Tuning the O-O bond formation pathways of molecular water oxidation catalysts on electrode surfaces via second coordination sphere engineering
CHINESE JOURNAL OF CATALYSIS
Authors: Zhuo, Qiming; Zhan, Shaoqi; Duan, Lele; Liu, Chang; Wu, Xiujuan; Ahlquist, Marten S. G.; Li, Fusheng; Sun, Licheng
Abstract
A molecular [Ru(bda)]-type (bda = 2,2 '-bipyridine-6,6 '-dicarboxylate) water oxidation catalyst with 4-vinylpyridine as the axial ligand (Complex 1) was immobilized or co-immobilized with 1-(trifluoromethyl)-4-vinylbenzene (3F) or styrene (St) blocking units on the surface of glassy carbon (GC) electrodes by electrochemical polymerization, in order to prepare the corresponding poly-1@GC, poly-1+P3F@GC, and poly-1+PSt@GC functional electrodes. Kinetic measurements of the electrode surface reaction revealed that [Ru(bda)] triggers the O-O bond formation via (1) the radical coupling interaction between the two metallo-oxyl radicals (I2M) in the homo-coupling polymer (poly-1), and (2) the water nucleophilic attack (WNA) pathway in poly-1+P3F and poly-1+PSt copolymers. The comparison of the three electrodes revealed that the second coordination sphere of the water oxidation catalysts plays vital roles in stabilizing their reaction intermediates, tuning the O-O bond formation pathways and improving the water oxidation reaction kinetics without changing the first coordination structures. (C) 2021, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.
In-situ catalytic cracking of coal pyrolysis tar coupled with steam reforming of ethane over carbon based catalyst
FUEL PROCESSING TECHNOLOGY
Authors: Di, Minna; Wang, Mingyi; Jin, Lijun; Li, Yang; Hu, Haoquan
Abstract
In-situ catalytic cracking of coal tar coupling with steam reforming of ethane (SRE) over activated carbon supported nickel (Ni/AC) was conducted to improve light tar yield. The results show that the content and yield of light tar (the fraction having boiling point below 360 degrees C) under ethane/steam reforming atmosphere increase by 58.7% and 62.2% with Ni/AC, respectively, and phenol oil raised by 112.5% compared with the non-upgrading tar. Compared with the upgrading process under N-2, the benzenes and phenols in the tar gained from upgrading process under ethane/steam mixed atmosphere increases by 99.3% and 21.5%, specially, C3 alkyl substituted benzene and cresol increases from 2.2% and 9.2% to 5.1% and 15.0%. Meanwhile, when using deuterated ethane (C2D6) and deuterated water (D2O) as tracers, tar component with deuterium atom can be detected by GC/MS and H-2 NMR. These reveal that Ni/AC can simultaneously catalyze coal tar cracking and SRE, thus the small radicals such as center dot CHx, center dot C2Hx and center dot H generated from SRE can combine with the radicals from tar cracking to avoid excessive cleavage of tar. Coupled with the MS analysis of typical substances, the reaction mechanism of upgrading process was inferred.