H2 Production Process Research Articles

Experimental investigation of the Ca-Cu process for H2 production: Evaluation of reduction/calcination strategies

The exothermic reduction of the CuO present in a bed of solids (39% wt. CuO, 24.5% wt. CaCO3 and 1.5% wt. Ni, being the rest inert species for the process) with a fuel gas, generated a pure CO2 stream once steam was condensed (and free of N2). In this way, a Cu/Ca molar ratio of approximately 2 in the bed of solids allowed for CaCO3 calcination efficiencies of around 95% molar basis at the reducing gases break-through. This allowed performing consecutive cycles of the main reaction steps involved in the Ca/Cu H2 production process. The mixture CaO-based sorbent, reforming catalyst and Cu-based material was able to produce a gas stream with a 94.0% vol. H2 at 10 bar during the CH4 sorption enhanced reforming stage. The Cu-based material was oxidized with a highly diluted air stream at 10 bar, reacting in a well defined reaction front. A pure CO2 gas stream was obtained at reactor exit during the calcination/reduction stage with a fuel gas typical composition of a Steam Methane Reforming (SMR) stage with low steam to carbon molar ratio (S/C). The experimental results indicated that it was possible to cool the bed and to produce a syngas with a H2/CO molar ratio of about 3.5 suitable for its use in the calcination/reduction stage, in a SMR stage with low (S/C). It was also possible to perform the calcination/reduction and SMR in one single stage.

Cost‐competitive methane steam reforming in a membrane reactor for H 2 production: Technical and economic evaluation with a window of a H 2 selectivity

Techno-economic viability studies of employing a membrane reactor (MR) equipped with H2 separation membranes for methane steam reforming (MSR) were carried out for H2 production in Korea using HYSYS®, a well-known chemical process simulator, including economic analysis based on itemized cost estimation and sensitivity analysis (SA). With the reaction kinetics for MSR reported by Xu and Froment, the effect of a wide range of H2 selectivity (10-10,000) on the performance in an MR was investigated in this study. Because of the equilibrium shift owing to the Le Chatelier's principle, great performance of enhancement of methane conversion ( ) and H2 yield and reaction temperature reduction was observed in an MR compared with a packed-bed reactor (PBR). A window of a H2 selectivity from 100 to 300 is proposed as a new criterion for better MR performance of MSR depending on potential applications from in-depth analysis of and H2 yield enhancements, a H2 purity, and temperature reduction. In addition, economic analysis to evaluate the feasibility of an MR technology for MSR was carried out focusing on a levelized cost of H2 based on itemized cost estimation of capital and operating costs as well as SA. Techno-economic assessment showed 36.7% cost reduction in an MR compared with a PBR and revealed that this MR technology can be possibly opted for a cost-competitive H2 production process for MSR.

Experimental Investigation of the Ca-Cu Process for H2 Production: Evaluation of Reduction/Calcination Strategies

The exothermic reduction of the CuO present in a bed of solids (39 % wt. CuO, 20 % wt. CaCO3 and 1.5 % wt. Ni, being the rest inert materials) with a fuel gas, generated a pure CO2 stream once steam was condensed (and free of N2). In this way, a Cu/Ca molar ratio of approximately 2 in the bed of solids allowed for CaCO3 calcination efficiencies of around 95 % molar basis at the reducing gases break-through. This allowed performing consecutive cycles of the main reaction steps involved in the Ca/Cu H2 production process. The mixture CaO-based sorbent, reforming catalyst and Cu-based material was able to produce a gas stream with a 94.0 % vol. H2 at 10 bar during the CH4 sorption enhanced reforming stage. The Cu-based material was oxidized with a highly diluted air stream at 10 bar, reacting in a well defined reaction front. A pure CO2 gas stream was obtained at reactor exit during the calcination/reduction stage with a fuel gas typical composition of a SMR stage at high temperature. The experimental results indicated that it was possible to cool the bed and to produce a syngas with a H2/CO molar ratio of about 3.5 suitable for its use in the calcination/reduction stage, in a SMR stage at high temperature. It was also possible to perform the calcination/reduction and SMR in one single stage.

