Pd Ag Membrane Reactor Research Articles

Parametric and sensitive analysis of Pd-Ag membrane reactor performance in biogas reforming to generate decarbonized hydrogen by Computational Fluid Dynamic-Response Surface Methodology

The efficient production of hydrogen from renewable sources is pivotal for the development of sustainable energy systems. Biogas steam reforming (BSR) conducted in palladium-based membrane reactors (MRs) offers a pathway for high-purity H2 generation at lower temperatures compared to traditional processes. In this study, a computational fluid dynamics (CFD) model was developed to simulate the BSR process within a Pd-Ag MR. The CFD model has integrated comprehensive kinetics, mass transport, and hydrodynamics, and its accuracy was confirmed through validation against experimental data, demonstrating substantial agreement. As a novel approach, to optimize the BSR reaction conditions to get the best MR performance, the CFD model was coupled with response surface methodology (RSM), which has been employed to enable the identification of optimal values for key parameters such as reaction temperature, pressure, gas hour space velocity, feed molar ratio, and sweep gas ratio, where the temperature was found to have the most significant impact on the MR’s performance within the examined intervals of input parameters. The objective of RSM method applied to CFD modeling was to maximize with high accuracy CH4 conversion, H2 recovery, and reduce CO2 emissions. RSM models effectively established correlations between input parameters and responses. The determined optimal conditions for the BSR process were a temperature of 683 K, a reaction pressure of 6 bar, a GHSV of 3000 h−1, a H2O/CH4 ratio of 1.34, and a sweep ratio of 9. Under these conditions, the system achieved remarkable results with 100 % CH4 conversion, 43 % H2 recovery, and an 81 % reduction in CO2 emissions. This study underscores the effectiveness of integrating CFD with RSM for the precise modeling and optimization of MRs in BSR reactions. The synergy between these approaches provides a robust framework for advancing the efficiency and sustainability of hydrogen production processes from renewable sources.

Use of Pd-Ag Membrane Reactors for Low-Temperature Dry Reforming of Biogas-A Simulation Study.

Biogas is a valuable renewable energy source that can help mitigate greenhouse emissions. The dry reforming of methane (DRM) offers an alternative hydrogen production route with the advantage of using two main greenhouse gases, CO2 and CH4. However, its real application is limited mainly due to catalyst deactivation by coke formation and the reverse water gas shift (RWGS) reaction that can occur in parallel. Additionally, the typical dry reforming temperature range is 700-950 °C, often leading to catalyst sintering. A low-temperature DRM process could be in principle achieved using a membrane reactor (MR) to shift the dry reforming equilibrium forward and inhibit the RWGS reaction. In this work, biogas reforming was investigated through the simulation of MRs with thin (3.4 µm) and thick (50 µm) Pd-Ag membranes. The effects of the feed temperature (from 450 to 550 °C), pressure (in the range of 2-20 bar), and biogas composition (CH4/CO2 molar ratios from 1/1 to 7/3) were studied for the thin membrane through the calculation and comparison of several process indicators, namely CH4 and CO2 conversions, H2 yield, H2/CO ratio and H2 recovery. Estimation of the CO-inhibiting effect on the H2 molar flux through the membrane was assessed for a thick membrane. Simulations for a thin Pd-Ag MR show that (i) CO2 and CH4 conversions and H2 yield increase with the feed temperature; (ii) H2 yield and average rate of coke formation increase for higher pressures; and (iii) increasing CH4/CO2 feed molar ratio leads to higher H2/CO ratios, but lower H2 yields. Moreover, simulations for a thick Pd-Ag MR showed that the average H2 molar flux decreases due to the CO inhibiting effect (ca. 15%) in the temperature range considered. In conclusion, this work showed that for the considered simulation conditions, the use of an MR leads to the inhibition of the RWGS reaction and improves H2 yield, but coke formation and CO inhibition on H2 permeation may pose limitations on its practical feasibility, for which proper strategies must be explored.

