CO-rich Syngas Research Articles

Industrial-scale 12-layered-bed vacuum pressure swing adsorption for fuel cell-grade H2 production from carbon-captured steam methane reforming syngas

Vacuum pressure swing adsorption (VPSA) is primarily used to produce high-purity H2 from CO2-rich syngas in steam methane reforming (SMR) plants. Since carbon capture is essential, the performance of current H2 VPSA processes is affected by feeding carbon-captured SMR syngas (CO2-lean SMR syngas). This study conducted the performance evaluation and optimization for a fuel cell-grade H2 production by an industrial-scale 12-layered-bed VPSA process with a 24-step cycle from CO2-lean SMR syngas. The multi-scale dynamic model for the VPSA process was validated with petrochemical industry data from a current SMR-VPSA plant. A sensitivity analysis using CO2-lean SMR syngas indicated the high loss of H2 during desorption steps, suggesting the need for optimization of the VPSA process. Owing to the complex interconnectivity of 12 beds via 24 steps, the framework of a dynamic model-based deep neural network (DNN) and DNN-based optimization was developed to design and optimize the VPSA process. Even without changing equipment or adsorbent configuration, the VPSA process achieved fuel cell-grade H2 production (>99.9999 % H2 and > 88 % recovery with < 0.2 ppm CO). The results indicate that CO2 capture rates, ranging from 90 to 99 %, can be independently determined under techno-economic and environmental conditions, as this capture range of CO2-lean SMR syngas gives a minor impact on the performance of VPSA process. The proposed three-step framework, which encompasses dynamic modeling, surrogate modeling, and multi-objective optimization, provides a systematic and feasible approach for designing and optimizing the VPSA process in an SMR plant integrated with a carbon capture process, to achieve a low-carbon economy.

Development of multiple alkali metals doped La-Ni based perovskites for CO2 gasification of biochar to produce CO rich syngas

Under the background of carbon neutrality, there is an urgent need for the production of high-valued syngas from renewable carbon resources. This work focused on the evaluation of multiple alkali metals doping on the catalytic activity of La-Ni based perovskite catalysts in CO2 gasification of biochar. The structure and property evolution of samples were analyzed by XRD, SEM, TEM, XPS, Raman spectra, CO2-TPD, etc. The experiment results found that Li+ exhibited a stronger catalytic gasification promotion effect than K+ and Na+, owing to the high mobility of the smallest radius ions in the lattice. Among the samples, La0.4K0.2Na0.2Li0.2NiO3 possessed the best catalytic performance with the maximum release rates of CO of 116.76 mL min−1·g−1 and 3.25 times in reactivity indexes in contrast to the LaNiO3. Correspondingly, it also showed significant resistance to ash in the cycle gasification experiments. Deep substitution with multiple alkali metals at A-site produced more active oxygen species ([O]) on the oxygen vacancies (Ov) and increased the proportion of Ni3+ of the La0.4K0.2Na0.2Li0.2NiO3, resulting in excellent catalytic CO2 gasification capacity. Furthermore, the adsorption and activation capacity of CO2 were also enhanced by the surface basic active sites generated by alkali metals substitution. Based on the experiments and characterization results, the redox recycling between Ni2+−Ov and Ni3+−[O] were proposed as the main reaction mechanisms for CO2 gasification of biochar. This study provides a valuable exploration for the complex substitution of perovskite catalysts and high-efficiency CO2 gasification of biochar.

In-situ plasma assisted lithium-ion battery cathodes to catalytically pyrolyze lignin for H2-rich syngas production