Biohydrogen production from alkaline wastewater: The stoichiometric reactions, modeling, and electron equivalent

Hydrogen gas (H2) is the cleanest energy carrier with 142 kJ/g energy content and without toxic byproducts release during combustion. There is interest to H2 production by biological process from sustainable resources including municipal and industrial wastewater and also solid waste. Here, we describe the biohydrogen production that involves first survey the effect of alkalinity on biohydrogen production based on stoichiometric reaction, followed by the electron equivalent balances determination and examination of prediction capability of Gamperts model for biohydrogen production.•The method uses a dark fermentation biological process for H2 production from wastewater.•As the influent alkalinity increased, the hydrogen production increased and then promptly descended.•The predicted gas volume, based on Gamperts model confirmed good agreement with experimental value.

Novel microreactors of polyacrylamide (PAM)[sbnd]CdS microgels for admirable photocatalytic H2 production under visible light

Cadmium sulfide, with its narrow band gap, can be used as a photocatalyst in the visible light region for the splitting of water, but its limited number of active sites and tendency to agglomerate are problematic for producing high yields of hydrogen. Therefore, an inverse emulsion polymerization method was used to fabricate polyacrylamide (PAM) microgels as a substrate to immobilize CdS nanoparticles (PAM-CdS). The PAM microgels not only immobilized the CdS nanoparticles, but also prevented aggregation. NCd bonds in the PAM-CdS microgels facilitated electron transfer from the PAM to the CdS resulting in more electrons participating in the H2 production process. The electrostatic interactions between the PAM and CdS also hindered the recombination of electron-hole pairs. These PAM-CdS microgels exhibit admirable photocatalytic H2 production performance with a H2 production rate of up to 5.21 mmol h−1 g−1.

Theoretical Study on PdCu/CeO2-Catalyzed Water–Gas Shift Reaction: Crucial Role of the Metal/Ceria Interface and O2 Enhancement Effects

Low-temperature water–gas shift (LT-WGS) is an important process for H2 production and purification. Recently, as promising LT-WGS catalysts, PdCu and PtCu bimetallic catalysts supported on ceria have been found. Existing studies showed that the addition of a small quantity of O2 not only promoted CO conversion but also enhanced the production of H2. In this study, by using density functional theory and microkinetic models, we investigated the reaction mechanisms of WGS reaction catalyzed by a PdCu/CeO2 catalyst and deciphered the underlying reasons for the O2 enhancement phenomenon. We compared the catalytic performance of the unsupported PdCu metal to that of the PdCu/CeO2 interface structures and found that only the PdCu/CeO2 interface structure was active toward WGS. The unsupported metal was incapable of activating water, whereas the metal and ceria sites on the interface structure work in tandem to activate water and promote CO conversion. With the addition of O2, WGS proceeded through a OH migratio...

AgI-BiOI-graphene composite photocatalysts with enhanced interfacial charge transfer and photocatalytic H2 production activity

BiOI-based photocatalysts were proved to exhibit photocatalytic H2 production activity. AgI-BiOI-graphene showed better H2 production activity than BiOI and BiOI-graphene. The surface chemistry, electronic property, phase structure, morphology, optical property and photocatalytic performance of these photocatalysts were studied. The interfacial electronic states of the photocatalysts were investigated through their C K-edge near-edge X-ray-absorption fine-structure (NEXAFS) spectra. Based on the in situ NEXAFS spectra measured with and without illumination, a mechanism about the transport of photoelectron from AgI to graphene through BiOI is proposed for the photocatalytic H2 production process. The incorporation of graphene restricted the three-dimensional self-assembly of BiOI nanocrystals and led to the formation of less extensively crystallized BiOI domains through a confined-space effect. Addition of AgNO3 precursor altered the crystal structure of BiOI from flower-like to horizontally stacked flat plates. The results of NEXAFS spectra, photoluminescence spectra and photocurrent tests reveal that the improved photocatalytic activity of the AgI-BiOI-graphene photocatalyst is attributable to the interfacial interaction among AgI, BiOI and graphene, which enhanced the separation of photogenerated electrons to generate H2. AgI-BiOI-graphene photocatalyst was a stable photocatalyst for the production of H2. After three cycles, 86% activity of recycled photocatalysts was retained.

Experimental Testing of a Bi-Functional Material Cu-Cao Composite within the Ca/Cu H2 Production Process

A novel CaO/CuO based composite material (53 wt% CuO/ 22 wt% CaO/ 25 wt% Ca12Al14O33), developed for combined CO2 capture and heat transfer for the Ca/Cu hydrogen production process, showed a maximum CO2 capture rate of 1.53*10-2 kmol CO2/h.kg material, at a linear gas velocity of 0.55 m/s when operating in a fixed bed reactor in presence of a commercial reforming catalyst during methane Sorption Enhanced Reforming (SER). The system was able to convert up to 2.4 kg CH4/h.kg catalyst, producing a gas stream with over 93 % vol. hydrogen (dry basis) at 10 bars for a steam to carbon molar ratio of 3.2.