Thermodynamic performance of solar-driven methanol steam reforming system for carbon capture and high-purity hydrogen production

• A solar MSR system via HPM reactor for high-purity hydrogen generation is proposed. • The conversion rate of methanol could exceed 99.9% between 150 and 250 °C. • The solar-to-fuel efficiency can reach 55.22% with 94.1% hydrogen separation. • Thermodynamic efficiencies of the system around a year is stable. • Standard coal saving rate is as high as 0.63 t/m 2 annually in this reactor. Solar energy storage via a thermochemical approach is a promising method to realize the efficient utilization of discontinuous sunlight. Traditional solar thermochemical conversion with the assistant of hydrocarbon requires the purification process of products, and a relatively high reaction temperature limits its thermodynamic efficiency. In this work, a thermodynamic study on solar-driven methanol steam reforming reaction in a Pd-Ag membrane reactor has been conducted. The partial pressure, conversion rate, and thermodynamic efficiency are studied and analyzed under different reaction temperatures (150–250 ˚C) and permeate pressures (10 −3 -1 bar). Via the membrane reactor, the equilibrium of reaction shifts forward and the conversion rate of methanol can reach as high as above 99.9% in 150–250 ˚C, and purified hydrogen and carbon dioxide can be collected separately. Under the optimized reaction temperature and pressure, the solar-to-fuel efficiency and exergy efficiency can reach as high as 55.2% and 74.79%, respectively. Due to the utilization of solar energy and membrane reactor, the annual coal saving rate and carbon dioxide reduction rate are predicted to be 0.63 t/m 2 and 1.53 t/m 2 , respectively. This thermodynamic research provides an efficient approach for solar energy conversion and storage without CO 2 emission.

Dry Reforming of Methane in a Pd-Ag Membrane Reactor: Thermodynamic and Experimental Analysis

The present work is a study of CO2 Reforming of Methane (DRM) carried out in a catalytic Pd-based membrane reactor. A detailed thermodynamic analysis is carried out, calculating the chemical equilibrium parameters in two different cases: (a) DRM along with the Reverse Water Gas Shift (RWGS) reaction and (b) DRM along with both RWGS and the Boudouard Reaction (BR). The performance of membrane reactor is then experimentally analyzed in terms of methane conversion, hydrogen recovery and H2/CO reaction selectivity by varying feed pressure and CO2/CH4 feed molar ratio and 500 °C and GHSV = 100 h−1. Among the obtained results, a CH4 conversion of about 26% and a H2 recovery of 47% are achieved at low feed pressures, exceeding the traditional reactor equilibrium conversion. This effect can be attributed to the favorable thermodynamics coupled to the hydrogen permeation through the membrane. This study further demonstrates the general effectiveness of membrane-integrated reaction processes, which makes the production of syngas more efficient and performing, providing important environmental benefits.

Theoretical study of hydrogen production by ethanol steam reforming: Technical evaluation and performance analysis of catalytic membrane reactor

Ethanol steam reforming over a Co/Al2O3 catalyst was studied theoretically in a catalytic PdAg membrane reactor (CMR). A mathematical model has been developed to elucidate the behavior of CMR by taking into account the chemical reactions, heat and mass transfer phenomena. The effect of operating parameters on the performance of CMR has been evaluated in terms of ethanol conversion, hydrogen recovery and hydrogen yield. The results revealed the high performance of this configuration is related to the continuous removal of hydrogen from the retentate side, shifting the reaction equilibrium towards hydrogen formation. Sensitivity analysis of operating parameters indicate that ethanol conversion is favored at higher temperatures, pressures, sweep ratios and feed molar ratios. Moreover, increasing the feed molar ratio enhances the ethanol conversion, and decreases the hydrogen recovery due to reduction of partial pressure of hydrogen and consequently decreasing the driving force for the hydrogen permeation through the membrane.

Theoretical evaluation of Pd[sbnd]Ag membrane reactor performance during biomass steam gasification for hydrogen production using CFD method

In recent years, biomass has been introduced as a promising solution for environmental crisis. Biomass steam gasification is a valuable process for hydrogen production. Main problem of this process is low conversion and low partial pressure of hydrogen in product stream. PdAg membrane reactor (MR) can be used in biomass steam gasification to improve the process efficiency. Hence, Computational fluid dynamic (CFD) method was used in this study for a detail modeling and analyzing the biomass steam gasification in a two-dimensional PdAg MR. After good agreement of CFD model results with literature experimental data, simulation results was indicated that the PdAg MR has better efficiency compared with traditional reactor (TR). Biomass conversion of near 100%, CO selectivity in the range 0–14 and H2 recovery of 70% in the best condition were achieved. In addition, different flow patterns (cocurrent and counter-current modules) were compared for MR and overall efficiency (biomass conversion) of counter-current model was obtained higher than co-current model. In summary, for all operating conditions and modules, PdAg MR was showed better efficiency compared with TR.

