Improvement Of Catalyst Activity Research Articles

Stimulating Electron Delocalization of Lanthanide Elements through High-Entropy Confinement to Promote Electrocatalytic Water Splitting.

High-entropy alloys (HEAs) have aroused extensive attention in the field of catalysis. However, due to the integration of multiple active sites in HEA, it exhibits excessive adsorption behavior resulting in difficult desorption of active species from the catalyst surfaces, which hinders the catalytic efficiency. Therefore, adjusting the adsorption strength of the active site in HEA to enhance the catalytic activity is of great importance. By introducing rare-earth (RE) elements into the high-entropy alloy, the delocalization of 4f electrons can be achieved through the interaction between the multimetal active site and RE, which benefits to regulate the adsorption strength of the HEA surface. Herein, the RE Ce-modified hexagonal-close-packed PtRuFeCoNiZn-Ce/C HEAs are synthesized and showed an excellent electrocatalytic activity for hydrogen evolution reaction and oxygen evolution reaction with ultralow overpotentials of 4, 7 and 156, 132 mV, respectively, to reach 10 mA cm-2 in 0.5 M H2SO4 and 1.0 M KOH solutions, and the assembled water electrolysis cell only requires a voltage of 1.43 V to reach 10 mA cm-2, which is much better than the performance of PtRuFeCoNiZn/C. Combined with the results of in situ attenuated total reflection infrared spectroscopy and density functional theory (DFT), the fundamental reasons for the improvement of catalyst activity come from two aspects: (i) local lattice distortion of HEA caused by the introduction of RE with large atomic radius induces 4f orbital electron delocalization of RE elements and enhances electron exchange between RE and active sites. (ii) The electronegativity difference between the RE element and the active site forms a surface dipole in HEA, which optimizes the adsorption of the active intermediate by the HEA surface site. This study provides an insightful idea for the rational design of high-performance HEA- and RE-based electrocatalysts.

Eugenol Hydrodeoxygenation Over Mixed Mo-W Carbides.

The modification of molybdenum carbide catalysts by another transition metal has raised an increasing research interest due to the significant improvement of catalyst activity in hydrodeoxygenation of lignin derivatives. At par with the commonly used Co and Ni that add a strong hydrogenation functionality, it was found that the addition of the more oxophilic W restricts ring hydrogenation while allowing the deoxygenation of oxygenated compounds and thus yielding higher selectivity toward the formation of non-oxygenated aromatic compounds. The coexistence of Mo2C with W2C along with metallic W altered the electronic properties of Mo2C which resulted in an increase of catalyst active site density and facilitated further total eugenol deoxygenation. Propyl-benzene selectivity of up to 83 % was reached at close to 100 % eugenol conversion. These findings will allow a better overview of the effect of different metal phases of mixed carbides on the catalyst performance and raise the prospect of optimizing catalyst design for a hydrodeoxygenation processing of lignin depolymerization products.

Carbon bridge effects regulate TiO2-acrylate fluoroboron coatings for efficient marine antifouling

Synergy strategy of photocatalysts and polymer resins are promising technology for marine antifouling. However, it is still a main challenge to obtain a green, safe, and efficient antifouling coatings. Herein, carbon (graphene or CNT) modified TiO2 photocatalyst was synthesized via hydrothermal and annealing process and has successfully applied in acrylate fluoroboron polymer (ABFP) composite coating. Morphology and chemical composition were detailed characterized. The graphene or CNT acted as a bridge with supplemental spatial structures (petal gaps, entanglement) and new functional groups (C-O, C-Ti-O, etc.) on TiO2 particle. Carbon nanotube (CNT) modified TiO2-ABFP coatings (BTCP) achieved excellent antibacterial and anti-diatom adhesion rate of 89.33%-96.70% and 99.00%-99.50%, which was 1.84-4.94-fold more than that of the single ABFP. CNT or graphene served as electronic bridges was considered as the crucial mechanism, which significantly improved the light absorption range and capacity, conductivity, and photoelectric response of TiO2, and further accelerated the generation and transfer of free radicals to the surface of BTCP or FTGP. Moreover, the improvement of catalyst activity synergizes with the smooth surface, hydrophilicity, and slow hydrolysis of composite coatings, achieved long-term and efficient antifouling performance. This work provides a new insight into the modification of TiO2 and antifouling mechanism of polymer coating.

