Morphology effect of nanostructure ceria on the Cu/CeO2 catalysts for synthesis of methanol from CO2 hydrogenation

Sustainable methanol production from carbon dioxide: advances, challenges, and future prospects

The urgent need to address global carbon emissions and promote sustainable energy solutions has led to a growing interest in carbon dioxide (CO2) conversion technologies. Among these, the transformation of CO2 into methanol (MeOH) has gained prominence as an effective mitigation strategy. This review paper provides a comprehensive exploration of recent advances and applications in the direct utilization of CO2 for the synthesis of MeOH, encompassing various aspects from catalysts to market analysis, environmental impact, and future prospects. We begin by introducing the current state of CO2 mitigation strategies, highlighting the significance of carbon recycling through MeOH production. The paper delves into the chemistry and technology behind the conversion of CO2 into MeOH, encompassing key themes such as feedstock selection, material and energy supply, and the various conversion processes, including chemical, electrochemical, photochemical, and photoelectrochemical pathways. An in-depth analysis of heterogeneous and homogeneous catalysts for MeOH synthesis is provided, shedding light on the advantages and drawbacks of each. Furthermore, we explore diverse routes for CO2 hydrogenation into MeOH, emphasizing the technological advances and production processes associated with this sustainable transformation. As MeOH holds a pivotal role in a wide range of chemical applications and emerges as a promising transportation fuel, the paper explores its various chemical uses, transportation, storage, and distribution, as well as the evolving MeOH market. The environmental and energy implications of CO2 conversion to MeOH are discussed, including a thermodynamic analysis of the process and cost and energy evaluations for large-scale catalytic hydrogenation.

Tuning Catalytic Activity of CO2 Hydrogenation to C1 Product via Metal Support Interaction Over Metal/Metal Oxide Supported Catalysts

The metal supported catalysts are emerging catalysts that are receiving a lot of attention in CO2 hydrogenation to C1 products. Numerous experiments have demonstrated that the support (usually an oxide) is crucial for the catalytic performance. The support metal oxides are used to aid in the homogeneous dispersion of metal particles, prevent agglomeration, and control morphology owing to the metal support interaction (MSI). MSI can efficiently optimize the structural and electronic properties of catalysts and tune the conversion of key reaction intermediates involved in CO2 hydrogenation, thereby enhancing the catalytic performance. There is an increasing attention is being paid to the promotion effects in the catalytic CO2 hydrogenation process. However, a systematically understanding about the effects of MSI on CO2 hydrogenation to C1 products catalytic performance has not been fully studied yet due to the diversities in catalysts and reaction conditions. Hence, the characteristics and modes of MSI in CO2 hydrogenation to C1 products are elaborated in detail in our work.

A Review on Green Hydrogen Valorization by Heterogeneous Catalytic Hydrogenation of Captured CO2 into Value-Added Products

The catalytic hydrogenation of captured CO2 by different industrial processes allows obtaining liquid biofuels and some chemical products that not only present the interest of being obtained from a very low-cost raw material (CO2) that indeed constitutes an environmental pollution problem but also constitute an energy vector, which can facilitate the storage and transport of very diverse renewable energies. Thus, the combined use of green H2 and captured CO2 to obtain chemical products and biofuels has become attractive for different processes such as power-to-liquids (P2L) and power-to-gas (P2G), which use any renewable power to convert carbon dioxide and water into value-added, synthetic renewable E-fuels and renewable platform molecules, also contributing in an important way to CO2 mitigation. In this regard, there has been an extraordinary increase in the study of supported metal catalysts capable of converting CO2 into synthetic natural gas, according to the Sabatier reaction, or in dimethyl ether, as in power-to-gas processes, as well as in liquid hydrocarbons by the Fischer-Tropsch process, and especially in producing methanol by P2L processes. As a result, the current review aims to provide an overall picture of the most recent research, focusing on the last five years, when research in this field has increased dramatically.