Hydrogen production by a Pd[sbnd]Ag membrane reactor during glycerol steam reforming: ANN modeling study

In the present work, an artificial neural networks (ANNs) model has been developed for investigation of glycerol steam reforming (GSR) process with PdAg membrane reactor (MR) in the presence of Co/Al2O3 catalyst. Reaction pressure and sweep factor as independent variables (Inputs) and glycerol conversion, hydrogen recovery, hydrogen yield, H2 selectivity, CO selectivity and CO2 selectivity as dependent variables (outputs) are chosen for ANN modeling of GSR. The ANN model was developed by feed-forward back propagation network with trainlm algorithm and topology (2: 10: 6) and Sigmoid transfer function for hidden and output layers. A good agreement between predicted values using ANN with experimental results was observed (R2 and MSE values were 0.9998 and 3.48 × 10−6 (based on normalized data), respectively). Modeling results indicated that all selected factors (reaction pressure and sweep factor) were effective on output variables. It was found that the reaction pressure with a relative importance of 59% was the most effective parameter in the GSR process with PdAg MR in the presence of Co/Al2O3 catalyst.

Highly efficient methane reforming over a low‐loading Ru/γ‐Al2O3 catalyst in a Pd‐Ag membrane reactor

Natural gas can be reformed to syngas (CH4 + H2O = CO + 3H2), at temperatures above 850°C. Membrane catalytic reformers can provide high CH4 conversions at temperatures below 650°C, by separating H2 from the reactive mixture. Traditional Ni‐based catalysts suffer from low activity at low temperatures and deactivate rapidly by coking, particularly at low steam/carbon ratios. In this study, an ultralow loading (0.15 wt %) Ru/γ‐Al2O3 catalyst was implemented in a lab‐scale membrane reformer, using a supported 5μm Pd‐Ag film membrane. Methane conversions above 90% were achieved at 650°C, 8 bar, and H2O/CH4 = 2, 3 with contact times of ca. 10 s. The system generated up to 3.5 mol of ultrapure H2 per mol of CH4 fed, with a maximum power density of 0.9 kW/L. No significant deactivation was observed after 200 h time on stream, even when using low H2O:CH4 ratios. © 2018 American Institute of Chemical Engineers AIChE J, 64: 3101–3108, 2018

Production of Pure Hydrogen from Diesel Fuel by Steam Pre-Reforming and Subsequent Conversion in a Membrane Reactor

The results of experimental study and mathematical modeling of a fuel processor for the production of pure hydrogen from diesel fuel with a productivity of 600–700 g (H2)/h, consisting of an adiabatic reactor for diesel fuel pre-reforming followed by steam conversion of pre-reforming products in a catalytic Pd–Ag membrane reactor for hydrogen extraction are presented. The membrane reactor consists of 32 membrane modules arranged in 8 sections of 4 modules each. A mathematical model has been developed and two schemes of layout of the modules in the membrane reactor have been simulated. One scheme involves the cross-flow distribution of flue gas and fuel gas reformate to individual modules and leads to overheating of the input modules and cooling of the output modules. The other scheme with the cocurrent distribution of streams, along both the reactant path and the flue gas path, is preferable from the viewpoint of the temperature uniformity of different modules within a section. On the basis of the data obtained, an estimated calculation of the parameters of a power generation unit with a battery of low-temperature fuel cells has been made. For the example considered, the thermal efficiency of the fuel processor is 87%. With an efficiency of the fuel cell battery of 42%, the electrical efficiency of the fuel cell power unit will be 36%.