Improvement of catalyst activity in cracking of n-hexane via metal (Fe/Ga) impregnation over ZSM-12 catalyst

In this research, zeolite ZSM-12 with Si/Al ratio = 80 was synthesized by hydrothermal method. The synthesized zeolite ZSM-12 was modified using Fe and Ga metals and a combination of these two metals, 1 % iron metals (Z80-Fe) and 1 % gallium metals(Z80-Ga), and a 2 % combination of these two metals (Z80-Fe-Ga). The physicochemical properties of synthesized zeolites were evaluated and compared by XRD, EDX-dot-mapping, NH3-TPD, BET, FT-IR, and TGA analyses. The catalytic assessment of synthesized zeolites in the HTO (n-hexane to olefins) process in a fixed bed reactor under atmospheric pressure and Weight hourly space velocity (WHSV) equal to 4 h−1 at 550 °C was evaluated. Various parameters such as selectivity towards light olefins, propylene to ethylene (P/E ratio), production of light alkanes, and aromatic compounds (BTX) were investigated. The results show that using metals led to the improvement and adjustment of the acid sites of zeolite, and the highest amount of light olefin and the lowest amount of coke were obtained. The result of the n-hexane to olefin process showed that the yield of light olefins was significantly improved in all modified catalysts compared to parent zeolite MTW. Compared to other modified zeolites, Z80-Fe-Ga zeolite has the highest yield of light olefins, equal to 59 %. This zeolite performs better due to the presence of gallium and iron metals and shows the highest propylene selectivity (P/E = 2.4). In addition, according to the results of the TGA analysis, the content of coke on the Z80-Fe-Ga catalyst after the catalytic reaction is much less than that of other catalysts after the catalytic reactor test.

CuCo2O4@ACoNi-LDH (A=Fe, Cu, Zn, Cr) as efficient electrocatalyst for freshwater, seawater and urea oxidation reaction

Water electrolysis has a promising prospect in the production of green hydrogen energy, but its oxygen evolution reaction kinetics is relatively slow. Therefore, in this experiment, CuCo2O4@ACoNi-LDH (A = Fe, Cu, Zn, Cr) with heterogeneous core-shell catalytic material was firstly prepared by means of hydrothermal and calcination process, and its anodic oxidation reaction in freshwater, seawater and urea was investigated. In the oxygen evolution reaction (OER) of electrolytic water, CuCo2O4@CuCoNi-LDH displays the best catalytic activity. When the current density is 10 mA cm−2, only the overpotential of 199 mV is needed (potential of 1.429 V). The competitive oxidation and corrosion of chloride ions in seawater result in the decrease of catalytic activity. For urea oxidation reaction (UOR), CuCo2O4@FeCoNi-LDH displays the best catalytic performance, only potential of 1.292 V was required with the same current density, and the catalyst had good stability during the reaction for 12 h. Density functional theory calculation shows that CuCo2O4 plays an important role in the catalytic process. The synergistic catalysis of FeCoNi-LDH and CuCo2O4 results in the improvement of catalyst activity and stability. The CuCo2O4 material plays a key role in catalyzing urea splitting and the FeCoNi-LDH material protects CuCo2O4 from corrosion according to experimental results and density functional theory calculations. This experiment provides a new idea for the hydrogen production, exploration and the treatment of urea wastewater for transition metal oxides and layered hydroxides electrocatalyst with core-shell heterostructure.

Influence of chalcopyrite removal and mechanical exfoliation on the performance of molybdenite catalysts supported on activated bauxite for alcohol synthesis by Fischer-Tropsch process

The top-down approach was used to develop catalysts for higher alcohol synthesis by starting with low-grade molybdenite concentrate and mesoporous activated bauxite as the active metal and support, respectively. The results of the study showed that the process of chemical leaching significantly reduced copper in the form of chalcopyrite in the concentrate by over 95%. This reduction in copper content of purified catalysts led to an increase in the selectivity for C3+ alcohols compared to catalysts based on impure molybdenite. Additionally, the process of exfoliation not only reduced the particle size of the active component but also increased the selectivity for C3+ alcohols and the conversion of CO. The chemical–mechanical activation process developed in this study resulted in an improvement in catalyst activity of more than 50%.

