Surface Alloy or Metal–Cation Interaction‐The State of Zn Promoting the Active Cu Sites in Methanol Synthesis Catalysts

Utilization of CO2 as feedstock to produce fine chemicals and renewable fuels is a highly promising field, which presents unique challenges in its implementation at scale. Heterogeneous catalysis with its simple operation and industrial compatibility can be an effective means of achieving this challenging task. This review summarizes the current developments in heterogeneous thermal catalysis for the production of carbon monoxide, alcohols and hydrocarbons from CO2. A detailed discussion is provided regarding structure-activity correlations between catalyst surface and intermediate species which can aid in rational design of future generation catalysts. Effects of active metal components, catalyst supports, and promoters are discussed in each section, which will guide researchers to synthesize new catalysts with improved selectivity and stability. Additionally, a brief overview regarding process design considerations has been provided. Future research directions are proposed with special emphasis on the application scope of new catalytic materials and possible approaches of increasing catalyst performance.

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“…104 Based on this study, major focus has been given to Cu-based catalysts, mainly Cu-Zn combinations. [105][106][107][108][109]…”

Section: Co2 To Methanolmentioning

confidence: 99%

Advances in the Design of Heterogeneous Catalysts and Thermocatalytic Processes for CO₂ Utilization

et al. 2020

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“…Much effort has been devoted to studying the interaction and oxidation state of ZnO x species in CuZn-based catalysts in the calcined state 29 , 32 − 34 and before/after 33 , 35 − 39 or during 14 , 32 , 40 − 43 exposure to reducing atmospheres at (near-)ambient pressures (up to 8 bar). On the basis of those results, it is still inconclusive whether the oxidation state of ZnO x slightly changes 35 , 36 , 40 and whether Cu–Zn alloys are formed 14 , 38 , 44 or not.…”

Section: Introductionmentioning

confidence: 99%

Insight into the Nature of the ZnO_x Promoter during Methanol Synthesis

et al. 2022

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Despite the great commercial relevance of zinc-promoted copper catalysts for methanol synthesis, the nature of the Cu–ZnO x synergy and the nature of the active Zn-based promoter species under industrially relevant conditions are still a topic of vivid debate. Detailed characterization of the chemical speciation of any promoter under high-pressure working conditions is challenging but specifically hampered by the large fraction of Zn spectator species bound to the oxidic catalyst support. We present the use of weakly interacting graphitic carbon supports as a tool to study the active speciation of the Zn promoter phase that is in close contact with the Cu nanoparticles using time-resolved X-ray absorption spectroscopy under working conditions. Without an oxidic support, much fewer Zn species need to be added for maximum catalyst activity. A 5–15 min exposure to 1 bar H 2 at 543 K only slightly reduces the Zn(II), but exposure for several hours to 20 bar H 2 /CO and/or H 2 /CO/CO 2 leads to an average Zn oxidation number of +(0.5–0.6), only slightly increasing to +0.8 in a 20 bar H 2 /CO 2 feed. This means that most of the added Zn is in a zerovalent oxidation state during methanol synthesis conditions. The Zn average coordination number is 8, showing that this phase is not at the surface but surrounded by other metal atoms (whether Zn or Cu), and indicating that the Zn diffuses into the Cu nanoparticles under reaction conditions. The time scale of this process corresponds to that of the generally observed activation period for these catalysts. These results reveal the speciation of the relevant Zn promoter species under methanol synthesis conditions and, more generally, present the use of weakly interacting graphitic supports as an important strategy to avoid excessive spectator species, thereby allowing us to study the nature of relevant promoter species.

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“…Grosmann et al. have reported the promoting effect of ZnO (Zn 2+ ) on SBA‐15 supported Cu in methanol synthesis . The effect of addition of Fe as a dopant to silica supported Cu catalyst for furfural hydrodeoxygenation has been studied by Sheng and Lobo .…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effect of Cr³⁺ on Layered Double Hydroxide Supported Cu⁰ Nanoparticles for the Oxidation of Alcohols and Hydrocarbons

Choudhary

Sharma

et al. 2019

ChemistrySelect

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Chromium(III)‐doped layered double hydroxide supported copper nanoparticles (Cr3+‐Cu0/LDH) has been prepared as an efficient and reusable catalyst using simple and versatile synthetic method. Effect of doping of Cr3+ to the layered double hydroxide supported Cu0 nanoparticles was evaluated for the oxidation of alcohols and hydrocarbons by varying the amount of Cr3+ loading in the catalyst. The catalyst with Cu:Cr ratio= 1:1 afforded highest catalytic activity among the synthesized catalysts towards the oxidation using TBHP (tBuOOH) in aqueous medium and was structurally characterized by Fourier Transform Infrared Spectroscopy (FTIR), X‐Ray Diffraction Spectroscopy (XRD), Field Emission Gun‐Scanning Electron Microscopy (FEG‐SEM), Energy‐dispersive X‐Ray Spectroscopy (EDX), High Resolution‐Transmission Electron Spectroscopy (HR‐TEM), Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP‐AES) and X‐Ray Photoelectron Spectroscopy (XPS). The high activity and selectivity was assigned to the synergistic electronic interaction between copper(0) nanoparticles and chromium(III) ions based on experimental data and XPS results. Moreover, the high stability of Cu0 and Cr3+ in the catalyst was attributed to the strong metal‐support interactions, which make the catalyst recyclable upto five runs.

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Surface Alloy or Metal–Cation Interaction‐The State of Zn Promoting the Active Cu Sites in Methanol Synthesis Catalysts

Abstract: Ilya Sinev, [a] and WolfgangG r ünert* [a]

Cited by 26 publications

References 45 publications

Advances in the Design of Heterogeneous Catalysts and Thermocatalytic Processes for CO₂ Utilization

Advances in the Design of Heterogeneous Catalysts and Thermocatalytic Processes for CO₂ Utilization

Insight into the Nature of the ZnO_x Promoter during Methanol Synthesis

Synergistic Effect of Cr³⁺ on Layered Double Hydroxide Supported Cu⁰ Nanoparticles for the Oxidation of Alcohols and Hydrocarbons

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Surface Alloy or Metal–Cation Interaction‐The State of Zn Promoting the Active Cu Sites in Methanol Synthesis Catalysts

Abstract: Ilya Sinev, [a] and WolfgangG r ünert* [a]

Cited by 26 publications

References 45 publications

Advances in the Design of Heterogeneous Catalysts and Thermocatalytic Processes for CO2 Utilization

Advances in the Design of Heterogeneous Catalysts and Thermocatalytic Processes for CO2 Utilization

Insight into the Nature of the ZnOx Promoter during Methanol Synthesis

Synergistic Effect of Cr3+ on Layered Double Hydroxide Supported Cu0 Nanoparticles for the Oxidation of Alcohols and Hydrocarbons

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Product

Resources

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Advances in the Design of Heterogeneous Catalysts and Thermocatalytic Processes for CO₂ Utilization

Advances in the Design of Heterogeneous Catalysts and Thermocatalytic Processes for CO₂ Utilization

Insight into the Nature of the ZnO_x Promoter during Methanol Synthesis

Synergistic Effect of Cr³⁺ on Layered Double Hydroxide Supported Cu⁰ Nanoparticles for the Oxidation of Alcohols and Hydrocarbons