Search Results (23)

Given the critical need for scalable technologies that decouple industrial production from fossil feedstocks, this study introduces a green hydrogen-driven and carbon-negative industrial complex that employs renewable energy to simultaneously produce methanol and Fischer–Tropsch hydrocarbon products via feedstocks of carbon dioxide (CO₂) and water. The proposed complex (FARMOW) integrates six major sections: (i) a Fischer–Tropsch synthesis process (FTSP), (ii) an alkaline water electrolysis process (AWEP), (iii) a reverse water–gas shift process (RWGSP), (iv) a methanol synthesis process (MSP), (v) an off-gas combustion process (OGCP), and (vi) a water treatment process (WTP). In this complex, the green hydrogen produced from AWEP is reacted with CO₂ from a carbon capture unit and sent to the MSP and FTSP sections, respectively, to generate methanol and Fischer–Tropsch hydrocarbon products. The byproduct (water) from the complex is utilized to generate steam through rigorous process simulation, and the technical efficacy of the complex has been modeled and validated, yielding high-value hydrocarbons, methanol, steam, and oxygen. Furthermore, a comprehensive techno-economic assessment with sensitivity analysis is performed to evaluate the commercial flexibility of the system under varying market conditions. Full article

As the global imperative for climate neutrality intensifies, hydrogen (H₂) from fossil fuels remains central to decarbonizing hard-to-abate sectors. Conventional production via steam methane reforming (SMR), however, is carbon-intensive and, even with carbon capture and storage (CCS), incurs energy penalties and long-term storage constraints. This review develops a harmonized well-to-gate, market-oriented framework to evaluate methane pyrolysis (MP) relative to SMR and autothermal reforming (ATR), with or without CCS, moving beyond reactor-focused assessments toward system-level commercialization analysis. MP decomposes methane into hydrogen and solid carbon, avoiding direct CO₂ formation and the need for CCS infrastructure. Integrating with the reverse water–gas shift (RWGS) reaction enables flexible syngas production with adjustable H₂:CO ratios for methanol and chemical synthesis. A central finding is the dominant role of the “carbon lever”: MP generates approximately 3 kg of solid carbon per kg of H₂, making the carbon market’s absorptive capacity the primary scalability constraint. While carbon monetization can reduce levelized hydrogen costs, large-scale deployment would rapidly saturate existing carbon black and specialty carbon markets. Techno-economic evidence indicates that carbon prices above $500/ton are required to achieve parity with gray hydrogen, whereas $150–200/ton enables competitiveness with blue hydrogen. Lifecycle assessments further show that climate superiority over SMR or ATR with CCS requires upstream methane leakage below 0.5% and very low-carbon electricity. Commercial readiness varies, with plasma MP at TRL 8–9 and thermal, catalytic, and molten-media pathways remaining at the pilot or demonstration stage. Parametric decision-space analysis under harmonized boundary assumptions shows that MP is not a universal substitute for reforming but a conditional pathway competitive only under aligned conditions of low-leakage gas supply, low-carbon electricity, credible carbon monetization, and supportive policy incentives. The review concludes with a roadmap that highlights standardized carbon certification, end-of-life accounting, and long-duration operational data as priorities for commercialization. Full article

The non-thermal plasma-driven cascade process for CO₂-to-methanol conversion shows significant potential in the field of green methanol synthesis. This process innovatively couples a plasma activation module with a catalytic synthesis module via a multi-stage pressurization device, establishing an efficient two-step pathway that converts CO₂ into methanol via a CO intermediate. Such an arrangement establishes an energy conversion system characterized by both low carbon emissions and high efficiency. This work involved an initial technical evaluation employing a custom-built, lab-scale apparatus. The optimum parameters determined through this assessment were a plasma input voltage of 40 V combined with a subsequent reaction temperature of 240 °C. Operation at these specified parameters yielded a CO₂ conversion of 48%, with the methanol selectivity and production rate reaching 40% and 502 g_MeOH${·\mathrm{kg}}_{\mathrm{cat}}^{-1}$·h⁻¹, respectively. Furthermore, industrial-scale process design and scale-up were performed, accompanied by process simulation using Aspen Plus and a subsequent techno-economic evaluation. The results indicate that, compared to the conventional direct CO₂ hydrogenation process, the proposed cascade route can reduce the capital investment by approximately 17%. Full article