Defect engineered Janus MoSiGeN4 as highly efficient electrocatalyst for hydrogen evolution reaction

It is well known that defect engineering is very important to the improvement of catalyst activity. In this paper, defect engineering is introduced into Janus MoSiGeN4 to regulate hydrogen evolution reaction (HER) activity. Based on density functional theory, a theoretical study is carried out to clarify the roles of vacancy and transition metal (TM) atom doping in Janus MoSiGeN4. Five different vacancies are considered, and results suggest that outmost N vacancy can effectively enhance the HER activities. For VN2@MoSiGeN4 and VN1@MoSiGeN4 structures, the hydrogen adsorption Gibbs free energy (ΔGH*) is 0.015 eV and 0.145 eV, respectively. Moreover, a systematic screening of eleven non-precious TM atoms (V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ta and W) doped MoSiGeN4 as HER catalysts reveals that Fe-, Mn-, and Nb-doped MoSiGeN4 show better HER activity than that of Pt with theΔGH* of 0.013 eV, 0.061 eV, and 0.087 eV, respectively. Electronic properties, electron charge density difference and Bader charge are employed to explore the origin of electrocatalytic activity. Our study confirms that vacancy and TM atom doping are effective means to enhance electrocatalytic performance and defect engineered Janus MoSiGeN4 can be served as highly efficient HER catalyst.

Cationic Palladium Catalyzed Nonalternating Copolymerization of Ethylene with Carbon Monoxide: Microstructure Analysis and Computational Study†

Comprehensive SummaryThe introduction of carbonyl group with a high density in polyethylene backbone corresponds to polyketone materials, which features excellent mechanical strength, crystallinity, photodegradability, hydrophilicity, surface and barrier properties. Due to the extremely high binding affinity of carbon monoxide (CO) and kinetic preference for its subsequent insertion, the formation of nonalternating structure with extra ethylene insertion is exceptionally challenging, however, this nonalternating strategy is of significant importance for polymer modification in term of processing and solubility. Here, we have communicated our study on cationic palladium coordinated diphosphazane monoxide (PNPO) for the nonalternating copolymerization of ethylene with CO, the systematical investigation on the amine and phosphine oxide moieties in PNPO platform in term of electronic and steric modulation has been performed. It is discovered that the installation of aliphatic structure on amine moiety favors the improvement of catalyst activity and longevity, while the amino groups on phosphine oxide moiety promotes the nonalternating copolymerization. In particular, we have computationally investigated herein the aspects of the nonalternating degree by comparing with PNPO platform and 1,3‐bis(diphenylphosphanyl)propane ligands based palladium catalysts. These mechanistic studies can help to understand the catalyst structure and polyketone property relationships and shed light on future design of high‐performance copolymerization catalysts.

Acid-Modified Sepiolite-Supported Pt (Noble Metal) Catalysts for HCHO Oxidation at Ambient Temperature

The critical need to enhance the quality of indoor air leads to the improvement of catalyst activity for the removal of formaldehyde. Sepiolite can be utilized in catalytic reactions for its unique structure, composition and high surface area. The adhesion between sepiolite fibers and the blocked microporous channel (by impurities) demands the activation of natural sepiolite through acid treatment. This treatment successfully produces acid-modified sepiolite Pt-supported samples. The impacts of different acid concentrations, Pt loading content and calcination temperature on catalytic activity for formaldehyde (HCHO) oxidation are studied. The catalytic activity of HCHO is characterized and evaluated by techniques including specific surface area, X-ray diffraction, Fourier transform infrared spectrum, X-ray photoelectron spectroscopy and transmission electron microscopy. The results show the maximum specific area of sepiolite at the optimized 0.06 M acid concentration. Among all the prepared samples, the 0.02Pt/Sep catalyst calcined at 500 °C exhibits the highest catalytic activity for the oxidation of HCHO.

Ni-Foam-Structured Ni-Al2O3 Ensemble as an Efficient Catalyst for Gas-Phase Acetone Hydrogenation to Isopropanol.

