以含浸法合成金屬奈米多孔銅基粉末觸媒應用於糠醛的電氫化反應

Abstract

電化學加氫(Electrochemical hydrogenation)最近成為一種綠色且創新的方法，用於將生物質衍生的化合物，如糠醛(furfural)，轉化為糠醇(FOL)和2-甲基呋喃(MF)，這兩者作為可持續燃料和原材料都具有價值。FOL因其優秀的化學性質，主要應用於製造樹脂；而MF具有高能量密度和良好的燃燒性能，常被用於製作燃料添加劑。 然而，低法拉第效率和產物生產率在大多數情況下仍然是電催化正在面臨的一個挑戰。本研究利用化學去合金的方式，將銅鋁合金製備為奈米多孔銅(NPC)。NPC作為觸媒具有高電化學活性表面積的特性，提供更多的氫吸附位點(Hads)參與還原反應，以提高產物選擇性和產量。與商業銅粉相比，NPC在兩小時定電壓實驗結果顯示，在-1V (V vs. Ag/AgCl)電位下，FOL和MF的法拉第效率分別從43.2%提升至83.0%和從0%提升至12.5%，且各產物的產量均增加了4-6倍。NPC高比表面積的特性除了反應在法拉第效率和產率外，同時NPC在催化過程中亦能夠抑制氫析出反應，與商業銅粉相比，將H2的法拉第效率從12.7%抑制到0.6%。 此外，本研究成功利用含浸法，將鈷、鎳和鈀分別擔載到NPC擔體上，進行糠醛電催化實驗。這在過去的研究中並沒有使用NPC作為擔體的先例。通過這些實驗，本研究旨在探討雙金屬觸媒在糠醛電催化中的協同效應。 結果表明，Ni/NPC觸媒的催化活性顯著優於商業銅粉，其歸因於NPC作為擔體的高電化學活性表面積特性。同時，Ni/NPC相較於NPC，傾向於產MF，在-1V (V vs. Ag/AgCl)電位下將MF的選擇性提高19.1%，且在各電位下其MF的產量皆大於NPC兩倍，表明了Ni/NPC在糠醛電催化中的應用潛力。本研究強調了NPC觸媒在糠醛電催化領域中的高催化活性，並可透過含浸法製備M/NPC觸媒，進一步調整產物選擇性。

Electrochemical hydrogenation (ECH) has recently become a green and innovative method for converting biomass-derived compounds, such as furfural (FF), into furfuryl alcohol (FOL) and 2-methylfuran (MF), both of which are valuable as sustainable fuels and raw materials. However, low Faradaic efficiency(FE) and product yield remain challenges in most cases of electrocatalysis. This study used chemical dealloying to prepare nanoporous copper (NPC) from a Cu-Al alloy. NPC, as a catalyst, has a high electrochemically active surface area, providing more hydrogen adsorption sites for the reduction reaction, thereby enhancing product selectivity and yield. Compared to commercial copper powder, NPC showed in 2hr constant potential experiments at -1V an increase in FE for FOL from 43.2% to 83.0% and for MF from 0% to 12.5%, with product yields increasing by 4-6 times. The high surface area of NPC not only improves FE and yield but also suppresses the hydrogen evolution reaction, reducing the FE for H2 from 12.7% to 0.6% compared to Cu powder. Additionally, this study successfully employed an impregnation method to load Co, Ni, and Pd onto the NPC support for FF ECH experiments. This is the first instance of using NPC as a support in such studies. Through these experiments, the study aimed to investigate the synergistic effects of bimetallic catalysts on ECH of FF. The results indicated that the catalytic activity of the Ni/NPC catalyst significantly outperformed copper powder, attributed to the high ECSA of the NPC support. Furthermore, Ni/NPC, compared to NPC alone, tended to produce more MF, increasing MF selectivity by 19.1% at -1V, with MF yields being twice as high at all tested potentials. This demonstrates the potential of Ni/NPC for FF ECH. This study highlights the high catalytic activity of NPC catalysts in FF ECH and suggests that M/NPC catalysts can further tune product selectivity.