In-situ plasma assisted lithium-ion battery cathodes catalysis was investigated to pyrolyze lignin to H2-rich syngas, oil and char. The effects of temperature, cathode to lignin ratio and plasma current on syngas production were investigated by using the typical ternary cathode NCM111 (LiNi1/3Co1/3Mn1/3O2) as catalyst and adopting dielectric barrier discharge mode. Response surface methodology based on BOX-BEHNKEN design was used to analyze the significance and interactions of process factors on the syngas yield. The conditions of 837℃, 10.4 %, and 185 mA for obtaining high-yield syngas (22.58 %) were more stringent; thereinto, from high to low, the intensity of factors on the yield was temperature, plasma current, and cathode ratio. Furthermore, different cathodes (non-cathode, NCM811 (LiNi4/5Co1/10Mn1/10O2), LCO (LiCoO2), and LMO (LiMn2O4)) were applied to decouple the catalytic effects of three metals in the NCM111. NCM111 enhanced both lignin gasification and carbonization by reducing condensable components, and NCM811 further improved gasification, but LCO and LMO had weaker gasification ability. NCM111 increased H2 volume fraction from 22.35 % to 67.31 %, NCM811 elevated the micro-discharge performance, promoting the hydrogasification reactions between energetic H species and char to produce more CH4, while LCO and LMO tended to produce the CO-rich syngas. Besides, in-situ plasma and its synergy with cathodes inhibited the formation of heavy aromatics and produced some high-value bio-oils rich in light aromatics, in which NCM111 achieved 92.30 % selectivity towards MAHs. High Ni ratio was beneficial for improving the char porosity, and the chars obtained by using NCM811 had a surface area of 409.29 m2/g, and a pore volume of 0.401 cm3/g. Comparably, the degree of catalytic lignin gasification for preparing H2-rich syngas could be ranked as Ni > Co > Mn in the ternary cathode.

Synergistic interactions between cellulose and plastics (PET, HDPE, and PS) during CO2 gasification-catalytic reforming on Ni/CeO2 nanorod catalyst

CO2 gasification-reforming is a promising approach for the transformation of carbonaceous materials into CO-rich syngas. Within municipal solid waste and agricultural waste streams, plastics are commonly found intermixed with biomass waste. This study delves into the CO2 gasification-reforming of biomass (cellulose) and various plastics (PET, HDPE, and PS) using a self-built online weighing fixed bed reactor and a two-stage fixed bed reactor. During the gasification-reforming of cellulose-plastic mixtures without the catalyst, the experimental gas production rate of cellulose slightly decreased, with the peak of gas production migrating to a higher temperature range. This phenomenon can be attributed to the molten plastic adhering to the cellulose surface, which impeded heat and mass transfer essential for cellulose decomposition. Furthermore, the gas production from plastics was suppressed in the mixtures, likely due to the interference of cellulose char in the decomposition of plastics. The incorporation of 2%Ni/CeO2 catalysts not only augmented gas yields and production rates but also emphasized the synergistic interactions. For the cellulose-HDPE mixture, the total gas yield was reduced by 14.9 mmol gsample−1 relative to the theoretical value. Given that HDPE possessed the highest decomposition temperature, the synergistic interaction was predominantly driven by the inhibitive nature of cellulose char. In contrast, the total gas yields for cellulose-PET and cellulose-PS mixtures increased by 8.7 mmol gsample−1 and 13.3 mmol gsample−1, respectively. The free radicals emanating from cellulose could trigger the decomposition of volatile components from plastics. Concurrently, the decomposition products of plastic could serve as hydrogen donors to stabilize the volatiles of cellulose. The interactions primarily affect the volatiles and tar components of the mixtures. The catalysts amplified gas yields by facilitating the CO2 reforming of tar, therefore, the synergistic interaction became evident upon catalyst addition. Gas chromatography-mass spectrometry analyses of the tar also corroborated the described interaction mechanisms between cellulose and plastics. Thermogravimetric analysis of used catalysts indicated that the synergistic action between cellulose and plastic could effectively diminish coke deposition, thereby preventing swift catalyst deactivation.

Enhancing CO2 gasification-reforming of municipal solid waste with Ni/CeO2 and Ni/ZrO2 catalysts

CO2 gasification-reforming facilitates CO2 utilization and yields CO-rich syngas for municipal waste management. Catalysts are essential for enhancing syngas production via catalytic tar reforming.

CO rich syngas production from catalytic CO2 gasification-reforming of biomass components on Ni/CeO2

The advancement of biomass utilization technology is vital for addressing global climate change and the depletion of fossil resources. CO rich syngas production from the CO2 gasification-reforming of biomass components (cellulose, xylan, lignin, and starch) was investigated by a two-stage fixed bed reactor. The four biomass components were heated from room temperature to 600 °C in a CO2 atmosphere, among which lignin exhibited the highest residue fraction (51.6 wt.%) and the lowest gas yield (5.7 mmol gbiomass−1), whereas cellulose demonstrated the highest gas yield from CO2 gasification-reforming (14.6 mmol gbiomass−1). Nanorod CeO2 supported Ni catalysts were used to enhance volatile (tar) CO2 reforming reactions, and the gas yield increased by 104.3 % for cellulose, 103.3 % for xylan, 149.3 % for lignin, and 128.3 % for starch compared with noncatalytic CO2 gasification-reforming. Furthermore, the structure of fresh and used catalysts were characterized by X-ray diffraction (XRD), N2 adsorption/desorption isotherm, scanning electron microscope (SEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), H2-temperature programmed reduction (H2-TPR), and thermogravimetry (TGA). For the CO2 gasification-reforming of cellulose, the optimum CO yield of 27.6 mmol gbiomass−1 was achieved at a gasification/reforming temperature of 600/700 °C and a biomass/catalyst ratio of 6.25 using 2 %Ni/CeO2 catalyst. The stability tests of catalysts showed an approximately linear decrease in CO yield with the increase of the number of cycles, and catalyst deactivation resulted from Ni sintering and coke deposition.

