Conventional Methanol Reactor Research Articles

On improving the hydrogen and methanol production using an auto-thermal double-membrane reactor: Model prediction and optimisation

The concentric configured thermally-coupled double-membrane reactor (TCDMR) was optimised to improve the co-production of hydrogen and methanol. Using a detailed approach, we identified the non-linear differential evolution (DE) algorithm as the most suitable optimisation tool among the most used optimisation algorithms in reactor design (GA, PSO, and DE) due to its ability to converge to the optimal solution with fewer iterations. Considering DE algorithm with the industry benchmark data, we optimised the key operational parameters of TCDMR (as OTCDMR), leading to the improved reactor performance (regarding the overall heat transfer and methanol/hydrogen production) compared to the conventional methanol reactor (CMR) and TCDMR. Simulation results show that the methanol production rate of OTCDMR could reach 315.7 tonnes day−1, representing a 22.6% enhancement than CMR (257 tonnes day−1). For the hydrogen production, OTCDMR is predicted to deliver 19.7 tonnes of hydrogen per day, surpassing the 15.5 tonnes day−1 production rate by TCDMR.

Development of an Efficient Methanol Production Process for Direct CO2 Hydrogenation over a Cu/ZnO/Al2O3 Catalyst

Carbon capture and utilization as a raw material for methanol production are options for addressing energy problems and global warming. However, the commercial methanol synthesis catalyst offers a poor efficiency in CO2 feedstock because of a low conversion of CO2 and its deactivation resulting from high water production during the process. To overcome these barriers, an efficient process consisting of three stage heat exchanger reactors was proposed for CO2 hydrogenation. The catalyst volume in the conventional methanol reactor (CR) is divided into three sections to load reactors. The product stream of each reactor is conveyed to a flash drum to remove methanol and water from the unreacted gases (H2, CO and CO2). Then, the gaseous stream enters the top of the next reactor as the inlet feed. This novel configuration increases CO2 conversion almost twice compared to one stage reactor. Also to reduce water production, a water permselective membrane was assisted in each reactor to remove water from the reaction side. The proposed process was compared with one stage reactor and CR from coal and natural gas. Methanol is produced 288, 305, 586 and 569 ton/day in CR, one-stage, three-stage and three-stage membrane reactors (MR), respectively. Although methanol production rate in three-stage MR is a bit lower than three stage reactors, the produced water, as the cause of catalyst poisoning, is notably reduced in this configuration. Results show that the proposed process is a strongly feasible way to produce methanol that can competitive with a traditional synthesis process.

Performance Study of a Thermally Double Coupled Multi-Tubular Reactor by Considering the Effect of Flow Type Patterns

Abstract In this study, a steady-state heterogeneous one-dimensional model predicts the performance of a thermally double coupled auto-thermal multi-tubular reactor for simultaneous production of hydrogen, benzene, methanol and dimethyether (DME) in an economical approach for both co- and counter- current modes of operation. Reversed flow of cyclohexane has been considered for the counter-current flow regime. The simulation results for co- and counter-current modes have been investigated and compared with corresponding predictions for conventional methanol reactor and traditional coupled methanol reactor. In addition, various operating parameters along the reactor have been studied. The simulation results present that methanol yield in co- and counter- current modes are reached to 0.3735 and 0.3363 in a thermally double coupled reactor, respectively. Also, results for counter-current mode show a superior performance in hydrogen and benzene production. Finally, the results of simulation illustrate that the coupling of these reactions could be beneficial.

