Water Gas Shift Membrane Reactor Research Articles

Integration of catalytic methane oxy-reforming and water gas shift membrane reactor for intensified pure hydrogen production and methanation suppression over Ce0.5Zr0.5O2 based catalysts

The production of pure hydrogen from methane or biomethane is a multistep process that can be intensified by the use of membrane reactors. In this study we have synthetized by microemulsion technique Rh and Pt supported over Ce0.5Zr0.5O2 to be applied to the catalytic methane oxy-reforming and water gas shift (WGS) reaction respectively. At first the reformate produced by the reforming process at 750 °C was purified using and hydrogen selective empty Pd-based membrane operated at 400 °C. This led to pure hydrogen production but it resulted also in a not-fully exploitation of the membrane performances. Thus, the Pt-based catalyst was loaded in the membrane reactor configuration leading to in situ hydrogen production that helped to increase the separation driving force. The water gas shift reaction downstream oxy-reforming was also studied on the Pt/Ce0.5Zr0.5O2 catalyst and evidenced the consumption of hydrogen by methanation at high H2/H2O ratio. Comparing the WGS membrane reactor with a classical fixed bed demonstrated that removing hydrogen led to increased CO conversion over the equilibrium of an analogous fixed bed, higher H2 yield and suppression of the methanation reaction, even at high inlet H2/H2O ratio. Optimizing the reaction conditions allowed to reach high hydrogen recoveries (89 %) for the integrated oxy-reforming/membrane water gas shift at high GHSV and without the need of a sweep gas.

Ensemble process for producing high-purity H2 via simultaneous in situ H2 extraction and CO2 capture

To produce fuel-cell-grade hydrogen (H 2 ) via fossil fuel reforming processes, an efficient H 2 purification method with a carbon capture unit is necessary. In this study, a sorption-enhanced water-gas shift membrane reactor (SE-WGS-MR) system combining a state-of-the-art MgO-based catalyst, carbon dioxide sorbent, and Pd/Ta membrane is developed to simultaneously capture carbon dioxide and purify H 2 . With the optimal sorption-enhanced configuration (SE-WGS), the carbon monoxide conversion is significantly enhanced to 86.6%, compared with 68.5% using the commercial catalyst only. Coupling of the Pd/Ta membrane with the WGS catalyst (WGS-MR) enable over 95% H 2 recovery, with the production of high-purity H 2 . Eventually, the ensemble of the three processes (SE-WGS-MR) afford 99.99% of carbon monoxide conversion and the extraction of high-purity H 2 with 99.5% recovery. This study demonstrates the potential of the single process integrating the catalytic reaction, adsorptive separation, and membrane purification for the production of H 2 with ultra-high purity and recovery. • Integration of WGS catalyst and CO 2 sorbent with a Pd/Ta membrane is examined • Coupling of the Pd/Ta membrane with the WGS catalyst enables over 95% H 2 recovery • Simultaneous CO 2 capture and H 2 purification shifts the CO conversion to 99.99% • The ensemble of the processes extracts ultra-pure H 2 with over 99.5% recovery Jin et al. propose an effective ensemble process for producing pure H 2 via simultaneous in situ H 2 extraction and CO 2 capture. Integration of MgO-based catalyst and CO 2 sorbent with a Pd/Ta composite membrane shifts the CO conversion to 99.99%, enabling the extraction of pure H 2 with over 99.5% recovery.

