Exothermic Side Research Articles

Hydrogen/methanol production in a novel multifunctional reactor within situadsorption: modeling and optimization

SUMMARY This work proposes a novel multifunctional reactor for simultaneous production of hydrogen and methanol in which zeolite 4A is considered as water adsorbent. For this purpose, in the exothermic side of the proposed configuration, a gas-flowing solid-fixed bed reactor (GFSFBR) is used. The remarkable advantage of GFSFBR over the conventional sorption-enhanced reaction process is the continuous adsorbent regeneration in this novel reactor. MR takes the advantages of adsorption and couple technique simultaneously. The new configuration is designed as a double pipe reactor where highly exothermic methanol synthesis reactions in the exothermic side are coupled with dehydrogenation of cyclohexane. A one-dimensional, steady-state heterogeneous model is used to simulate the proposed reactor configuration. Simulation result demonstrates that selective adsorption of water in the exothermic side leads to 22.5%, 9.85% and 7.1% enhancement in methanol, benzene and hydrogen production, respectively, compared with the zero solid mass flux condition. Subsequently, the aforementioned reactor is optimized using differential evolution algorithm to maximize the hydrogen mole fraction in the endothermic side as well as the methanol yield in the exothermic side. Copyright © 2013 John Wiley & Sons, Ltd.

Sorption-enhanced reaction process in Fischer–Tropsch synthesis for production of gasoline and hydrogen: Mathematical modeling

This work proposes a sorption enhanced-thermally coupled reactor (SE-TCR) for simultaneous production of gasoline and hydrogen in which Zeolite 4A, with the composition of Na12(Si12Al12O48)·27H2O, is considered as water adsorbent. For this purpose, in the exothermic side of proposed configuration, a gas-flowing solids-fixed bed reactor (GFSFBR) is used. The main advantage of GFSFBR over the conventional sorption-enhanced reaction process is the continuous adsorbent regeneration in this novel configuration. SE-TCR takes the advantages of adsorption and couple technique simultaneously. The new configuration is designed as a double pipe reactor where exothermic Fischer–Tropsch synthesis (FTS) reactions in the exothermic side are coupled with dehydrogenation of cyclohexane. Simulation result demonstrates that selective adsorption of water from FTS in SE-TCR leads to 45% and 57% enhancement in gasoline and hydrogen yields and 84% reduction in CO2 production in comparison with the zero solid mass flux condition, respectively. This paper shows how the concept of in-situ water adsorption is feasible and beneficial for gasoline production in thermally coupled reactor.

Enhancement of methanol, DME and hydrogen production via employing hydrogen permselective membranes in a novel integrated thermally double-coupled two-membrane reactor

In this paper, a thermally double-coupled two-membrane reactor for simultaneous production of methanol, hydrogen and dimethylether (DME) by employing Pd/Ag membranes in co-current mode has been investigated. In this novel multi-tubular reactor configuration, cyclohexane dehydrogenation as an endothermic reaction has coupled with two exothermic reactions of methanol production and direct DME synthesis from syngas. Two Pd/Ag membranes are used for improving the efficiency of hydrogen production and other products in exothermic sides by separation of hydrogen from unconverted outputs of exothermic sides that are recycled to the reactor. A steady state heterogeneous catalytic reaction model is applied to analyze the performance of thermally double-coupled two-membrane reactor and comparison of the result with corresponding predictions for a conventional methanol reactor, thermally coupled reactor (coupling of methanol synthesis with cyclohexane dehydrogenation only) and thermally double coupled reactor.Modeling results show that by employing this novel configuration, methanol yield reaches to 0.4017 in comparison with 0.3885, 0.3735 and 0.362 for conventional methanol reactor, thermally double coupled reactor and thermally coupled reactor respectively.Also methanol production increases 3.39%, 7.03% and 10.94% compared with conventional methanol reactor, thermally double coupled reactor and thermally coupled reactor respectively. Simulation results illustrate that by using Pd/Ag membranes, DME production raises from 277.24 kmol h−1 in thermally double coupled reactor to 325.3 kmol h−1 in thermally double-coupled two-membrane reactor. Additionally, hydrogen production in endothermic side of thermally double coupled reactor is enhanced from 1076 to 1219 kmol h−1 in thermally double-coupled two-membrane reactor.