Production of Hydrogen, Methanol and Benzene Simultaneously in an Industrial Scale Reactor by Considering Effect of Flow Type Regimes

In this study, exothermic reaction of methanol synthesis is coupled with endothermic reaction of dehydrogenation of cyclohexane in a two-packed bed reactor in order to simultaneous production of hydrogen, methanol and benzene. Steady-state, heterogeneous model predicts the performance of this configuration. The simulation results for co-current and counter-current modes in thermally coupled methanol reactor (TCMR) are investigated and compared with data of an industrial scale conventional methanol reactor (CMR) with same feed conditions. In addition, the variation of different operating parameters along the reactor has been considered. The simulation results represent 1.89 % enhancements in methanol recovery yield of co-current mode in TCMR in comparison with CMR. Also, results show that hydrogen recovery yield in dehydrogenation of cyclohexane side in co-current and counter-current modes of TCMR is equal to 2.352 and 2.255, respectively. Finally, TCMR in co-current mode is a feasible reactor for cost reduction because it has benefits such as production of multiple products, enhancement of productivity by shifting equilibrium of reactions to forward, large savings in the operational and capital costs, compact and efficient process.

Sorption-enhanced methanol synthesis in a dual-bed reactor: Dynamic modeling and simulation

This work considers a dynamic mathematical model of a dual-bed multifunctional methanol reactor (DMMR) in the face of long term catalyst deactivation. A configuration of two catalyst beds instead of one single bed with selective adsorption of water inside the first bed is developed for methanol production. Synthesis gas and flowing adsorbents are both fed to the first reactor of DMMR. Contact of gas and fine solid particles inside packed bed results in the selective adsorption of water from the methanol synthesis system which increases temperature and methanol production. This reactor functions at a higher than normal operating temperature and at very high yield. In the second converter, the heat of reaction is used to pre-heat the synthesis gas to the first bed. Thus, a more favorable temperature profile is observed in DMMR compared to single-bed multifunctional methanol reactor (SMMR), and conventional methanol reactor (CMR). This way, the catalysts are exposed to less extreme temperatures and hence, declining the catalyst deactivation via sintering. Moreover, a differential evolution (DE) algorithm as a robust method is applied to optimize the reactors length ratio. The results of this study show a higher methanol production and longer catalyst lifetime for DMMR.

Sorption-enhanced methanol synthesis: Dynamic modeling and optimization

Owing to the global energy concerns in today's world, alternative fuels such as methanol have become an increasingly attractive option to meet the growing power demand. This work considers a dynamic mathematical model of a gas-flowing solids-fixed bed reactor (GFSFBR) with in situ water adsorption for methanol synthesis in the face of long term catalyst deactivation. Contact of gas and fine solid particles inside packed bed results in the selective adsorption of water from the methanol synthesis that leads to higher methanol production compared to the conventional methanol reactor (CMR). Moreover, a theoretical investigation has been performed in order to evaluate the optimal operating conditions and maximize the methanol production in a GFSFBR using differential evolution (DE) algorithm as a robust method. Dynamic optimization result has shown that under optimum values of inlet temperature of gas phase, inlet temperature of flowing solid phase, and inlet temperature of shell side the highest methanol production can be achieved during the operating period.

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.

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.

Dynamic modeling of a H2O-permselective membrane reactor to enhance methanol synthesis from syngas considering catalyst deactivation

In this paper, the effect of water vapor removal on methanol synthesis capacity from syngas in a fixed-bed membrane reactor is studied considering long-term catalyst deactivation. A dynamic heterogeneous one-dimensional mathematical model that is composed of two sides is developed to predict the performance of this configuration. In this configuration, conventional methanol reactor is supported by an alumina-silica composite membrane layer for water vapor removal from reaction zone. To verify the accuracy of the considered model and assumptions, simulation results of the conventional methanol reactor is compared with the industrial plant data under the same process condition. The membrane reactor improves catalyst life time and enhances CO2 conversion to methanol by overcoming the limitation imposed by thermodynamic equilibrium. This configuration has enhanced the methanol production capacity about 4.06% compared with the industrial methanol reactor during the production time.

