Catalysts

Research

Jump to: Review

18 pages, 4372 KiB

Open AccessArticle

Mesostructured γ-Al₂O₃-Based Bifunctional Catalysts for Direct Synthesis of Dimethyl Ether from CO₂

by Fausto Secci, Marco Sanna Angotzi, Valentina Mameli, Sarah Lai, Patrícia A. Russo, Nicola Pinna, Mauro Mureddu, Elisabetta Rombi and Carla Cannas

Catalysts 2023, 13(3), 505; https://doi.org/10.3390/catal13030505 - 28 Feb 2023

Cited by 2 | Viewed by 1678

Abstract

In this work, we propose two bifunctional nanocomposite catalysts based on acidic mesostructured γ-Al₂O₃ and a Cu/ZnO/ZrO₂ redox phase. γ-Al₂O₃ was synthesized by an Evaporation-Induced Self-Assembly (EISA) method using two different templating agents (block copolymers Pluronic [...] Read more.

In this work, we propose two bifunctional nanocomposite catalysts based on acidic mesostructured γ-Al₂O₃ and a Cu/ZnO/ZrO₂ redox phase. γ-Al₂O₃ was synthesized by an Evaporation-Induced Self-Assembly (EISA) method using two different templating agents (block copolymers Pluronic P123 and F127) and subsequently functionalized with the redox phase using an impregnation method modified with a self-combustion reaction. These nanocomposite catalysts and their corresponding mesostructured supports were characterized in terms of structural, textural, and morphological features as well as their acidic properties. The bifunctional catalysts were tested for the CO₂-to-DME process, and their performances were compared with a physical mixture consisting of the most promising support as a dehydration catalyst together with the most common Cu-based commercial redox catalyst (CZA). The results highlight that the most appropriate Pluronic for the synthesis of γ-Al₂O₃ is P123; the use of this templating agent allows us to obtain a mesostructure with a smaller pore size and a higher number of acid sites. Furthermore, the corresponding composite catalyst shows a better dispersion of the redox phase and, consequently, a higher CO₂ conversion. However, the incorporation of the redox phase into the porous structure of the acidic support (chemical mixing), favoring an intimate contact between the two phases, has detrimental effects on the dehydration performances due to the coverage of the acid sites with the redox nanophase. On the other hand, the strategy involving the physical mixing of the two phases, distinctly preserving the two catalytic functions, assures better performances. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Figure 1

13 pages, 8302 KiB

Open AccessArticle

Ru- and Rh-Based Catalysts for CO₂ Methanation Assisted by Non-Thermal Plasma

by Eugenio Meloni, Liberato Cafiero, Simona Renda, Marco Martino, Mariaconcetta Pierro and Vincenzo Palma

Catalysts 2023, 13(3), 488; https://doi.org/10.3390/catal13030488 - 28 Feb 2023

Cited by 6 | Viewed by 1899

Abstract

The need to reduce the concentration of CO₂ in the atmosphere is becoming increasingly necessary since it is considered the main factor responsible for climate change. Carbon Capture and Utilization (CCU) technology offers the opportunity to obtain a wide range of chemicals [...] Read more.

The need to reduce the concentration of CO₂ in the atmosphere is becoming increasingly necessary since it is considered the main factor responsible for climate change. Carbon Capture and Utilization (CCU) technology offers the opportunity to obtain a wide range of chemicals using this molecule as a raw material. In this work, the catalytic Non-Thermal Plasma (NTP)-assisted hydrogenation of CO₂ to CH₄ (methanation reaction) in a Dielectric Barrier Discharge (DBD) reactor was investigated. Four different Ru- and Rh-based catalysts were prepared starting from γ-Al₂O₃ spheres, characterized and tested in both thermal and NTP-assisted methanation under different operating conditions. The experimental tests evidenced the very positive effect of the NTP application on the catalytic performance, highlighting that for all the catalysts the same CO₂ conversion was reached at a temperature 150 °C lower with respect to the conventional thermal reaction. Among the prepared catalysts, the bimetallic ones showed the best performance, reaching a CO₂ conversion of 97% at about 180 °C with a lower energy consumption with respect to similar catalysts present in the literature. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Figure 1

14 pages, 2221 KiB

Open AccessArticle

Transient Absorption Spectrum Analysis for Photothermal Catalysis Perovskite Materials

by Jindan Tian, Lili Liu, Hongqiang Nian, Qiangsheng Guo, Na Sha and Zhe Zhao

Catalysts 2023, 13(3), 452; https://doi.org/10.3390/catal13030452 - 21 Feb 2023

Viewed by 1546

Abstract

To gain insight into photocatalytic behavior, transient absorption spectroscopy (TAS) was used to study LaCo_xMn_1−xO₃, LaMn_xNi_1−xO₃ and LaNi_xCo_1−xO₃ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) [...] Read more.