Design and energy analysis of solid oxide fuel cell and gas turbine hybrid systems with membrane reactor

ABSTRACT The methanol-reforming solid oxide fuel cell (SOFC) emits high concentration of CO2 from the anode outlet. To achieve the goal of clean and low-carbon power generation, a CO2 capture unit is integrated with SOFC. In this work, the CO2 capture unit were set at different places in the conventional SOFC and gas turbine (GT) hybrid system. One was to place the water-gas-shift membrane reactor (WGSMR) at the anode inlet (SOFC-MRpre) and the other at the anode outlet (SOFC-MRpost). The key parameters, including the anode off-gas recycling ratio (RR), steam-to-carbon ratio (S/C), and operating pressure, have been investigated. Besides, the effects of the parameters on the power production, electrical efficiency, system efficiency, and CO2 capture capacity of the two processes were analyzed. It was found that the electrical and system efficiencies reached 53.3% and 41.8% for the SOFC-MRpre process, while 62.0% and 60.4% for the SOFC-MRpost process, respectively. The results show that placing the membrane reactor at the anode outlet can significantly reduce the energy consumption of the vacuum and blower, thus increasing the system efficiency. Besides, near-zero carbon emissions with only a 7.3% energy penalty can be achieved by the SOFC-MRpost process. These results reveal that the SOFC-MRpost process has more advantages than the SOFC-MRpre process.

Simulation study on the performance of low-temperature water gas shift membrane reactor system

In order to understand the behavior of the low-temperature water gas shift (WGS) reaction membrane reactor system and obtain better performance of the reactor, numerical simulations are performed with a two-dimensional axisymmetric model. Dimensionless analysis is applied to the governing equations, and then a set of dimensionless parameters are established. The effect of the parameters of Damkohler number (Da) and membrane permeability (Pp) over a wide range on the performance of CO conversion and hydrogen recovery is studied, and the discussion of reaction phenomenon is presented. The WGS reaction is simulated under the operating conditions of 2 atm and two temperatures of 200 and 300 °C. The simulation results suggest that Da=10−4 and Pp=10−1 are the optimum operating conditions for the reactor system where the conversion reaches nearly 100% exceeding the thermodynamic equilibrium conversion by 11% at 300 °C and the optimal hydrogen recovery is achieved simultaneously. The distribution of components along the axis of the reactor is checked, and then two crucial indicators are raised to assess the extent of reaction and hydrogen separation respectively, for the purpose of guidance for the length design of the reactor. Finally, the analysis of the effect of sweep gas on reactor performance suggests that the optimum flow rate of sweep gas is 0.2–0.5 L/min, and further enhancement of performance can be achieved by using counter-current sweep gas configuration.

Carbon Nanotube Formation on Cr-Doped Ferrite Catalyst during Water Gas Shift Membrane Reaction: Mechanistic Implications and Extended Studies on Dry Gas Conversions

A nanocrystalline chromium-doped ferrite (FeCr) catalyst was shown to coproduce H2 and multiwalled carbon nanotubes (MWCNTs) during water gas shift (WGS) reaction in a H2-permselective zeolite membrane reactor (MR) at reaction pressures of ~20 bar. The FeCr catalyst was further demonstrated in the synthesis of highly crystalline and dimensionally uniform MWCNTs from a dry gas mixture of CO and CH4, which were the apparent sources for MWCNT growth in the WGS MR. In both the WGS MR and dry gas reactions, the operating temperature was 500 °C, which is significantly lower than those commonly used in MWCNT production by chemical vapor deposition (CVD) method from CO, CH4, or any other precursor gases. Extensive ex situ characterizations of the reaction products revealed that the FeCr catalyst remained in partially reduced states of Fe3+/Fe2+ and Cr6+/Cr3+ in WGS membrane reaction while further reduction of Fe2+ to Fe0 occurred in the CO/CH4 dry gas environments. The formation of the metallic Fe nanoparticles or catalyst surface dramatically improved the crystallinity and dimensional uniformity of the MWCNTs from dry gas reaction as compared to that from WGS reaction in the MR. Reaction of the CO/CH4 mixture containing 500 ppmv H2S also resulted in high-quality MWCNTs similar to those from the H2S-free feed gas, demonstrating excellent sulfur tolerance of the FeCr catalyst that is practically meaningful for utilization of biogas and cheap coal-derived syngas.

