Methanol Synthesis Reaction Research Articles

Flexible and synergistic methanol production via biomass gasification and natural gas reforming

Sustainable liquid fuels are essential for decarbonization of various means of transportation which are challenging to address through electrification or hydrogen use. A possible method for producing low-carbon liquid fuel is through the thermochemical biomass to liquid (BTL) process. In this study, we conduct a technoeconomic-environmental analysis of two processes which take advantage of integration of natural gas reforming and biomass gasification, with the objective of improving the economics. By integrating H2-rich syngas (a mixture of H2/CO) obtained from natural gas reforming with carbon-rich syngas from biomass gasification, we harness synergistic effects. This combination allows us to achieve the optimal H2/CO ratio required for methanol synthesis, while also ensuring efficient carbon utilization. In the first design, natural gas is reformed in an autothermal reformer (ATR) to produce syngas. A Solid Oxide Electrolysis Cell (SOEC) is utilized to supply the O2 for both gasification and reforming processes. The H2 produced by the SOEC adjusts the H2 content in the syngas before the methanol synthesis reactor. In the second design, natural gas is reformed in a gas-heated-reformer (GHR) before an ATR, while an Air Separation Unit (ASU) produces the O2 for the process. As a benchmark, the economics and flexible operation of both processes are compared to a conventional BTL process. In addition, the techno-economic impact of operating in biomass-only or natural gas-only modes are investigated. For a 134 MWth plant with 50 % of entering carbon from biomass, the levelized cost of methanol (LCOMeOH) of ATR+SOEC case is 34 % higher than the BTL reference case, while that of ATR+GHR case is 24 % lower than the BTL reference case. A lifecycle analysis (LCA) is conducted for these designs. Utilizing renewable electricity and 50 % biogenic carbon, the ATR+SOEC case emits 908 kgCO2e /tonne MeOH for a 100-year Global Warming Potential (GWP), while the ATR+GHR case emits 721 kgCO2e /tonne MeOH. For a 20-year GWP, these emissions are 1055 and 915 kgCO2e /tonne MeOH, respectively. These emissions correspond to more than 50 % reduction in LCA emissions when compared to natural gas based LCA emissions.

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 hydrogenation to methanol on efficient Pd modified α-MoC1−x catalysts

It is a potentially desirable process of utilizing CO2 as a feedstock to make valuable chemicals such as methanol. Results from the current study demonstrate Pd modified α-MoC1−x is a high active and selective catalyst for CO2 hydrogenation to methanol. α-MoC1−x is active for both methanol synthesis and RWGS reaction. The addition of 0.1 wt% Pd to α-MoC1−x decreases the CO2 hydrogenation reaction activation energy and increases the CH3OH selectivity due to the H2 spillover effect of Pd. RWGS + CO-hydro pathway as a non-competitive parallel pathway to the dominant formate pathway is verified on Pd/α-MoC1−x/C-N, which increases threefold methanol STY compared with α-MoC1−x/C-N catalyst. This work supplies a feasible strategy for creating a dual active site to enhance the efficiency of methanol synthesis.

Exergy analysis of direct method for conversion of natural gas to methanol

The exergy analysis of a direct method for the conversion of natural gas to methanol is reported in this work. The study is part of a process development effort to identify areas of improvement to the technology of direct conversion of natural gas to methanol. Prior to the exergy analysis, different configurations of the direct conversion process were developed and simulated. Two heat-integrated configurations designated as Case I and Case II were considered plausible. The exergy efficiency, excluding exergy of the rejected heat, of Case I and Case II were determined as 33% and 36%, respectively. The 9% increase in efficiency of Case II relative to Case I did not justify the installation of an expander and was therefore screened out. Exergy balance in Case I showed that a total of 56% of the exergy input was lost to internal consumption. The majority of exergy destruction was found to be due to the methanol synthesis reactor (36.0%), heat exchangers (30.1%) and combustion (25.0%). Further analyses of the losses across all heat exchangers indicated a nonlinear relationship between exergy destruction contribution and minimum approach temperature (ΔTmin), with a minimal at ΔTmin of 10 °C. The methanol product was determined to represent 18% of exergy input, excluding the air separation unit. The overall process efficiencies were found to be 18% (LHV) and 24% (LHV) for recycle split fractions of 90% and 98%, respectively. The results of this work would provide further insight into the exergy viability of the technology of direct conversion of natural gas to methanol.