Simultaneous dimethyl ether synthesis and decalin dehydrogenation in an optimized thermally coupled dual membrane reactor

The efficient coupling of exothermic and endothermic reactions in a membrane reactor reduces the size of reactors and operational costs, improves thermal efficiency and also increases the production rate in the processes. In the present study, a thermally coupled dual-membrane reactor for simultaneous production of hydrogen, dimethyl ether (DME) and naphthalene is proposed. In this configuration, the exothermic DME synthesis reaction is coupled with the endothermic dehydrogenation of decalin to improve the heat transfer between the endothermic and exothermic sides. Furthermore, in order to increase the production rate, a Pd/Ag membrane and a hydroxy sodalite (H-SOD) membrane are assisted for separation of pure hydrogen from the endothermic side and permeation of water from the exothermic side respectively. The operating conditions of thermally coupled dual-membrane reactor are optimized via differential evolution (DE) method to maximize outlet DME mole fraction in the exothermic side as well as outlet hydrogen mole fraction in the endothermic side. Then a comparison is made between the optimized thermally coupled dual-membrane reactor (OTCDMR), the optimized thermally coupled reactor (OTCR) and conventional DME synthesis reactor (CR). The outlet DME mole fraction increases about 34.2% and 3.42% in OTCDMR and optimized thermally coupled reactor respectively, compared with conventional one. Hydrogen mole fraction in the outlet point of OTCDMR also improves about 6.4% in comparison with the one in optimized thermally coupled reactor. In addition to the enhancement of hydrogen and DME mole fractions, a more favorable profile of temperature is achieved in OTCDMR compared with other reactors.

Comparative Study on Simultaneous Production of Methanol, Hydrogen, and DME Using a Novel Integrated Thermally Double-Coupled Reactor

The present paper focuses on simulation of a catalytic thermally double-coupled reactor (TDCR) in cocurrent mode. In this novel configuration, the endothermic reaction of cyclohexane dehydrogenation has coupled with two exothermic reactions: methanol production and direct DME synthesis from syngas to improve the heat transfer between the endothermic and the exothermic sides. A multitubular reactor with 2962 three concentric tubes has been considered for TDCR. A steady state heterogeneous catalytic reaction model is applied to analyze the performance of TDCR for simultaneous production of methanol, hydrogen, and dimethyl ether (DME). Simulation results of TDCR have been compared with corresponding predictions for an industrial methanol reactor (CMR) and thermally coupled reactor (coupling of methanol synthesis with cyclohexane dehydrogenation), operated at the same feed conditions. Results showed that by this novel configuration production of methanol and hydrogen increases from 345.48 to 373.21 kmol h–1 and 250.6 to 1066.3 kmol h–1 in comparison with TCR, respectively. In addition, production of DME with a rate of 277.24 kmol h–1 is another superiority of TDCR. In addition, hydrogen production in the endothermic side of TDCR in each of the three concentric tubes (0.1 mol s–1) is higher than hydrogen consumption in methanol synthesis (0.076 mol s–1).

