Characterization and Catalytic Activity of CuCl2-Al2O3Ethylene Oxychlorination Catalysts

Finocchio, Elisabetta; Rossi, Nicoletta; Busca, Guido; Padovan, M.; Leofanti, G.; Cremaschi, B.; Marsella, A.; Carmello, D.

doi:10.1006/jcat.1998.2248

Cited by 40 publications

(18 citation statements)

References 28 publications

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“…They directly participate in a catalytic reaction cycle and are energetically favored to support the reaction. The nature and reactivity of active sites of the oxychlorination catalysts have been intensively investigated. ,− ,,− However, the identified active sites in the literature are rather controversial. Here, we review all the proposed active sites and the experimental evidence, try to make a critical analysis, and unify the active site at the end.…”

Section: Cu-based Catalysts For Ethylene Oxychlorinationmentioning

confidence: 97%

Critical Review of Catalysis for Ethylene Oxychlorination

Wang

et al. 2020

ACS Catal.

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Ethylene oxychlorination is the key technology in vinyl chloride (VCM, the monomer of PVC, polyvinyl chloride) production to close the chlorine loop by consuming the HCl released from the former cracking step. Due to the high demand for PVC, this leads to ethylene oxychlorination being one of the most important processes in the industry. This Review covers an indepth analysis of the dynamic nature of active sites for the main and side reactions involved in ethylene oxychlorination, featuring the findings and viewpoints from the dynamic kinetics study and analysis under industrial operating conditions. A unified picture of the mechanism of the surface reactions, and the effect of supports and promoters, has been presented based on the decoupled redoxcycle experiments, which leads to a significantly better understanding of the mechanism and provides valuable guidelines for effective catalyst design. Operando techniques and kinetic tools of the rate-diagram, as well as their application to the study of the redox-cycle in ethylene oxychlorination and kinetic models on both the main product and byproduct, are also reviewed. Perspectives on challenges and new process development and future research focus for better study of the VCM production chemistry are also proposed.

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Section: Cu-based Catalysts For Ethylene Oxychlorinationmentioning

confidence: 97%

Critical Review of Catalysis for Ethylene Oxychlorination

Wang

et al. 2020

ACS Catal.

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“…Based on pulse reactor studies and in situ infrared spectroscopy (IR), Busca et al demonstrated that the free alumina surface could play a negative role in ethylene oxychlorination, due to its ability to dehydrochlorinate EDC and other chloroalkanes. 147 Among others, VCM and 1,1,2-trichloroethane (TCE) were the predominant byproducts, which were suggested to originate from the reported that EDC dehydrochlorination to VCM occurred on the Lewis acid sites of alumina surface. 148 This agrees with a recent report by Lamberti et al who studied various promoted copper chloride catalysts supported on γ-alumina for ethylene oxychlorination, and found a positive trend between the density of Lewis acid sites and byproduct selectivity in the temperature range of 503-573 K. 149 However, such correlation was not found for the density and strength of Brønsted acid sites.…”

Section: Side Reactionmentioning

confidence: 99%

Halogen-Mediated Conversion of Hydrocarbons to Commodities

2017

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Halogen chemistry plays a central role in the industrial manufacture of various important chemicals, pharmaceuticals, and polymers. It involves the reaction of halogens or halides with hydrocarbons, leading to intermediate compounds which are readily converted to valuable commodities. These transformations, predominantly mediated by heterogeneous catalysts, have long been successfully applied in the production of polymers. Recent discoveries of abundant conventional and unconventional natural gas reserves have revitalized strong interest in these processes as the most cost-effective gas-to-liquid technologies. This review provides an in-depth analysis of the fundamental understanding and applied relevance of halogen chemistry in polymer industries (polyvinyl chloride, polyurethanes, and polycarbonates) and in the activation of light hydrocarbons. The reactions of particular interest include halogenation and oxyhalogenation of alkanes and alkenes, dehydrogenation of alkanes, conversion of alkyl halides, and oxidation of hydrogen halides, with emphasis on the catalyst, reactor, and process design. Perspectives on the challenges and directions for future development in this exciting field are provided.

