Maximum Methanol Yield Research Articles

Optimization of methanol yield and carbon dioxide utilization in methanol synthesis process

The method of CO2 hydrogenation to methanol can effectively reduce carbon emission and has wide application prospects in chemical industry and environment. Therefore, methanol synthesis is an important way to save energy, reduce emission and transform energy utilization. In this paper, the mathematical model of methanol synthesis reactor is established. Under the condition of controllable cooling temperature, the optimization is carried out with maximum methanol yield and CO2 utilization rate. The results show that the methanol yield can be increased by 6.57% and CO2 utilization rate can be increased to 39.1% by adjusting the cooling temperature control strategy. The comparative study found that the optimal cooling temperatures all show up and down variations, with local minima and maxima. In addition, an industrial application method of methanol yield maximization cooling strategy is proposed. When the stage cooling at different temperatures is adopted, the methanol yield could be increased by 5.38%.

CO2 photoreduction integrated with oxidative coupling of amines over WO3/Cu(BTC) nanocomposite

Here, we report an efficient integrated CO2 photoreduction to methanol accompanied with the simultaneous oxidation of benzyl amines to corresponding imines using quadrangular WO3 nanoplates grafted with Cu(BTC) as a photocatalyst under visible light, enabling to provide efficient use of the photogenerated electrons and holes. Under the optimized reaction conditions, the maximum yield of methanol and N-(4-methoxybenzyl)-1-(4-methoxyphenyl)methanimine was found to be 642 μmol-g−1 and 98 %, respectively. The developed integrated dual functional system comprising CO2 reduction coupled with the oxidative organic synthesis opens a new window for value chain up gradation at both ends using sustainable solar energy.

Experimental and kinetic modelling studies for the design of fixed bed methanol reactor over CuZA catalyst

Direct conversion of CO2 via hydrogenation to value-added chemicals is a vital approach for utilising CO2 emitted into the atmosphere. In this paper, a critical analysis of reaction kinetic modelling studies is explored in a fixed bed reactor to improve methanol yield for different H2 to CO2 ratios by simulating a lab-scale reactor for adiabatic and isothermal conditions. The feed inlet temperature and pressure variations are applied to study the effect of both configurations on methanol production. The results show that the isothermal configuration yields 2.76% more methanol yield compared to the adiabatic reactor. The effect of H2 to CO2 molar ratios of 3, 6 and 9 on the performance of the catalyst and the influence of CO and CO2 hydrogenation is investigated with model simulations. The overall methanol yield is increased from 19.03% to 36.41% with increase in H2 to CO2 molar ratio from 3 to 9. Experiments are performed using commercial copper-based catalyst for different temperatures of 210, 230 and 250 °C at a pressure of 40 bar for H2/CO2 of 3 and GHSV of 720 h−1 as well as at optimal temperature of 250 °C and 50 bar with varying H2/CO2 of 3, 6, 9 for 3 g and 6 g catalyst. The maximum methanol yield of 2.53% and space time yield of 13.59 mg/gcat.h is obtained at H2/CO2 ratio of 9.

Vegetal route for synthesis of CQDs/CdS nanocomposites for photocatalytic reduction of CO2 to methanol under visible light