CFD analysis of Pd-Ag membrane reactor performance during ethylbenzene dehydrogenation process

In this study, the catalytic dehydrogenation of ethylbenzene (EB) to styrene production was investigated in a tubular Pd-Ag membrane reactor (MR) in presence of a commercial iron oxide catalyst. To this purpose, a 2D-axisymmetric, isothermal model based on computational fluid dynamic (CFD) method is presented to investigate the Pd-Ag MR performance during EB dehydrogenation process for styrene and hydrogen production. The proposed CFD model provides the local information of velocity, pressure and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of model results was carried out by experimental data and a good agreement between model results and experimental data was achieved. It was found that the efficient removal of hydrogen in the Pd-Ag MR could significantly increase the EB conversion. Moreover, using CFD simulation runs, effects of operating parameters such as reaction temperature, pressure and gas hour space velocity (GHSV) values on the Pd-Ag MR performance with two various flow patterns was evaluated in terms of EB conversion and COx-free hydrogen recovery. It can be concluded that the EB conversion realized in Pd-Ag MR with countercurrent flow is higher than the ones achieved for Pd-Ag MR with cocurrent flow and also for traditional reactor (TR) during EB dehydrogenation reaction, in all the studied cases. In particular, under the optimal reaction conditions, 40% enhancement in EB conversion can be obtained in the Pd-Ag MR with countercurrent flow with respect to TR.

Heavy water decontamination tests through a Pd-Ag membrane reactor: Water Gas Shift and Isotopic Swamping performances

A Pd-Ag membrane reactor has been studied to assess its ability in heavy water decontamination through Isotopic Swamping (IS) and Water Gas Shift (WGS) reactions under different operating conditions (i.e. reactor temperature, lumen pressure, feeding molar ratio and isotopic swamping). The reactor has been installed in a new facility of the ENEA Membrane Laboratory called HyFraMe, by testing two catalysts. The results are reported in terms of decontamination factor or DF (the amount of gaseous deuterium recovered from heavy water). Both catalysts demonstrate, in the WGS reactions, low methane production (1.72mol% in the worst case) and high DF, almost 80%, at pressure of 400–500kPa at 623K. The IS reaction tests exhibited a lower performance (DF=67% at the best).

Performance assessment and evaluation of catalytic membrane reactor for pure hydrogen production via steam reforming of methanol

The steam reforming of methanol was investigated in a catalytic Pd–Ag membrane reactor at different operating conditions on a commercial Cu/ZnO/Al2O3 catalyst. A comprehensive two-dimensional non-isothermal stationary mathematical model has been developed. The present model takes into account the main chemical reactions, heat and mass transfer phenomena in the membrane reactor with hydrogen permeation across the PdAg membrane in radial direction. Model validation revealed that the predicted results satisfy the experimental data reasonably well under the different operating conditions. Also the impact of different operating parameters including temperature, pressure, sweep ratio and steam ratio on the performance of reactor has been examined in terms of methanol conversion and hydrogen recovery. The modeling results have indicated the high performance of the membrane reactor which is related to continuous removal of hydrogen from retentate side through the membrane to shift the reaction equilibrium towards formation of hydrogen. The obtained results have confirmed that increasing the temperature improves the kinetic properties of the catalyst and increase in the membrane's H2 permeance, which results in higher methanol conversion and hydrogen production. Also it is inferred that the hydrogen recovery is favored at higher temperature, pressure, sweep ratio and steam ratio. The model prediction revealed that at 573 K, 2 bar and sweep ratio of 1, the maximum hydrogen recovery improves from 64% to 100% with increasing the steam ratio from 1 to 4.

The production of hydrogen through the use of a 77 wt% Pd 23 wt% Ag membrane water gas shift reactor

Hydrogen as an energy carrier has the potential to decarbonize the energy sector. This work presents the application of a palladium-silver (Pd–Ag) membrane-based reactor. The membrane reactor which is made from Pd–Ag film supported by porous stainless steel (PSS) is evaluated for the production of hydrogen and the potential replacement of the current two-stage Water-Gas Shift (WGS) reaction by a single stage reaction. The permeability of a 20 μm Pd–Ag membrane reactor was examined at 320 °C, 380 °C and 430 °C. The effect of continuous hydrogen exposure on the Pd–Ag membrane at high temperature and low temperature was examined to investigate the thermal stability and durability of the membrane. During continuous operation to determine thermal stability, the membrane reactor exhibited stable hydrogen permeation at 320 °C for 120 h and unstable hydrogen permeation at 430 °C was observed. For the WGS reaction, the reactor was loaded with Ferrochrome catalyst. The membrane showed the ability to produce high purity hydrogen, with a CO conversion and an H2 recovery of 84% and 88%, respectively. The membrane suffered from hydrogen embrittlement due to desorption and adsorption of hydrogen on the membrane surface. SEM analysis revealed cracks that occurred on the surface of the membrane after hydrogen exposure. XRD analysis revealed lattice expansion after hydrogen loading which suggests the occurrence of phase change from α-phase to the more brittle β-phase.