The free-standing Ni-Al2O3 ensemble derived from NiAl-layered double hydroxides (NiAl-LDHs) grown onto a Ni-foam has been developed for the exothermic gas-phase acetone hydrogenation to isopropanol. This approach works effectively and efficiently to achieve a unique combination of high activity/selectivity and enhanced heat/mass transfer stemmed from the Ni-foam. The outstanding catalyst is obtained by direct reduction of the un-calcined NiAl-LDH/Ni-foam, with a high turnover frequency of 0.90 s-1, being capable of converting 90.8% acetone into isopropanol with almost 100% selectivity under stoichiometric H2/acetone molar ratio, atmospheric pressure at 80 °C, and a WHSVacetone of 10 h-1. The catalyst derivation using the un-calcined NiAl-LDH/Ni-foam enables the Ni nanoparticles to be intertwined with Al2O3 to form a large Ni-Al2O3 interface, without interruption of impurities such as irreducible NiO (in the case of calcined NiAl-LDH/Ni-foam samples), which markedly improves the strong acetone adsorption next to the Ni0 hydrogenation sites, thereby leading to a dramatic improvement of catalyst activity.

Long-range order, short-range disorder: Engineering one-dimensional flow channel arrays with hierarchically porous reaction interfaces for electrocatalytic reduction of oxygen

Fuel cell performance depends heavily on electrochemical reaction kinetics and mass transport. Rapid kinetics requires high-activity catalysts while good mass transport demands efficient transport domains. Recent fundamental studies in these areas focus more on the improvement in catalyst activity, whereas the importance of mass transport should not be underestimated, which is the focal point of this work. Hierarchical pores are generally considered to be conducive to enhancing reaction kinetics and mass transport, but the degree of order of pore structures has a significant influence over the fuel cell performance. Herein, we introduce the concept of ‘long-range order, short-range disorder’ to design transport domains and reaction interfaces: dispensing with conventional microfabrication techniques, well-ordered, one-dimensional channel arrays are constructed using vascular bundles of natural material, capable of decreasing tortuosity, increasing porosity, optimizing reactant distribution and thus minimizing concentration losses; further, intrinsic biominerals and tissues of organisms existing on the inner and outer walls of channel arrays are harnessed to form hierarchically porous domains, that is, raising the roughness of reaction interfaces by increasing the degree of short-range disorder. The combination of one-dimensional flow channels (long-range order) and hierarchically porous reaction interfaces (short-range disorder), analogous to blood vessels composed of arteries/veins and capillaries, ensures the optimization of mass transport and catalytic kinetics, leading to an electrocatalytic oxygen reduction performance enhancement over a wide array of biomass-derived carbonaceous materials. Accordingly, this work provides inspiration for finding the right balance between mass transport and reaction kinetics from an order perspective.

CoB/C3N4 photocatalyst for rapid hydrogen evolution from hydrolysis of sodium borohydride under light irradiation

For practical application of sodium borohydride (NaBH[Formula: see text] hydrolysis to generate hydrogen, metallic catalysts with low cost but excellent activity are highly desired. However, it remains a big challenge to further improve the activity of non-noble metal catalysts. In this work, photocatalysis technology was successfully introduced to enhance the catalyst activity for NaBH4 hydrolysis. By means of conventional impregnation-reduction method, CoB nanocatalyst was evenly deposited on graphitic carbon nitride surface, resulting in a Schottky-type photocatalyst (CoB/CN). As expected, hydrogen generation rate was greatly boosted owing to light irradiation. According to the results of capture experiments, photoexcited electron from g-C3N4 could enrich the electron density of CoB surface, which leads to the improvement of catalyst activity. Additionally, the light irradiation facilitates the remarkable decrease of apparent activation energy. Compared with some reported noble metal catalysts, the CoB/CN presents higher activity, especially under light irradiation.

High efficiency photocatalytic degradation of indoor formaldehyde with silver-doped ZnO/g-C3N4 composite catalyst under the synergistic effect of silver plasma effect and heterojunction

Abstract Ag/ZnO/g-C3N4 ternary heterojunction structure was synthesized by a (hydrothermal reaction - calcination - reduction) three-step method. The combination of flake porous ZnO and fluffy porous g-C3N4 and silver makes the ternary composite catalyst exhibit good photocatalytic performance against formaldehyde pollutants. ZnO/g-C3N4 and Ag/ZnO/g-C3N4 catalysts can degrade formaldehyde to 74.1% and 81.2%, respectively. The photocatalytic activity of the ternary catalyst is 1.3 times and 2.6 times of that of pure ZnO and g-C3N4. The improvement of catalyst activity is mainly due to the synergistic effect of heterogeneous junction and plasma effect of metal silver. Heterojunction can effectively improve the charge transfer ability. The plasma effect of silver makes silver not only act as the electron transfer medium but also expand the photoresponse range of catalyst. Through the catalyst cycle experiment, it can be seen that the composite catalyst Ag/ZnO/g-C3N4 has good sustainable performance. In this experiment, the catalyst preparation method is simple and the raw materials are readily available, which provides a scheme that can be studied in depth for the effective removal of formaldehyde in the real environment.

