On the nature of Cu-carbon interaction through N-modification for enhanced ethanol synthesis from syngas and methanol

• Published in: Physical chemistry chemical physics : PCCP 2024-07, Vol.26 (3), p.247-2482
• Main Authors: Yang, Mingxue, Bai, Bing, Bai, Hui, Wei, Zhongzeng, Cao, Haojie, Zuo, Zhijun, Gao, Zhihua, Vinokurov, Vladimir A, Zuo, Jianping, Wang, Qiang, Huang, Wei
• Format: Article
• Language: English
• Subjects: Carbon; Catalysts; Copper; Direct conversion; Doping; Electron transfer; Ethanol; Graphene; Hydrogenation; Methanol; Molecular orbitals; Reaction mechanisms; Synthesis gas
• ISSN: 1463-9076; 1463-9084; 1463-9084
• DOI: 10.1039/d4cp01599a

Direct conversion of syngas into ethanol is an attractive process because of its short route and high-added value, but remains an enormous challenge due to the low selectivity caused by unclear active sites. Here, the Cu(111) supported N-modified graphene fragments C 13− m N m /Cu(111) ( m = 0-2) are demonstrated to be an efficient catalyst for fabricating ethanol from syngas and methanol. Our results suggest that the Cu-carbon interaction not only facilitates CO activation, but also significantly affects the adsorption stability of C 2 intermediates and finally changes the fundamental reaction mechanism. The impeded hydrogenation performance of C 13 /Cu(111) due to the introduced Cu-carbon interaction is dramatically improved by N-doping. Multiple analyses reveal that the promoted electron transfer and the enhanced electron endowing ability of C 13− m N m /Cu(111) ( m = 1-2) to the co-adsorbed CH 3 CH x OH ( x = 0-1) and H are deemed to be mainly responsible for the remarkable enhancement in hydrogenation ability. From the standpoint of the frontier molecular orbital, the decreased HOMO-LUMO gap and the increased overlap extent of HOMO and LUMO with the doping of N atoms also further verify the more facile hydrogenation reactions. Clearly, the Cu-carbon interaction through N-modification is of critical importance in ethanol formation. The final hydrogenation reaction during ethanol formation is deemed to be the rate-controlling step. The insights gained here could shed new light on the nature of Cu-carbon interaction in carbon material modified Cu-based catalysts for ethanol synthesis, which could be extended to design and modify other metal-carbon catalysts. The N-enhanced Cu-carbon interaction facilitates ethanol synthesis from syngas and methanol due to the promoted electron transfer.