Environmentally benign synthesis of amides and ureas via catalytic dehydrogenation coupling of volatile alcohols and amines in a Pd-Ag membrane reactor

In this study, we report the direct synthesis of amides and ureas via the catalytic dehydrogenation of volatile alcohols and amines using the Milstein catalyst in a Pd-Ag/ceramic membrane reactor. A series of amides and ureas, which could not be synthesized in an open system by catalytic dehydrogenation coupling, were obtained in moderate to high yields via catalytic dehydrogenation of volatile alcohols and amines. This process could be monitored by the hydrogen produced. Compared to the traditional method of condensation, this catalytic system avoids the stoichiometric pre-activation or in situ activation of reagents, and is a much cleaner process with high atom economy. This methodology, only possible by employing the Pd-Ag/ceramic membrane reactor, not only provides a new environmentally benign synthetic approach of amides and ureas, but is also a potential method for hydrogen storage.

Theoretical study of hydrogen production using inorganic membrane reactors during WGS reaction

The main purpose of present study is the theoretical analysis and the comparison of inorganic membrane reactor (MR) performances, namely, silica MR performance with respect to dense Pd–Ag MR during water gas shift (WGS) reaction. To this target, a one-dimensional, isothermal numerical model was developed and its validation was realized by literature experimental data, where a good agreement between modeling results and experimental data was found. After model validation, the effects of the some important operating parameters (temperature, pressure and gas hour space velocity (GHSV)) on the performance of both MRs were studied in terms of carbon monoxide conversion and hydrogen recovery. The modeling results showed that the silica MR presents weaker performance around 5% with respect to the dense Pd–Ag MR. In particular, hydrogen recovery and CO conversion were improved in both types of MRs by increasing the reaction pressure at most ranges of GHSV, while reaction temperature showed dual effects at various GHSV values for both cases of MRs. Furthermore, in order to improve of the silica MR performance, different ideal hydrogen selectivities (H2/other gases) via changing hydrogen permeance for silica membrane was also increased. This simulation analysis indicated that the silica MR during WGS reaction presents acceptable performance in comparison with the dense Pd–Ag MR when the ideal hydrogen selectivity (H2/other gases) is higher than 400 and hydrogen permeance is more than 5 × 10−7 mol/m2 Pa s.

Evaluation of dense Pd–Ag membrane reactor performance during methanol steam reforming in comparison with autothermal reforming using CFD analysis

This study presents a 2D-axisymmetric computational fluid dynamic (CFD) model to investigate the performance of dense Pd–Ag MR during methanol steam reforming (MSR) in comparison with methanol autothermal reforming (MATR) reaction for hydrogen production. The proposed CFD model provided the local information of velocity, pressure and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of dense Pd–Ag MR during MSR reaction was carried out by experimental data and a good agreement between modeling results and experimental data was achieved. In the MR model, a dense Pd–Ag membrane with 50 μm thickness and also a commercial Cu/ZnO/Al2O3 catalyst in reaction zone were considered. The effects of the some important operating parameters (temperature, pressure and sweep gas ratio) on the performances of Pd–Ag MR were studied in terms of methanol conversion and hydrogen recovery. The CFD results showed that the Pd–Ag MR during MATR reaction presents higher performance in term of the methanol conversion and hydrogen recovery with respect to once obtained in the MSR reaction. In particular, in the best operating condition, hydrogen production rate in reaction zone show an enhancement around 11% in the MATR reaction over once achieved in the MSR reaction.