The green pathway for the synthesis of nanoparticles targeting the photoreduction of CO2 to value-added chemicals is a potential approach to control industrial CO2 emission. In this study, we synthesized bio-based CdS(bio) nanorods using plant-based phytochemicals found in Aegle marmelos and carbon quantum dots (CQDs) using orange peels. CQDs (7 nm) were homogeneously incorporated into CdS(bio) nanorods via simple deposition, forming CQDs/CdS(bio) nanocomposites. The catalysts were thoroughly characterized using diffraction, microscopic, spectroscopic, and electrochemical techniques. CQDs/CdS(bio) composites had a diameter and length of 73 nm and 822 nm with 82.25 m2/g specific surface area. CQDs/CdS(bio) composites showed a fourfold increase in both photocurrent density (0.38 μA/cm2) and CO2 adsorption capacity (0.292 mmol/g) compared to CdS(bio) nanorods alone. The conduction band of the composite (−0.92 eV) becomes more negative compared to CdS(bio) (−0.85 eV). Moreover, the composite formation notably improved decay time by 2.35 folds and reduced photoluminescence intensity by 59.23% compared to CdS(bio), indicating enhanced charge separation and reduced charge carrier recombination. Furthermore, the photocatalytic activity of CQDs/CdS(bio) nanocomposites was investigated for CO2 reduction to methanol under visible light (250 W, λ > 420 nm, 2.2 W/m2, 4.2719 ×1018 photons/m2.s) without any sacrificial reagent. The effect of the mass fraction of CQDs on CdS and catalyst loading on photocatalytic CO2 reduction has been investigated. The optimal CQDs/CdS(bio) loading (0.50% w/w) exhibited the maximum methanol yield of 1060.52 μmol/g·h (apparent quantum efficiency 7%) over 5 h. CQDs/CdS(bio) nanocomposites exhibited strong stability (test up to 25 h in five consecutive cycles), retaining the morphological (0.11% variation in size) and structural (4.2% variation in crystallinity index) attributes. This work would provide valuable insights into the development of bio-based CdS-based composites for efficient PCO2RR into valuable chemicals.

Comparative assessment of different grades of coal for methanol production: Simulation, optimization, environmental and economic analysis

The present study reports the modeling and simulation of methanol production through the gasification of freshly mined three coal samples having different wt.% of ash, viz., low-ash coal (LAC), medium-ash coal (MAC), and high-ash coal (HAC), collected from three different locations in India. The effect of the input parameters such as steam-to-coal mass ratio and gasification temperature on process performance parameters such as stoichiometric number, syngas yield, green house gas emissions from the process stream or net stream carbon dioxide equivalent, and methanol yield was studied through process sensitivity analysis and input parameters are optimized for the maximum methanol yield and minimum green house gas emission. Primary economic investigation at optimized conditions revealed that an internal rate of return of 5.93% is achieved for HAC at minimum plant scale and setting the methanol selling price of 400 USD/ton whereas IRR obtained as 3.20% and 5.87% for LAC and MAC, respectively, at this condition. The coal sample, HAC, performed better due to a high internal rate of return (i.e., 7.53% at base case) and subsequently low production cost. The present study's findings can be decisive for the countries with substantial low-grade high-ash coal reserves concerning coal diversification for its sustainable consumption in methanol production.

Photo-assisted thermal catalysis for methanol synthesis from methane oxidation on Cu-MOR/g-C3N4

Methanol synthesis from methane oxidation at low reaction temperature on Cu-zeolites is a hot topic recently. However, methanol yield is low due to the high energy barrier of methane activation. In this work, we tried to study photothermal catalysis for methanol synthesis from methane oxidation by using O2 as the oxidant on Cu-MOR/g-C3N4, in which g-C3N4 is an absorbent under visible light. Methanol synthesis from methane oxidation on Cu-MOR/g-C3N4 is photoassisted thermal catalysis. The maximum methanol yield under visible light is 3.09 μmol h−1 gcat−1 at the reaction temperature of 200 ℃, 1 atm and 24/3/8 CH4/O2/H2O, which is 1.85 times by thermal catalysis. The reason is that the interaction between Cu-MOR and g-C3N4 is conducive to methanol formation. On the other hand, part of O2 is reduced to O2− on g-C3N4 under visible light, and the oxidation capacity of O2− is greater than of O2. The result will be useful for the design of methanol synthesis from methane oxidation at low reaction temperature.

