This study reports a novel method for γ-valerolactone (GVL) production from ethyl levulinate (EL) utilizing non-noble metal catalysts within a supercritical isopropanol (IPA) system. Nickel-loaded nickel–aluminum oxide nanosheets (NiAl-R) were fabricated via hydrothermal treatment of Ni–Al layered double hydroxide precursors, followed by hydrogen reduction at 550 °C for 1.5 h. Using NiAl-R as the catalyst and IPA as the hydrogen donor, we achieved notable results: 82.7% EL conversion, 73.6% GVL yield, and 1.178 mol g h reaction efficiency after 1.5 h in supercritical IPA. The catalytic activity of NiAl-R remained stable over five catalytic cycles. The surface of NiAl-R exhibits abundant oxygen vacancies and unsaturated Al species (Al), which promote the initial transfer hydrogenation of EL to form the ethyl 4-hydroxypentanoate (4-HPE) intermediate. Simultaneously, the supercritical IPA environment overcomes mass transfer limitations at the solid–liquid interface between 4-HPE and the catalyst, thereby facilitating the Al-catalyzed intramolecular esterification of 4-HPE into GVL.

中文翻译：

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镍铝氧化物纳米片上超临界异丙醇催化转移氢化从乙酰丙酸乙酯高效合成γ-戊内酯

本研究报告了一种在超临界异丙醇 (IPA) 系统中利用非贵金属催化剂从乙酰丙酸乙酯 (EL) 生产 γ-戊内酯 (GVL) 的新方法。通过水热处理 Ni-Al 层状双氢氧化物前体，然后在 550 °C 下氢还原 1.5 小时，制备了负载镍的镍铝氧化物纳米片 (NiAl-R)。使用 NiAl-R 作为催化剂，IPA 作为氢供体，我们取得了显着的结果：在超临界 IPA 中 1.5 小时后，EL 转化率为 82.7%，GVL 产率为 73.6%，反应效率为 1.178 mol gh。 NiAl-R的催化活性在五个催化循环中保持稳定。 NiAl-R的表面表现出丰富的氧空位和不饱和Al物种(Al)，促进EL的初始转移氢化形成4-羟基戊酸乙酯(4-HPE)中间体。同时，超临界IPA环境克服了4-HPE和催化剂之间固液界面的传质限制，从而促进了Al催化的4-HPE分子内酯化成GVL。