双功能
催化作用
化学
甲醇
生物柴油生产
碳阳离子
吸附
钴
双功能催化剂
无机化学
介孔材料
生物柴油
光化学
有机化学
作者
Hao Guo,Jun Cheng,Yuxiang Mao,Lei Qian,Yang Shao,Weijuan Yang
出处
期刊:Fuel
[Elsevier]
日期:2022-04-11
卷期号:322: 124172-124172
被引量:16
标识
DOI:10.1016/j.fuel.2022.124172
摘要
A magnetic acid-base bifunctional catalyst with different coordination states of Co and uncoordinated N sites was prepared for the conversion of acidic microalgal lipids into biodiesel. The catalytic activity of Co atoms in different coordination states and three uncoordinated N sites was explored. Density functional theory calculations revealed that the adsorption energy of free fatty acid (FFA) on Co nanoparticle sites (-1.345 eV) exceeded that on other single Co atom sites (Co-N4, Co-N3, Co-N2, Co-C4). The stronger interaction between FFA and active site led to more electron transfer, which reduced the electron cloud density near the carbonyl carbon of FFA and activated it into a carbocation. Carbocation with higher electropositivity was more likely to be attacked by methanol for esterification. The free energy change for the adsorption of methanol on pyridinic-N sites and further conversion to activated methoxy anions (+1.686 eV) for transesterification was lower than that on pyrrolic-N (+3.705 eV) and graphitic-N (+3.279 eV), indicating that the pyridinic-N sites possessed the best catalytic activity. The generated structural defects formed a mesopore-dominated structure, facilitating the diffusion of large lipid molecules. Thus, the catalytic conversion efficiency of the obtained catalyst reached 96.0%. Moreover, the catalyst was magnetically separated and exhibited good recyclability.
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