Process kinetic studies of biohydrogen production by co-fermentation of fruit-vegetable wastes and cottage cheese whey

Hydrogen (H2) is considered as fuel for future and its biological production from renewable feedstocks is very promising. Dark fermentation of fruit-vegetable waste (FVW) and cottage cheese whey (CCW) for the production of H2 constitutes a promising way for combining energy generation and lignocellulosic waste management. In this work, process kinetics of biohydrogen production via dark fermentation of FVW and CCW by pretreated anaerobic sludge inocula were investigated. To inhibit H2 consuming methanogens, the effects of various inoculum pretreatment, viz., 2-bromoethanesulfonate, heat-shock, acid, alkali, UV, and ultrasonication on H2-production were investigated which revealed 2-bromoethanesulfonate, heat-shock and acid-treated inoculum resulted in maximum bioH2 production and yield of 118.12 ± 1.05, 93.37 ± 1.3, 96.32 mMol/L and 1.66, 1.22 ± 0.01, 1.39 ± 0.02 mMol/gCODinitial, respectively. The effects of system initial pH, substrate to inoculum (S0/X0) and carbon to nitrogen (C/N) ratio on H2-production were evaluated which revealed maximum H2 production and yield could be achieved at pH 7, S0/X0 of 10.6 gCOD/gVS, and C/N 26.8. Modified Gompertz model and Modified Logistic model were used to define various kinetic parameters pertaining to cumulative H2-production which showed high R2 values (≥0.98). The influence of pH on H2 and ethanol/volatile fatty acids production kinetics were evaluated using Andrew's and Ratkowsky's model showing relatively good R2 values (≥0.62). Remarkably high production of ethanol (2.43 ± 0.28 mg/L) was noticed alongside H2 production at pH 7 suggesting that bioethanol can be recovered at the end of fermentative H2 production. Terminal Restriction Fragment Length Polymorphism and 16s rDNA sequencing revealed dominance of 9 bacterial species such as Escherichia coli, Clostridium butyricum, Streptococcus henryi, and 6 others uncultured bacteroides. This research determined different kinetic parameters for an enhanced H2 production strategy by co-fermentation of FVW and CCW providing an understanding of process behavior which will in turn help in the upscaling of the H2-production processes.

Complete Ca/Cu cycle for H2 production via CH4 sorption enhanced reforming in a Lab-Scale fixed bed reactor

The three main reaction stages of a H2 production process based on the combination of the CaO/CaCO3 and Cu/CuO loops have been experimentally studied in a lab scale fixed bed reactor. The solid bed contained the three functional materials required to run the process, namely a commercial Ni-based catalyst, a CaO-Ca12Al14O33 CO2 sorbent and a CuO-Al2O3 material in a proportion that resulted in a bed with 43.3% wt. CuO, 25.6% wt. CaO and 1.7% wt. Ni. The system was able to convert 13.5 kg CH4 h−1 kg Ni−1, at 675 °C producing a gas stream with a 93.5% vol. H2 at 10 bar. The Cu-based material presented high oxidation kinetics, being totally converted in a narrow reaction front with a highly diluted air stream at 10 bar. The Cu-based material presented also fast reduction kinetics and it was completely converted with a fuel gas with typical composition of a Steam Methane Reforming stage at high temperature. A Cu/Ca molar ratio of 2 allowed for calcination efficiencies over 85% molar basis at the CO and H2 break-through, and 95% of the CO2 from CaCO3 exited the reactor at CH4 break-through. The experimental results have been validated with an existing pseudo homogeneous reactor model that had been developed in previous works for the three reaction stages. The model was able to predict product gas compositions, bed breakthrough, and temperature profiles along bed.

