Pd修飾的ZnO-Au雜化材料高效光催化甲烷轉化為乙烯的中間體形成和脫氫
作者：
小柯機器人發布時間：2020/12/31 23:22:44
中國科學技術大學熊宇傑團隊揭示了Pd修飾的ZnO-Au雜化材料高效光催化甲烷轉化為乙烯的中間體形成和脫氫過程。相關研究成果於2020年12月29日發表在國際頂尖學術期刊《美國化學會志》。
光催化為在溫和條件下將甲烷轉化為多碳化合物(C2+)提供了一種有趣的方法；然而，由於甲基自由基是唯一的反應中間體，目前的C2+產品主要是乙烷，對乙烯的選擇性可以忽略不計，而乙烯是一種關鍵的化工原料，具有比乙烷更高的附加值。
該文中，研究人員開發了一種直接的光催化甲烷轉化為乙烯的途徑，涉及在Pd修飾的ZnO–Au雜化催化劑上烷氧基（即甲氧基和乙氧基）中間體的形成和脫氫。在各種原位表徵的基礎上，揭示了催化劑的Pd誘導脫氫能力是開啟該途徑的關鍵。在反應過程中，甲烷分子在鈀的輔助下首先在氧化鋅表面分解成甲氧基。這些中間產物可與乙烯進一步偶聯成甲氧基，然後再與乙氧基脫氫。
結果表明，經過優化的ZnO-AuPd雜化材料在光照8h後，甲烷轉化率為536.0μmol g-1，C2+化合物選擇性為96.0%（C2H4和C2H6的總生成量分別為39.7%和54.9%）。
該工作為溫和條件下甲烷轉化途徑提供了新的見解，並強調了脫氫對於增強光催化活性和不飽和烴產物選擇性的重要性。
附：英文原文
Title: Pd-Modified ZnO–Au Enabling Alkoxy Intermediates Formation and Dehydrogenation for Photocatalytic Conversion of Methane to Ethylene
Author: Wenbin Jiang, Jingxiang Low, Keke Mao, Delong Duan, Shuangming Chen, Wei Liu, Chih-Wen Pao, Jun Ma, Shuaikang Sang, Chang Shu, Xiaoyi Zhan, Zeming Qi, Hui Zhang, Zhi Liu, Xiaojun Wu, Ran Long, Li Song, Yujie Xiong
Issue&Volume: December 29, 2020
Abstract: Photocatalysis provides an intriguing approach for the conversion of methane to multicarbon (C2+) compounds under mild conditions; however, with methyl radicals as the sole reaction intermediate, the current C2+ products are dominated by ethane, with a negligible selectivity toward ethylene, which, as a key chemical feedstock, possesses higher added value than ethane. Herein, we report a direct photocatalytic methane-to-ethylene conversion pathway involving the formation and dehydrogenation of alkoxy (i.e., methoxy and ethoxy) intermediates over a Pd-modified ZnO–Au hybrid catalyst. On the basis of various in situ characterizations, it is revealed that the Pd-induced dehydrogenation capability of the catalyst holds the key to turning on the pathway. During the reaction, methane molecules are first dissociated into methoxy on the surface of ZnO under the assistance of Pd. Then these methoxy intermediates are further dehydrogenated and coupled with methyl radical into ethoxy, which can be subsequently converted into ethylene through dehydrogenation. As a result, the optimized ZnO–AuPd hybrid with atomically dispersed Pd sites in the Au lattice achieves a methane conversion of 536.0 μmol g–1 with a C2+ compound selectivity of 96.0% (39.7% C2H4 and 54.9% C2H6 in total produced C2+ compounds) after 8 h of light irradiation. This work provides fresh insight into the methane conversion pathway under mild conditions and highlights the significance of dehydrogenation for enhanced photocatalytic activity and unsaturated hydrocarbon product selectivity.
DOI: 10.1021/jacs.0c10369
Source: https://pubs.acs.org/doi/10.1021/jacs.0c10369