The decarbonization of hard-to-defossilize sectors, such as international maritime transport, requires innovative, and at times disruptive, energy solutions that combine efficiency, scalability, and climate benefits. Therefore, power-to-liquid (PtL) routes have stood out for their potential to use low-emission electricity for the production of synthetic fuels, via electrolytic hydrogen and CO₂ capture. However, the high energy demand inherent to these routes poses significant challenges to large-scale implementation. Moreover, PtL routes are usually at most neutral in terms of CO₂ emissions. This study evaluates, from a thermo-energetic perspective, the optimization potential of an e-methanol synthesis route through integration with a biomass oxy-fuel combustion process, making use of electrolytic oxygen as the oxidizing agent and the captured CO₂ as the carbon source. From the standpoint of a first-law thermodynamic analysis, mass and energy balances were developed considering the full oxygen supply for oxy-fuel combustion to be met through alkaline electrolysis, thus eliminating the energy penalty associated with conventional oxygen production via air separation units. The balance closure was based on a small-scale plant with a capacity of around 100 kta of methanol. In this integrated configuration, additional CO₂ surpluses beyond methanol synthesis demand can be directed to geological storage, which, when combined with bioenergy with carbon capture and storage (BECCS) strategies, may lead to net negative CO₂ emissions. The results demonstrate that electrolytic oxygen valorization is a promising pathway to enhance the efficiency and climate performance of PtL processes. Full article

The CO₂ hydrogenation process is thought to be one of the feasible methods for producing methanol fuel, which might be used to fulfill future energy demands. Improving the catalytic efficiency and understanding of the process are essential elements for the viability of CO₂ conversion routes. Here, a co-precipitation method was used to synthesize Ni-Cu bimetallic catalysts supported by chromium oxide (Cr₂O₃). To examine nickel (Ni)’s promoting role, the synthesized catalysts were incorporated with different concentrations of Ni. The N₂ adsorption–desorption isotherm exposed the mesoporous nature of Cr₂O₃-based Ni-Cu catalysts. A Fourier Transform Infrared (FTIR) spectroscopy investigation revealed the effective doping of Ni-Cu metal oxides on the surface of Cr₂O₃ by instigating an FTIR absorption band in the region associated with the FTIR absorption of metal oxides. The uniform morphology and homogenous, as well as highly dispersed, form of both Ni and Cu metal were recorded using a Field Emission Scanning Electron Microscope (FESEM) and X-ray Diffraction (XRD) techniques. The surface chemistry, metal–metal, and metal–support interactions of the Ni-Cu/Cr₂O₃ catalysts were disclosed via temperature program reduction (TPR) as well as X-ray photoelectron spectroscopy (XPS). The synergism between the Ni and Cu metals was revealed using both XPS and TPR techniques, which resulted in improving the catalytic profile of Ni-Cu/Cr₂O₃ catalysts. The activity data obtained by applying a slurry reactor demonstrated the active profile of Ni for CO₂ reduction to methanol in terms of the methanol synthesis rate. The promoting role of Ni was established by observing the progressing and linear increase in methanol selectivity by Ni enrichment to the Ni-Cu/Cr₂O₃ catalysts. Structure and activity studies recognized the promoting role of Ni by experiencing metal–metal and metal–support interactions with highly dispersed metal oxides over the Cr₂O₃ support in the current case. Full article