Process Design and Techno-Economic Assessment of biogenic CO2 Hydrogenation-to-Methanol with innovative catalyst

A small-scale 10 ton per day methanol (MeOH) synthesis plant, from CO2 and hydrogen, is designed and simulated with Aspen Plus and a techno-economic analysis is conducted. The e-fuel (MeOH) is produced in a conventional fixed bed reactor featuring an innovative Cu/Zn/Al/Zr catalyst, converting biogenic CO2 from a biogas upgrading plant with H2 produced by a grid powered PEM electrolyzer. The process is thermally autonomous as a result of heat integration and combustion of purged unconverted reactants. A sensitivity analysis is carried out in order to evaluate and compare the impact of the different technical (purge fraction, Gas Hourly Space Velocity and Pressure of the methanol synthesis) and economic parameters (Capital Charge Factor, electricity and H2 cost) on the Levelized Cost Of Methanol (LCOM). Results show that, although the energy efficiency is greater (47.4 % electricity to methanol conversion) in the scenario with “self-sufficiency” in which all the net heat required by the process is provided by off-gas streams, the case with the highest profitability is the one with maximum methanol yield and, therefore, minimum purge and non-zero thermal energy import (provided by a biogas boiler). The best case scenario features a LCOM equal to 1,361 €/tonMeOH, with a GHSV of 7,500 h−1 and synthesis reactor operating at 70 bar, 250 °C. H2 production cost is the key variable and shall be reduced from the base case value of 5.8 €/kgH2 to 1.6 €/kgH2 in order to make the CO2 to methanol plant competitive with a MeOH market price of 550 €/tonMeOH; synthesis reactor operating conditions have more limited impact from a cost perspective, except for the purge fraction that shall be optimized to maximize the amount of MeOH produced.

Visible light irradiated photocatalytic reduction of CO2 to hydrocarbons using hybrid polyaniline/ CuO nanocomposite in aqueous system

ABSTRACT The ever-increasing energy demand has resulted in an increase in CO2 emissions and global warming. Photocatalytic reduction of CO2 to methanol, which is considered to be the next generation alternate fuel is gaining interest to combat global warming and to move towards a methanol economy. The present work focuses on photocatalytic reduction of CO2 using Polyaniline/CuO (PANI/CuO) nanocomposite to methanol, formic acid, and formaldehyde under visible light irradiation. CuO nanoparticles were synthesised using the aqueous extract of Tectona grandis (teak) leaves and further used in the synthesis of PANI/CuO nanocomposite with different CuO loading. PANI/CuO nanocomposite exhibited visible light activity in the reduction of CO2 to form methanol, formic acid, and formaldehyde. Photocatalytic reduction of CO2 with PANI/CuO nanocomposite containing 13.7% by weight of CuO resulted in a maximum yield of methanol. The band gap energy of the nanocomposite was found to be 2.28 eV, thus confirming its good visible light activity and the PANI-CuO heterojunction-based mechanism of photocatalysis is proposed. The synthesis of PANI-CuO photocatalyst uses CuO which is synthesised by an eco-friendly route with the utilisation of teak leaves, a timber industry waste and thus it can serve as a greener catalyst.

Nanoarchitectonics of chlorophyll and Mg co-modified hierarchical BiOCl microsphere as an efficient photocatalyst for CO2 reduction and ciprofloxacin degradation

It is of great significance to develop an efficient photocatalyst through simple methods for solar energy conversion and environmental pollution treatment. In this research, chlorophyll (Chl) and Mg co-modified hierarchical BiOCl microsphere photocatalyst with high performance was synthesized using a simple low temperature wet-chemical method. The synthesized photocatalyst with the optimal content of Chl and Mg showed superior photocatalytic performance for CO2 reduction, where the maximum yield of methanol was 100.2 µmol/(h·gcat), which was about three times superior than that of pure BiOCl. Besides, the Chl-Mg/BiOCl also showed high performance (93.7%) for degradation of ciprofloxacin (CIP, a kind of antibiotic). Various characterization techniques were applied to determine the structure and evaluate the origin of the improved performance of Chl-Mg/BiOCl. Meanwhile, a possible mechanism for the excellent photocatalytic performance of Chl-Mg/BiOCl was proposed. Notably, Chl on the surface of BiOCl can lead to the formation of singlet state of Chl-Mg* after absorbing light and act as an electron donor which can enhance the stability and activity of the photocatalyst. What’s more, Mg not only acts as an electron capture site to inhibit the photogenerated carrier recombination, but also forms a complex with Chl to improve the stability of catalyst. This study would represent a promising candidate organic–inorganic hybrid photocatalyst for solar energy conversion and antibiotic pollution treatment.

