Thermodynamic analysis of the CO2 methanation reaction with in situ water removal for biogas upgrading

Faria, A. Catarina; Miguel, Carlos V.; Madeira, Luís M.

doi:10.1016/j.jcou.2018.05.005

Cited by 49 publications

(12 citation statements)

References 34 publications

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“…For the two parts in Figure a, the Gibbs reactors (RGibbs) were used, and thermodynamic-equilibrium states were achieved under the investigated conditions. The ISWR process for each section was modeled by the method reported by Catarina Faria et al, where water in the system and generated in the Gibbs reactors was removed by a sequence of separators (see Figure b); a global value of the water-removal fraction ( R ) was given by where is the mole flow rate of water removed from separator k , and is the mole flow rate of water in stream 2 (see Figure b). A water-removal fraction, R , can be achieved by adjusting the number of separators, Z .…”

Section: Methodsmentioning

confidence: 99%

“…The ISWR process can be achieved by applying membrane reactors and the sorption-enhanced reaction process . The application of membrane reactors (MRs) with ISWR for different processes involving CO 2 hydrogenation (e.g., methanol synthesis, ,− DME synthesis, − and the methanation process) has been widely investigated, and attractive potentials were shown in the improvement of CO 2 conversion. Less attention has been separately paid to the RWGS process, but it is included as an important side reaction in the aforementioned processes with a system of CO/CO 2 /H 2 /H 2 O/fuel, and zeolite membranes are suggested , for the reactor designs.…”

Section: Introductionmentioning

confidence: 99%

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Thermodynamic Analyses of a Moderate-Temperature Process of Carbon Dioxide Hydrogenation to Methanol via Reverse Water–Gas Shift with In Situ Water Removal

Cui

Kær

2019

Ind. Eng. Chem. Res.

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CO 2 hydrogenation to methanol via the reverse water−gas shift (the CAMERE process) is an alternative method for methanol synthesis. High operating temperatures (600−800 °C) are required for the reverse water−gas shift (RWGS) process because of the thermodynamic limit. In this study, moderate temperatures (200−300 °C) were used for the RWGS part of the CAMERE process by the application of in situ water removal (ISWR). Thermodynamic analyses were conducted on this process using the Gibbs-free-energy-minimization method. The analyses show that by using ISWR with high water-removal fractions (e.g., 0.80−0.99), the CO 2 conversion of the RWGS part can be significantly improved at moderate operating temperatures. One-step CO 2 hydrogenation to methanol (CTM) with ISWR was also investigated, and it resulted in similar methanol yields. Both processes showed high potential and the ability to promote CO 2 hydrogenation to methanol through the use of ISWR.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermodynamic Analyses of a Moderate-Temperature Process of Carbon Dioxide Hydrogenation to Methanol via Reverse Water–Gas Shift with In Situ Water Removal

Cui

Kær

2019

Ind. Eng. Chem. Res.

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“…The composition of biogas is mainly dependent on the type of biomass used (i.e., landfill, sewage digester, and organic waste) . Hence, two case studies corresponding to different CH 4 /CO 2 molar ratios in the feed stream (i.e., 1.11 and 2.96, cf. Table ) and, inherently, to different biomass sources, namely landfill and organic waste, respectively, were considered.…”

Section: Resultsmentioning

confidence: 99%

Modeling and Simulation of a Steam-Selective Membrane Reactor for Enhanced CO₂ Methanation

Faria

Miguel

Rodrigues

et al. 2020

Ind. Eng. Chem. Res.

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A modeling and simulation study of a hydroxy sodalite (H-SOD) membrane reactor for in situ steam removal during CO2 methanation reaction is presented. A nonisothermal, steady-state, pseudohomogeneous 1D mathematical model with axial dispersion was proposed to describe and compare the performance obtained with traditional fixed-bed and membrane reactors. The model was validated against experimental data taken from the literature, first concerning CO2 conversion in a fixed-bed reactor and then regarding mixture separation factors through the membrane. The reactor’s performance was assessed considering the CO2 conversion and CH4 outlet purity under different operating conditions. The membrane selectivity toward H2 is more significant than that for the other species (i.e., CH4 and CO2). Hence, if hydrogen is used as sweep gas it can be co-delivered from the permeate side, which was found to significantly enhance the membrane reactor performance. The permeate-to-retentate pressure ratio (P ratio) increases the CO2 conversion but only up to an optimum value (P ratio*), which depends on the reaction conditions and feed composition. This holds true particularly when processing raw biogas: increasing the P ratio leads to a trade-off situation, where CO2 conversion increases but CH4 purity decreases. High water selectivity of the membrane enables a significant improvement compared to the traditional reactor performance, particularly at high temperature, pressure, and contact time, even if some reactants are lost to the permeate. Notably, the membrane reactor excels over the traditional fixed-bed reactor even at milder temperatures and pressures, which is particularly relevant for improving the overall energy efficiency of power-to-methane processes.