To gain insight into photocatalytic behavior, transient absorption spectroscopy (TAS) was used to study LaCo_xMn_1−xO₃, LaMn_xNi_1−xO₃ and LaNi_xCo_1−xO₃ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1.0) on a microsecond time scale. The results show that the electron lifetime is key to determining the photocatalytic reduction of CO₂. This is the first time that the photogenerated electron lifetime in perovskite has been proposed to express the performance of the photocatalytic reduction of CO₂ with H₂O into CH₄. In all cases, the decay curve can be well explained by two consecutive first-order kinetics, indicating that the electron exists within two major populations: one with a short lifetime and the other one with a long lifetime. The long-lived electrons are the rate-limiting species for the photocatalytic reaction and are related to the activity of the photocatalytic reduction of CO₂ with H₂O to produce CH₄. For different photocatalysts, we find that the longer the electron decay lifetime is, the stronger the electron de-trapping ability is, and the electrons perform more activity. In this paper, TAS can not only detect the micro-dynamics process of carriers, but it is also demonstrated to be an easy and effective method for screening the most active catalyst in various catalysts for the photocatalytic reduction of CO₂ with H₂O accurately and quickly. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Figure 1

12 pages, 7103 KiB

Open AccessArticle

Bimetallic Metal-Organic Framework Derived Nanocatalyst for CO₂ Fixation through Benzimidazole Formation and Methanation of CO₂

by Aasif Helal, Mohammed Ahmed Sanhoob, Bosirul Hoque, Muhammad Usman and Md. Hasan Zahir

Catalysts 2023, 13(2), 357; https://doi.org/10.3390/catal13020357 - 6 Feb 2023

Cited by 9 | Viewed by 2148

Abstract

In this paper, a bimetallic Metal-Organic Framework (MOF) CoNiBTC was employed as a precursor for the fabrication of bimetallic nanoalloys CoNi@C evenly disseminated in carbon shells. These functional nanomaterials are characterized by powdered X-ray diffraction (PXRD), Fourier Transform Infra-Red spectroscopy (FTIR), surface area [...] Read more.

In this paper, a bimetallic Metal-Organic Framework (MOF) CoNiBTC was employed as a precursor for the fabrication of bimetallic nanoalloys CoNi@C evenly disseminated in carbon shells. These functional nanomaterials are characterized by powdered X-ray diffraction (PXRD), Fourier Transform Infra-Red spectroscopy (FTIR), surface area porosity analyzer, X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Hydrogen Temperature-Programmed Reduction (H₂ TPR), CO₂ Temperature-Programmed Desorption (CO₂-TPD), and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). This nanocatalyst was utilized in the synthesis of benzimidazole from o-phenylenediamine in the presence of CO₂ and H₂ in a good yield of 81%. The catalyst was also efficient in the manufacture of several substituted benzimidazoles with high yield. Due to the existence of a bimetallic nanoalloy of Co and Ni, this catalyst was also employed in the methanation of CO₂ with high selectivity (99.7%). Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Graphical abstract

13 pages, 4325 KiB

Open AccessArticle

Optimizing Temperature Treatment of Copper Hollow Fibers for the Electrochemical Reduction of CO₂ to CO

by Khalid Khazzal Hummadi, Anne Sustronk, Recep Kas, Nieck Benes and Guido Mul

Catalysts 2021, 11(5), 571; https://doi.org/10.3390/catal11050571 - 29 Apr 2021

Cited by 5 | Viewed by 2009

Abstract

Copper hollow fibers were prepared via dry-wet spinning of a polymer solution of N-methylpyrrolidone, Polyetherimide, Polyvinyl Pyrolidone, and copper particles of sizes in the range of 1–2 µm. To remove template molecules and to sinter the copper particles, the time of calcination was [...] Read more.

Copper hollow fibers were prepared via dry-wet spinning of a polymer solution of N-methylpyrrolidone, Polyetherimide, Polyvinyl Pyrolidone, and copper particles of sizes in the range of 1–2 µm. To remove template molecules and to sinter the copper particles, the time of calcination was varied in a range of 1–4 h at 600 °C. This calcination temperature was determined based on Thermal Gravimetric Analysis (TGA), showing completion of hydrocarbon removal at this temperature. Furthermore, the temperature of the subsequent treatment of the fibers in a flow of 4% H₂ (in Ar) was varied in the range of 200 °C to 400 °C, at a fixed time of 1 h. Temperature programmed reduction experiments (TPR) were used to analyze the hydrogen treatment. The Faradaic Efficiency (FE) towards CO in electrochemical reduction of CO₂ was determined at −0.45 V vs. RHE (Reversible Hydrogen Electrode), using a 0.3 M KHCO₃ electrolyte. A calcination time of 3 h at 600 °C and a hydrogen treatment temperature of 280 °C were found to induce the highest FE to CO of 73% at these constant electrochemical conditions. Optimizing oxidation properties is discussed to likely affect porosity, favoring the CO₂ gas distribution over the length of the fiber, and hence the CO₂ reduction efficiency. Treatment in H₂ in the range of 250 to 300 °C is proposed to affect the content of residual (subsurface) oxygen in Cu, which leads to favorable properties on the nanoscale. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Figure 1