Boosting the gasoline production via a novel multifunctional Fischer–Tropsch reactor: Simulation and optimization

Energy and the environment are two of the most important issues this century. Multifunctional reactor has been recognized as one of the most promising configurations for simultaneous production of gasoline and hydrogen; as well stabilizing the atmospheric green house gases level. This paper focuses on mathematical modeling and optimization of a novel multifunctional reactor (MR) in order to enhance the production of gasoline and reduces CO2 and CH4 emission. Fischer–Tropsch synthesis is carried out in exothermic side and supplies the necessary heat for the benzene synthesis reaction. The proposed reactor configuration consists of two catalytic fixed beds separated by the solid wall and also two Pd/Ag membranes, one is used for ultrapure hydrogen production from the endothermic side and the subsequent is applied in order to selectively hydrogen addition to the exothermic side. A one-dimensional, steady-state heterogeneous model and the differential evolution (DE) method, as a strong and powerful optimization method, are applied to simulate and optimize the proposed reactor configuration. The results of optimized multifunctional rector (OMR) represent 40.91% enhancement in the yield of gasoline in comparison with conventional Fischer–Tropsch reactor (CR). Moreover, 75% and 34.46% decrease in the yield of methane and carbon dioxide as undesired products, respectively. On the other hand, a favorable temperature profile along the reactor length of OMR is achieved in comparison with CR.

Differential Evolution Strategy for Optimization of Hydrogen Production via Coupling of Methylcyclohexane Dehydrogenation Reaction and Methanol Synthesis Process in a Thermally Coupled Double Membrane Reactor

The present paper focuses on optimization of a thermally coupled double membrane methanol reactor (TCDMR). This novel configuration is used in order to increase methanol production and achieve pure hydrogen. To reach this goal, the exothermic methanol synthesis reaction is coupled with endothermic dehydrogenation of methylcyclohexane to improve the heat transfer between the endothermic and exothermic sides. Methylcyclohexane (MCH) has been proposed as a potential candidate among the cycloalkanes to produce gaseous hydrogen and a liquid aromatic product toluene (TOL). Two different membrane layers are assisted in TCDMR to improve mass transfer between the exothermic/endothermic side and both permeation sides. A Pd/Ag membrane is used for separation of pure hydrogen from the endothermic side and a hydroxy sodalite (H-SOD) membrane is used for permeation of water from the exothermic side. It has been shown that in situ water removal from the exothermic side has certain advantages. H2O removal improves the activity and selectivity control of the methanol synthesis as well as inhibits the catalyst recrystallization. A steady state heterogeneous model predicts the performance of this innovative configuration. The optimization results have been compared with corresponding predictions for a conventional methanol reactor, thermally coupled methanol reactor, and thermally coupled double membrane reactor. The differential evolution (DE) is a simple and efficient global optimization algorithm applied to optimize the thermally coupled double membrane reactor considering the summation of methanol, toluene, and H2 recovery yields as the objective function. The simulation results demonstrate that lower water production rate in the optimized TCDMR (OTCDMR) caused 13.8% enhancement in methanol yield in comparison with a conventional reactor and the hydrogen recovery permeation side reaches 2.15 yields.

Simultaneous production and utilization of methanol for methyl formate synthesis in a looped heat exchanger reactor configuration

In this investigation, a novel thermally coupled reactor (TCR) containing methyl formate (MF) production in the endothermic side and methanol synthesis in the exothermic side has been investigated. The interesting feature of this TCR is that productive methanol in the exothermic side could be recycled and used as feed of endothermic side for MF synthesis. Other important advantages of the proposed system are high production rates of hydrogen and MF. The configuration consists of two thermally coupled concentric tubular reactors. In these coupled reactors, autothermal system is obtained within the reactor. A steady-state heterogeneous model is used for simulation of the coupled reactor. The proposed model has been utilized to compare the performance of TCR with the conventional methanol reactor (CMR). Noticeable enhancement can be obtained in the performance of the reactors. The influence of operational parameters is studied on reactor performance. The results show that coupling of these reactions could be feasible and beneficial. Experimental proof-of-concept is required to validate the operation of the novel reactor.