Competition between reverse water gas shift reaction and methanol synthesis from CO2: influence of copper particle size

Converting CO₂ into value-added chemicals and fuels, such as methanol, is a promising approach to limit the environmental impact of human activities. Conventional methanol synthesis catalysts have shown limited efficiency and poor stability in a CO₂/H₂ mixture. To design improved catalysts, crucial for the effective utilization of CO₂, an in-depth understanding of the active sites and reaction mechanism is desired. The catalytic performance of a series of carbon-supported Cu catalysts, with Cu particle sizes in the range of 5 to 20 nm, was evaluated under industrially relevant temperature and pressure, i.e. 260 °C and 40 bar(g). The CO₂ hydrogenation reaction exhibited clear particle size effects up to 13 nm particles, with small nanoparticles having the lower activity, but higher methanol selectivity. MeOH and CO formation showed a different size-dependence. The TOF_CO increased from 1.9 × 10^-3 s^-1 to 9.4 × 10^-3 s^-1 with Cu size increasing from 5 nm to 20 nm, while the TOF_MeOH was size-independent (8.4 × 10^-4 s^-1 on average). The apparent activation energies for MeOH and CO formation were size-independent with values of 63 ± 7 kJ mol^-1 and 118 ± 6 kJ mol^-1, respectively. Hence the size dependence was ascribed to a decrease in the fraction of active sites suitable for CO formation with decreasing particle size. Theoretical models and DFT calculations showed that the origin of the particle size effect is most likely related to the differences in formate coverage for different Cu facets whose abundancy depends on particle size. Hence, the CO₂ hydrogenation reaction is intrinsically sensitive to the Cu particle size.

Evaluation of Porous Honeycomb-Shaped CuO/CeO2 Catalyst in Vapour Phase Glycerol Reforming for Sustainable Hydrogen Production

This study presented an optimisation study of two-stage vapour-phase catalytic glycerol reforming (VPCGR) using response surface methodology (RSM) with a central composite experimental design (CCD) approach. Characterisation through Brunauer–Emmett–Teller analysis (BET), small-angle X-ray scattering (SAXS), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX), atomic force microscopy (AFM) and particle X-ray diffraction (PXRD) were carried out to understand the physiochemical activity of the honeycomb morphology CuO/CeO2 catalyst. Notably, in this study, we achieved the desired result of glycerol conversion (94%) and H2 production (81 vol.%) under the reaction condition of Cu species loading (10 wt.%), reaction temperature (823 K), WHSV (2 h−1) and glycerol concentration (15 wt.%). From the RSM analysis, an optimum predicted model for VPCGR was obtained and further integrated into Microsoft Excel and Aspen Plus to perform an energy analysis of the VPCGR plant at a scale of 100 kg h−1 of glycerol feed. As a whole, this study aimed to provide an overview of the technical operation and energy aspect for a sustainable frontier in glycerol reforming.

Promoting effects of indium doped Cu/CeO2 catalysts on CO2 hydrogenation to methanol

Combining catalyst modification by indium doping and chemometric optimization, the Cu/CeO2 system showed high selectivity to methanol (99.3%) with no CO formation during CO2 hydrogenation.

In–Co–Zn/C–N catalysts derived from ZIFs for selective hydrogenation of CO2 into methanol

In2O3 combines ZIF derived Co–Zn/C–N catalyst perform a CO2 conversion of 7.0% with methanol selectivity over 77% and the STY of methanol is 3.3 mmol gcat−1 h−1 under the condition of CO2/H2 = 3 : 1, 2 MPa, 300 °C and GHSV = 6 L gcat−1 h−1.