Solution Combustion Synthesised Cu‐CeO2 Catalysts For CO2 Hydrogenation to Methanol‐ the Effect of the Fuel

AbstractThe tunability of structural properties such as oxygen vacancies, Cu surface composition, reducibility of CuO, and basicity by solution combustion synthesised (SCS) Cu‐CeO2 catalysts was investigated. Five different fuels, viz. urea (U), tartaric acid (TA), citric acid (CA), ethylene glycol (EG) and oxalyl dihydrazide (ODH), were employed in the synthesis of the catalysts. Raman spectroscopy, O2‐TPD and XPS revealed that the urea synthesised catalyst had the highest concentration of oxygen vacancies, the amount of which was controlled by the fuel used. The oxygen vacancies were the catalytic sites for CO2 adsorption and promoted electron donation to Cu at the Cu‐CeO2 junction, thus improving H2 adsorption and spillover, which was beneficial for methanol synthesis. The better catalytic performance of the urea synthesised Cu‐CeO2 catalyst with a methanol STY of 163 gCH3OH kg−1cat h−1 compared to the other solution combustion synthesis fuels, was attributable to higher oxygen vacancies, more facile Cu reduction, larger Cu surface area and higher Cu surface composition. Based on the absence of the Cu+ species capable of directing the methanol synthesis reaction through the CO intermediate based on XPS data, we surmised that the formate route was the preferred pathway for the studied Cu‐CeO2 catalysts.

Guided experimental design for static nonparametric modeling

Sequential or goal-oriented experimental design methods help achieve the target cheaply and quickly. In this work, we exploit Bayesian Optimization to obtain accurate and reliable static models for physical phenomena in cases where parametric models are unavailable. Our Guided Design of Experiments (G-DoE) workflow is proposed with a purely explorative acquisition function and an empirical stopping criterion. Two stopping criteria are proposed, one that is based on convergence rates of the prediction uncertainty and another that is based on a tolerance limit. Stopping criteria thresholds are established by studying factors like noise level and dimension size and their impact on prediction uncertainty convergence. Furthermore, we compare the G-DoE framework with classical Full Factorial and Response Surface strategies in terms of the suggested number of experiments and corresponding accuracy of fit. The proposed algorithm is tested using a methanol synthesis reaction experiment, a vapor pressure experiment, and a synthetic example.

Experimental PSA reactor for methanol-enhanced production VIA CO2 hydrogenation

Methanol synthesis via catalytic CO2 hydrogenation has emerged as one of the main ways to valorize CO2. The main problem is that the methanol synthesis reaction is thermodynamically controlled, and there is a parallel endothermic reaction, reverse water gas shift (RWGS), so low methanol production ratios are achieved.In this scenario, process intensification, particularly multifunctional reactors where reaction and separation occur simultaneously, is of great interest. Sorption-enhanced reaction processes (SERP) technologies are widely used in equilibrium-controlled processes to increase reagent conversion through selective product removal.Various authors have proposed SERP processes for CO2 hydrogenation to methanol, but most of them are simulations studies and it is difficult to find experimental data. The aim of the work is the experimental study of the CO2 conversion and selectivity to methanol of a SERP process based on a four-step PSA reactor. The process has been carried out with a commercial Cu/ZnO/Al2O3 catalyst and commercial 3A zeolite as adsorbent.Conversions beyond the equilibrium have been achieved in the SERP process, even complete conversion of CO2 at 50 bar, 250 °C, and 300 °C. In the cyclic process, high CO2 conversions far from equilibrium are achieved in all the range of temperatures, 200–300 °C. The best results of methanol yield are achieved at 250 °C and 50 bar, followed closely by 200 °C. It is worth mentioning that methane is detected in the transitory state at 300 °C and 50 bar. Also, the purge step has been studied, concluding that it is necessary for adsorbent regeneration, improving CO2 conversion in the cyclic steady state.

Kinetics of CO2 hydrogenation to methanol over CuO/ZnO/ZrO2 catalyst: Comparison of the differential and integral methods of kinetic analysis

AbstractThe experimental data over CuO/ZnO/ZrO2 catalyst for a wide range of operating conditions were used to develop the kinetics of the reaction CO2 hydrogenation to methanol. Three kinetic models such as the power law model, the Graaf kinetic model, and the Park kinetic model were tested against the experimental data. Both the mechanistic models have been developed based on the Langmuir‐Hinshelwood‐Hougen‐Watson approach and are specific only to the methanol synthesis from CO/CO2 hydrogenation. In an attempt to reduce the number of parameters in the two models, the abridged forms of these models were also tried. Overall, 25 kinetic rate equations were tested and the best‐fit kinetic rate expression with optimized parameters was worked out. Both the integral and differential methods of kinetic analysis were employed and their efficacy in finding the best‐fit expression was compared. The MATLAB built‐in function fminsearch was employed to perform the regression of the data. The Graaf model in its parent form, but with the new optimized values of the parameters, was found to be the best‐fit rate model. The Graaf kinetics, with re‐estimated parameters, could be helpful in designing and simulating a methanol synthesis reactor operating on CO2 and H2 feed and utilizing a CuO/ZnO/ZrO2 catalyst.

