Gao De,Han Feng,Waterhouse Geoffrey I. N.,Li Yan,Zhang Lili
A series of FeTPP-N/C-X catalysts were successfully prepared by adsorption of Fe tetraphenylporphine (FeTPP) onto a porous nitrogen-doped carbon (N/C) support using an ultrasonication method. The FeTPP-N/C catalysts were then used for the preparation of 5-hydroxymethyl-2-furan acid (HMFCA) by catalytic oxidation of 5-hydroxymethylfurfural (HMF) at 80 °C. The effects of reaction temperature, NaOH dosage, reaction time, and oxygen pressure on HMF conversion and HMFCA yield were systematically investigated. Under optimized testing conditions, a FeTPP-N/C-1 catalyst prepared using equal masses of FeTPP and N/C delivered a HMF conversion in water of 92.4%, with a selectivity to HMFCA of 97.2% over 6 h at an oxygen pressure of 1.0 MPa. Further, the catalyst showed good stability in five consecutive HMF oxidation tests. Based on the catalytic tests, and detailed catalyst characterization studies before and after reaction, a probable reaction mechanism was proposed for the selective oxidation of HMF to HMFCA by the FeTPP-N/C catalysts. Graphical Abstract
A series of FeTPP-N/C
catalysts were successfully prepared by the adsorption of iron
tetraphenylporphine (FeTPP) onto a porous nitrogen-doped carbon (N/C) support
using an ultrasonication method. The FeTPP-N/C catalysts were then used for the
catalytic aerobic oxidation of HMF to HMFCA. Under the optimized reaction conditions (temperature
80 °C, reaction time 6 h, O 2 pressure 1 MPa), a high HMF conversion
of 92.4% and a remarkable HMFCA selectivity of 97.2% were obtained, suggesting
that the developed noble-metal free catalyst has excellent promise for the
synthesis of valuable HMFCA from HMF.
Bao-Xia Dong,She-Liang Qian,Fan-Yan Bu,Yi-Chen Wu,Li-Gang Feng,Yun-Lei Teng,Wen-Long Liu,Zong-Wei Li
Heterogeneous electrocatalysis provides better control of the chemical surroundings of the catalyst’s active site for improved performance, offers the possibility of overcoming drawbacks of deactivation caused by aggregation or dimerization in homogeneous condition, and permits the use of benign aqueous solutions. Employing metal–organic frameworks (MOFs) or covalent–organic frameworks (COFs) to support the active molecular catalyst of porphyrin for electrochemical conversion of CO2 to CO is a promising strategy. We have rationally introduced a 3D highly stable porphyrin-based MOF of PCN-222(Fe) into heterogeneous catalysis through the simple dip-coating method. The composite catalyst PCN-222(Fe)/C (mass ratio = 1:2) exhibited high catalytic performance for electrochemical conversion of CO2 to CO with 494 mV overpotential (where j = 1.2 mA cm–2) and maximum 91% FECO in a CO2-saturated 0.5 M KHCO3 aqueous solution, achieving a TOF of 0.336 site–1 s–1. The catalyst was found to retain its crystallinity and stability after 10 h of electrolysis at −0.60 V versus RHE (average FECO 80.4%; RHE, reversible hydrogen electrode), which generates 334 μmol of CO with the TOF of 0.012 s–1 (0.286 site–1 s–1). These results indicate that the PCN-222(Fe)/C has a substantial catalytic effect on the electrochemical reduction of CO2 due to the combination of the intrinsic activity of the porphyrin molecule, and the promising CO2 adsorption ability endowed by the conserved porosity, as well as the high conductivity of carbon black.
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