Production of hydrogen and methanol enhancement via a novel optimized thermally coupled two-membrane reactor

This study focuses on optimum operating conditions for thermally coupled two-membrane reactor (TCTMR) to maximize ultrapure hydrogen and methanol production as alternative environmentally friendly fuels. Hydrogen is used in chemical and petrochemical industries especially applicable in fuel cell technologies, with zero CO2 emission. In the proposed configuration, methanol synthesis is carried out in the exothermic side by hydroxy sodalite membrane and supplies the necessary heat for the endothermic side. Dehydrogenation of cyclohexane is carried out in the endothermic side with hydrogen-permselective Pd/Ag membrane wall. A one-dimensional, steady-state heterogeneous model and the differential evolution method, as a strong and powerful optimization method, are applied to simulate and optimize the proposed reactor configuration. The simulation results have been shown that there are optimal values of the initial molar flow rate of endothermic, outer and the inner permeation stream, inlet temperature of exothermic, endothermic, outer and inner permeation sides and inlet pressure of inner permeation side to maximize the objective function. The optimization results show 5.87 and 10.51% increase in the methanol production in optimized TCTMR compared with TCTMR and a conventional reactor, respectively. Moreover, this novel configuration with optimal conditions raises the hydrogen production rate about 1.1847 ton/day. Copyright © 2012 John Wiley & Sons, Ltd.

Simultaneous hydrogen injection and in-situ H2O removal in a novel thermally coupled two-membrane reactor concept for Fischer–Tropsch synthesis in GTL technology

Gas-to-Liquids (GTL) technology converts natural gas, through Fischer–Tropsch synthesis, into liquid and ultra-clean hydrocarbons such as gasoline, light oils, naphtha, diesel, and wax. In this study, a novel thermally coupled multi-tubular two-membrane reactor (TCTMR) is proposed in order to enhance of gasoline production. Fischer–Tropsch synthesis is carried out in the exothermic side with two different membranes and supplies the necessary heat for the endothermic side. Decomposition of ammonia is carried out in the endothermic side with hydrogen-permselective Pd/Ag membrane layer. Therefore, the proposed reactor consists of two different membranes, one for permeation of pure hydrogen from exothermic into endothermic side and another one for separation of water from exothermic side. Water produced during FTS negative influences the reaction by re-oxidation of catalysts, increasing water/gas shift activity and decreasing partial pressures of the products. A steady-state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The achieved results of this simulation have been compared with the results of the conventional fixed-bed reactor (CR) at identical process conditions. The simulation results show 27.14% enhancement in the gasoline yield and 35.2% decrease in CO2 yield of TCTMR in comparison with the one in CR due to a favorable profile of temperature along the TCTMR.

A comparative study of two different membranes applied for auto-thermal methanol synthesis process

The growing demand for energy and environmental concerns make finding economical and environmentally sustainable solutions for the effective and more utilization of natural gas, as the cleanest fossil fuel, imperative. Among different approaches to reach this goal, chemical conversion is of great interest. Future energy carriers such as hydrogen and methanol can be produced by the natural gas conversion. Recently, the auto-thermal methanol synthesis (AMS) process has become an important alternative for natural gas conversion and monetization. Concerning the equilibrium limitation of methanol synthesis reactions, there are two different configurations for membrane reactor, which may be used in this process. In the first configuration (in situ H2 addition configuration), the Pd/Ag membrane was applied while in the other one (in situ H2O removal configuration) H-SOD membrane was used. Generally, the proposed reactor is composed of three concentric tubes of which the inner tube is separated by a membrane from second one (exothermic side). A steady-state heterogeneous model was developed to investigate the possibility of improving AMS performance by means of two different membranes. The proposed model has been used to compare the performance of two different auto-thermal configurations with respect to the non-membrane one under identical process conditions. It was found that the reactor in the in situ water removal configuration operates with higher methanol yield, higher carbon dioxide removal which causes a lower environmental impact and longer exothermic catalyst life as a result of the more favourable temperature profile as well as reducing H2O promoted catalyst deactivation. However, thermal efficiency of reactions is declined and the dehydrogenation reaction yield in both configurations is not significantly different. Finally, the influence of inlet temperature of sweep gas as one of the key operating variables is investigated on products yield. The results suggest that utilization of this reactor could be feasible and beneficial.