Process simulation and integration of IGCC systems with novel mixed ionic and electronic conducting membrane-based water gas shift membrane reactors for CO2 capture

A mixed ionic and electronic conducting (MIEC) membrane provides an alternative to the palladium alloy membrane for water gas shift membrane reactor. It exhibits much better sulfur resistance performance than the palladium alloy membrane. In this paper, the thermodynamic performance of the integrated gasification combined cycle (IGCC) system with MIEC membrane reactor is predicted for the first time. The effects of reactor operation parameters on system flowsheet and performance are investigated and illustrated by sensitive analysis. When the reactor operation temperature is 900 °C and the H2O decomposition ratio is 0.5, the system net efficiency is about 38.90%, which is 2.6% points higher than that of the IGCC with Selexol. The system net efficiency increases with the decrease of operation temperature. With the net efficiency of the conventional system as the reference, the minimum H2O decomposition ratios at different operating temperatures are provided.

Development and implementation of advanced control strategies for power plant cycling with carbon capture

In this paper, three model predictive control (MPC) strategies are developed and implemented for coal-fired power plant cycling applications. These strategies correspond to a dynamic matrix control (DMC)-based linear MPC, the proposed nonlinear MPC (NLMPC) and a nonlinear MPC from the literature (L-NMPC) as benchmark. For application purposes, dynamic models of two different coal-fired power plants with carbon capture are addressed: an integrated gasification combined cycle power plant with a water-gas shift membrane reactor (IGCC-MR) and a supercritical pulverized coal-fired power plant with monoethanolamine-based post-combustion carbon capture (SCPC-MEA). Successful MPC implementations on IGCC-MR system and SCPC-MEA carbon capture subsystem are addressed, including cycling trajectory tracking and disturbance rejection scenarios. The closed-loop results show that the proposed nonlinear MPC (NLMPC) improves the control performance by up to 96% when compared to the DMC controller in terms of the integral squared error (ISE) results.

Performance analysis of a water–gas shift membrane reactor for integrated coal gasification combined cycle plant

In integrated gasification combined cycle (IGCC) systems, the water–gas shift reaction, which promotes the conversion of CO present in syngas mixtures into hydrogen, is an important step for hydrogen production. Application of the water–gas shift membrane reactor (WGSMR) in IGCC systems is an attractive option for CO2 capture compared with conventional methods because of smaller heat loss in gas purification and high CO conversion by selectively removing hydrogen from the reaction zone through the membrane. In this study, we proposed and evaluated commercial-scale WGSMR models combined with IGCC using reported laboratory-scale experimental data to optimize their operational parameters. Various models were developed using the Aspen Plus® Ver. 8.6 process simulator to investigate the impacts of hydrogen separation, pressure loss, and the flow direction between the sweep gas on the permeate side and syngas on the retentate side on the WGSMR performance with respect to CO conversion, H2 yield, and reactor temperature. The membrane reactor model gave approximately 20% higher CO conversion than a reactor model without H2 separation and approximately 4% lower CO conversion than a membrane reactor model with a pressure drop. A counter-current membrane reactor model gave approximately 2% higher CO conversion than a co-current model; the H2 yield on the permeate side was 9.3% higher in the counter-current model by separation of H2 through the membrane. A sensitivity analysis indicated that a high flow rate and low pressure of sweep gas are advantageous for H2 recovery, and high catalyst loading and high syngas inlet temperature are preferable for higher CO conversion.

Modelling and Simulation of Hydrogen Production via Water Gas Shift Membrane Reactor

Modelling and Simulation of Hydrogen Production via Water Gas Shift Membrane Reactor

Analysis and assessment of a hydrogen production plant consisting of coal gasification, thermochemical water decomposition and hydrogen compression systems