The increasing global demand for clean energy and sustainable industrial processes necessitates innovative approaches to energy production and chemical synthesis. This study proposed and simulated an innovative integrated system for the co-production of power, hydrogen, and dimethyl ether (DME), combining the high-efficiency Allam–Fetvedt cycle with co-electrolysis and indirect DME synthesis. The Allam–Fetvedt cycle generated electricity while capturing CO₂, which, along with water, was used in solid oxide electrolyzers (SOEs) to produce syngas via co-electrolysis. The resulting syngas was converted to methanol and subsequently to DME. Aspen HYSYS was used to model and simulate the process, and heat/mass integration strategies were implemented to reduce energy demand and optimize resource utilization. The proposed integrated process enabled an annual production of 980,021 metric tons of DME, 189,435 metric tons of hydrogen, and 7698.27 metric tons of methanol. The energy efficiency of the Allam–Fetvedt cycle reached 55%, and heat integration reduced the system’s net energy demand by 14.22%. Despite the high energy needs of the electrolyzer system (81.28% of net energy), the overall energy requirement remained competitive with conventional methods. Carbon emissions per kilogram of DME were reduced from 1.16 to 0.77 kg CO₂ through heat integration and can be further minimized to 0.0308 kg CO₂/kg DME (near zero) with renewable electrification. Results demonstrated that 96% of CO₂ was recycled within the Allam–Fetvedt cycle, and the rest (the 4% of CO₂) was captured and converted to syngas, achieving net-zero carbon emissions. This work presents a scalable and sustainable pathway for integrated clean energy and chemical production, advancing toward industrial net-zero targets. Full article

This paper deals with the proposition of a kinetic model for the direct synthesis of DME via CO₂ hydrogenation in view of the necessary optimization of the catalytic system, reactor design, and process strategy. Despite the fact that DME synthesis is typically treated as a mere combination of two separated catalytic steps (i.e., methanol synthesis and methanol dehydration), the model analysis is now proposed by taking into account the improvements related to the process running over a hybrid catalyst in a rational integration of the two catalytic steps, with boundary conditions properly assumed from the thermodynamics of direct DME synthesis. Specifically, the CO₂ activation step at the metal–oxide interface in the presence of ZrO₂ has been described for the first time through the introduction of an ad hoc mechanism based on solid assumptions from inherent studies in the literature. The kinetic modeling was investigated in a tubular fixed-bed reactor operating from 200 to 260 °C between 1 and 50 bar as a function of a gas hourly space velocity ranging from 2500 to 60,000 NL/kg_cat/h, in a stoichiometric CO₂/H₂ feed mixture of 1:3 v/v. A well-detailed elementary mechanism was used to predict the CO₂ conversion rate and identify the key reaction pathways, starting with the analysis of the implicated reactions and corresponding kinetic mechanisms and expressions, and finally estimating the main parameters based on an appropriate modeling of test conditions. Full article

During Fischer–Tropsch synthesis, O atoms are dissociated on the surface of Fe-based catalysts. However, most of the dissociated O would be removed as H₂O or CO₂, which results in a low atom economy. Hence, a comprehensive study of the O removal pathway as formic acid has been investigated using the combination of density functional theory (DFT) and kinetic Monte Carlo (kMC) to improve the economics of Fischer–Tropsch synthesis on Fe-based catalysts. The results show that the optimal pathway for the removal of dissociated O as formic acid is the OH pathway, of which the effective barrier energy (0.936 eV) is close to that of the CO activation pathway (0.730 eV), meaning that the removal of dissociated O as formic acid is possible. The main factor in an inability to form formic acid is the competition between the formic acid formation pathway and other oxygenated compound formation pathways (H₂O, CO₂, methanol-formaldehyde); the details are as follows: 1. If the CO is hydrogenated first, then the subsequent reaction would be impossible due to its high effective Gibbs barrier energy. 2. If CO reacts first with O to become CO₂, it is difficult for it to be hydrogenated further to become HCOOH because of the low adsorption energy of CO₂. 3. When the CO + OH pathway is considered, OH would react easily with H atoms to form H₂O due to the hydrogen coverage effect. Finally, the removal of dissociated O to formic acid is proposed via improving the catalyst to increase the CO₂ adsorption energy or CO coverage. Full article

