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Efficient and selective oxidation of 5-hydroxymethylfurfural catalyzed by metal porphyrin supported by alkaline lignin: Solvent optimization and catalyst loading
Molecular Catalysis ( IF 3.9 ) Pub Date : 2021-09-06 , DOI: 10.1016/j.mcat.2021.111765
Yuchen Zhu 1 , Hao Wu 2 , Zheng Fang 1, 3 , Xiaobing Yang 4 , Kai Guo 1, 3 , Wei He 4
Affiliation  

Cobalt (II)-meso-tetra(4-carboxyphenyl) porphyrin supported by deprotected lignin was synthesized through the covalent linkage between carboxy groups in the porphyrin and hydroxyl groups in the lignin. The resulting supporting catalysts were applied in the selective oxidation of 5-hydroxymethylfurfural. Through solvent optimization, 5-hydroxymethyl-2-furancarboxylic acid and 2,5-furandicarboxylic acid could be selectively obtained. Steric effect of lignin prevented unwanted aggregation-caused quenching, avoiding catalyst deactivation. Thus, supported catalysts displayed better catalytic efficiency compared free metal porphyrin catalyst. Unlike the excessive use of sodium hydroxide in the oxidation of HMF catalyzed by metal catalysts, an equivalent amount of sodium hydroxide was used in this oxidation process. Meanwhile, lower activation energy was detected when metal porphyrin supported by deprotected lignin was used. By adjusting the pH in the reaction, supported catalysts could be reused. The catalytic activity remained stable during the recycling experiments.



中文翻译:

碱性木质素负载金属卟啉催化5-羟甲基糠醛的高效选择性氧化:溶剂优化和催化剂负载

通过卟啉中的羧基和木质素中的羟基之间的共价键,合成了脱保护木质素负载的钴 (II)-内消旋四 (4-羧基苯基) 卟啉。所得负载催化剂用于5-羟甲基糠醛的选择性氧化。通过溶剂优化,可以选择性地得到5-羟甲基-2-呋喃甲酸和2,5-呋喃二甲酸。木质素的空间效应防止了不需要的聚集引起的猝灭,避免了催化剂失活。因此,与游离金属卟啉催化剂相比,负载型催化剂表现出更好的催化效率。与在金属催化剂催化的 HMF 氧化中过度使用氢氧化钠不同,在该氧化过程中使用了等量的氢氧化钠。同时,当使用由脱保护木质素支持的金属卟啉时,检测到较低的活化能。通过调节反应中的 pH 值,负载型催化剂可以重复使用。在循环实验期间催化活性保持稳定。

更新日期:2021-09-06
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