Porous TiO2 thin film-based photocatalytic windows for an enhanced operation of optofluidic microreactors in CO2 conversion

SummaryUsing a photocatalytic window can simplify the design of an optofluidic microreactor, providing also a more straightforward operation. Therefore, the development of TiO2 coatings on glass substrates seems appealing, although a priori they would imply a reduced accessible area compared with supported nanoparticle systems. Considering this potential drawback, we have developed an endurable photocatalytic window consisting on an inner protective SiO2 layer and an outer mesoporous anatase layer with enhanced surface area and nanoscopic crystallite size (9–16 nm) supported on a glass substrate. The designed photocatalytic windows are active in the CO2-to-methanol photocatalytic transformation, with maximum methanol yield (0.52 μmol·h−1·cm−2) for greatest porosity values and minimum crystallite size. Compared with benchmark supported nanoparticle systems, the nanoscopic thickness of the coatings allowed to save photoactive material using only 11–22 μg·cm−2, while its robustness prevented the leaching of active material, thus avoiding the decay of performance at long working periods.

Influence of Reaction Temperature on CO2-to-methanol Hydrogenation over MZrOx (M = Al, Mn, Cu, Zn, Ga, and In)

Abstract To open up the possibility of synthesizing useful substances from CO2, we have developed new catalysts that hydrogenate CO2 to methanol with high yield at 300 °C and higher. In this study, methanol synthesis via CO2 hydrogenation at 250–350 °C and 10 bar was investigated using Zr-based metal oxide catalysts, MZrOx (M = Al, Mn, Cu, Zn, Ga, and In). The different metals (M) determined the suitable reaction temperature wherein the maximum yield of methanol was obtained. CuZrOx was a suitable catalyst for low-temperature methanol synthesis because the yield decreased with increasing reaction temperature from 250 °C to 350 °C. In contrast, ZnZrOx, GaZrOx, and InZrOx were suitable for methanol synthesis at 300 °C and higher. In particular, ZnZrOx afforded the highest yield of methanol (60 mLSTP h−1 g−1 at 300 °C) among the prepared MZrOx catalysts.

Direct growth of nanostructural MoS2 over the h-BN nanoplatelets: An efficient heterostructure for visible light photoreduction of CO2 to methanol

Abstract Photocatalytic conversion of CO2 has attracted immense attention as a clean and sustainable approach to produce chemicals and fuels. Several semiconductors and heterojunction-based photocatalysts have been explored for efficient conversion of CO2 into high-value chemicals and opened new opportunities for tailoring optoelectronic properties of 2D materials. In the present study, nanostructural molybdenum disulfide (MoS2) is grown over the hexagonal boron nitride (h-BN) nanoplatelets by a hydrothermal approach and prepared the h-BN-MoS2 heterostructure. The chemical, structural, morphological, and optical features of h-BN-MoS2 hybrid are evaluated using XPS, Raman, XRD, HRTEM, UV–vis, and PL analyses. The potential of h-BN-MoS2 hybrid as a photocatalyst is explored for photoreduction of CO2 under the visible light irradiation. Pristine h-BN and MoS2 nanomaterials are not pertinent for the photoreduction of CO2 as former is inactive and later afforded a low yield in comparison to h-BN-MoS2 hybrid under identical conditions. The effective charge separation in h-BN-MoS2 hybrid extended the life of photo-excited electrons and enhanced the photoreduction of CO2. The maximum yield of methanol using h-BN-MoS2 hybrid is found to be 5994 μmol.g−1cat, which is 3.8 folds higher than the pristine MoS2 under the visible light irradiation.