Biomass-derived activated carbon catalysts for the direct dimethyl ether synthesis from syngas

The direct DME synthesis from syngas was studied by using activated carbon-based bifunctional catalytic beds. Two kinds of activated carbons, prepared by physical (by CO2 partial gasification) and chemical (with phosphoric acid) activation of olive stones, were used as supports for the preparation of the catalysts. The chemically activated carbon presented a considerable amount of thermally and chemically stable surface phosphorus complexes, which played an important role on the catalytic performance of the prepared catalysts. A Zr-loaded P-containing activated carbon presented a relatively high activity, selectivity and stability for the production of DME from methanol and was used as methanol dehydration catalyst. On the other hand, Cu-Zn was loaded on both P-containing and P-free activated carbon supports for the preparation of methanol synthesis catalysts. The presence of surface-phosphorus on the carbon support resulted in a strong metal-support interaction, hindering the catalytic activity for the hydrogenation of CO to methanol. However, the catalyst that did not contain phosphorus showed noticeable activity for this reaction. The physical mixing of the methanol synthesis and methanol dehydration catalysts resulted in the preparation of carbon-based bifunctional catalytic beds, which performed very efficiently in the direct DME synthesis from syngas in a fixed-bed reactor. Different mass ratios of the individual (metallic and acid) catalysts were studied. An acid/metallic catalyst mass ratio of 2 provided the catalytic bed with enough acid sites to promote methanol dehydration to its maximum extent and make the overall product distribution controlled by the methanol synthesis reaction on the metallic phase.

Copper nanoparticles encapsulated in zeolite 13X for highly selective hydrogenation of CO2 to methanol

High dispersion of active metal is always approved for better catalytic performance in CO2 hydrogenation to methanol. Herein, a strategy was proposed to encapsulate copper nanoparticles in supercages of zeolite 13X, and hence the growth of copper nanoparticles can be controlled. In the present work, catalysts were prepared using ion-exchange and hydrogen reduction at a tiny positive pressure. The results show that as-synthesized catalyst consists of metallic copper and FAU-type zeolite. Excessive amount of copper will destroy zeolite frameworks, and the amount of 5.9 at% is appropriate for considerable BET surface area and ideal copper dispersion. Meanwhile, copper nanoparticles may grow outside from zeolite at high reduction temperatures (≥220 °C), resulting in serious surface area decline and metallic copper agglomeration. Afterwards catalytic tests reveal good stability of the optimal CX-220 catalyst in continuous reactions. The CX-220 achieves remarkably high methanol selectivity of ≥ 95% within wide ranges of reaction temperatures and reaction pressures. Further analyses reveal that the encapsulation of copper nanoparticles reduces micropores and enriches mesopores in zeolite. The apparent activation energy for methanol synthesis over CX-220 catalyst has been lowered to a very low level because of the unique microstructure, and thus the methanol synthesis reaction is dominant in CO2 hydrogenation for dramatic methanol selectivity. Therefore, this work gives important insights and applicable routes for catalysts analyses of CO2 hydrogenation to methanol.

Mechanism of methanol synthesis from CO2 on Cu/CeO2 and Cu/W-CeO2: a DFT investigation into the nature of W-doping

The modified text: DFT calculations indicate that W-doping changes the reaction of methanol synthesis from CO2 at the Cu8/CeO2-Ov from the RWGS + CO hydrogenation pathway to the formate pathway by weakening the interaction of Cu–Oup but enhancing the C–Odown bond.