A novel hydrogen production plant is proposed, including a thermochemical water decomposition cycle, a pressurized entrained flow gasifier, a water gas shift membrane reactor, a cryogenic air separation unit, a hydrogen-fueled combined cycle for power production and a hydrogen compression system. The syngas produced by the pressurized entrained flow gasifier undergoes the shift reaction in the water gas shift membrane reactor. The stripping of hydrogen is done simultaneously with the shift reaction in the water gas shift membrane reactor to capture more hydrogen and increase the shift reaction conversion percentage. The remaining syngas is combusted in the Brayton cycle and power is produced through Brayton cycle gas turbine. The hot exhausts exiting the Brayton cycle gas turbine goes to the heat recovery steam generation unit where steam is produced. The generated steam goes to the copper-chlorine cycle to produce hydrogen. Part of the power generated by the Brayton cycle is used for the electrolysis reactor in the copper-chlorine cycle. Then, a small part of the hydrogen produced passes to the combined cycle to overcome the needed work rate by the components in the plant. The remaining larger portion of the hydrogen produced goes to the compression system to compress hydrogen to 700 bar for storage. The hydrogen production plant is developed and modeled in the Aspen Plus software package. Energy and exergy analyses are performed on the hydrogen production integrated system. The overall energy and exergy efficiencies of the proposed hydrogen production plant are found to be 51.3% and 47.6% respectively.

Membrane-based reactive separations for process intensification during power generation

We present here a study of the water gas shift membrane reactor (WGS-MR) in the context of its potential application in the IGCC process for power generation from coal. In our research, we use in the WGS-MR a sour-shift WGS catalyst and carbon molecular sieve (CMS) membranes, and show that the reactor displays higher conversions than a conventional packed-bed reactor (PBR) under the IGCC-relevant conditions, i.e., for temperatures up to 300°C and pressures up to 25bar. Our experimental results manifest the ability of the WGS-MR to operate under the desired conditions and to improve the efficiency of the WGS reaction. They demonstrate, in addition, the potential of the MR to carry out the in-situ separation of hydrogen using the CMS membranes. We conclude from our study, that the CMS-membrane-based WGS-MR is a good candidate technology for incorporation into IGCC power plants for environmentally-benign power generation.

Development of an integrated system for electricity and hydrogen production from coal and water utilizing a novel chemical hydrogen storage technology

A coal gasification-based integrated system is proposed to produce electrical power and hydrogen. The hydrogen produced is stored in a chemical storage medium, which is ammonia. The integrated system contains a water gas shift membrane reactor, a hybrid thermochemical water decomposition cycle based on the chemical couple copper and chlorine and a multistage ammonia production system. A hydrogen fueled supporting combined cycle is used to meet the electrical requirement of the integrated system. Coal is gasified, and the resulting syngas is water shifted in a membrane reactor, which produces hydrogen. The remaining syngas is combusted to generate power through a gas turbine, and the turbine hot exhaust is used to provide the required thermal energy of the water decomposition cycle. The hydrogen outputs from the coal gasification and the water decomposition cycle are fed to the ammonia production system and the supporting combined cycle. The ammonia production system contains multiple stages to achieve a high conversion percentage of hydrogen. The nitrogen fed to the ammonia reactor is provided by the cryogenic air separation unit, which also provides oxygen to the gasifier. The proposed system is simulated with the process simulation software Aspen Plus. The system performance is evaluated through energy and exergy efficiencies. The integrated system is found to have an energy efficiency of 48.7% and an exergy efficiency of 48.4%. The system is capable of producing 0.18kg/s of hydrogen and 1.2MW of power per 1.5kg/s of coal.

Advances of zeolite based membrane for hydrogen production via water gas shift reaction

Hydrogen is considered as a promising energy vector which can be obtained from various renewable sources. However, an efficient hydrogen production technology is still challenging. One technology to produce hydrogen with very high capacity with low cost is through water gas shift (WGS) reaction. Water gas shift reaction is an equilibrium reaction that produces hydrogen from syngas mixture by the introduction of steam. Conventional WGS reaction employs two or more reactors in series with inter-cooling to maximize conversion for a given volume of catalyst. Membrane reactor as new technology can cope several drawbacks of conventional reactor by removing reaction product and the reaction will favour towards product formation. Zeolite has properties namely high temperature, chemical resistant, and low price makes it suitable for membrane reactor applications. Moreover, it has been employed for years as hydrogen selective layer. This review paper is focusing on the development of membrane reactor for efficient water gas shift reaction to produce high purity hydrogen and carbon dioxide. Development of membrane reactor is discussed further related to its modification towards efficient reaction and separation from WGS reaction mixture. Moreover, zeolite framework suitable for WGS membrane reactor will be discussed more deeply.