The Effect of Modifiers on the Performance of Ni/CeO2 and Ni/La2O3 Catalysts in the Oxy-Steam Reforming of LNG

This work interrogates for the first time the catalytic properties of various monometallic Ni catalysts in the oxy-steam reforming of LNG. Various research techniques, including X-ray diffraction (XRD), specific surface area and porosity analysis (BET method), scanning electron microscopy with X-ray microanalysis (SEM-EDS), temperature-programmed desorption of ammonia (TPD-NH₃), temperature-programmed reduction (TPR-H₂) and the FTIR method, were used to study their physicochemical properties. The mechanism of the oxy-steam reforming of LNG is also discussed in this paper. The high activity of monometallic catalysts supported on 5% La₂O₃-CeO₂ and 5% ZrO₂-CeO₂ oxides in the studied process have been proven and explained on the basis of their acidity, specific surface area, sorption properties in relation to the reaction products, the crystallite size of the metallic nickel and their phase composition.

Facet-Dependent Reactivity of Ceria Nanoparticles Exemplified by CeO2-Based Transition Metal Catalysts: A Critical Review

The rational design and fabrication of highly-active and cost-efficient catalytic materials constitutes the main research pillar in catalysis field. In this context, the fine-tuning of size and shape at the nanometer scale can exert an intense impact not only on the inherent reactivity of catalyst’s counterparts but also on their interfacial interactions; it can also opening up new horizons for the development of highly active and robust materials. The present critical review, focusing mainly on our recent advances on the topic, aims to highlight the pivotal role of shape engineering in catalysis, exemplified by noble metal-free, CeO2-based transition metal catalysts (TMs/CeO2). The underlying mechanism of facet-dependent reactivity is initially discussed. The main implications of ceria nanoparticles’ shape engineering (rods, cubes, and polyhedra) in catalysis are next discussed, on the ground of some of the most pertinent heterogeneous reactions, such as CO2 hydrogenation, CO oxidation, and N2O decomposition. It is clearly revealed that shape functionalization can remarkably affect the intrinsic features and in turn the reactivity of ceria nanoparticles. More importantly, by combining ceria nanoparticles (CeO2 NPs) of specific architecture with various transition metals (e.g., Cu, Fe, Co, and Ni) remarkably active multifunctional composites can be obtained due mainly to the synergistic metalceria interactions. From the practical point of view, novel catalyst formulations with similar or even superior reactivity to that of noble metals can be obtained by co-adjusting the shape and composition of mixed oxides, such as Cu/ceria nanorods for CO oxidation and Ni/ceria nanorods for CO2 hydrogenation. The conclusions derived could provide the design principles of earth-abundant metal oxide catalysts for various real-life environmental and energy applications.

Methanol synthesis over Cu/CeO2–ZrO2 catalysts: the key role of multiple active components

Importance of well-dispersed copper species and well-developed ceria–zirconia surface during catalytic carbon dioxide hydrogenation to methanol.

Approaching full-range selectivity control in CO2 hydrogenation to methanol and carbon monoxide with catalyst composition regulation

P-Modified In₂O₃ with composition regulation for approaching full-range selectivity control in CO₂ hydrogenation to methanol and carbon monoxide.

Pt-Ni/ZnO-rod catalysts for hydrogen production by steam reforming of methanol with oxygen

Ni, Pt and a mixture of Ni and Pt supported on ZnO-rods were evaluated in autothermal steam reforming of methanol (ASRM) for hydrogen production as a function of the reaction temperature. The catalytic materials were characterized by SEM-EDS, XRD, TEM, HRTEM, TPR and BET. Analysis by SEM and TEM showed structural modifications on the surface of the ZnO rods after Ni impregnation. The reactivity of the catalytic materials in the range of 200–500 °C showed that the bimetallic sample had better catalytic activity among all the catalysts studied. This finding could be associated to PtZn and NiZn alloys present in this catalyst, which were identified by XRD and HRTEM analyses. Catalyst characterization by XRD after the catalytic testing showed that the intermetallic PtZn phase was stable during the reaction in the Pt/ZnO-rod sample. The cubic Ni_0.75–Zn_0.25 structure identified in the Ni/ZnO-rod sample was transformed to Zn_0.1–Ni_0.9–O and metallic Ni phases, respectively. On the bimetallic PtNi/ZnO-rod sample, the cubic Ni_0.75–Zn_0.25 structure remained, although the tetragonal NiZn structure is unstable and was destroyed during the ASRM reaction and then a new phase of Ni_0.7Pt_0.3 emerged. The promotion effect of Pt and/or Ni on the ZnO-rod was clearly shown.