17 pages, 16721 KiB

Open AccessArticle

CO₂ Methanation Using Multimodal Ni/SiO₂ Catalysts: Effect of Support Modification by MgO, CeO₂, and La₂O₃

by Maria Mihet, Monica Dan, Lucian Barbu-Tudoran and Mihaela D. Lazar

Catalysts 2021, 11(4), 443; https://doi.org/10.3390/catal11040443 - 30 Mar 2021

Cited by 28 | Viewed by 4556

Abstract

Ni/oxide-SiO₂ (oxide: MgO, CeO₂, La₂O₃, 10 wt.% target concentration) catalyst samples were prepared by successive impregnation of silica matrix, first with supplementary oxide, and then with Ni (10 wt.% target concentration). The silica matrix with multimodal [...] Read more.

Ni/oxide-SiO₂ (oxide: MgO, CeO₂, La₂O₃, 10 wt.% target concentration) catalyst samples were prepared by successive impregnation of silica matrix, first with supplementary oxide, and then with Ni (10 wt.% target concentration). The silica matrix with multimodal pore structure was prepared by solvothermal method. The catalyst samples were structurally characterized by N₂ adsorption-desorption, XRD, SEM/TEM, and functionally evaluated by temperature programmed reduction (TPR), and temperature programmed desorption of hydrogen (H₂-TPD), or carbon dioxide (CO₂-TPD). The addition of MgO and La₂O₃ leads to a better dispersion of Ni on the catalytic surface. Ni/LaSi and Ni/CeSi present a higher proportion of moderate strength basic sites for CO₂ activation compared to Ni/Si, while Ni/MgSi lower. CO₂ methanation was performed in the temperature range of 150–350 °C and at atmospheric pressure, all silica supported Ni catalysts showing good CO₂ conversion and CH₄ selectivity. The best catalytic activity was obtained for Ni/LaSi: CO₂ conversion of 83% and methane selectivity of 98%, at temperatures as low as 250 °C. The used catalysts preserved the multimodal pore structure with approximately the same pore size for the low and medium mesopores. Except for Ni/CeSi, no particle sintering occurs, and no carbon deposition was observed for any of the tested catalysts. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Figure 1

7 pages, 2832 KiB

Open AccessCommunication

Porous Copper/Zinc Bimetallic Oxides Derived from MOFs for Efficient Photocatalytic Reduction of CO₂ to Methanol

by Zhenyu Wang, Xiuling Jiao, Dairong Chen, Cheng Li and Minghui Zhang

Catalysts 2020, 10(10), 1127; https://doi.org/10.3390/catal10101127 - 1 Oct 2020

Cited by 22 | Viewed by 3227

Abstract

A novel metal organic framework (MOF)-derived porous copper/zinc bimetallic oxide catalyst was developed for the photoreduction of CO₂ to methanol at a very fast rate of 3.71 mmol g_cat⁻¹ h⁻¹. This kind of photocatalyst with high activity, selectivity [...] Read more.

A novel metal organic framework (MOF)-derived porous copper/zinc bimetallic oxide catalyst was developed for the photoreduction of CO₂ to methanol at a very fast rate of 3.71 mmol g_cat⁻¹ h⁻¹. This kind of photocatalyst with high activity, selectivity and a simple preparation catalyst provides promising photocatalyst candidates for reducing CO₂ to methanol. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Graphical abstract

Review

Jump to: Research

30 pages, 6749 KiB

Open AccessReview

Recent Progress in Two-Dimensional Materials for Electrocatalytic CO₂ Reduction

by Song Lu, Fengliu Lou and Zhixin Yu

Catalysts 2022, 12(2), 228; https://doi.org/10.3390/catal12020228 - 17 Feb 2022

Cited by 27 | Viewed by 5821

Abstract

Electrocatalytic CO₂ reduction (ECR) is an attractive approach to convert atmospheric CO₂ to value-added chemicals and fuels. However, this process is still hindered by sluggish CO₂ reaction kinetics and the lack of efficient electrocatalysts. Therefore, new strategies for electrocatalyst design [...] Read more.