Screening of Ni-Cu bimetallic catalysts for hydrogen and carbon nanofilaments production via catalytic decomposition of methane

The catalytic decomposition of methane (CDM) is a H2 production process in which the CO2 emission of conventional processes is avoided and from which carbon nanofilaments can be obtained as a high added value by-product. In this work, we present a thermogravimetry-based screening of catalysts according to their carbon production in the CDM reaction. Catalysts studied were based on Ni as active phase, using two textural promoters (Al2O3 or MgO) and Cu as dopant element in different proportions: 2.5, 5.0, 7.5 and 10 mol %. Cu doping resulted in an increase in both the maximum temperature of activity (>100 °C) and the carbon formation rate, which were maximum for a Cu content of 7.5 mol %, regardless of the textural promoter used. The formation of a solid solution of Ni(x)Cu(1-x), with lattice constants and particle size distribution highly dependent on the Cu content, led to the formation of fishbone carbon nanofibers with different morphological features, such as the α angle between the graphene stacks and the growth axis of the nanofilament, the diameter, the length and the formation or not of an inner hollow.

Determination of the oxidation kinetics of high loaded CuO-based materials under suitable conditions for the Ca/Cu H2 production process

In this work, the oxidation reaction of high loaded CuO-based materials was investigated under atmospheric and pressurized conditions. The oxygen transport capacity of the materials was firstly tested in the TGA and no losses greater than 5% were observed along 100 oxidation/reduction cycles. The kinetic parameters governing the oxidation reactions of the selected CuO-based materials were determined using a shrinking core model with chemical reaction control. The experimental results suggested that a SCM with chemical reaction control is able to predict the oxidation conversion of high loaded CuO-based materials in powder and pellet form. On the other hand, the effect of total pressure on materials reactivity was analyzed. The kinetic parameters obtained under atmospheric conditions were applied to fit the experimental data obtained under pressurized conditions. The results confirmed that the pressure has not an important effect on the oxidation kinetics of high loaded CuO-based materials and the parameters obtained at atmospheric pressure can be applied to study the oxidation under pressurized conditions.

Development of Suitable CuO-Based Materials Supported on Al2O3, MgAl2O4, and ZrO2 for Ca/Cu H2 Production Process

Functional materials for the sorption enhanced reforming process for H2 production coupled to a Cu/CuO chemical loop have been synthesized. The performance of CuO-based materials supported on Al2O3, MgAl2O4, and ZrO2 and synthesized by different routes has been analyzed. Highly stable materials supported on Al2O3 or MgAl2O4 synthesized by coprecipitation and mechanical mixing with sufficient Cu loads (around 65% wt) have been successfully developed. However, it has been found that coprecipitation under these conditions is not a suitable route for ZrO2. Spray-drying and deposition precipitation did not provide the best chemical features to the materials. As the Ca/Cu process is operated in fixed bed reactors, the best candidates were pelletized and their stability was again assessed. Pellets with high chemical and mechanical stability, high oxygen transport capacity, and good mechanical properties have been finally obtained by coprecipitation. The good homogeneity that provides this route would allow an ea...

Chemical looping hydrogen production using activated carbon and carbon black as multi-function carriers

The application of a chemical looping process for methane thermo-catalytic decomposition using activated carbon (AC) as a catalyst has been recognized as an advanced process for continuous high-purity H2 production in the carbon constrained world due to its low CO2 formation. AC is able to provide reasonable kinetics, however, it suffers from fast deactivation. Deep regeneration of spent AC catalyst using steam is able to eliminate catalytic deactivation, and this process sacrifices part of the catalyst. The catalytic performance of AC and carbon black (CB) catalysts exhibit opposite deactivation behavior with time. AC provides a better activity, but it deactivates quickly. Though the catalytic activity of CB is low, its activity not only can be maintained, but also shows an increase during the test. Our approach for AC modification was inspired by analyzing the factors that lead to the different performance. Results indicate that the catalytic performance of AC and CB exhibit opposite deactivation behavior with time, and the deposited carbon on their surfaces are in different shape, orientation, and chemical structure. The outward growing cone-like graphene layers and tubular-shaped nanostructures are key factors that help maintain the catalyst's porosity and activity; and the cause of different deposit carbon may be attributed to the irregular, cross-linking graphene layers of AC and the spherical bent graphene layers of CB.

Theoretical investigation of aerobic and anaerobic oxidative inactivation of the [NiFe]-hydrogenase active site.