PtZn and NiZn alloys on ZnO-1D samples were evaluated in the ASRM. Bifunctional behavior between PtZn, NiZn alloys and the ZnO were reported. The ZnO provides the adsorption sites for the reagents and the alloy particles facilitate the H₂ transfer.

Methanol Synthesis at a Wide Range of H2 /CO2 Ratios over a Rh-In Bimetallic Catalyst

There is increasing interest in capturing H₂ generated from renewables with CO₂ to produce methanol. However, renewable hydrogen production is expensive and in limited quantity compared to CO₂ . Excess CO₂ and limited H₂ in the feedstock gas is not favorable for CO₂ hydrogenation to methanol, causing low activity and poor methanol selectivity. Now, a class of Rh-In catalysts with optimal adsorption properties to the intermediates of methanol production is presented. The Rh-In catalyst can effectively catalyze methanol synthesis but inhibit the reverse water-gas shift reaction under H₂ -deficient gas flow and shows the best competitive methanol productivity under industrially applicable conditions in comparison with reported values. This work demonstrates a strong potential of Rh-In bimetallic composition, from which a convenient methanol synthesis based on flexible feedstock compositions (such as H₂ /CO₂ from biomass derivatives) with lower energy cost can be established.

Recent Advances on the Rational Design of Non-Precious Metal Oxide Catalysts Exemplified by CuOx/CeO2 Binary System: Implications of Size, Shape and Electronic Effects on Intrinsic Reactivity and Metal-Support Interactions

Catalysis is an indispensable part of our society, massively involved in numerous energy and environmental applications. Although, noble metals (NMs)-based catalysts are routinely employed in catalysis, their limited resources and high cost hinder the widespread practical application. In this regard, the development of NMs-free metal oxides (MOs) with improved catalytic activity, selectivity and durability is currently one of the main research pillars in the area of heterogeneous catalysis. The present review, involving our recent efforts in the field, aims to provide the latest advances—mainly in the last 10 years—on the rational design of MOs, i.e., the general optimization framework followed to fine-tune non-precious metal oxide sites and their surrounding environment by means of appropriate synthetic and promotional/modification routes, exemplified by CuOx/CeO2 binary system. The fine-tuning of size, shape and electronic/chemical state (e.g., through advanced synthetic routes, special pretreatment protocols, alkali promotion, chemical/structural modification by reduced graphene oxide (rGO)) can exert a profound influence not only to the reactivity of metal sites in its own right, but also to metal-support interfacial activity, offering highly active and stable materials for real-life energy and environmental applications. The main implications of size-, shape- and electronic/chemical-adjustment on the catalytic performance of CuOx/CeO2 binary system during some of the most relevant applications in heterogeneous catalysis, such as CO oxidation, N2O decomposition, preferential oxidation of CO (CO-PROX), water gas shift reaction (WGSR), and CO2 hydrogenation to value-added products, are thoroughly discussed. It is clearly revealed that the rational design and tailoring of NMs-free metal oxides can lead to extremely active composites, with comparable or even superior reactivity than that of NMs-based catalysts. The obtained conclusions could provide rationales and design principles towards the development of cost-effective, highly active NMs-free MOs, paving also the way for the decrease of noble metals content in NMs-based catalysts.

Engineering well-defined rare earth oxide-based nanostructures for catalyzing C1 chemical reactions

In this review, we summarize the nanostructural engineering and applications of rare earth oxide-based nanomaterials with well-defined compositions, crystal phases and shapes for efficiently catalyzing C1 chemical reactions.