Electrocatalytic CO₂ reduction (ECR) is an attractive approach to convert atmospheric CO₂ to value-added chemicals and fuels. However, this process is still hindered by sluggish CO₂ reaction kinetics and the lack of efficient electrocatalysts. Therefore, new strategies for electrocatalyst design should be developed to solve these problems. Two-dimensional (2D) materials possess great potential in ECR because of their unique electronic and structural properties, excellent electrical conductivity, high atomic utilization and high specific surface area. In this review, we summarize the recent progress on 2D electrocatalysts applied in ECR. We first give a brief description of ECR fundamentals and then discuss in detail the development of different types of 2D electrocatalysts for ECR, including metal, graphene-based materials, transition metal dichalcogenides (TMDs), metal–organic frameworks (MOFs), metal oxide nanosheets and 2D materials incorporated with single atoms as single-atom catalysts (SACs). Metals, such as Ag, Cu, Au, Pt and Pd, graphene-based materials, metal-doped nitric carbide, TMDs and MOFs can mostly only produce CO with a Faradic efficiencies (FE) of 80~90%. Particularly, SACs can exhibit FEs of CO higher than 90%. Metal oxides and graphene-based materials can produce HCOOH, but the FEs are generally lower than that of CO. Only Cu-based materials can produce high carbon products such as C₂H₄ but they have low product selectivity. It was proposed that the design and synthesis of novel 2D materials for ECR should be based on thorough understanding of the reaction mechanism through combined theoretical prediction with experimental study, especially in situ characterization techniques. The gap between laboratory synthesis and large-scale production of 2D materials also needs to be closed for commercial applications. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Figure 1

30 pages, 2184 KiB

Open AccessEditor’s ChoiceReview

Catalytic Reaction of Carbon Dioxide with Methane on Supported Noble Metal Catalysts

by András Erdőhelyi

Catalysts 2021, 11(2), 159; https://doi.org/10.3390/catal11020159 - 23 Jan 2021

Cited by 24 | Viewed by 5722

Abstract

The conversion of CO₂ and CH₄, the main components of the greenhouse gases, into synthesis gas are in the focus of academic and industrial research. In this review, the activity and stability of different supported noble metal catalysts were compared [...] Read more.

The conversion of CO₂ and CH₄, the main components of the greenhouse gases, into synthesis gas are in the focus of academic and industrial research. In this review, the activity and stability of different supported noble metal catalysts were compared in the CO₂ + CH₄ reaction on. It was found that the efficiency of the catalysts depends not only on the metal and on the support but on the particle size, the metal support interface, the carbon deposition and the reactivity of carbon also influences the activity and stability of the catalysts. The possibility of the activation and dissociation of CO₂ and CH₄ on clean and on supported noble metals were discussed separately. CO₂ could dissociate on metal surfaces, this reaction could proceed via the formation of carbonate on the support, or on the metal–support interface but in the reaction the hydrogen assisted dissociation of CO₂ was also suggested. The decrease in the activity of the catalysts was generally attributed to carbon deposition, which can be formed from CH₄ while others suggest that the source of the surface carbon is CO₂. Carbon can occur in different forms on the surface, which can be transformed into each other depending on the temperature and the time elapsed since their formation. Basically, two reaction mechanisms was proposed, according to the mono-functional mechanism the activation of both CO₂ and CH₄ occurs on the metal sites, but in the bi-functional mechanism the CO₂ is activated on the support or on the metal–support interface and the CH₄ on the metal. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Figure 1

26 pages, 16195 KiB

Open AccessFeature PaperReview

Recent Advances in Metal Catalyst Design for CO₂ Hydroboration to C1 Derivatives

by Sylwia Kostera, Maurizio Peruzzini and Luca Gonsalvi

Catalysts 2021, 11(1), 58; https://doi.org/10.3390/catal11010058 - 2 Jan 2021

Cited by 31 | Viewed by 4125

Abstract

The use of CO₂ as a C1 building block for chemical synthesis is receiving growing attention, due to the potential of this simple molecule as an abundant and cheap renewable feedstock. Among the possible reductants used in the literature to bring about [...] Read more.

The use of CO₂ as a C1 building block for chemical synthesis is receiving growing attention, due to the potential of this simple molecule as an abundant and cheap renewable feedstock. Among the possible reductants used in the literature to bring about CO₂ reduction to C1 derivatives, hydroboranes have found various applications, in the presence of suitable homogenous catalysts. The current minireview article summarizes the main results obtained since 2016 in the synthetic design of main group, first and second row transition metals for use as catalysts for CO₂ hydroboration. Full article

(This article belongs to the Special Issue Catalysis for CO₂ Conversion)

► Show Figures

Graphical abstract

Journal Menu

Journal Browser

Catalysis for CO₂ Conversion

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Related Special Issue

Published Papers (10 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

Journal Menu

Journal Browser

Catalysis for CO2 Conversion

Share This Special Issue

Special Issue Editor

Special Issue Information

Keywords

Related Special Issue

Published Papers (10 papers)

Research

Review

Further Information

Guidelines

MDPI Initiatives

Follow MDPI

Catalysis for CO₂ Conversion