New insight into the catalytic mechanism of ester hydrogenation over the Cu/ZnO catalyst: the contribution of hydrogen spillover

Gao, Lin; Ding, Guoqiang; Zhu, Lei; Yu, Zhanqiu; Li, Hongju; Li, Guoqiang; Zhu, Yulei; Xiang, Hongwei; Wen, Xiaodong; Yang, Yong; Li, Yongwang

doi:10.1039/d3dt04268e

“…Although Cu–Cr catalysts possess excellent performance, the toxicity and pollution associated with Cr 3+ have led researchers to focus on the development of chromium-free Cu-based catalysts. , The Cu/zinc oxide (ZnO)/Al 2 O 3 catalyst, with its simple preparation method, low cost, and outstanding catalytic performance, has become one of the most promising catalysts for replacing Cr-containing catalysts in the HDMM process. ,− Turek et al investigated the gas-phase HDMM process over Cu/ZnO catalyst at 473–513 K and 0.2–3.5 MPa. A higher copper surface area was obtained when the molar content of Al in the catalyst was 5%, and the deactivation of the catalyst was mainly attributed to the loss of the copper surface area.…”

Section: Introductionmentioning

confidence: 99%

Revealing the Reaction Network for Dimethyl Maleate Hydrogenation on the Active Sites of Cu/ZnO Catalysts Combining DFT with kMC Analysis

Li,

Zhang,

Yu

et al. 2024

ACS Catal.

1

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The Cu/zinc oxide (ZnO)/Al2O3 catalyst is highly favored in the hydrogenation of dimethyl maleate (HDMM) to coproduction of 1,4-butanediol (BDO), γ-butyrolactone (GBL), and tetrahydrofuran, and an in-depth study on its catalytic principle has a long-standing interest in the current study. Herein, by combining density functional theory and kinetic Monte Carlo simulations, we revealed the dominant pathways and reaction network of the HDMM process on the ZnO/Cu(111) surface. The effect of Cu–ZnO synergy is reflected in promoting the anchoring of ester carbonyls and decreasing the difficulty of hydroxyl group formation, which was clarified by mechanisms, density of states, and Bader charge analyses. From the perspective of constructive modification of active sites, a strategy was proposed to improve the GBL formation rate by decreasing the barrier of methanol removal based on the concepts of degree of rate control, and the BDO selectivity could be improved by increasing the barrier of the out-of-ring C–O bond cleavage in GBL hydrogenation. From the perspective of the external environment, the optimal reaction conditions of different target products were determined by manipulating the temperature and pressure. This study provides a guide for modifying active sites in Cu/ZnO/Al2O3 catalysts and potential possibilities for studying the complex reaction systems involving C4+ substances by multiscale simulation.

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Value‐Added Upcycling of PET to 1,4‐Cyclohexanedimethanol by a Hydrogenation/Hydrogenolysis Relay Catalysis

Sun,

Wang,

Lin

et al. 2024

Angewandte Chemie

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We present an innovative process for directly transforming poly(ethylene terephthalate) (PET), a polymer extensively used in food and beverage packaging, into trans‐isomer‐enriched 1,4‐cyclo‐ hexanedimethanol (CHDM), a key ingredient in advanced specialty polymers. Our approach leverages a dual‐catalyst system featuring palladium on reduced graphene oxide (Pd/r‐GO) and oxalate‐gel‐derived copper‐zinc oxide (og‐CuZn), utilizing hydrogenation/hydrog‐ enolysis relay catalysis. This method efficiently transforms PET into polyethylene‐1,4‐cyclohexanedicarboxylate (PECHD), which is then converted into CHDM with an impressive overall yield of 95% in a two‐stage process. Our process effectively handles various post‐consumer PET plastics, converting them into CHDM with yields between 78% and 89% across different substrates. Additionally, we demonstrate the applicability and scalability of this approach through a temperature‐programmed three‐stage relay process on a 10‐gram scale, which results in purified CHDM with an isolated yield of 87% and a notably higher trans/cis ratio of up to 4.09/1, far exceeding that of commercially available CHDM. This research not only provides a viable route for repurposing PET waste but also enhances the control of selectivity patterns in multistage relay catalysis.

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Value‐Added Upcycling of PET to 1,4‐Cyclohexanedimethanol by a Hydrogenation/Hydrogenolysis Relay Catalysis

Sun,

Wang,

Lin

et al. 2024

Angew Chem Int Ed

5

0

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We present an innovative process for directly transforming poly(ethylene terephthalate) (PET), a polymer extensively used in food and beverage packaging, into trans‐isomer‐enriched 1,4‐cyclo‐ hexanedimethanol (CHDM), a key ingredient in advanced specialty polymers. Our approach leverages a dual‐catalyst system featuring palladium on reduced graphene oxide (Pd/r‐GO) and oxalate‐gel‐derived copper‐zinc oxide (og‐CuZn), utilizing hydrogenation/hydrog‐ enolysis relay catalysis. This method efficiently transforms PET into polyethylene‐1,4‐cyclohexanedicarboxylate (PECHD), which is then converted into CHDM with an impressive overall yield of 95% in a two‐stage process. Our process effectively handles various post‐consumer PET plastics, converting them into CHDM with yields between 78% and 89% across different substrates. Additionally, we demonstrate the applicability and scalability of this approach through a temperature‐programmed three‐stage relay process on a 10‐gram scale, which results in purified CHDM with an isolated yield of 87% and a notably higher trans/cis ratio of up to 4.09/1, far exceeding that of commercially available CHDM. This research not only provides a viable route for repurposing PET waste but also enhances the control of selectivity patterns in multistage relay catalysis.

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New insight into the catalytic mechanism of ester hydrogenation over the Cu/ZnO catalyst: the contribution of hydrogen spillover

Abstract: The dimethyl maleate hydrogenation activity of Cu, ZnO-X and physical-mixed Cu+ZnO-X samples were systematically investigated to probe the essential role of ZnO in esters hydrogenation processes. Cu samples exhibited high...

Cited by 4 publications

References 34 publications

Revealing the Reaction Network for Dimethyl Maleate Hydrogenation on the Active Sites of Cu/ZnO Catalysts Combining DFT with kMC Analysis

Revealing the Reaction Network for Dimethyl Maleate Hydrogenation on the Active Sites of Cu/ZnO Catalysts Combining DFT with kMC Analysis

Value‐Added Upcycling of PET to 1,4‐Cyclohexanedimethanol by a Hydrogenation/Hydrogenolysis Relay Catalysis

Value‐Added Upcycling of PET to 1,4‐Cyclohexanedimethanol by a Hydrogenation/Hydrogenolysis Relay Catalysis

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