Palladium based membranes and membrane reactors for hydrogen production and purification: An overview of research activities at Tecnalia and TU/e

In this paper, the main achievements of several European research projects on Pd based membranes and Pd membrane reactors for hydrogen production are reported. Pd-based membranes have received an increasing interest for separation and purification of hydrogen. In addition, the integration of such membranes in membrane reactors has been widely studied for enhancing the efficiency of several dehydrogenation reactions. The integration of reaction and separation in one multifunctional reactor allows obtaining higher conversion degrees, smaller reactor volumes and higher efficiencies compared with conventional systems. In the last decade, much thinner dense Pd-based membranes have been produced that can be used in membrane reactors. However, the thinner the membranes the higher the flux and the higher the effect of concentration polarization in packed bed membrane reactors. A reactor concept that can circumvent (or at least strongly reduce) concentration polarization is the fluidized bed membrane reactor configuration, which improves the heat transfer as well. Tecnalia and TU/e are involved in several European projects that are related to development of fluidized bed membrane reactors for hydrogen production using thin Pd-based (<5 μm) supported membranes for different application: In DEMCAMER project a water gas shift (WGS) membrane reactor was developed for high purity hydrogen production. ReforCELL aims at developing a high efficient heat and power micro-cogeneration system (m-CHP) using a methane reforming fluidized membrane reactor. The main objective of FERRET is the development of a flexible natural gas membrane reformer directly linked to the fuel processor of the micro-CHP system. FluidCELL aims the Proof-of-Concept of a m-CHP system for decentralized off-grid using a bioethanol reforming membrane reactor. BIONICO aims at applying membrane reactors for biogas conversion to hydrogen. The fluidized bed system allows operating at a virtually uniform temperature which is beneficial in terms of both membrane stability and durability and for the reaction selectivity and yield.

Comparison between WGS membrane reactors operating with and without sweep gas: Limiting conditions for co-current flow

In this work, a comparative study is carried out to analyze the behavior of a water gas shift membrane reactor operating with and without sweep gas. The present study includes thermal effects that play a key role in reaction and permeation rates involved in the membrane reactor. Based on a 1-D mathematical model, the effect of the most important operating variables on the membrane reactor performance is comparatively studied. Additionally, novel algebraic expressions are developed when operating without sweep gas, that only depend on inlet variables to calculate the limiting membrane reactor conversions and recovery values. An algebraic equation is developed to estimate limiting recovery when operating with sweep gas. The dependence of limiting membrane reactor conversion and recovery values operating with and without sweep gas on operating parameters is included. From the comparative analysis, some guidelines for an improved operation of the membrane reactor are proposed.

Modeling and performance assessment of a new integrated gasification combined cycle with a water gas shift membrane reactor for hydrogen production

Abstract This paper investigates the effects of flow rate of gasification oxidant, gasification agent and coal type on the energy efficiency and hydrogen production rate of a proposed system. The present system consists of a pressurized entrained flow gasifier integrated with a cryogenic air separation unit, a water gas shift membrane reactor and a combined cycle. Aspen Plus software is used to develop and simulate the integrated system. Three different types of coal are fed to the gasifier. A Gibbs free energy based model of the gasification process is developed and validated. The Gibbs free energy based model is then used to assess the effect of gasification parameters since it is more straightforward regarding changing input flow rates. It is found that gasifying low grade coal is preferable in terms of energy efficiency to gasifying high grade coals, which are more advantageous for combustion regarding energy efficiency.