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“…CuCl 2 / γ-Al 2 O 3 -based catalysts are effective in catalyzing ethylene, HCl, and oxygen to produce EDC in ethylene oxychlorination . It has been proved that the reaction follows a three-step redox mechanism where copper is cycled by Cu(II) reduction and Cu(I) oxidation. − …”

Section: Introductionmentioning

confidence: 99%

“…The understanding of the detailed reaction mechanism is limited due to the complicated structure of the active site and the dynamic evolution of the active site under the reaction conditions, despite that substantial research has been devoted to investigating the nature of the active phase. ,− Lamberti and co-workers , reported that three different copper species are present: a highly dispersed copper chloride phase, a Cu–aluminate phase, and an aggregated paratacamite (Cu 2 (OH) 3 Cl) phase. The inactive surface copper aluminate forms at low loadings, where the copper ions occupy octahedral vacancies of the alumina surface.…”

Section: Introductionmentioning

confidence: 99%

Cluster-Size-Dependent Interaction between Ethylene and CuCl₂ Clusters Supported via γ-Alumina

Fenes

et al. 2020

J. Phys. Chem. C

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Alumina-supported copper chloride serves as an industrial catalyst for ethylene oxychlorination, resulting from its high activity and selectivity. A better understanding of the detailed active site structure and reaction mechanism is highly desired. The present work aims to explore the dependence of the structure of active sites and the adsorption of ethylene on differently sized (CuCl 2 ) n (n = 1−4) clusters supported by γ-Al 2 O 3 . The effect of the support facets (i.e., ( 110) and ( 100) surfaces) on the interface structures between the active component CuCl 2 and the support was also investigated. The stronger CuCl 2 −support interaction was found on the (110) surface compared to the (100) surface, which is attributed to the stronger Lewis acidity of Al of the (110) surface. The adsorption strength of (CuCl 2 ) n) (n = 1−4) clusters becomes weak with the increment of cluster size on the (110) surface. The cluster size has a profound influence on the interaction between ethylene and the clusters. Ethylene binds to a copper atom on the small clusters (i.e., CuCl 2 and (CuCl 2 ) 2 ), while it extracts two chlorine atoms to form dichloroethane from the large clusters (i.e., (CuCl 2 ) 3 and (CuCl 2 ) 4 ), which explains the high activity of catalysts with high loadings upon exposure to ethylene. The effects of cluster size and alumina facets on the short d-band center and the Bader charge of the active sites result in the distinct formation energy of the chlorine vacancy and the interaction energy between C 2 H 4 and the clusters. Thus, an improved catalyst could be achieved by the modification of the surface electronic structure via finetuning the support or adding promoters.

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Characterization and Catalytic Activity of CuCl2-Al2O3Ethylene Oxychlorination Catalysts

Cited by 40 publications

References 28 publications

Critical Review of Catalysis for Ethylene Oxychlorination

Critical Review of Catalysis for Ethylene Oxychlorination

Halogen-Mediated Conversion of Hydrocarbons to Commodities

Cluster-Size-Dependent Interaction between Ethylene and CuCl₂ Clusters Supported via γ-Alumina

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Characterization and Catalytic Activity of CuCl2-Al2O3Ethylene Oxychlorination Catalysts

Cited by 40 publications

References 28 publications

Critical Review of Catalysis for Ethylene Oxychlorination

Critical Review of Catalysis for Ethylene Oxychlorination

Halogen-Mediated Conversion of Hydrocarbons to Commodities

Cluster-Size-Dependent Interaction between Ethylene and CuCl2 Clusters Supported via γ-Alumina

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Cluster-Size-Dependent Interaction between Ethylene and CuCl₂ Clusters Supported via γ-Alumina