Upcycling of spent plastics has become a more emergent topic than ever before due to the rapid generation of plastic waste associated with the change of lifestyles of the human society. Polyethylene terephthalate (PET) is a major aromatic plastic and herein, the conversion of PET back into arenes was demonstrated in a one-pot reaction combining depolymerization and hydrodeoxygenation (HDO) over a Co/TiO catalyst. The effectiveness of the Co/TiO catalyst in HDO and the underlining reaction pathway were established using the PET monomer terephthalic acid (TPA) as the substrate. Quantitative TPA conversion together with 75.2 mol% xylene and toluene selectivity under 30 bar initial H pressure at 340 °C was achieved after 4 h reaction. More encouragingly, the catalyst induced both depolymerization and HDO reaction via C-O bond cleavage when PET was used as a substrate. 78.9 mol% arenes (toluene and xylene) was obtained under optimized conditions.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1002/cssc.202100956 | DOI Listing |
Sci Bull (Beijing)
December 2024
School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address:
In Fenton-like reactions, high-valent cobalt-oxo (Co=O) has attracted increasing interests due to high redox potential, long lifetime, and anti-interference properties, but its generation is hindered by the electron repulsion between the electron rich oxo- and cobalt centers. Here, we demonstrate Co=O generation from peroxymonosulfate (PMS) activation over cobalt single-atom catalysts (Co-SACs) using in-situ Co K-edge X-ray absorption spectra, and discern that Co=O generation is dependent on the support work-function (W) due to the strong electronic metal-support interaction (EMSI). Supports with a high W value like anatase-TiO facilitate the binding of PMS-terminal oxo-ligand to Co sites by extracting Co-d electrons, thus decreasing the generation barrier for the critical intermediate (Co-OOSO).
View Article and Find Full Text PDFSci Total Environ
December 2024
School of Engineering, Deakin University, Geelong, Victoria 3216, Australia. Electronic address:
In this study, inexpensive earth-abundant catalyst of Co/TiO is coupled with a low-temperature modification approach to enhance NH adsorption capacity on wheat straw (WS). The highest NH uptake achieved is 111.9 mg/g, with 80.
View Article and Find Full Text PDFJ Environ Sci (China)
March 2025
Xiamen Key Laboratory of Materials for Gaseous Pollutant Control, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; CAS Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address:
Cerium and cobalt loaded Co-Ce/TiO catalyst prepared by impregnation method was investigated for photothermal catalytic toluene oxidation. Based on catalyst characterizations (XPS, EPR and H-TPR), redox cycle between Co and TiO (Co + Ti ↔ Co + Ti) results in the formation of Co, Ti and oxygen vacancies, which play important roles in toluene catalytic oxidation reaction. The introduction of Ce brings in the dual redox cycles (Co + Ti ↔ Co + Ti, Co + Ce ↔ Co + Ce), further promoting the elevation of reaction sites amount.
View Article and Find Full Text PDFACS Catal
August 2024
Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
X-ray diffraction/scattering computed tomography (XRS-CT) was used to create two-dimensional images, with 20 μm resolution, of passivated Co/TiO/Mn Fischer-Tropsch catalyst extrudates postreaction after 300 h on stream under industrially relevant conditions. This combination of scattering techniques provided insights into both the spatial variation of the different cobalt phases and the influence that increasing Mn loading has on this. It also demonstrated the presence of a wax coating throughout the extrudate and its capacity to preserve the Co/Mn species in their state in the reactor.
View Article and Find Full Text PDFACS Catal
July 2024
Department of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.
Modifying traditional Co/TiO-based Fischer-Tropsch (FT) catalysts with Mn promoters induces a selectivity shift from long-chain paraffins toward commercially desirable alcohols and olefins. In this work, we use gas cell scanning transmission electron microscopy (STEM) with energy-dispersive X-ray spectroscopy (EDS) elemental mapping, and near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) to demonstrate how the elemental dispersion and chemical structure of the as-calcined materials evolve during the H activation heat treatment required for industrial CoMn/TiO FT catalysts. We find that Mn additions reduce both the mean Co particle diameter and the size distribution but that the Mn remains dispersed on the support after the activation step.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!