The extraordinary capability of [NiFe]-hydrogenases to catalyse the reversible interconversion of protons and electrons into dihydrogen (H2) has stimulated numerous experimental and theoretical studies addressing the direct utilization of these enzymes in H2 production processes. Unfortunately, the introduction of these natural H2-catalysts in biotechnological applications is limited by their inhibition under oxidising (aerobic and anaerobic) conditions. With the aim of contributing to overcome this limitation, we studied the oxidative inactivation mechanism of [NiFe]-hydrogenases by performing Density Functional Theory (DFT) calculations on a very large model of their active site in which all the amino acids forming the first and second coordination spheres of the NiFe cluster have been explicitly included. We identified an O2 molecule and two H2O molecules as sources of the two oxygen atoms that are inserted at the active site of the inactive forms of the enzyme (Ni-A and Ni-B) under aerobic and anaerobic conditions, respectively. Furthermore, our results support the experimental evidence that the Ni-A-to-Ni-B ratio strongly depends on the number of reducing equivalents available for the process and on the oxidizing conditions under which the reaction takes place.

Hydrogen Production by γ-Ray Irradiation from Different Types of Zeolites in Aqueous Solution

Dihydrogen (H2) production via irradiation of zeolite–water mixtures was studied to investigate the effect of zeolites on the reaction process for H2 production. Four types of zeolites were comparatively examined under anoxic and aerated conditions. High yields of H2 were observed for the zeolites with high aluminum contents, A-type and X-type zeolites, compared to the Y-type and mordenite-type zeolites. The difference in the H2 yields was considerable at weight fractions of water below 50 wt % under anoxic conditions. The experimental results demonstrated a reaction pathway for H2 production that has different yields between the four zeolites. The H2 yields were compared with chemical analyses of the zeolites, and the comparison suggested that the extraframework aluminum species in the zeolites are involved in the reaction pathway for H2 production. On the other hand, under aerated conditions, the H2 yields from the zeolites were lower than under anoxic conditions probably due to the H2O2 that was produc...

Sorption enhanced steam methane reforming on catalyst-sorbent bifunctional particles: A CFD fluidized bed reactor model

Sorption Enhanced Steam Methane Reforming (SE-SMR) has been proposed as an efficient novel technology to increase hydrogen yield and reduce the environmental footprint in comparison to state of art H2 production processes. Sorbent/catalyst materials characterized by stable behaviour over multiple reforming/calcination cycles may ensure to achieve almost stationary operating conditions utilizing a dual fluidized bed system (the reformer and the sorbent regenerator) with a solid circulation loop. Bifunctional, Combined Sorbent-Catalyst Materials (CSCM) are under development to integrate endothermic catalytic reforming and heterogeneous CO2 sorption in one particle, decrease mass and heat transfer resistances and reduce the solid hold-up in the reactors.This paper deals with the numerical simulation of a pilot scale bubbling fluidized bed SE-SMR reactor by means of a Two-Dimensional Computational Fluid-Dynamic (2D CFD) approach. The hydrodynamic picture is supplemented with a comprehensive Particle Grain Model (PGM) previously developed to describe the kinetics of catalytic and sorption functions, and successfully validated with micro-reactor reactivity tests and multi-cycle thermo-gravimetric sorption tests. The effect of repeated carbonation-calcination steps (the “history” of the granular material) is included in the computation of the reactor performance by utilizing the appropriate size of the sorbent grains in the carbonation rate expression.The numerical results show quantitatively the positive influence of carbon dioxide sorption on the reforming process, at different operating conditions, specifically the enhancement of hydrogen yield and reduction of methane residual concentration in the reactor outlet stream. A preliminary validation of CFD simulations is also carried out utilizing experimental data obtained from a pilot scale bubbling fluidized bed SE-SMR reactor (total bed mass≈14kg).An estimate is provided for the inward heat flow that would be required to operate the reactor in stationary temperature conditions: it is substantially reduced by the exothermic sorption process and could be satisfied by means of the solid circulation loop connecting the SE-SMR reactor to the high temperature calciner in the whole dual fluidized bed system.

