:1的高H 2 / CO 2比下,C 5+烃的产率为19.7%。提出了单一FeAlO x催化剂中晶体/非晶结构活性位的概念。含有表面氧空位的可还原磁铁矿(Fe 3 O 4)相促进了逆水煤气变换(RWGS)反应通过CO 2加氢形成CO ,随后通过Hägg碳化铁进行的C–C偶联降低了烯烃(C 2 –C 4 =)。然后,通过对C的再吸收,在无定形氧化铝(AlO x)的表面上形成长链LAO。2 –C 4 =。另外,无定形的AlO x相增强了CO 2和H 2的吸附,从而通过RWGS反应促进了碳酸盐,碳酸氢盐和甲酸的形成,并通过费托反应促进了长链烃的形成。双功能FeAlO x催化剂在长达450小时的运行中表现出出色的稳定性,证明了其作为将CO 2转化为增值液体燃料和化学品的实用规模催化剂的潜力。
更新日期:2020-09-20
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