CO2 Hydrogenation over Nanoceria-Supported Transition Metal Catalysts: Role of Ceria Morphology (Nanorods versus Nanocubes) and Active Phase Nature (Co versus Cu)

In this work we report on the combined impact of active phase nature (M: Co or Cu) and ceria nanoparticles support morphology (nanorods (NR) or nanocubes (NC)) on the physicochemical characteristics and CO2 hydrogenation performance of M/CeO2 composites at atmospheric pressure. It was found that CO2 conversion followed the order: Co/CeO2 > Cu/CeO2 > CeO2, independently of the support morphology. Co/CeO2 catalysts demonstrated the highest CO2 conversion (92% at 450 °C), accompanied by 93% CH4 selectivity. On the other hand, Cu/CeO2 samples were very selective for CO production, exhibiting 52% CO2 conversion and 95% CO selectivity at 380 °C. The results obtained in a wide range of H2:CO2 ratios (1-9) and temperatures (200-500 °C) are reaching in both cases the corresponding thermodynamic equilibrium conversions, revealing the superiority of Co- and Cu-based samples in methanation and reverse water-gas shift (rWGS) reactions, respectively. Moreover, samples supported on ceria nanocubes exhibited higher specific activity (µmol CO2·m-2·s-1) compared to samples of rod-like shape, disclosing the significant role of support morphology, besides that of metal nature (Co or Cu). Results are interpreted on the basis of different textural and redox properties of as-prepared samples in conjunction to the different impact of metal entity (Co or Cu) on CO2 hydrogenation process.

Metal-Support Interactions in CeO2- and SiO2-Supported Cobalt Catalysts: Effect of Support Morphology, Reducibility, and Interfacial Configuration

With the increasing demand for highly efficient and durable catalysts, researchers have been doing extensive research to engineer the shape, size, and even phase (e.g., hcp or fcc Co) of individual catalyst nanoparticles, as well as the interface structure between the catalyst and support. In this work, cobalt oxides were deposited on ceria with rod-like morphology (CeO₂NR) and cube-like morphology (CeO₂NC) and silica with sphere-like morphology (SiO₂NS) via a precipitation-deposition method to investigate the effects of support morphology, surface defects, support reducibility, and the metal-support interactions on redox and catalytic properties. XRD, Raman, XPS, BET, H₂-TPR, O₂-TPD, CO-TPD, TEM, and TPR/TPO cycling measurements have been mainly employed for catalysts characterization. Compared with CeO₂NC and SiO₂NS supports, as well as CeO₂NC- and SiO₂NS-supported cobalt catalysts, CeO₂NR counterparts exhibited enhanced reducibility and CO oxidation performance at a lower temperature. Both the apparent activation energy and CO conversion demonstrated the following catalytic activity order: 10 wt % CoO _x/CeO₂NR > 10 wt % CoO _x/CeO₂NC > 10 wt % CoO _x/SiO₂NS. These results showed a strong support-dependent reducibility, CO oxidation, and redox cycling activity/stability of the as-prepared catalysts. Moreover, the significantly enhanced catalytic CO oxidation of the 10 wt % CoO _x/CeO₂NR catalyst indicated the vital role of CeO₂NR support with rich surface oxygen vacancies, superior oxygen storage capacity and mobility, and excellent adsorption/desorption behavior of CO and O₂ species.

Ceria-Based Materials in Hydrogenation and Reforming Reactions for CO2 Valorization

Reducing greenhouse emissions is of vital importance to tackle the climate changes and to decrease the carbon footprint of modern societies. Today there are several technologies that can be applied for this goal and especially there is a growing interest in all the processes dedicated to manage CO2 emissions. CO2 can be captured, stored or reused as carbon source to produce chemicals and fuels through catalytic technologies. This study reviews the use of ceria based catalysts in some important CO2 valorization processes such as the methanation reaction and methane dry-reforming. We analyzed the state of the art with the aim of highlighting the distinctive role of ceria in these reactions. The presence of cerium based oxides generally allows to obtain a strong metal-support interaction with beneficial effects on the dispersion of active metal phases, on the selectivity and durability of the catalysts. Moreover, it introduces different functionalities such as redox and acid-base centers offering versatility of approaches in designing and engineering more powerful formulations for the catalytic valorization of CO2 to fuels.