Use of an optofluidic microreactor and Cu nanoparticles synthesized in ionic liquid and embedded in TiO2 for an efficient photoreduction of CO2 to methanol

The slow kinetics in the photocatalytic reduction of CO2, as well as the low quantum efficiencies achieved, directly related to the photocatalyst and reactor configuration applied, limit the widespread use of this technology. In light of this, the main objective of this work is to evaluate the continuous photocatalytic conversion of CO2 into methanol in an optofluidic microreactor (with enhanced mass transport, large volume/active area ratio and uniform light distribution) using Cu nanoparticles synthesized in the hydrophilic 3-methyl-n-butylimidazolium tetrafluoroborate (BMIm.BF4) ionic liquid and embedded in TiO2 (P25). The ionic liquid not only acts as a template to control the size of the nanoparticles but also as a stabilizing agent. The analysis includes the effect of structural parameters of the photoactive layer such as Cu content (from 0.8 to 6.8 wt%) and photocatalyst loading (0.5–3 mg·cm−2), as well as operating variables such as UV and visible light intensities (2.5–10 mW·cm−2) and cell configuration (i.e. one or two compartments). The maximum methanol yield reached from the continuous transformation of CO2 is r = 230.3 µmol∙g−1∙h−1 at 2 wt% Cu content, photocatalyst loading of 2 mg·cm−2, UV light intensity of 10 mW·cm−2 and a two-compartment microreactor configuration. This result outperforms the values previously reported for Cu/TiO2-based systems using optofluidic microreactors, as well as most of those in common CO2 photoreactors.

Influence of oxygen vacancies on the performance of ZnO nanoparticles towards CO2 photoreduction in different aqueous solutions

CO2 photoreduction is a promising technique for fuel production using semiconductors as photocatalysts. However, introducing defects on the crystal structure of the photocatalysts affects greatly on its photocatalytic activity. In this regard, defected ZnO nanoparticles were synthesized at 300, 350, and 400 °C by thermal decomposition method. XPS data revealed the presence of oxygen vacancies for ZnO samples. These results were furtherly confirmed by Raman, FTIR, and SEM analysis. It was pointed out that Methanol was the major attainable product through the photochemical reduction of CO2 under UV-light. Importantly, the created oxygen vacancies have played a dynamic role in facilitating the charge transfer rather than recombination sites, hence improving the catalytic activity. The highest efficiency was detected over ZnO sample prepared at 350 °C using HCO3− anion in aqueous solution with about 113 umol/g maximum yield of methanol. Different scenarios were discussed implying the synergic effect of anion type and oxygen vacancies. A hypothesis investigation of the reaction mechanism of CO2 photoreduction over ZnO was proposed.

Experimental Study of CO2 Conversion into Methanol by Synthesized Photocatalyst (ZnFe2O4/TiO2) Using Visible Light as an Energy Source