A COMPARISON OF A NOVEL RECUPERATIVE CONFIGURATION AND CONVENTIONAL METHANOL SYNTHESIS REACTOR

Coupling energy-intensive endothermic reaction systems with suitable exothermic reactions improves the thermal efficiency of processes and reduces the capital cost of the reactors. In this study, a steady-state heterogeneous model for a novel thermally coupled reactor, containing methanol synthesis reactions and cyclohexane dehydrogenation, was developed. This heat exchanger reactor consists of two fixed beds separated by a wall, where heat is transferred across the surface of the tube from the exothermic into the endothermic side. The co-current mode is investigated, and the simulation results are compared with corresponding data for an industrial methanol fixed bed reactor operated at the same feed conditions. The results show that although methanol productivity in the thermally coupled reactor is not higher than that in the conventional methanol reactor, benzene is also produced as an additional valuable product in a favorable manner, and autothermality is achieved within the reactor. This novel configuration can increase the methanol synthesis temperature at the first part of the reactor for higher process rates and then reduce the temperature at the second part of reactor for increasing thermodynamic equilibrium; those are two key issues in methanol reactor configurations. The influence of inlet temperature, molar flow rate, and shell diameter of the endothermic stream on reactor behavior is investigated. The results suggest that coupling of these reactions in co-current mode could be feasible and beneficial. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor.

Hydrogen looping approach in optimized methanol thermally coupled membrane reactor

In this study, cyclohexane and hydrogen loop approach is proposed in optimized thermally coupled dual reactors in methanol production via Differential Evolution (DE) method. This new generation of thermally coupled membrane reactors uses simultaneously the advantages of hydrogen carrier characteristic and multifunctional reactors. This configuration is named thermally coupled dual methanol reactor (TCDMR). In the first reactor, cyclohexane dehydrogenation reaction is coupled with methanol production reactions. Cyclohexane is produced in the second reactor due to carrying all produced hydrogen from the first reactor to the second reactor for benzene hydrogenation reaction. The operating conditions of TCDMR are optimized via DE method and six decision variables are considered to investigate its performance. Since cyclohexane is produced continuously in the second reactor and enters the first reactor as the endothermic feed, the external cyclohexane injection rate is minimized, too. A comparison is made between the optimized TCDMR (OTCDMR), TCDMR and Thermally coupled methanol reactor (TCMR) and conventional methanol reactor (CMR). The modeling results demonstrate the superiority of OTCDMR to all previously proposed configurations. A continuous system is achieved and slight amount of exterior cyclohexane injection rate (3.6 mol h −1) is required in this configuration. Furthermore, the hydrogen storage problem is solved by this configuration owing to simultaneous hydrogen production and utilization. In addition, produced benzene in OTCDMR is about 10% of the one in TCMR which can be appealing from the environmental viewpoint.

Methanol production in an optimized dual-membrane fixed-bed reactor

Coupling reaction and separation in a membrane reactor improves the reactor efficiency and reduces purification cost in the following stages. This paper focuses on modeling and optimization of methanol production in a dual-membrane reactor. In this configuration, conventional methanol reactor is supported by Pd/Ag membrane tubes for hydrogen permeation and alumina–silica composite membrane tubes for water vapor removal from the reaction zone. A steady state heterogeneous one-dimensional mathematical model is developed to predict the performance of this novel configuration. In order to verify the accuracy of the model, simulation results of the conventional reactor is compared with available industrial plant data. The main advantages of the optimized dual-membrane reactor are: higher CO 2 conversion, the possibility of overcoming the limitation imposed by thermodynamic equilibrium, improvement of the methanol production rate and its purity. Genetic algorithm as an exceptionally simple evolution strategy is employed to maximize the methanol production as the objective function. This configuration has enhanced methanol production rate by 13.2% compared to industrial methanol synthesis reactor.