Effect of spent fluid catalytic cracking (FCC) catalyst on syngas production from pyrolysis and CO2-assisted gasification of waste tires

With growing demands for improved energy recovery from waste tires, incorporating waste catalysts from different sectors can provide synergistic solution. This paper investigates the effect of using spent fluid catalytic cracking (FCC) catalyst on evolutionary behavior and yield of syngas (CO, H2, and light hydrocarbons), and char and energy yields during pyrolysis and CO2-assisted gasification of waste tires at 900 °C in a fixed-bed semi-batch reactor. The effect of catalyst position (in-situ and quasi-in-situ catalytic modes) and temperature was also examined during catalytic CO2-assited gasification for energy and chemicals production. The results reveal that the presence of spent FCC catalyst resulted in higher syngas and energy yields. The CO2-assisted gasification provided CO-rich syngas with higher yields than pyrolysis. The quasi-in-situ gasification provided increased syngas and energy yields by 24% and 23% respectively, as compared to in-situ catalytic gasification, which revealed that quasi-in-situ catalytic gasification to be more efficient and effective for increased syngas yields. Increasing temperature to 950 °C increased the yields syngas and energy owing to improved reforming and cracking reactions. This viability of utilizing spent FCC catalyst offers improved waste management economics for FCC plants while simultaneously improving the energy recovery from waste tires.

Two-stage thermochemical conversion of polyethylene terephthalate using steam to produce a clean and H2- and CO-rich syngas

Two-stage thermochemical conversion of polyethylene terephthalate using steam to produce a clean and H2- and CO-rich syngas

Design framework for dimethyl ether (DME) production from coal and biomass‐derived syngas via simulation approach

AbstractA comprehensive thermodynamic study was conducted to evaluate the comparative efficacy of methanol and dimethyl ether (DME) synthesis using CO2 rich syngas feed. The first part of our study included assessing the relative performances of the methanol synthesis system, two step DME synthesis system, and one step DME synthesis system in terms of the COx conversion and product yield (methanol/DME) based on the Gibbs free energy minimization approach. The wide range of composition of CO2‐enriched syngas feed produced by the coal and biomass gasification was simulated using Aspen Plus and the following evaluation parameters were analyzed for a broad parameter range: reaction temperature (180–280°C), reaction pressure (10–80 bar), stoichiometry number (SN) (0–11), and CO2/(CO2 + CO) molar feed ratio (0–1) for isothermal as well as adiabatic conditions. Based on the equilibrium yield, one‐step DME synthesis was discovered as the most viable process to utilize the co‐gasification derived syngas effectively. In the second part of our study, the overall process efficiency was inspected through the process design of 1 tonnes per day (TPD) DME plant inclusive of heat integration, resulting in significant CO2 abatement and DME production with high product purity and minimum energy consumption. Consequently, one‐step DME production via CO2‐enriched syngas obtained through the coal or biomass gasification process is identified as the leading technology based on energy utilization and CO2 abatement.

Molten salt-mediated carbon capture and conversion

The post-combustion capture is a promising technology to reduce industrial CO2 emission. This review articles concluded the recent advances in molten salt strategies for CO2 capture and conversion. In terms of CO2 capture, MgO-based sorbents can efficiently capture CO2 through a reversible carbonation/calcination reaction at intermediate temperatures (300–500 °C). The addition of alkali metal molten salt to MgO-based sorbents can greatly promote the CO2 uptake, which are promising candidates applied in the post combustion CO2 capture technology. Besides, molten salts such as ZnCl2/NaCl can be served as both activating agents and templates for synthesis of porous carbons from biomass and plastics. Particularly, N-doped porous carbons with highly microporous structures are more suitable for CO2 capture under ambient conditions. In terms of CO2 conversion, the electrochemical reduction in molten salts has been widely developed for producing carbon materials and fuels. Additionally, molten salts (normally single and mixed alkali metal carbonates) acting as both catalysts and heat transfer mediums can enhance the CO2 gasification of carbon feedstocks to produce CO-rich syngas. A significant challenge in the CO2 gasification of biomass/coal and their chars in molten alkali metal carbonates is the potential agglomeration between alkali metal species and minerals in the ash under high temperatures. To achieve sorbents regeneration and CO2 utilization, it is strongly recommended that more further researches should be performed on the integrated CO2 capture and in-situ electro-/thermo-chemical conversion processes for selectively production of high-value chemicals and fuels, which can alleviate the crisis of fossil fuels shortage and reduce the greenhouse gas emission.