Removal of Rhodamine B dye from aqueous solution by heterogeneous UV-Fenton catalytic process

In this study, the removal of Rhodamine B at high concentrations (25–100 ppm) from aqueous solution was carried out via the heterogeneous UV-Fenton catalytic process based on Fe3O4 nanoparticles. The removal efficiency of Rhodamine B (C0 = 50 ppm) reached 100% after 4 hours treatment, corresponding to the mineralization efficiency of 70%. In comparison with the conventional Fenton processes, the assistance of UV irradiation boosted the OH• radical generation and prevented the formation of ionic complexes between Fe3+ and Rhodamine B, permitting the catalyst activity improvement. In addition, Fe3O4 nanoparticles could be easily separated by an external magnet and then re-cycled several times with minimal loss of catalyst activity.

Improving platinum group metal–free oxygen reduction reaction electrocatalyst activity: suggestions from density functional theory studies

In this opinion, the limitations of platinum group metal–free oxygen reduction reaction electrocatalyst activity based on scaling laws and resulting Balandin-Sabatier volcano plots are presented. Previous theoretical work aimed at overcoming this limitation is discussed. A theoretical study of a novel approach toward catalyst activity improvement, dynamic strain engineering , is proposed and tested for a possible platinum group metal–free oxygen reduction reaction active site. It is shown that not only can this approach produce thermodynamic limiting potentials well beyond scaling law relationship limits but also be capable of doing so in an energy-efficient manner.

Polymerization Kinetics of Propylene with the MgCl2-Supported Ziegler-Natta Catalysts—Active Centers with Different Tacticity and Fragmentation of the Catalyst

The catalytic activity and stereospecificity of olefin polymerization by using heterogeneous TiCl4/MgCl2 Ziegler-Natta (Z-N) catalysts are determined by the structure and nature of active centers, which are mysterious and fairly controversial. In this work, the propylene polymerization kinetics under different polymerization temperatures by using Z-N catalysts were investigated through monitoring the concentration of active centers [C*] with different tacticity. SEM was applied to characterize the catalyst morphologies and growing polypropylene (PP) particles. The lamellar thickness and crystallizability of PP obtained under different polymerization conditions were analyzed by DSC and SAXS. The PP fractions and active centers with different tacticity were obtained with solvent extraction fractionation method. The catalytic activity, active centers with different tacticity and propagation rate constant kp, fragmentation of the catalyst, crystalline structure of PP are correlated with temperature and time for propylene polymerizations. The polymerization temperature and time show complex influences on the propylene polymerization. The higher polymerization temperature (60 °C) resulted higher activity, kp and lower [C*], and the isotactic active centers Ci* as the majority ones producing the highest isotactic polypropylene (iPP) components showed much higher kp when compared with the active centers with lower stereoselectivity. Appropriate polymerization time provided full fragmentation of the catalyst and minimum diffusion limitation. This work aims to elucidate the formation and evolution of active centers with different tacticity under different polymerization temperature and time and its relations with the fragmentation of the PP/catalyst particles, and provide the solutions to the improvement of catalyst activity and isotacticity of PP.

Fuels and energy carriers from single-site catalysts prepared via surface organometallic chemistry

The petrochemical industry relies on catalysts for hydrocarbon conversions that often contain ill-defined active metal sites, hampering rational improvement. Surface organometallic chemistry (SOMC) has enabled the design of catalysts with tailored metal sites, often referred to as single sites. In this Perspective, I consider how SOMC has opened routes to synthesis of fuels and energy carriers not possible via traditional approaches and led to the discovery of alkane homologation processes, by giving access to a large proportion of low coordinated and highly reactive surface sites. While challenges lie ahead, particularly with respect to the improvement of catalyst activity and lifetime, as well as further control and characterization of active/surface site structure, SOMC is effective for increasing molecular level understanding of catalytic events as found in related industrial systems. Furthermore, single-site catalysts can also be used to provide molecular level precision in complex systems such as supported nanoparticles where dopant and support effects are ubiquitous, but poorly understood. Industrial hydrocarbon conversions often use catalysts with ill-defined active metal sites, which may hamper rational improvement. This Perspective explores how surface organometallic chemistry can allow the design of catalysts with more well-defined active sites for the production of energy carriers.