High purity hydrogen production from sorption enhanced chemical looping glycerol reforming: Application of NiO-based oxygen transfer materials and potassium promoted Li2ZrO3 as CO2 sorbent

Ni based oxygen transfer materials (OTMs) and Li2ZrO3 based sorbent have been synthesized for their potential use in a sorption enhanced chemical looping steam reforming (SE-CLSR) process. Ni based OTMs were firstly tested under chemical looping steam reforming (CLSR) process and the gaseous products with temperature variety during this process were measured and analyzed. Experimental results indicated that both of the OTMs exhibited good activities and stability during multiple glycerol reduction-air oxidation cycles towards H2 production. The desired maximum hydrogen selectivities of 87.9% and 84.7% were obtained for NiO/NiAl2O4 and NiO/ZrO2 for steam to carbon ratio of 3 at 550°C. The fuel feed step of reduction process could be divided into two periods with the OTMs possessing a dual function of oxygen carrier and catalyst. The decrease of conversions and selectivity for both OTMs was mainly due to the coke deposition, which reduced the catalytic effect in the reforming reaction as well as the oxygen transfer effect in the reduction reaction. Sorption enhanced chemical looping steam reforming (SE-CLSR) process for H2 production with in-situ CO2 removal was carried out with OTM/sorbent ratio of 1 and multi-cyclic reaction/regeneration processes under 550°C/850°C with a steam/carbon ratio of 3 was also achieved. H2 purity were both enhanced by the two OTMs and sorbent in SE-CLSR. Therefore, it is possible to utilize oxygen from NiO and steam to oxidize glycerol, while enhancing the water-gas-shift reaction by capturing CO2 at the same time.

Techno-economic assessment of hydrogen production based on dual fluidized bed biomass steam gasification, biogas steam reforming, and alkaline water electrolysis processes

In this paper, three CO2-neutral H2 production processes were investigated. The three employed technologies were dual fluidized bed (DFB) biomass steam gasification, biogas steam reforming (BSR), and alkaline electrolysis (AEL) powered by renewable electricity with their necessary downstream separation and purification process steps. Aspen Plus process simulations were carried out in order to calculate the mass and energy balances of the three processes. In addition, a techno-economic assessment was carried out for a fictitious business producing H2 at a rate of 90kgh−1 in Austria in 2016. This assumption was used so that the economic feasibility of these investigated processes could be directly compared.The simulation results show that the DFB biomass steam gasification process has a higher H2 conversion rate (51.4%) but a lower fuel based H2 production efficiency (38.9%) than the BSR process (27.2% and 47.0%, respectively). Moreover, the alkaline electrolysis process shows the highest energy based H2 conversion efficiency at about 66%.The results of the economic assessment show that the DFB biomass steam gasification process has investment costs of 12.1 MEUR followed by the biogas steam reforming process with investment costs of 9.9 MEUR. The alkaline electrolysis process has investment costs of 4.4 MEUR. However, the after tax H2 break-even price of the DFB process is the lowest with 0.148EURkWh−1. The BSR process has an after tax H2 break-even price of 0.152EURkWh−1 and the AEL process has an after tax H2 break-even price of 0.191EURkWh−1. The net present value (NPV) calculations reveal that the BSR process has the highest NPV, followed by the AEL process and the DFB biomass steam gasification process. However, the NPV of all three processes are very similar. In general, all three H2 production processes perform at the same level based on the results of the process simulation and the chosen economic assumptions.

Validation of the H2 production stage via SER under relevant conditions for the Ca/Cu reforming process practical application

The joint performance of a CaO-based sorbent and a Ni-based commercial catalyst has been assessed under relevant conditions for the SER stage in the Ca/Cu H2 production process. These conditions comprise processing CH4 space velocities suitable for the scaling up of the process, operation of the system at pressure, and testing materials that had experienced up to 200 oxidation/reduction cycles. The system, catalyst and CaO-based sorbent, was able to fulfil the SER equilibrium composition up to 2.5kgCH4h−1kgcat−1, CH4 space velocity that would allow the scaling up of the process. In this way, a gas stream containing up to 95% vol. H2 was obtained at 923K, steam to carbon ratios of 3.2 and 4, sorbent to catalyst weight ratios from 4 to 15 and for operation pressures between 1 and 9bar. The effect of oxidation/reduction cycles on catalyst performance was assessed, and the mixture sorbent and aged catalyst was able to process up to 2.5kgCH4h−1kgcat−1, corroborating the operational limit determined for the fresh materials.The total operation pressure (from 1 to 9bar) did not have an important influence on H2 yield, and/or materials performance. Sorbent carbonation reaction rates up to 4.42*10−2kmolh−1kgsorb−1 were determined in the experiments, being this parameter responsible of the limit in CH4 space velocity that can be successfully converted through this sorbent/catalyst system. The experimental results have been successfully described by a pseudo-homogeneous reactor model that incorporates the main kinetic expressions of the reactions involved in the SER stage.