Machado Letícia F L, Andrade Luana S, Mandelli Dalmo, Carvalho Wagner A
Center for Natural Sciences and Humanities, Federal University of ABC (UFABC), Av. dos Estados, 5001, Santo André, SP CEP 09210-580, Brazil.
Department of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States.
ACS Omega. 2024 Nov 1;9(45):45328-45341. doi: 10.1021/acsomega.4c07030. eCollection 2024 Nov 12.
Carbons with Brønsted acidic sites and iron oxide modifications were prepared through hydrothermal carbonization and glycerol pyrolysis in the presence of sulfuric acid, magnetite, and iron(III) nitrate. The solids were tested as catalysts in converting fructose to 5-hydroxymethylfurfural (5-HMF). Characterization techniques revealed a uniform presence of 4.89 mmol g total acidic groups, including up to 1.87 mmol g sulfonic and carboxylic groups. Combined with a reduced surface area, the Brønsted and Lewis acidity enabled the conversion of 94% of fructose with selectivity values as high as 95% for 5-HMF in just 10 min at 140 °C, using microwave heating and dimethyl sulfoxide (DMSO) as the solvent. This performance was attributed to the selective heating of the catalyst surface by the microwave absorption capacity of the acidic groups and iron oxide, leading to the formation of "hot spots." The catalyst obtained by hydrothermal carbonization in the presence of FeO, HCC-20% FeO, demonstrated stability when reused for up to four consecutive cycles. A slight reduction in conversion and selectivity was observed after the first use, attributed to the presence of acid species not incorporated into the solid during the synthesis process.
通过在硫酸、磁铁矿和硝酸铁存在下进行水热碳化和甘油热解，制备了具有布朗斯台德酸性位点和氧化铁修饰的碳材料。这些固体作为催化剂用于将果糖转化为5-羟甲基糠醛（5-HMF）进行了测试。表征技术表明，总共存在4.89 mmol g的均匀酸性基团，其中包括高达1.87 mmol g的磺酸基和羧基。结合降低的表面积，布朗斯台德酸性和路易斯酸性使得在140°C下仅用10分钟，使用微波加热和二甲基亚砜（DMSO）作为溶剂时，果糖的转化率达到94%，5-HMF的选择性高达95%。这种性能归因于酸性基团和氧化铁的微波吸收能力对催化剂表面的选择性加热，导致形成“热点”。在FeO存在下通过水热碳化获得的催化剂HCC-20% FeO，在连续重复使用多达四个循环时表现出稳定性。首次使用后观察到转化率和选择性略有降低，这归因于在合成过程中未掺入固体中的酸性物质的存在。