Differential evolution (DE) strategy for optimization of methane steam reforming and hydrogenation of nitrobenzene in a hydrogen perm-selective membrane thermally coupled reactor

In this work, a thermally coupled membrane reactor is proposed for methane steam reforming and hydrogenation of nitrobenzene. The steam reforming process is carried out in the assisted membrane surface of the endothermic side, while the hydrogenation reaction of nitrobenzene to aniline is carried out on the other membrane surface of the exothermic side. The differential evolution (DE) strategy is applied to optimize this reactor considering nitrobenzene and methane conversion as the main objectives. The co-current mode is investigated in this study, and the achieved optimization results are compared with those of conventional steam reformer reactor operated under the same feed conditions. The optimum values of feed temperature of exothermic side, feed molar flow rate of nitrobenzene, the steam-to-nitrobenzene molar ratio and the hydrogen-to-nitrobenzene molar ratio are determined during the optimization process. The simulation results show that the methane conversion and consequently hydrogen recovery yield are increased by 39.3% and 1.57, respectively, which contribute to aniline production with 27.3% saving in hydrogen supply from external and a reduction in environmental problems due to 100% nitrobenzene conversion. The optimization results justify the feasibility of coupling these reactions. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor. Copyright © 2012 John Wiley & Sons, Ltd.

Boosting the gasoline octane number in thermally coupled naphtha reforming heat exchanger reactor using de optimization technique

Since the refineries are benefitted mostly from the catalytic naphtha reforming units, these units are of highly interest. This importance would generate continuous evolution of the technology in both the processing and equipment pieces of the technology. One of the promising developments in the naphtha reformers would be thermal coupling of the reactors in a heat exchanger configuration. In this study, the DE optimization technique has been used as a powerful tool to find the best operating parameters in the naphtha coupled reactors. Twenty-six decision variables have been considered in this optimization problem. The endothermic dehydrogenation of the catalytic naphtha reforming is coupled with an exothermic hydrogenation reaction (hydrogenation of nitrobenzene to aniline) through a shell and tube heat exchanger reactor. Catalyst mass distribution, exothermic inlet temperature, operating pressures, number of tubes in the exothermic side and the total molar flow rates are the most important optimized parameters. Maximizing the aromatics (octane number) in reformate is the best possible objective function in this research. The results show a significant increase in hydrogen and aromatics production rate of the optimized reactor compared with the non-optimized one. Hydrogen and aromatics have increased 72 and 41kmol/h, respectively. Besides, the exothermic tubes are considered for the third reactor in this work to maximize the aromatic and hydrogen production rates. These results are valuable for the procedure of designing a reactor in which both reactions are integrated.

The Behaviors of Endothermic and Exothermic of Wood and Wood Components between 100°C and 200°C

To clarify the mechanism of the heat-treatment for wood between 100°C and 200°C, the behaviors of endothermic and exothermic of wood and wood components (cellulose, hemicellulose, lignin) between 100°C and 200°C under the dried air condition were measured using the temperature-modulated DSC. The measurement were carried out in the heating processes under stepwise heating and cooling cycles (100°C→140°C→100°C→160°C→100°C→180°C→100°C→200°C, ±5°C/min). The total heat flow (THF) and the nonreversing heat flow (NRHF) curves of wood, cellulose and hemicellulose in the 1st heating process (100°C→140°C) were found in the exothermic side compared with the curves in other heating processes. The reversing heat flow (RHF) curves of wood in the 4th heating process (100°C→200°C) were found in the exothermic side compared with the curves in other heating processes. However the RHF curves of cellulose and hemicellulose were observed on the almost same line. The THF and NRHF curves of lignin were shifted to the exothermic side with the stepwise heating and cooling cycles. On the other hand, the RHF curves of lignin were shifted to the endothermic side with the cycles. These results suggest that the effects of the heat-treatment for wood between 100°C and 200°C are based on the thermodynamic stabilization of the conformation of cellulose, hemicellulose and especially lignin due to the heating history.

