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The transition towards sustainable and renewable energy sources is imperative in mitigating the environmental impacts of escalating global energy consumption. Methanol, with its versatile applications and potential as a clean energy carrier, a precursor chemical, and a valuable commodity, emerges as a promising solution within the realm of renewable energy technologies. This work explores the integration of electrochemistry with solar power to drive efficient methanol production processes, focusing on electrochemical reduction (ECR) of CO2 and methane oxidation reaction (MOR) as pathways for methanol synthesis. Through detailed analysis and calculations, we evaluate the thermodynamic limits and realistic solar-to-fuel (STF) efficiencies of ECR and MOR. Our investigation encompasses the characterization of multijunction light absorbers, determination of thermoneutral potentials, and assessment of STF efficiencies under varying conditions. We identify the challenges and opportunities inherent in both ECR and MOR pathways, shedding light on catalyst stability, reaction kinetics, and system optimization, thereby providing insights into the prospects and challenges of solar-driven methanol synthesis, offering a pathway towards a cleaner and more sustainable energy future. [ABSTRACT FROM AUTHOR]

Cu/ZnO/Al2O3 catalysts used to synthesize methanol undergo extensive deactivation during use, mainly due to sintering. Here, we report on formulations wherein deactivation has been substantially reduced by the targeted use of a small quantity of a Si-based promoter, resulting in accrued activity benefits that can exceed a factor of 1.8 versus unpromoted catalysts. This enhanced stability also provides longer lifetimes, up to double that of prior generation catalysts. Detailed characterization of a library of aged catalysts has allowed the most important deactivation mechanisms to be established and the chemical state of the silicon promoter to be identified. We show that silicon is incorporated within the ZnO lattice, providing a pronounced improvement in the hydrothermal stability of this component. These findings have important implications for sustainable methanol production from H2 and CO2. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2D CFD simulations and optimisation of an industrial-scale MeOH synthesis reactor. • Model predicts a temperature hot-spot and an excessive pressure drop. • Response surface reveals the impact of the reactor design on key output parameters. • Optimised reactor achieves 6.9 % higher MeOH production with 75 % lower pressure drop. • Higher yields could lead to more economic and sustainable MeOH production. Achieving our decarbonisation goals for the maritime transport sector requires the bulk production of liquid hydrocarbon fuels, suitable for the existing infrastructure, such as methanol (MeOH). For this, optimisation of fixed bed chemical reactors is vital. Unlike demonstration-scale setups, optimising the design of such reactors using Computational Fluid Dynamics (CFD) models is both cheaper and faster. In this study, using a 2D pseudo-homogeneous CFD model, a single tube from a multi-tubular industrial-scale MeOH reactor is simulated. Using available experimental data, the CFD model was validated yielding excellent accuracy, with an average error of 2.6 %. The model identified a temperature hot-spot near the bed entrance, while the predicted pressure drop was 11 % of the operating pressure. Both effects could considerably reduce the efficiency of the reactor, either by catalyst deactivation or by increasing the compressor requirements, respectively. Through a parametric study where the tube's length and diameter were varied within the ±50 % range, 53 total cases are produced and solved, creating an extensive pareto set of data for the key output parameters, such as methanol production, pressure, and temperature. A response surface was also generated, revealing the interconnection between the tube's design and the operating parameters. This enabled a performance optimisation of the reactor design for two industrially relevant scenarios, with the optimised reactor achieving a 6.9 % higher MeOH yield and a 75 % reduced pressure drop. Through industrial involvement, the reactor can be further optimised, and would act as a critical foundation for more extensive techno-economic and socio-economic evaluations for sustainable carbon–neutral methanol production. [ABSTRACT FROM AUTHOR]

[Display omitted] • 82 methanogenic strain were screened for methane production from carbon dioxide sequestration. • The isolate Methanobacterium sp. M11, efficiently produced 7.90 mol of methane from 8.34 mol of CO 2. • Integration of methanogenic bioreactor with methanotrophic reactor for methanol production. • Maximum methanol productivity was obtained from Methyloceanibacter sp. M31 was 0.470 mol in 24 h. Carbon dioxide (CO 2) poses a significant threat, contributing to global warming and climate change. This study focused on isolating efficient CO 2 -reducing methanogens and methanotrophs for converting methane into methanol. Samples from diverse regions in India were collected and processed, yielding 82 methanogenic and 48 methylotrophic isolates. Methanogenic isolate M11 produced a higher amount of methane, reaching 2.9 mol L−1 on the sixth day of incubation at 35 °C, pH 7.0, and CO 2 :H 2 (80:20) as feeding rates. Under optimized conditions, isolate M11 effectively converted 8.3 mol CO 2 to 7.9 mol methane in 24 h. Methylotrophic isolate M31 demonstrated significant soluble methane monooxygenase activity (450 nmol/ml) and produced 0.4 mol methanol in 24 h. 16S rRNA analysis identified Methanobacterium sp. and Methyloceanibacter sp. among the isolates, elucidating their taxonomic diversity. This study offers valuable insights into methanogens' potential in CO 2 sequestration and methane conversion to methanol through methanotrophism, a promising sustainable biofuel production. [ABSTRACT FROM AUTHOR]