Development and analysis of an integrated system with direct splitting of hydrogen sulfide for hydrogen production

This paper analyzes the thermodynamic performance of the combination of a water gas shift membrane reactor and an integrated coal gasification unit with a combined cycle, a carbon capture unit, and a unit for direct splitting of hydrogen sulfide into hydrogen and sulfur. The latter operates as an alternative process for disposing of hydrogen sulfide, while producing hydrogen. The purpose of the thermodynamic analysis is to determine whether the integration proposed is beneficial to the system in terms of thermodynamic performance, compared to the proposed systems in the open literature. The proposed system is simulated using Aspen Plus software, with two models for gasification. Some parametric studies are performed on the system to determine the effect of type of coal, steam flow rate in the single reheat supercritical Rankine cycle, and the main parameters of the membrane reactor on the overall energy and exergy efficiencies of the proposed system. The overall energy and exergy efficiencies of the proposed system are found to be 66.9% and 62.0% for Illinois #6 coal, and 60.7% and 57.0% for the Turkish coal Tuncbilek.

Performance of Pd composite membrane prepared by organic–inorganic method in WGS membrane reactor

ABSTRACTH2 production via water–gas shift (WGS) reaction in a Pd membrane reactor prepared by the electroless plating technique (ELP) “organic–inorganic” method was investigated. Pd nanoparticles embedded polyethylene glycol (PEG) was used as a polymer template during the activation step. Gas permeation results showed an infinite selectivity for H2/N2 with a H2 flux of 0.004–0.016 mol/m2·s depending on operating conditions while it decreased until 0.0005 mol/m2·s for gas mixtures. Furthermore, WGS membrane reactor experiments showed a maximum CO conversion of 98.5% with a H2 recovery of 16% at 450°C. The membrane performance was consistent during WGS catalytic membrane reactors (CMR) tests, thereby confirming the stability of the obtained membrane.

Performance Assessment of Water Gas Shift Membrane Reactors by a Two-dimensional Model

There is currently a large world effort towards developing hydrogen power as the next generation of clean energy for both the transportation and the electricity sectors. Water gas shift is a thermodynamically limited reaction, which has to operate at low temperatures, reducing kinetics rate, and increasing the amount of catalyst required to reach valuable carbon monoxide conversions. It has been widely demonstrated that the integration of hydrogen selective membranes is a promising way to enhance water gas shift reactors’ performance: a Pd-based membrane reactor operated successfully overcoming the thermodynamic constraints of a traditional reactor thanks to the removal of hydrogen from the reaction environment. In this work, the effect of hydrogen removal in membrane water gas shift reactors will be investigated by a two-dimensional, non-isothermal model in order to analyze the water gas shift reactor performance. In particular, the effects on the reactor performance of the gas space hourly velocity, reactor temperature, pressure difference, sweeping gas flow rate, and inlet flow rate composition have been deeply assessed.

Syngas upgrading in a membrane reactor with thin Pd-alloy supported membrane

In hydrogen production, the syngas streams produced by reformers and/or coal gasification plants contain a large amount of H2 and CO in need of upgrading. To this purpose, reactors using Pd-based membranes have been widely studied as they allow separation and recovery of a pure hydrogen stream. However, the high cost of Pd-membranes is one of the main limitations for scaling up technology. Therefore, many researchers are now pursuing the possibility of using supported membranes with as thin as possible Pd-alloy layers.In this work, the upgrading of a syngas stream is experimentally investigated in a water gas shift membrane reactor operated in a high temperature range with an ultra-thin supported membrane (3.6 micron-thick). The membrane permeance was measured before and after catalyst packing and also after reaction for 2100 h of operation in total.Membrane reactor performance was evaluated as a function of operating conditions such as temperature, pressure, gas hourly space velocity, feed molar ratio, and sweep gas. A CO conversion significantly higher than the thermodynamics upper limit of a traditional reactor was achieved, even at high gas hourly space velocities and a 25% less reaction volume than that of a traditional reactor was enough to achieve a 90% equilibrium conversion.