An experimental and modeling study of the application of membrane contactor reactors to methanol synthesis using pure CO2 feeds

We describe here a post-combustion CO2 capture and utilization (CCU) technology that converts the CO2 into methanol (MeOH), a valuable chemical, thus providing a way to monetize the carbon captured to offset process costs. Methanol synthesis (MeS) has been discussed recently for application to CCU, but thermodynamic limitations make it difficult to convert in a single pass a large CO2 fraction. Conventional catalysts show slow kinetics in converting CO2-rich syngas (or pure CO2) into MeOH. Our Group developed (Li and Tsotsis, 2019) a novel MeS process, employing a membrane contactor reactor (MCR) system that attains carbon conversions significantly higher than equilibrium. Our focus here is to process pure CO2 streams by combining the MCR with a separate reactor, which converts the CO2 into a syngas via the reverse water gas shift (RWGS) reaction. In this preliminary effort, the RWGS reactor (RWGSR) is assumed to reach equilibrium. Additional MeS kinetic rate data are generated validating experimentally the ability of the MeS-MCR to process as a feed the RWGSR exit stream. The performance of the combined (RWGSR/MeS-MCR) system is then simulated using a recently developed MeS-MCR model (Zejarbad et al., 2002). The findings are encouraging, and research is currently ongoing to experimentally validate the RWGSR/MeS-MCR system performance.

Direct Conversion of Renewable CO2-Rich Syngas to High-Octane Hydrocarbons in a Single Reactor

The synthesis of branched hydrocarbons for high-octane gasoline and sustainable aviation fuel directly from CO2-rich syngas in a single reactor holds potential to decrease capital and operating costs and increase overall energy and carbon efficiencies in a biorefinery. Here, we report the cascade chemistry of syngas to hydrocarbons under mild reaction conditions in a single reactor with C4+ single-pass yields of 13.7–44.9%, depending on the relative catalyst composition employing our dimethyl ether homologation catalyst, Cu/BEA zeolite. With co-fed CO2 at a concentration representative of biomass-derived syngas, 2.5:1:0.9 for H2:CO:CO2, a hydrocarbon yield of 12.2% was observed with similar selectivity to C4+ products compared to the CO2-free feed. Definitive evidence of CO2 incorporation into the hydrocarbon products was demonstrated with isotopically labeled 13CO2 co-feed experiments, where mass spectrometry confirmed the propagation of 13C into the C4+ hydrocarbons, highlighting the feasibility to co-convert CO and CO2 in this single reactor approach.

CO2 utilization potential of a novel calcium ferrite based looping process fueled with coal: Experimental evaluation of various coal feedstocks and thermodynamic integrated process analysis

Conversion of CO2 to CO was performed at 800–850 °C via reduction of calcium ferrite (CaFe2O4) with coal followed by oxidation of reduced CaFe2O4 with CO2 to produce CO and partially oxidized Ca ferrite. The process was evaluated with several types of coals which included lignite, sub-bituminous, bituminous, anthracite and pet-coke. Reduction of CaFe2O4 with sub-bituminous coal and lignite coal was more favorable than that with higher rank coals. Stable reactivity performance was demonstrated for 35-cycle test conducted with lignite coal/CaFe2O4 at 800 0C and with high conversion of CO2 to CO. The rate of conversion of CO2 to CO with reduced CaFe2O4 was found to be 1st order with respect to CO2 and had a low activation energy of 7.4 kJ/mol. Thermodynamic integrated process assessments suggest that two and three reactor process concepts can be realized and net CO2 utilization achievable. The Two reactor configuration shows the highest potential for CO2 utilization while generating a value-added CO rich syngas stream.