The transition towards a CO₂ neutral industry is currently spurring many new developments regarding processes for the conversion of CO₂, or CO₂-rich streams, into platform molecules such as methanol and dimethyl ether (DME). New processes give rise to new separation challenges, as well as novel opportunities for joint optimization of reaction and separation. In this context, the separation of CO₂ and DME can be performed very efficiently using the newly developed concept of stripping enhanced distillation (SED). SED is a distillation process that utilizes an additional stripping component (clearing gas) to promote the separation in the column. SED benefits from the utilization of the feedstock components as a clearing gas that can afterwards be recycled back to the conversion unit with the vapor distillate. Strongly improving the separation performance in the column, this approach also removes the need for external stripping mediums and, in addition, this recycling approach may significantly reduce the demand on the conversion unit upstream of SED. The benefits of using SED are demonstrated for two different processes for DME synthesis: (i) CO₂–DME separation after the sorption enhanced DME synthesis (SEDMES) process, using hydrogen as clearing gas, and (ii) CO₂–DME separation after direct DME synthesis via dry reforming (DIDR), using methane as a clearing gas. For the different cases, it is shown that, with minimal adaptations, the energy consumption for distillation is reduced by 20–30%, while product losses are minimized at the same time. Full article

The abundant C1 source CO₂ can be utilized to produce value-added chemicals through hydrogenation technology. A bifunctional catalyst consisting of reducible metal oxide Cr₂O₃ and acidic zeolite ZSM-5 was designed for the direct conversion of CO₂ + H₂ into valuable aromatics, especially para-xylene (PX), via the methanol-mediated pathway. The twin structure of ZSM-5 (ZSM-5^T), with sinusoidal channels that are predominantly exposed to the external surface, enhances the possibility of the transformation of methanol into PX due to the favorable diffusion dynamic of PX in the sinusoidal channels. Via the bifunctional catalyst Cr₂O₃&ZSM-5^T, a PX selectivity of 28.7% and PX space-time yield (STY) of 2.5 g_CH2 h⁻¹ kg_cat⁻¹ are achieved at a CO₂ conversion rate of 16.5%. Furthermore, we rationally modify the ZSM-5^T zeolite via Cu species doping and amorphous SiO₂ shell coating (Cu-ZSM-5^T@SiO₂). After combining with the Cr₂O₃ catalytic component, the CO₂ conversion (18.4%) and PX selectivity (33.8%) are increased to some extent, which systematically increases the STY of PX to 3.0 g_CH2 h⁻¹ kg_cat⁻¹. The physicochemical property of the acidic zeolite and the corresponding structure-function relationship in enhancing the PX productivity are discovered. Our work provides a novel catalyst design idea to boost PX synthesis performance from CO₂ hydrogenation. Full article

The CO₂ hydrogenation to dimethyl ether (DME) is a potentially promising process for efficiently utilizing CO₂ as a renewable and cheap carbon resource. Currently, the one-step heterogeneous catalytic conversion of CO₂ to value-added chemicals exhibits higher efficiency than photocatalytic or electrocatalytic routes. However, typical catalysts for the one-step CO₂ hydrogenation to DME still suffer from the deficient space–time yield and stability in industrial demonstrations/applications. In this perspective, the recent development of the one-step CO₂ hydrogenation to DME is focused on different catalytic systems by examining the reported experimental results and the reaction mechanism including the catalytic nature of active sites, activation modes and of CO₂ molecules under relevant conditions; surface intermediates are comparatively analyzed and discussed. In addition to the more traditional Cu-based, Pd-based, and oxide-derived bifunctional catalysts, a further emphasis is given to the characteristics of the recently emerged In₂O₃-based bifunctional catalysts for the one-step conversion of CO₂ to DME. Moreover, GaN itself, as a bifunctional catalyst, shows over 90% DME selectivity and a reasonably high activity for one-step CO₂ hydrogenation, and the direct hydrogenation of CO₂ via the unique non-methanol intermediate mechanism is highlighted as an important illustration for exploring new catalytic systems. With these analyses and current understandings, the research directions in the aspects of catalysis and DME economy are suggested for the further development of one-step DME synthesis from CO₂ hydrogenation. Full article

Cu/ZnO catalysts promoted with Mn, Nb and Zr, in a 1:1:1 ration, and supported on Al₂O₃ (CZMNZA) and SBA-15 (CZMNZS) were synthesized using an impregnation method. The catalytic performance of methanol synthesis from CO₂ hydrogenation was investigated in a fixed-bed reactor at 250 °C, 22.5 bar, GHSV 10,800 mL/g·h and H₂/CO₂ ratio of 3. The CZMNZA catalyst resulted in higher CO₂ conversion and MeOH selectivity of 7.22% and 32.10%, respectively, despite having a lower BET surface area and pore volume compared to CZMNZS. Methyl formate is the major product obtained over both types of catalysts. The CZMNZA is a promising catalyst for co-producing methanol and methyl formate via the CO₂ hydrogenation reaction. Full article