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“…CO 2 conversion (X CO 2 ) and CH 4 selectivity (S CH 4 ) were calculated according to Equations (7) and (8), respectively. F in CO 2 is the CO 2 inlet molar flow rate, while F out CH 4 and F out CO stand for the outlet molar flow rates of CH 4 and CO, respectively.…”

Section: Catalyst Assessmentmentioning

confidence: 99%

CO2 Methanation over Hydrotalcite-Derived Nickel/Ruthenium and Supported Ruthenium Catalysts

et al. 2019

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In this work, in-house synthesized NiMgAl, Ru/NiMgAl, and Ru/SiO 2 catalysts and a commercial ruthenium-containing material (Ru/Al 2 O 3 com. ) were tested for CO 2 methanation at 250, 300, and 350 • C (weight hourly space velocity, WHSV, of 2400 mL N,CO2 ·g −1 ·h −1 ). Materials were compared in terms of CO 2 conversion and CH 4 selectivity. Still, their performances were assessed in a short stability test (24 h) performed at 350 • C. All catalysts were characterized by temperature programmed reduction (TPR), X-ray diffraction (XRD), N 2 physisorption at −196 • C, inductively coupled plasma optical emission spectrometry (ICP-OES), and H 2 /CO chemisorption. The catalysts with the best performance (i.e., the hydrotalcite-derived NiMgAl and Ru/NiMgAl) seem to be quite promising, even when compared with other methanation catalysts reported in the literature.Extended stability experiments (240 h of time-on-stream) were performed only over NiMgAl, which was selected based on catalytic performance and estimated price criteria. This catalyst showed some deactivation under conditions that favor CO formation (high temperature and high WHSV, i.e., 350 • C and 24,000 mL N,CO2 ·g −1 ·h −1 , respectively), but at 300 • C and low WHSV, excellent activity (ca. 90% of CO 2 conversion) and stability, with nearly complete selectivity towards methane, were obtained. This is particularly relevant whenever the destination of methane is the injection into gas grid infrastructures, where the content of species like CO should be in accordance with natural gas specifications (typically a content up to 0.5 mol % can be tolerated (e.g., [8])). Hence, highly active and methane-selective catalysts for CO 2 methanation are required. In addition, catalyst stability under dynamic operation, i.e., with the capacity to withstand temperature variations, is also quite important and particularly relevant for application in PtM processes, where the reactor is operated intermittently and whenever surplus renewable power for H 2 production is available [6].Many metals have been tested for CO 2 methanation, for instance, Ni, Ru, Rh, Pd, and Co. Among these, ruthenium and nickel catalysts supported over various materials (e.g., Al 2 O 3 , SiO 2 , TiO 2 , CeO 2 , or ZrO 2 ) stand out [9,10]. Ruthenium-based catalysts have been reported in the literature, as well as in the catalogs of some catalyst suppliers (e.g., [11,12]), to be more suited for operation at low temperatures (T<200 • C), where CO formation is inhibited due to both restricted kinetics and the endothermic nature of the parallel RWGS reaction. On the other hand, nickel-based are the most widely investigated and commercialized catalysts for CO 2 methanation due to their high activity, availability, and low cost [4]. Improvement in their catalytic performance has been reported with hydrotalcite-derived Ni catalysts [13][14][15], as well as when combining nickel with ruthenium in the same bimetallic catalyst [16]. The use of hydrotalcite-derived Ni materials has also another important feature,...

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Thermodynamic analysis of the CO2 methanation reaction with in situ water removal for biogas upgrading

Cited by 49 publications

References 34 publications

Thermodynamic Analyses of a Moderate-Temperature Process of Carbon Dioxide Hydrogenation to Methanol via Reverse Water–Gas Shift with In Situ Water Removal

Thermodynamic Analyses of a Moderate-Temperature Process of Carbon Dioxide Hydrogenation to Methanol via Reverse Water–Gas Shift with In Situ Water Removal

Modeling and Simulation of a Steam-Selective Membrane Reactor for Enhanced CO₂ Methanation

CO2 Methanation over Hydrotalcite-Derived Nickel/Ruthenium and Supported Ruthenium Catalysts

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Thermodynamic analysis of the CO2 methanation reaction with in situ water removal for biogas upgrading

Cited by 49 publications

References 34 publications

Thermodynamic Analyses of a Moderate-Temperature Process of Carbon Dioxide Hydrogenation to Methanol via Reverse Water–Gas Shift with In Situ Water Removal

Thermodynamic Analyses of a Moderate-Temperature Process of Carbon Dioxide Hydrogenation to Methanol via Reverse Water–Gas Shift with In Situ Water Removal

Modeling and Simulation of a Steam-Selective Membrane Reactor for Enhanced CO2 Methanation

CO2 Methanation over Hydrotalcite-Derived Nickel/Ruthenium and Supported Ruthenium Catalysts

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Modeling and Simulation of a Steam-Selective Membrane Reactor for Enhanced CO₂ Methanation