Pure Hydrogen Production from Steam Reforming of Bio-Sources

Two synthetic mixtures simulating biogas (CH4 /CO2 = 66.2/33.8) and bioethanol (H2O/EtOH = 13/1) have been used for producing hydrogen by steam reforming reaction in a commercial dense self-supported Pd-Ag membrane reactor. The experimental campaign was subdivided into two parts. Firstly, we studied biogas steam reforming reaction, evaluating the reaction pressure influence (between 200 and 350 kPa) at 450°C, H2O/CH4feed molar ratio = 4/1, GHSV =2370h-1, sweep gas flow rate (N2) = 28.55 mL/min and countercurrent configuration. As best result, we reached 60% CH4 conversion and 40% hydrogen recovery at 350kPa.Successively, we carried out bioethanol steam reforming reaction studying the influence of reaction temperature between 350 and 400°C at 300 kPa of reaction pressure, GHSV=700 h-1 in the presence of sweep gas (N2 = 28.55 mL/min) and countercurrent configuration, obtaining - at 400 °C - maximum ethanol conversion, hydrogen yield and recovery equal to 70%, 50% and 65%, respectively. In addition, we compared the membrane reactor performance with a traditional reactor exercised at the same conditions, only varying the reaction pressure between 200 and 300 kPa. The aim of this work is constituted by the pure hydrogen production from bio-sources exploitation in membrane reactors at bench scale, starting with the utilization of commercial membranes available in the market and in the perspective of scaling up the process for potential industrial development.

Development of an active, selective and durable water-gas shift catalyst for use in membrane reactors

Rh(0.6%)/La2O3 and Rh(0.6%)/La2O3(27wt%)·SiO2were assayed for the WGS reaction at 673K and 1 atm. They were both more active than industrial Cr-Fe based catalysts. Rh(0.6%)/La2O3 was the most active but it progressively deactivated. To investigate its deactivation and the stability of the Rh(0.6%)/La2O3(27wt%)·SiO2, the WGS reaction was carried out in a DRIFTS cell in operando mode. The deactivation of the former was due to the strong adsorption of intermediate oxygenates. Another disadvantage of the Rh formulations was their methanation activity. Therefore, a series of formulations containing 0.1 wt% through 1.2 wt% Pt supported on La2O3(27wt%)·SiO2 were synthesized and catalytically evaluated in a fixed-bed reactor. The activity, methane formation and stability were carefully checked. The fresh and used catalysts were characterized through a battery of techniques including XRD, LRS and XPS. The Pt(0.1wt%) formulation resulted the most active one per gram of platinum and negligible methanation occurred. It maintained the activity and selectivity after 155h on stream. This catalyst was tested in a Pd-Ag membrane reactor to produce ultrapure H2 (<10ppm of CO) that can be used to feed a low temperature PEM fuel cell. Comparing our results with those already published, it is concluded that our system is one of the best ones reported so far.

Effect of temperature and pressure on hydrogen production from steam reforming of biogas with Pd–Ag membrane reactor

The steam reforming reaction of a biogas mixture was conducted with a hydrogen permeable palladium–silver membrane reactor at lower temperatures from 623 to 723 K and from 0.1 to 0.4 MPa of reaction side pressure. The biogas composition was in reference to that of the biogas obtained from the rice husk pyrolysis. In the experiment, the reaction with permeation achieved a higher hydrogen production than the reaction without permeation at the same conditions of temperature and pressure on reaction side, obtaining a maximum hydrogen yield of 80% at 723 K and 0.4 MPa on reaction side. Further, the hydrogen recovery increased with increasing temperature and pressure on reaction side in the case of the reaction with permeation. The mathematical model for the system in this study was proposed and calculated the profile of product and temperature in the reactor. The simulated profiles and the dimensionless groups derived from the mathematical model achieved the analysis of the kinetics in the reactor including that hydrogen and carbon dioxide production from methane and water was the main reaction.

Exergetic study of catalytic steam reforming of bio-ethanol over Pd–Rh/CeO2 with hydrogen purification in a membrane reactor

An exergy analysis of the ethanol steam reforming process using a Pd–Rh catalyst supported on ceria in a Pd–Ag membrane reactor has been performed based on experimental data. Both chemical and physical exergy for chemical species together with thermodynamic loss calculations have been considered to evaluate the exergy efficiency of the process. The system has been studied under different operational conditions in terms of temperature (873–923 K), pressure (4–12 bar), and feed flow rate using a water–ethanol mixture of 50–50% volume (S/C = 1.6). A significant exergy efficiency dependency on the fuel flow rate and pressure has been encountered when considering the heat loss from the reactor. The best results regarding the exergetic and thermal efficiency have been obtained at high flow rates and 8–12 bar, which has been attributed to the higher hydrogen permeation through the membrane. The chemical reactions involved in the reforming process and the heat losses are the main sources of exergy destruction.