Impact of La engineered stable phase mixed precursors on physico-chemical features of Cu- based catalysts for conversion of CO2 rich syngas to methanol

The conversion of carbon oxides (CO + CO2) to methanol is promising enough in concomitant decrease in greenhouse effect along with the mitigation of energy crisis. However, the process still confronts low levels of CO2 conversion and development of highly efficient catalyst is a bid challenge. In the present work, a syngas feed rich in CO2 was employed to produce methanol over a streak of La promoted Cu/ZnO/MgO catalysts where a harmonized synergy between the La and active Cu sites as a function of La content is reported. XRD analysis of Cu/ZnO/MgO/La2O3 precursors indicated the relative concentration of aurichalcite or malachite galleries. The optimized catalyst (2.5 mol% La) demonstrated the amplified population of malachite phase whereas suppression in aurichalcite phase. Presence of mixed phase precursor reflected well in Cu dispersion, small sized stable Cu particles and improved methanol synthesis activity with marginal deterioration in catalytic efficiency over 60 h on stream. A thorough investigation revealed that introducing La not only generated the required moderate basic sites but also enriched the catalytic surface with active Cu. XPS results indicated that La regulates interaction between Cu2+ and La3+ species, ultimately modifying the surface Cu/Zn ratio. CZ-M17.5La2.5 catalyst showed the highest carbon conversion with a methanol selectivity of 72.2% at 260 °C. This proves that La plays a crucial role towards methanol synthesis when blend of CO/CO2 is used as a feed.

Deciphering Mn modulated structure-activity interplay and rational statistical analysis for CO2 rich syngas hydrogenation to clean methanol

Methanol produced from chemical transformation of coal derived CO2 rich syngas can be a sustainable replacement for conventional crude oil based fuels with an impressive feature of reducing greenhouse gas emissions. Mostly industrial catalysts are promoted, however, lack of detailed insight into the mechanism of promotion has so far restricted the identification of non-precious promoter. In this work, a series of Cu–Zn–Mn oxide catalysts were synthesized by varying Mn loading from 0 to 30 mol% at pH near 7 and 70 °C via co-precipitation technique to elucidate the role of Mn-promoted malachite precursors in micro structural properties of catalyst. Investigation revealed that incorporating 20 mol% Mn (CuZn:Mn[0.2]) in malachite lattice resulted in better stabilization and dispersion of CuO domains owing to maximum dilution of Cu2+ ions as compared to other three analogous catalysts. Consequently, CuZn:Mn[0.2] catalyst unveiled ∼1.4-fold and ∼1.2-fold increase in CO conversion and methanol selectivity respectively as compared to the unpromoted catalyst. However, Mn loading beyond 20 mol% showed a detrimental effect on the catalytic efficiency due to dominant presence of an additional aurichalcite by-phase which revokes dilution of Cu2+ ions. Co-feeding CO2 in syngas improves dual active sites synergy (Cu0/Cu+) which helps in understanding catalytic mechanism of methanol synthesis. For best performing catalyst, statistically validated non-linear mathematical models were derived using response surface methodology along with central composite design. These models forecasted the correlations between process parameters as well as identified the relative contribution of each parameter. For maximising both methanol selectivity and CO conversion, desirability function predicted the optimum values of reaction temperature, pressure, and feed gas molar ratio (CO/CO2/H2) as 242 °C, 49 bar and 3 respectively. Under these conditions, 46% CO conversion and 93% methanol selectivity were obtained. Thus, the formulated coal to methanol process originating from catalyst design to optimization of process parameters paves the way for sustainable solutions referring to global “3E” issues, viz. energy, environment, and economic challenges.

Production of H2- and CO-rich syngas from the CO2 gasification of cow manure over (Sr/Mg)-promoted-Ni/Al2O3 catalysts

The valorization of cow manure (CM), as bio-waste, under a CO2 atmosphere could be an attractive strategy for tackling the environmental problems related to waste management and CO2 emission and producing valuable syngas. For this purpose, highly loaded Ni–Al2O3 catalysts with alkaline-earth metals (Mg and Sr) were synthesized and applied to the gasification of CM under CO2. The lowest yields of bio-oil (16.98 wt %) and coke (0.34 wt %) and the highest yield of syngas (55.09 wt %) were obtained from the catalytic decomposition of hydrocarbons when Sr was incorporated into Ni/Al2O3 (SN-AO). The highest selectivity for H2 (34.23 vol %) and CO (37.16 vol %) were obtained applying SN-AO followed by Mg-promoted Ni/Al2O3 (MN-AO) and Ni/Al2O3 (N-AO) catalysts. With increasing gasification temperature from 750 °C to 850 °C, the syngas yield (from 55.09 to 70.17 wt %) and H2 concentration (from 34.23 to 38.03 vol %) increased considerably because of the endothermic gasification process. The yield and selectivity of syngas (H2 and CO) increased under CO2 compared to those obtained under N2, indicating the high potential of CO2 for the thermal decomposition and dehydrogenation of the volatile matter.