Preparation and catalytic performance of an efficient Raney nickel catalyst for syngas methanation

A new strategy for preparing Raney nickel catalyst was proposed, which could significantly improve the catalytic activity of the catalyst in the methanation of syngas to substitute natural gas in a continuous flow microreactor. The new preparation strategy includes a hydrochloric acid solution quenching process interpolated between two alkali leaching steps. Raney Ni III catalyst showed the best activity with a CO conversion of almost 100% and a CH4 selectivity of 98% at 548 K under 1.0 MPa with the molar ratio of 3H2:1CO and a gas hourly space velocity of 10000 h−1. The catalysts were characterized by N2 adsorption–desorption, scanning electron microscopy, X-ray powder diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy and temperature-programmed desorption of hydrogen. The results of systematic characterization and catalytic activity evaluation show that the formation of 3Ni(OH)2·2H2O in the catalyst is beneficial to the adsorption and activation of hydrogen and the C=O bond, which greatly improves the activity of Raney nickel III in methanation of syngas. Meanwhile, high specific surface area leads to more active sites on the catalyst surface, which is also conducive to the improvement in catalyst activity.

Preparation and characterization of Ni‐Agx/SBA‐15 and its catalytic properties on the hydrogenation of soybean oil

AbstractNi‐Agx/SBA‐15 catalysts with different contents of the silver (Ag) promoter were prepared by the co‐impregnation method using the support of the mesoporous material SBA‐15. The Ni‐Agx/SBA‐15 catalysts were characterized by ICP‐OES, X‐ray diffraction (XRD), transmission electron microscope (TEM), and N2 adsorption–desorption isotherms. The activity of the catalysts on hydrogenation of soybean oil was evaluated. The results indicated that all the catalysts retained the hexagonally ordered structure of SBA‐15, the binding force between SBA‐15 and Ni was enhanced by the addition of the Ag promoter, and Ni was well loaded on the surface and the interior of the support that was beneficial to the improvement of catalyst activity. TEM images of the catalysts show that the addition of the silver can promote the dispersion of nickel particles over and inside the mesoporous channels of the SBA‐15 support, and the aggregation of metal nickel particles was decreased. The catalysts of Ra‐Ni (Raney Nickel), Ni/SBA‐15 and Ni‐Agx/SBA‐15 were used in the hydrogenation of soybean oil. The results show that Ni‐Ag0.15/SBA‐15 in hydrogenation processing has higher catalytic activity, and the obtained hydrogenated soybean oil has low trans fatty acids (TFAs) content. The use efficiency of the catalyst decreased to 60% after 8 cycles.Practical applicationsThe main objective of this work was to hydrogenate soybean oil. Very encouraging results were obtained with Ni‐Ag0.15/SBA15. This preparation had a higher catalyst activity to obtain low trans fatty acid content. This finding is very valuable for fat and oil processing at the industry level.

Development of Two Novel Processes for Hydrogenation of CO2 to Methanol over Cu/ZnO/Al2O3 Catalyst to Improve the Performance of Conventional Dual Type Methanol Synthesis Reactor

Conventional methanol synthesis process (CR configuration) consists of water-cooled and gas-cooled reactors in which methanol and water are condensed inside the gas-cooled reactor which deactivates the catalyst. In this study, two novel configurations (AW and ACW configurations) are represented to address this problem in which the gas-cooled reactor is replaced with adiabatic reactor. Moreover, a condenser is applied between adiabatic and water-cooled reactors in ACW configuration. Results show that temperature increases somewhat along the adiabatic reactor that prevents gas condensate formation. Besides, the adiabatic reactor maximum temperature is less than that of first reactor in CR configuration which prevents copper based catalyst thermal sintering. Moreover, a high cross section-to-length ratio of the adiabatic reactor leads to negligible pressure drop along the reactor and improvement in CO2 conversion to methanol that has positive environmental effects. Also, water mole fraction decreases along the reactors of AW and ACW configurations to prevent the deactivation of catalyst active sites. Eventually, methanol production rates by AW and ACW configurations are improved around 25.5% and 43.1% in comparison with CR configuration. So, novel AW and ACW configurations provide many benefits including improvement in catalyst activity and durability, CO2 conversion, and the methanol production rate.