CuZnO/Al₂O₃ is the industrial catalyst used for methanol synthesis from syngas (CO + H₂) and is also promising for the hydrogenation of CO₂ to methanol. In this work, we synthesized Al₂O₃ nanorods (n-Al₂O₃) and impregnated them with the CuZnO component. The catalysts were evaluated for the hydrogenation of CO₂ to methanol in a fixed-bed reactor. The support and the catalysts were characterized, including via in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The study of the CO₂ adsorption, activation, and hydrogenation using in situ DRIFT spectroscopy revealed the different roles of the catalyst components. CO₂ mainly adsorbed on the n-Al₂O₃ support, forming carbonate species. Cu was found to facilitate H₂ dissociation and further reacted with the adsorbed carbonates on the n-Al₂O₃ support, transforming them to formate or additional intermediates. Like the n-Al₂O₃ support, the ZnO component contributed to improving the CO₂ adsorption, facilitating the formation of more carbonate species on the catalyst surface and enhancing the efficiency of the CO₂ activation and hydrogenation into methanol. The synergistic interaction between Cu and ZnO was found to be essential to increase the space–time yield (STY) of methanol but not to improve the selectivity. The 3% CuZnO/n-Al₂O₃ displayed improved catalytic performance compared to 3% Cu/n-Al₂O₃, reaching a CO₂ conversion rate of 19.8% and methanol STY rate of 1.31 mmolg_cat⁻¹h⁻¹ at 300 °C. This study provides fundamental and new insights into the distinctive roles of the different components of commercial methanol synthesis catalysts. Full article

A series of mono- and bi-metallic copper and iron samples were prepared by impregnation method on micro-spherical silica and used for the synthesis of methanol via CO₂ hydrogenation. Compared with conventional carrier oxides, micro-spherical silica has obvious advantages in terms of absorption capacity and optimal distribution of active phases on its surface, also exhibiting excellent heat resistance properties and chemical stability. The prepared catalysts were characterized by various techniques including XRF, XRD, SEM, TEM, H₂-TPR and CO₂-TPD techniques, while catalytic measurements in CO₂ hydrogenation reaction to methanol were performed in a fixed bed reactor at a reaction pressure of 30 bar and temperature ranging from 200 to 260 °C. The obtained results revealed that the mutual interaction of copper–iron induces promotional effects on the formation of methanol, especially on systems where Fe enrichment on the silica support favours the presence of a larger concentration of oxygen vacancies, consequently responsible for higher CO₂ adsorption and selective methanol production. Surface reconstruction phenomena rather than coke or metal sintering were responsible for the slight loss of activity recorded on the catalyst samples during the initial phase of reaction; however, with no appreciable change on the product selectivity. Full article

There is a large worldwide demand for light olefins (C₂⁼–C₄⁼), which are needed for the production of high value-added chemicals and plastics. Light olefins can be produced by petroleum processing, direct/indirect conversion of synthesis gas (CO + H₂) and hydrogenation of CO₂. Among these methods, catalytic hydrogenation of CO₂ is the most recently studied because it could contribute to alleviating CO₂ emissions into the atmosphere. However, due to thermodynamic reasons, the design of catalysts for the selective production of light olefins from CO₂ presents different challenges. In this regard, the recent progress in the synthesis of nanomaterials with well-controlled morphologies and active phase dispersion has opened new perspectives for the production of light olefins. In this review, recent advances in catalyst design are presented, with emphasis on catalysts operating through the modified Fischer–Tropsch pathway. The advantages and disadvantages of olefin production from CO₂ via CO or methanol-mediated reaction routes were analyzed, as well as the prospects for the design of a single catalyst for direct olefin production. Conclusions were drawn on the prospect of a new catalyst design for the production of light olefins from CO₂. Full article