Application of water vapor and hydrogen-permselective membranes in an industrial fixed-bed reactor for large scale methanol production

Coupling reaction and separation in a membrane reactor improves the reactor efficiency and reduces purification cost in the next stages. In this work a novel reactor consisting two membrane layers has been proposed for simultaneous hydrogen permeation to reaction zone and water vapor removal from reaction zone in the methanol synthesis reactor. In this configuration conventional methanol reactor is supported by a Pd/Ag membrane layer for hydrogen permeation and alumina–silica composite membrane layer for water vapor removal from reaction zone. In this reactor syngas is fed to the reaction zone that is surrounded with hydrogen-permselective membrane tube. The water vapor-permselective membrane tube is placed in the reaction zone. A steady state heterogeneous one-dimensional mathematical model is developed for simulation of the proposed reactor. To verify the accuracy of the model, simulation results of the conventional reactor is compared with the available plant data. The membrane fixed bed reactor benefits are higher methanol production rate, higher quality of outlet product and consequently lower cost in product purification stage. This configuration has enhanced the methanol yield by 10.02% compared with industrial reactor. Experimental proof-of-concept is needed to establish the safe operation of the proposed configuration.

Production of ultrapure hydrogen via utilizing fluidization concept from coupling of methanol and benzene synthesis in a hydrogen-permselective membrane reactor

In this work, a novel fluidized-bed thermally coupled membrane reactor has been proposed for simultaneous hydrogen, methanol and benzene production. Methanol synthesis is carried out in exothermic side which is a fluidized-bed reactor and supplies the necessary heat for the endothermic side. Dehydrogenation of cyclohexane is carried out in endothermic side with hydrogen-permselective Pd/Ag membrane wall. Selective permeation of hydrogen through the membrane in endothermic side is achieved by co-current flow of sweep gas through the permeation side. A steady-state fixed-bed heterogeneous model for dehydrogenation reactor and two-phase theory in bubbling regime of fluidization for methanol synthesis reactor is used to model and simulate the integrated proposed system. This reactor configuration solves some observed drawbacks of new thermally coupled membrane reactor such as internal mass transfer limitations, pressure drop, radial gradient of concentration and temperature in both sides. The proposed model has been used to compare the performance of a fluidized-bed thermally coupled membrane reactor (FTCMR) with thermally coupled membrane reactor (TCMR) and conventional methanol reactor (CR) at identical process conditions. This comparison demonstrates that fluidizing the catalytic bed in the exothermic side of reactor caused a favorable temperature profile along the FTCMR. Furthermore, the simulation results represent 5.6% enhancement in the yield of hydrogen recovery in comparison with TCMR.

Enhancement of hydrogen production via coupling of MCH dehydrogenation reaction and methanol synthesis process by using thermally coupled heat exchanger reactor

In the present study, hydrogen and methanol production rates are simultaneously investigated through the process intensification (PI) concept. PI is a strategy for reduction of emissions as well as consumption of energy and materials. Endothermic dehydrogenation of methylcyclohexane is supposed to occur in the shell side of conventional methanol synthesis reactor. The reactor is consisted of two thermally coupled concentric tubular reactors. The rate of the dehydrogenation reaction can be adjusted according to the generated heat in the exothermic side. This is like a smart cooler. By using this new configuration, the equilibrium condition in the methanol synthesis (at the last part of the reactor) can be controlled in order to enhance the production rate. The effect of various operating conditions is investigated through this article. The results of simulation are compared with the corresponded outcome of the conventional methanol reactor. Innovations in reactor configuration, which somehow could be the heart of chemical processes, are often preferred to be the starting point of revamping a process. An investigation in relation to the environmental aspects, commercial viability and economic feasibility of the proposed configuration is necessary in order to consider commercialization of the process.