[Display omitted] • One traditional and three novel biomass-to-methanol (BTM) processes are proposed. • Clean H 2 production pathways are used to maximize carbon utilization potential. • Novel BTM processes all enhance methanol production and carbon mitigation. • Integration of methane pyrolysis pathway is preferred in technical performances. • Deployment of methane chemical looping pathway shows stronger economic advantages. Concerns about depleted fossil fuels and the climate crisis have intensified the interest in producing biomass-derived methanol. However, the traditional biomass-to-methanol (BTM) process suffers from low carbon conversion ability and serious CO 2 emissions caused by the water–gas-shift (WGS) unit. In this study, three novel BTM processes coupled with solid oxide electrolysis, methane pyrolysis, and methane chemical looping technologies are proposed to eliminate WGS unit, and the systematic heat integration is considered to achieve energy cascade utilization. Meanwhile, process performances are comprehensively evaluated to compare the technical, economic, and environmental attractiveness of three novel BTM processes. It is found that compared with the original BTM process, three novel processes significantly improve carbon efficiency by 22%. Meanwhile, CO 2 emissions are reduced by 60%. Moreover, the application of methane chemical looping technology is more economical, and the associated net production cost decreases by more than 30%. Additionally, the BTM process coupled with solid oxide electrolysis is more environmentally friendly, whereas the process with methane pyrolysis technology is more exergy-efficient. Overall, the integrated processes have significant application prospects for carbon conversion and mitigation ability as well as economic attractiveness. [ABSTRACT FROM AUTHOR]

• Utilizing CO 2 and H 2 S waste streams for sustainable methanol production. • Improving methanol yields and value-added product generation. • Reducing operational costs and environmental emissions. • Employing factorial design and ANOVA for process optimization. • Increasing profitability through energy integration. Greenhouse gas emissions, specifically CO 2 and H 2 S, are recognized as a serious environmental issue. To address this, various strategies have been suggested. Among these, an economic-environmental study is presented, focusing on a methanol production process that utilizes CO 2 and H 2 S waste streams from a natural gas sweetening plant. The study aims to identify conditions that enhance the production of value-added products and increase methanol yields while reducing costs. Given the complexity of processes involving numerous variables such as pressure, temperature, flow rates, and others, pinpointing the most impactful variables for effective manipulation poses a significant challenge. To tackle this, the study adopts a factorial experimental design coupled with ANOVA analysis to determine the variables that most significantly affect the process. Based on this analysis, the study suggests process improvement through energy integration. Results, derived from the experimental design and ANOVA analysis, reveal that reactor temperatures play a crucial role in influencing the process's effectiveness. [Display omitted] [ABSTRACT FROM AUTHOR]

A novel and efficient multigeneration system aiming to achieve near-zero CO 2 emissions is proposed. The system employs a methanol production process utilizing captured CO 2 from the flue gas of a biomass-gasification plant. The proposed system successfully generates green H 2 through water electrolysis, supported by thermal power, with a portion of the hydrogen reacting with CO 2 to produce e-methanol. Additionally, the system produces other valuable products, including power, cooling, O 2 , and CO 2 , in a coherent manner, benefiting from a low-emission framework and exhibiting high thermodynamic performance. The proposed multigeneration system consists of a biomass-gasification-based power plant, a water electrolyzer, a methanol generation unit, a carbon capture unit, and a steam jet ejector-based refrigeration cycle. The integrated multigeneration system is analyzed from the energy, exergy, and economic aspects. The results demonstrate the system's ability to achieve production rates of 430.25 kg/h of e-methanol and 190 kg/h of green H 2. Furthermore, the energy and exergy efficiencies of the system are found to be 78.13% and 71.63%, respectively. The CO 2 emissions analysis reveals that the proposed system significantly reduced total CO 2 emission to 78.5% (0.61 kg CO2 /kg). The total cost of production is estimated to be 0.087 $/kg. [Display omitted] • Novel integrated biomass-based multigeneration system for power, methanol, H 2 , O 2 , and Cooling. • Captured CO 2 is utilized to produce synthetic e-methanol. • Flue gas from gasification mixed with H 2 from electrolyzer for methanol synthesis. • Obtained the total energy and exergy efficiencies of 78.1 % and 71.6 %, respectively. • Total methanol production and total production cost to be 430.25 kg/h and 0.108$/kg. [ABSTRACT FROM AUTHOR]