Ozone layer depletion is a serious threat due to the extensive release of greenhouse gases. The emission of carbon dioxide (CO2) from fossil fuel combustion is a major reason for global warming. Energy demands and climate change are coupled with each other. CO2is a major gas contributing to global warming; hence, the conversion of CO2 into useful products such as methanol, formic acid, formaldehyde, etc., under visible light is an attractive topic. Challenges associated with the current research include synthesizing a photocatalyst that is driven by visible light with a narrow band gap range between 2.5 and 3.0 eV, the separation of a mixed end product, and the two to three times faster recombination rate of an electron–hole pair compared with separation over yield. The purpose of the current research is to convert CO2 into useful fuel i.e., methanol; the current study focuses on the photocatalytic reduction of CO2into a useful product. This research is based on the profound analysis of published work, which allows the selection of appropriate methods and material for this research. In this study, zinc ferrite (ZnFe2O4) is synthesized via the modified sol–gel method and coupled with titanium dioxide (TiO2). Thereafter, the catalyst is characterized by Fourier transform infrared (FTIR), FE-SEM, UV–Vis, and XRD characterization techniques. UV–Vis illustrates that the synthesized catalyst has a low band gap and utilizes a major portion of visible light irradiation. The XRD pattern was confirmed by the formation of the desired catalyst. FE-SEM illustrated that the size of the catalyst ranges from 50 to 500 nm and BET analysis determined the surface area, which was 2.213 and 6.453 m2/g for ZnFe2O4 and ZnFe2O4/TiO2, respectively. The continuous gas flow photoreactor was used to study the activity of the synthesized catalyst, while titanium dioxide (TiO2) has been coupled with zinc ferrite (ZnFe2O4) under visible light in order to obtain the maximum yield of methanol as a single product and simultaneously avoid the conversion of CO2 into multiple products. The performance of ZnFe2O4/TiO2was mainly assessed through methanol yield with a variable amount of TiO2 over ZnFe2O4 (1:1, 1:2, 2:1, 1:3, and 3:1). The synthesized catalyst recycling ability has been tested up to five cycles. Finally, we concluded that the optimum conditions for maximum yield were found to be a calcination temperature of ZnFe2O4at 900 °C, and optimum yield was at a 1:1 w/w coupling ratio of ZnFe2O4/TiO2. It was observed that due to the enhancement in the electron–hole pair lifetime, the methanol yield at 141.22 μmol/gcat·h over ZnFe2O4/TiO2was found to be 7% higher than the earlier reported data.

Tuning adsorption properties of GaxIn2−xO3 catalysts for enhancement of methanol synthesis activity from CO2 hydrogenation at high reaction temperature

Abstract Light olefins can be produced from CO2 hydrogenation in a single reactor using a combination of a methanol synthesis catalyst and a methanol-to-olefin (MTO) catalyst. However, commercial methanol synthesis catalysts are active at low temperatures (200–260 °C), while MTO reaction is feasible at higher temperatures (>300 °C). Herein, we report the CO2 hydrogenation to methanol at high temperatures (320–400 °C) over GaxIn2−xO3 catalysts. By tuning the Ga/In ratios, phase, crystallinity, pore structure, morphology, electronic properties as well as adsorptive properties of GaxIn2−xO3 catalysts can be modified. At the lowest temperature (320 °C), the pure In2O3 shows the highest methanol yield. However, the maximum methanol yield declines significantly with increasing reaction temperatures. Incorporation of Ga into the In2O3 crystal lattices at x = 0.4 (Ga0.4In1.6O3) maximizes the methanol yield at higher reaction temperatures of 340–360 °C. This enhancement can be attributed to an increased binding energy of adsorptive molecules with the catalyst surface to promote the hydrogenation of CO2 to methanol. Further increasing Ga content (x > 0.4) leads to greatly strengthen the binding for adsorptive molecules, resulting in a lower methanol yield and the formation of methane. The surface chemisorbed oxygen is found to be a key factor determining the CO yield.

Core-shell Ni/NiO grafted cobalt (II) complex: An efficient inorganic nanocomposite for photocatalytic reduction of CO2 under visible light irradiation

The present paper describes the first successful synthesis of an inorganic nanocomposite by grafting of cobalt (II) phthalocyanine (CoPc) on the core-shell Ni/NiO (NNO) semiconductor for the photocatalytic reduction of CO2 to methanol under visible illumination using triethylamine as a sacrificial donor. The synthesised photocatalyst exhibited a remarkable enhancement in the yield of methanol as compared to the semiconductor Ni/NiO and CoPc for CO2 reduction under identical conditions. The maximum yield of methanol was found to be 3641.2 μmol/g with the conversion rate of 151.7 μmol g−1 h−1 which was much higher than that observed with CoPc and semiconductor alone under identical experimental conditions. Furthermore, the synthesised nanocomposite showed superior activity as compared to the previously reported organic semiconductor bound cobalt complex photocatalyst. The composite photocatalyst was found to be highly stable which showed consistent recyclability for four runs without any significant loss in activity.