Investigation of Short-Circuit Scenarios in a Lithium-Ion Battery Cell

A short-circuited lithium-ion battery cell is likely to generate sufficient heat to initiate exothermic side reactions causing thermal runaway. A 2D coupled electrochemical-thermal model was developed to investigate a prismatic LiNi0.8Co0.15Al0.05O2|LiPF6, EC/EMC (3:7)|MAG-10 battery cell that is short-circuited. Three short-circuit scenarios are investigated during the events from when short circuit occurs until exothermic side reactions initiate. The scenarios are an external short circuit, a nail penetration and an impurity-induced short circuit. The model is used to predict the temperature increase within the cell and to explain how the interrelation between the electrochemical processes and the thermal properties affects the increase. Important safety measures are also examined with the model. The simulation results highlight general short-circuit characteristics and critical distinctions between the scenarios. The mass transport of lithium ions in the electrolyte is found to be the most important general characteristic that determines the rate of the temperature increase. The electric resistance distinguishes the scenarios from each other. The rate of the temperature increase is dictated by the mass transport in the electrolyte even when large variations in available active material are made and it is shown to be difficult to slow down the rate by cooling.

Incorporating multi-membrane tubes for simultaneous management of H2/HC and hydrogenation of nitrobenzene to aniline in naphtha heat exchanger reactor

The present contribution seeks theoretically the behavior of a novel membrane heat exchanger reactor in the field of process intensification. The performance of the catalytic naphtha reforming (as a key process in the refineries) is investigated and improved through thermal coupling with the exothermic hydrogenation of nitrobenzene to aniline. A bundle of tubular reactors, which contain the exothermic catalyst, is supposed to be substituted in the first and the second reactors of conventional naphtha reforming process to provide the necessary heat of straight run naphtha reforming. Moreover, membrane concept is introduced into this configuration in order to supply the exothermic side reaction (to provide hydrogen) and simultaneously controls the hydrogen doze (H2/HC) in the endothermic side. The new integrated design has the superiority to enhance hydrogen and aromatic production rates compared with the current conventional catalytic reformers (CTR). A detailed one-dimensional model in conjunction with the Smith's model for naphtha reforming is employed to predict the performance of this configuration. Such combination promises to result in a process, which is more compact and less capital intensive, and with potential of substantial savings in processing costs. Finally, the new configuration can be considered as an option in revamping the available conventional plants or set up new ones.

Optimal design of a thermally coupled fluidised bed heat exchanger reactor for hydrogen production and octane improvement in the catalytic naphtha reformers

AbstractThe present study combines simultaneously the definition of fluidisation and process intensification (thermally coupled heat exchanger reactor) concept and determines the optimum operational conditions in both sides of the reactor, using Differential Evolution (DE) optimisation approach. The exothermic hydrogenation of nitrobenzene to aniline takes place in a set of tubular reactors which is placed inside the naphtha reactors and thermally handle the endothermic reaction of reforming. A single objective function consists of four terms including aromatic mole fraction of the reformate and hydrogen production from each reactor in the endothermic side as well as the total molar flow rate of aniline and nitrobenzene conversion in the exothermic side is defined. Seven decision variables such as inlet temperature of exothermic and endothermic sides, exothermic molar flow rates for the first and the second reactors and the number of tubes are considered during the optimisation procedure. Temperature constraints have been considered in both sides during the optimisation in order to reduce the possibility of rapid catalyst deactivation by sintering. Results show approximately 464.4 and 598.9 kg/h increase in aromatic and aniline production rates in optimised thermally coupled fluidised bed naphtha reactor (OTCFBNR) compared with non‐optimised case (TCFBNR), respectively. Such a theoretical study is necessary prior to designing new pilot plants and revamping industrial units. © 2011 Canadian Society for Chemical Engineering