A novel configuration for hydrogen production from coupling of methanol and benzene synthesis in a hydrogen-permselective membrane reactor

Coupling energy intensive endothermic reaction systems with suitable exothermic reactions improve the thermal efficiency of processes and reduce the size of the reactors. One type of reactor suitable for such a type of coupling is the heat-exchanger reactor. In this work, a distributed mathematical model for thermally coupled membrane reactor that is composed of three sides is developed for methanol and benzene synthesis. Methanol synthesis takes place in the exothermic side and supplies the necessary heat for the endothermic dehydrogenation of cyclohexane reaction. Selective permeation of hydrogen through the Pd/Ag membrane is achieved by co-current flow of sweep gas through the permeation side. A steady-state heterogeneous model of the two fixed beds predicts the performance of this novel configuration. The co-current mode is investigated and the simulation results are compared with corresponding predictions for an industrial methanol fixed-bed reactor operated at the same feed conditions. The results show that although methanol productivity is the same as conventional methanol reactor, but benzene is also produced as an additional valuable product in a favorable manner, and auto-thermal conditions are achieved within the both reactors and also pure hydrogen is produced in permeation side. This novel configuration can increase the rate of methanol synthesis reaction and shift the thermodynamics equilibrium. The performance of the reactor is numerically investigated for various key operating variables such as inlet temperatures, molar flow rates of exothermic and endothermic streams, membrane thickness and sweep gas flow rate. The reactor performance is analyzed based on methanol yield, cyclohexane conversion and hydrogen recovery yield. The results suggest that coupling of these reactions in the presence of membrane could be feasible and beneficial. Experimental proof-of-concept is needed to establish the validity and safe operation of the novel reactor.

Dynamic optimization of membrane dual-type methanol reactor in the presence of catalyst deactivation using genetic algorithm

This paper presents a study on optimization of a membrane dual-type methanol reactor in the presence of catalyst deactivation. A theoretical investigation has been performed in order to evaluate the optimal operating conditions and enhancement of methanol production in a membrane dual-type methanol reactor. A mathematical heterogeneous model has been used to simulate and compare the membrane dual-type methanol reactor with conventional methanol reactor. An auto-thermal dual-type methanol reactor is a shell and tube heat exchanger reactor which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. In a membrane dual-type reactor the wall of the tubes in the gas-cooled reactor is covered with a pd–Ag membrane, which is only hydrogen-permselective. The simulation results have been shown that there are optimum values of reacting gas and coolants temperatures to maximize the overall methanol production. Here, genetic algorithms have been used as powerful methods for optimization of complex problems. In this study, the optimization of the reactor has been investigated in two approaches. In the first approach, the optimal temperature profile along the reactor has been studied and then a stepwise approach has been followed to determine the optimal profiles for saturated water and gas temperatures in three steps during the time of operations to maximize the methanol production rate. The optimization methods have enhanced 5.14% and 5.95% additional yield throughout 4 years of catalyst lifetime for first and second optimization approaches, respectively.

Dynamic Simulation and Optimization of a Dual‐Type Methanol Reactor Using Genetic Algorithms

AbstractIn this investigation, a dynamic simulation and optimization for an auto‐thermal dual‐type methanol synthesis reactor was developed in the presence of catalyst deactivation. Theoretical investigation was performed in order to evaluate the performance, optimal operating conditions, and enhancement of methanol production in an auto‐thermal dual‐type methanol reactor. The proposed reactor model was used to simulate, optimize, and compare the performance of a dual‐type methanol reactor with a conventional methanol reactor. An auto‐thermal dual‐type methanol reactor is a shell‐and‐tube heat exchanger reactor in which the first reactor is cooled with cooling water and the second one is cooled with synthesis gas. The proposed model was validated against daily process data measured of a methanol plant recorded for a period of 4 years. Good agreement was achieved. The optimization was achieve by use of genetic algorithms in two steps and the results show there is a favorable profile of methanol production rate along the dual‐type reactor relative to the conventional‐type reactor. Initially, the optimal ratio of reactor lengths and temperature profiles along the reactor were obtained. Then, the approach was followed to get an optimal temperature profile at three periods of operation to maximize production rate. These optimization approaches increased by 4.7 % and 5.8 % additional yield, respectively, throughout 4 years, as catalyst lifetime. Therefore, the performance of the methanol reactor system improves using optimized dual‐type methanol reactor.