Efficient Photocatalytic Reduction of CO2 Present in Seawater into Methanol over Cu/C-Co-Doped TiO2 Nanocatalyst Under UV and Natural Sunlight

Photocatalytic reduction of CO2 in seawater into chemical fuel, methanol (CH3OH), was achieved over Cu/C-co-doped TiO2 nanoparticles under UV and natural sunlight. Photocatalysts with different Cu loadings (0, 0.5, 1, 3, 5, and 7 wt%) were synthesized by the sol–gel method and were characterized by XRD, SEM, UV–Vis, FTIR, and XPS. Co-doping with C and Cu into TiO2 remarkably promoted the photocatalytic production of CH3OH. This improvement was attributed to lowering of bandgap energy, specific catalytic effect of Cu for CH3OH formation, and the minimization of photo-generated carrier recombination. Co-doped TiO2 with 3.0 wt% Cu was found to be the most active catalyst, giving a maximum methanol yield rate of 577 μmol g-cat−1 h−1 under illumination of UV light, which is 5.3-fold higher than the production rate over C-TiO2 and 7.4 times the amount produced using Degussa P25 TiO2. Under natural sunlight, the maximum rate of the photocatalytic production of CH3OH using 3.0 wt% Cu/C-TiO2 was found to be 188 μmol g-cat−1 h−1, which is 2.24 times higher than that of C-TiO2, whereas, no CH3OH was observed for P25.

Ternary rGO/InVO4/Fe2O3 Z-Scheme Heterostructured Photocatalyst for CO2 Reduction under Visible Light Irradiation

The present paper describes an excellent improvement in photoreduction of CO2 to methanol using a newly developed rGO/InVO4/Fe2O3 Z-scheme heterostructured photocatalyst, which was readily synthesized from chitosan-functionalized reduced graphene oxide and InVO4/Fe2O3 via a facile deposition–precipitation method. The maximum yield of methanol was reached at 16.9 mmol g–1cat over the Z-scheme photocatalyst by using TEA as a sacrificial electron donor. The obtained yield of methanol was very much higher in comparison to the rGO, InVO4, and InVO4/Fe2O3 semiconductors, i.e., 2.3, 1.1, and 9.8 mmol g–1cat, respectively, under identical experimental conditions. The synergistic effect of all components in the ternary rGO/InVO4/Fe2O3 Z-scheme heterostructure resulted in efficient charge carrier separation and charge mobility on a catalyst surface which led to highly efficient CO2 reduction and excellent improvement in methanol yield.

Atmospheric Pressure and Room Temperature Synthesis of Methanol through Plasma-Catalytic Hydrogenation of CO2

CO2 hydrogenation to methanol is a promising process for CO2 conversion and utilization. Despite a well-developed route for CO hydrogenation to methanol, the use of CO2 as a feedstock for methanol synthesis remains underexplored, and one of its major challenges is high reaction pressure (usually 30–300 atm). In this work, atmospheric pressure and room temperature (∼30 °C) synthesis of methanol from CO2 and H2 has been successfully achieved using a dielectric barrier discharge (DBD) with and without a catalyst. The methanol production was strongly dependent on the plasma reactor setup; the DBD reactor with a special water-electrode design showed the highest reaction performance in terms of the conversion of CO2 and methanol yield. The combination of the plasma with Cu/γ-Al2O3 or Pt/γ-Al2O3 catalyst significantly enhanced the CO2 conversion and methanol yield compared to the plasma hydrogenation of CO2 without a catalyst. The maximum methanol yield of 11.3% and methanol selectivity of 53.7% were achieved ov...