Start-up and Dynamic Analysis of a Novel Thermally Coupled Reactor for the Simultaneous Production of Methanol and Benzene

Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes, achieving the autothermality within the reactor, reducing the size of the reactors, and achieving a multiple reactants–multiple products configuration. In this study, a dynamic heterogeneous model for a novel thermally coupled reactor—containing methanol synthesis reactions and cyclohexane dehydrogenation—is developed to consider the startup and transient response of the system. This heat-exchanger reactor consists of two fixed beds separated by a wall, where heat is transferred across the surface of tube from the exothermic side to the endothermic side. The proposed model was validated against conventional methanol synthesis reactor, and a good agreement was achieved. Dynamic simulation results for the co-current mode have been investigated to present the response of the reactor outlet temperature, methanol yield, and cyclohexane conversion in the cases of a step change in the initial molar flow rate and inlet temperature of both sides. The challenges posed by the transient operation of thermally coupled reactor are identified to avoid severe issues that can arise in the course of operating the reactor (such as reactor extinction). The results suggest that control of this coupled reactor could be feasible and beneficial.

Mathematical simulation and optimization of methanol dehydration and cyclohexane dehydrogenation in a thermally coupled dual-membrane reactor

Thermally coupling of endothermic and exothermic reactions in a membrane reactor improves thermal efficiency and production rate in the processes, reduces the size of reactors and decreases purification cost. This paper focuses on modeling and optimization of a thermally coupled dual-membrane reactor for simultaneous production of hydrogen, dimethyl ether (DME) and benzene. A steady state heterogeneous mathematical model is developed to predict the performance of this novel configuration. The catalytic methanol dehydration reaction takes place in the exothermic side that supplies the necessary heat for the catalytic dehydrogenation of cyclohexane to benzene in the endothermic side. Selective permeation of hydrogen and water vapor through the Pd/Ag and composite membranes are achieved by co-current flow of sweep gas through the membrane wall. The differential evolution method is applied to optimize the thermally coupled dual-membrane reactor considering the summation of DME and benzene mole fractions from reaction sides and hydrogen mole fraction in the permeation side as the main objectives. The optimization results are compared with corresponding predictions for an industrial methanol dehydration adiabatic reactor operated at the same feed conditions. Methanol conversion enhances about 5.5% in the optimized thermally coupled dual-membrane reactor relative to the conventional DME reactor. The results suggest that coupling of these reactions in the proposed configuration could be feasible and beneficial.

Simultaneous production of ultrapure hydrogen and gasoline in a novel thermally coupled double-membrane reactor

SUMMARY In this study, simultaneous production of ultrapure hydrogen and gasoline via a novel catalytic fixed-bed double-membrane reactor with co-current flow was investigated, mathematically. The thermally coupled double-membrane reactor (TCDMR) consists of two Pd/Ag membranes, one for separation of pure hydrogen from endothermic side and another one for permeation of hydrogen from endothermic into exothermic side. Ammonia decomposition reaction is coupled with the Fischer–Tropsch Synthesis (FTS) reaction to improve the heat transfer between endothermic and exothermic sides. Some of the produced hydrogen via ammonia decomposition reaction is utilized in FTS reaction, and the other is extracted and stored. A steady-state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The achieved results of this simulation have been compared with the results of the conventional fixed-bed reactor (CR) at identical process conditions. The simulation results show 67.34% hydrogen production in the permeation side and 32.66% hydrogen utilization in the exothermic side for compensates of hydrogen lack in the FTS reaction through the TCDMR configuration. Moreover, the gasoline yield in TCDMR increases about 18.42% because of a favorable profile of temperature along the TCDMR in comparison with the one in CR. Therefore, this approach utilizes and produces large amounts of pure hydrogen and decreases environmental impacts owing to ammonia emission. Copyright © 2011 John Wiley & Sons, Ltd.