Rates and reversibility of CO2 hydrogenation on Cu-based catalysts

Kinetics of reaction pathways involved in the conversion of CO2 to methanol and CO on Cu/ZnO/Al2O3 are resolved using in situ chemical titration, steady-state kinetic measurements, and mathematical formalisms for reversibility to probe salient species governing methanol selectivity and yield during CO2 hydrogenation. Across a range of H2:CO2 = 1:1 to H2:CO2 = 80.5:1, active site density determined from in situ chlorine uptake remained invariant; hence, observed trends in rates can be interpreted as only arising from reaction kinetics and not from changing active site density. Kinetic and thermodynamic contributions to rates are decoupled to evaluate forward and reverse rates of methanol synthesis and reverse water-gas shift (RWGS) reactions. These kinetic analyses show that the forward rates of methanol synthesis exhibit persistent first order dependence on hydrogen pressure and are inhibited by water more significantly than the forward rates of RWGS. In contrast, the reverse rates of methanol synthesis and RWGS are both inhibited by H2. Consequently, without any modifications to the Cu/ZnO/Al2O3 catalyst formulation, methanol selectivity can be increased to > 80 % by increasing inlet H2 partial pressure and methanol yield can be enhanced by ∼ 20 % by adding water adsorbents even under conditions far from equilibrium. The kinetic treatments presented herein demonstrate a dearth of H* species during catalysis, provide thermodynamic constraints precluding sequential RWGS and CO hydrogenation as the pathway for methanol synthesis, reveal PH2 and PH2O as salient in determining methanol selectivity and yield by impacting both the forward and reverse rates of CO2 hydrogenation on Cu/ZnO/Al2O3, and explicate the fundamentals of novel sorption-enhanced methanol synthesis, which not only alleviates equilibrium constraints but also alters the intrinsic rate at which the system approaches equilibrium.

An innovative pillow-plate reactor for the synthesis of methanol from biogas: A simulation study

This work investigates the performances of a pillow-plate heat exchanger utilized as reactor for small-scale methanol synthesis. When downscaled, multi-tubular packed bed reactors are complicated to use since they undergo rapid losses in catalyst activity. A possible pathway to improve the unit performances is to diminish the tubes diameter and number. As this kind of reactors is governed by convective heat transfer, though, the use of long tubes is required to keep the mixture velocity high. This leads to the use of very long reactors, which cannot be easily realized with traditional designs. In order to tackle this issue, we propose the utilization of an innovative design, the pillow-plate reactor, increasing heat and mass transfer and the unit compactness. The study compares the performances of a packed-bed and a pillow-plate reactor through temperature profiles and methanol productivity at varying reactor lengths (1 – 6 m). It is proved that the pillow-plate unit, unlike the multi-tubular one, well manages scale reduction: when 1 m long reactors are employed, the outlet methanol fraction is close to equilibrium (5.8% vs. 4.9% for packed beds) and the hot-spots are well controlled (537 K vs. 557 K for tubular reactors). Moreover, it is also shown that the distance of metal layers in the pillow arrangement remarkably influences heat exchange, which is very effective for close layers, with a hot-spot of 518 K with a 3 mm gap, and much worse for the 12 mm design (552 K).

Preparation of polymeric-ceramic composite membranes for use in the methanol synthesis reaction

A new kind of ceramic-polymeric membranes has been prepared and characterized towards its use in membrane reactors for synthesis of methanol from CO2 and hydrogen. In this way, PBI membranes were prepared on a ceramic support by varying parameters of the preparation process. The effect of those parameters on the separation of the compounds involved in the reaction was measured under conditions (temperature, pressure and gas composition) simulating those of the reaction. The prepared membranes were able to selectively remove water from a mixture containing hydrogen and CO2. H2O/CO2 and H2O/H2 separation factors over 18 and 12, respectively, were achieved at 160°C. The separation factors decreased by increasing the temperature with a 3-layer membrane but were quite stable with a 4-layer membrane.

Robust Design and Operation of a Multistage Reactor for Methanol Synthesis from Renewable Resources

Methanol is an important raw material widely used in the chemical industry. This article addresses the challenge of fluctuations in green hydrogen as a feed stream for methanol production from renewable feedstock. For a staged reactor design, robust operating conditions are generated through the simultaneous steady-state optimization of 50 process scenarios. The feed can be split and fed separately to the different reactor stages. However, neglected transient effects may render this design infeasible under dynamic conditions concerning carbon conversion and reactor temperature constraints. To overcome this, an additional dynamic optimization is conducted to ensure a feasible operation by an optimized feed-forward control of feed distribution and shell temperatures. In practice, this is possible because the disturbance, i.e., fluctuation, is measurable and predictable in a short time frame. The optimization yields optimal operating conditions, resulting in a reactor that is dynamically feasible for measurable fluctuating inlet conditions.