Experimental investigations and model-based optimization of CZZ/H-FER 20 bed compositions for the direct synthesis of DME from CO2-rich syngas

Kinetic investigations and model-based optimization of CuO/ZnO/ZrO2 : H-FER 20 catalytic systems for direct DME synthesis from CO2-rich syngas.

Sustainable DME synthesis from CO2–rich syngas in a membrane assisted reactor–microchannel heat exchanger system

One–step syngas–to–dimethyl ether (DME) conversion is modeled in a cascade of packed–bed reactors (PBRs) and microchannel heat exchangers (micro–HEXs). Each reactor, loaded with mixtures of Cu–ZnO/Al2O3 and HZSM–5 for adiabatic syngas hydrogenation and methanol dehydration, respectively, is connected to a micro–HEX for cooling PBR effluent. HEXs involve layers of sodalite membrane allowing selective H2O and H2 exchange between reactive stream and cooling channels. Membraneless and membrane–integrated systems are simulated at inlet syngas conditions of 50 bar, 523 K, and ∼0.8 mol/s, resembling syngas throughput of a pilot–scale gasifier. Although PBR effluents become H2O–lean in syngas–cooled membrane–integrated HEXs, CO2 conversion and DME yield remain almost identical with those of the membraneless (benchmark) case (∼6 and 10 %, respectively), suggesting that reactions are not constrained by steam. Cooling by pure H2 allows its penetration into reactive stream. H2–enriched PBR feeds are transformed under kinetic and thermodynamic promotions giving CO2 conversion and DME yield up to ∼72 and ∼57 %, respectively. Improved metrics occur at elongated contact of the fluids with membrane, necessitating voluminous HEX units. Nevertheless, membrane aided molar DME production and CO2 consumption per volume remain up to 1.6 and 2.3 times higher than the benchmark values. Membrane assistance also improves benchmark catalyst weight–based DME productivity and CO2 utilization by factors up to 7 and 13, respectively. Proposed cascade system allows scalable and sustainable DME production via increased CO2 valorization.

Process modelling for the production of hydrogen-rich gas from gasification of coal using oxygen, CO2 and steam reactants

This process modelling studied the effect of different reactants on syngas composition and gasifier heat duty (heat energy required to carry out the operation) and the downstream treatment of CO rich syngas to maximise hydrogen yield. The process modelling was validated against experimental data obtained from a large bench-scale entrained flow gasifier. Results show that considering the H2/CO ratio, the steam-O2 reactant favours the most compared to those of the pure oxygen and oxygen-CO2 reactants. Under comparable operating conditions, the highest H2/CO ratio of 0.74 was determined using steam-O2 reactant compared to that of 0.31 and 0.33 using steam-CO2 and pure oxygen reactant. The catalytic water-gas shift reaction (WGSR) favours the yield of H2 with complete CO conversion at a temperature of 400 °C using the steam/coal ratio of 1.2. Supplying steam in the gasifier requires more heat energy to be supplied to drive endothermic gasification reaction and maintain the gasifier temperature. Under complete carbon conversion, steam-CO2 and steam-oxygen reactants require 5–65 kW more energy than pure oxygen.

In Situ Conditioning of CO2-Rich Syngas during the Synthesis of Methanol

The synthesis of methanol from biomass-derived syngas can be challenging because of the high CO2 content in the bio-syngas, resulting in lower kinetics and higher catalyst deactivation. This work explores the in situ pre-treatment of a CO2-rich syngas with a CO2/CO ratio equal to 1.9 through the reverse-water gas shift reaction with the aim of adjusting this ratio to a more favorable one for the synthesis of methanol with Cu-based catalysts. Both reactions take place in two catalytic beds placed in the same reactor, thus intensifying the methanol process. The water produced during syngas conditioning is removed by means of a sorbent zeolite to prevent the methanol catalyst deactivation and to shift the equilibrium towards the methanol formation. The combination of the CO2 shifting and the water sorption strategies lead to higher productivities of the catalytic bed and, under certain reaction conditions, to higher methanol productions.