College of Environmental Science and Engineering, Nankai University, No. 38, Tongyan Road, Jinnan District, Tianjin 300350, China.
Agro-Environmental Protection Institute, Chinese Academy of Agricultural Sciences, No. 31, Fukang Road, Nankai District, Tianjin 300191, China.
Int J Biol Macromol. 2023 Jun 15;240:124451. doi: 10.1016/j.ijbiomac.2023.124451. Epub 2023 Apr 14.
The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) has attracted much attention, as GVL can be used as biofuel, green solvent, and platform chemical. Inspired by Stöber method, various lignin-metal coordinated colloidal nanospheres (LCS) from lignin and cetyltrimethylammonium bromide (CTAB) were synthesized in which the metal ions (Co) replace formaldehyde as the crosslinker. The characterization of the catalyst revealed that alkali lignin was first self-assembled with CTAB through electrostatic attraction to form a lignin polymer, the subsequent addition of metal ions (Co) promoted the aggregation of lignin polymers and generated the LCS. Increasing calcination temperature for LCS resulted in the Co being reduced to metallic Co. The lignin-metal coordinated colloidal nanospheres calcined at 500 °C possess both CoO and metallic Co active sites, which effectively accelerated the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) than simplex metallic Co active sites. A 99.8 % yield of GVL with 100 % LA conversion was obtained after 60 min reaction time at 200 °C and 2 MPa H.
将乙酰丙酸（LA）加氢转化为γ-戊内酯（GVL）引起了广泛关注，因为 GVL 可用作生物燃料、绿色溶剂和平台化学品。受 Stöber 方法的启发，通过木质素与十六烷基三甲基溴化铵（CTAB）之间的配位作用，合成了各种木质素-金属配位胶体纳米球（LCS），其中金属离子（Co）取代了甲醛作为交联剂。催化剂的表征表明，碱木质素首先通过静电吸引与 CTAB 自组装形成木质素聚合物，随后加入金属离子（Co）促进木质素聚合物的聚集并生成 LCS。升高 LCS 的煅烧温度会导致 Co 被还原为金属 Co。在 500°C 下煅烧的木质素-金属配位胶体纳米球具有 CoO 和金属 Co 活性位，比单纯的金属 Co 活性位更有效地加速了乙酰丙酸（LA）到γ-戊内酯（GVL）的加氢反应。在 200°C 和 2 MPa H 的条件下，反应 60 分钟后，LA 的转化率达到 100%，GVL 的收率达到 99.8%。