Development of an Improved Kinetic Model for CO2 Hydrogenation to Methanol

The kinetics of methanol synthesis remains debatable for various reasons, such as the lack of scientifically conclusive agreement about reaction mechanisms. The focus of this paper is on the evaluation of the intrinsic kinetics of the methanol synthesis reaction based on CO2 hydrogenation and the associated reverse water–gas shift as overall reactions. The industrial methanol synthesis catalyst, Cu/ZnO/Al2O3/MgO, was used for performing the kinetic studies. An optimal kinetic model was assessed for its ability to predict the experimental data from differential to integral conditions, contrary to the typical fitting of only the integral conditions’ data (common practice, as reported in the literature). The catalyst testing and kinetic evaluations were performed at various temperatures (210–260 °C) and pressures (40–77 bar), and for different stoichiometric numbers (0.9–1.9), H2/CO2 ratios (3.0–4.4) and carbon oxide ratios (0.9–1.0), in an isothermal fixed bed reactor, operated in a plug-flow mode. Experiments with CO in the feed were also generated and fitted. Different literature kinetic models with different assumptions on active sites, rate-determining steps, and hence, model formulations were fitted and compared. The original Seidel model appeared to fit the kinetic data very well, but it has twelve parameters. The modified model (MOD) we propose is derived from this Seidel model, but it has fewer (nine) parameters—it excludes CO hydrogenation, but it takes into consideration the morphological changes of active sites and CO adsorption. This MOD model, with three active sites, gave the best fit to all the data sets.

Techno-economic evaluation of simultaneous methanol and hydrogen production via autothermal reforming of natural gas

The demand for clean energy and efficient resource utilization needs the existing processes to be modified for optimal performance. The study investigates the production of high purity methanol through the autothermal reforming (ATR) process technology. Two cases were developed: Case I, where only methanol is produced from syngas via natural gas reforming, and Case II, where co-production of high-purity hydrogen and methanol was made possible. In Case II, the adjustment of the module number was used to optimize the conversion in the methanol synthesis reactor by manipulating the recycle split ratio. Results show that by adjusting the split ratio, approximately 21.12 t/h of high purity H2 can be produced along with 101.99 t/h of AA-grade methanol. However, the co-production of hydrogen is made at the expense of decreased methanol production. The proposed co-production route offers process flexibility to produce hydrogen and methanol as per customer demand. The study also examined the process efficiency and found that the proposed Case II consumes less energy in the methanol synthesis and methanol purification sections compared to Case I. The process efficiency is 55 % and 57.5 % for Case I and Case II respectively, on the other hand, Case I requires 13.05 GJ, while Case II requires 17.55 GJ for fuel production. A sensitivity analysis has been performed to study the effect of varying split ratio on the module number, and the results show that as the split ratio increases, methanol production decreases, which reduces the total energy requirement of the process. Finally, a detailed economic comparison has been conducted to ascertain the production of dual fuel versus single fuel, and the results show that Case II is more profitable than Case I over the project lifetime.

Process design and energy analysis on synthesis of liquid fuels in an integrated CCUS system

Under the high attention of the international community to CO2 emissions, the capture utilization and storage (CCUS) and the CO2 hydrogenation fuel production have become two popular directions, especially for the combination of the two processes. In this paper, the production of liquid fuels via the methanol synthesis pathway in an integrated CCUS system based on Aspen Plus models was studied. The NH3-CO2-H2O absorption was used to capture CO2 and hydrogen was provided by water electrolysis using renewable energy sources. A two-stage reactor with a recirculating stream was specified for the process of CO2 hydrogenation to synthesize methanol, and the liquid fuel dimethyl ether (DME) was reproduced by dehydrating methanol (Power-to-Liquid). The amount of absorbent used for the carbon capture process was determined and the yield differences due to the number of cycles in the intermediate methanol synthesis reaction were analyzed. It is possible to convert 4.15 t of CO2 per tonne of DME produced at the mass material balance of the process. The optimization of the heat exchange network and the energy requirements for the total process were evaluated. It is calculated that the energy involved in producing 1 ton of DME in the process model is 176 GJ. The analysis of the overall process and the evaluation of models could provide options for the possibility of CCUS engineering application.

(Invited) Electrocatalytic Conversion of CO2 to Syngas with Controlled CO/H2 Ratios

One of the main research challenges for electrocatalysis that produces carbon-containing products from CO2 is avoiding the competing hydrogen evolution reaction. Instead of totally eliminating hydrogen, our approach makes use of the readily available protons in aqueous electrolyte to co-produce CO and H2, making synthesis gas (syngas) with a tunable CO:H2 ratio. The resulting syngas can then be used as feedstock for existing thermocatalytic processes, such as Fischer–Tropsch and methanol synthesis reactions [1]. We will present our results in identifying palladium hydride (PdH), formed under electrocatalytic reaction conditions, as an effective electrocatalyst that enables the syngas production [2]. We will also report our efforts in reducing the loading of Pd by alloying Pd with inexpensive secondary metals, supporting Pd on transition metal carbides and nitrides, and utilizing single atom Pd catalysts. For each type of the catalysts, we monitor the phase transition from Pd to PdH under reaction conditions with in-situ synchrotron-based X-ray absorption and X-ray diffraction techniques. We also identify descriptors for syngas production on PdH, bimetallic PdH, and supported PdH catalysts by performing DFT calculations of the effect of PdH formation on the binding strength of reaction intermediates. The research methodology established here should be useful not only for continued optimization of Pd-based syngas-producing electrocatalysts, but also for enhancing activity while reducing the loading of precious metals for other electrocatalytic applications. Furthermore, we will discuss our recent results in utilizing a tandem scheme of electrocatalytic-thermocatalytic processes to convert CO2 to C3 oxygenates [3].[1] B.M. Tackett, E. Gomez and J.G. Chen, “Net reduction of CO2 via its thermocatalytic and electrocatalytic transformation reactions in standard and hybrid processes”, Nature Catalysis, 2 (2019) 381.[2] B.M. Tackett, J.H. Lee and J.G. Chen, “Electrochemical Conversion of CO2 to Syngas with Palladium-Based Electrocatalysts”, Accounts of Chemical Research, 53 (2020) 1535.[3] A.N. Biswas, Z. Xie, R. Xia, S. Overa, F. Jiao and J.G. Chen, “Tandem Electrocatalytic-Thermocatalytic Reaction Scheme for CO2 Conversion to C3 Oxygenates”, ACS Energy Letters, 7 (2022) 2904

Improving Biomethanol Synthesis via the Addition of Extra Hydrogen to Biohydrogen Using a Reverse Water–Gas Shift Reaction Compared with Direct Methanol Synthesis

Conventionally, methanol is derived from a petroleum base and natural gas, but biomethanol is obtained from biobased sources, which can provide a good alternative for commercial methanol synthesis. The fermentation of molasses to produce biomethanol via the production of biohydrogen (H2 and CO2) was studied. Molasses concentrations of 20, 30, or 40 g/L with the addition of 0, 0.01, or 0.1 g/L of trace elements (TEs) (NiCl2 and FeSO4·7H2O) were investigated, and the proper conditions were a 30 g/L molasses solution combined with 0.01 g/L of TEs. H2/CO2 ratios of 50/50% (v/v), 60/40% (v/v), and 70/30% (v/v) with a constant feed rate of 60 g/h for CO2 conversion via methanol synthesis (MS) and the reverse water–gas shift (RWGS) reaction were studied. MS at temperatures of 170, 200, and 230 °C with a Cu/ZnO/Al2O3 catalyst and pressure of 40 barg was studied. Increasing the H2/CO2 ratio increased the maximum methanol product rate, and the maximum H2/CO2 ratio of 70/30% (v/v) resulted in methanol production rates of 13.15, 17.81, and 14.15 g/h, respectively. The optimum temperature and methanol purity were 200 °C and 62.9% (wt). The RWGS was studied at temperatures ranging from 150 to 550 °C at atm pressure with the same catalyst and feed. Increasing the temperature supported CO generation, which remained unchanged at 21 to 23% at 500 to 550 °C. For direct methanol synthesis (DMS), there was an initial methanol synthesis (MS) reaction followed by a second methanol synthesis (MS) reaction, and for indirect methanol synthesis (IMS), there was a reverse water–gas shift (RWGS) reaction followed by methanol synthesis (MS). For pathway 1, DMS (1st MS + 2nd MS), and pathway 2, IMS (1st RWGS + 2nd MS), the same optimal H2/CO2 ratio at 60/40% (v/v) or 1.49/1 (mole ratio) was determined, and methanol production rates of 1.04 (0.033) and 1.0111 (0.032) g/min (mol/min), methanol purities of 75.91% (wt) and 97.98% (wt), and CO2 consumptions of 27.32% and 57.25%, respectively, were achieved.