Methanol Synthesis Reaction Research Articles

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.

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.

Preparation and performance of Cu-based monoliths for methanol synthesis

Methanol synthesis from syngas could be carried out in steel monoliths coated with CuO/ZnO/Al 2O 3 catalysts. The Cu-based coatings were prepared using different techniques: slurry coating of CuO/ZnO/Al 2O 3 obtained via 2-stage co-precipitation, sol–gel coating of Al 2O 3 followed by Cu–Zn impregnation, colloid coating of Al 2O 3 followed by Cu–Zn impregnation, and colloid coating of Al 2O 3 followed by deposition–precipitation of Cu–Zn. The coated monoliths were characterized (XRD, BET, N 2O titration) and studied in the methanol synthesis reaction at 80 bar. Comparison was made to similarly prepared powder catalysts subjected to characterization and laboratory scale fixed bed reactor (FBR) experiments. Monoliths with high activity for the methanol synthesis reaction were obtained with slurry coating of CuO/ZnO/Al 2O 3, whereas the impregnation and deposition–precipitation methods gave insufficient Cu dispersion. Higher activity of the monolith relative to FBR experiments with the same catalyst was ascribed to the thermal properties of the steel monolith.

Cu/Cr2O3·3Al2O3 and Au–Cu/Cr2O3·3Al2O3 catalysts for methanol synthesis and water gas shift reactions

A comparative study of the physicochemical properties of Cu/Cr2O3·3Al2O3 and Au–Cu/Cr2O3·3Al2O3 supported catalysts and their catalytic activity in methanol synthesis and water gas shift reactions were the main subject of this study. The promotion effect of gold addition to Cu/support catalysts in the methanol synthesis reaction was proved. The formation of an Au–Cu alloy was confirmed by XRD technique. Methanol selectivity increased after gold introduction onto the catalyst surface, which can be explained by the creation of nucleation centers for copper crystallization by metallic gold particles during catalyst reduction.

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.

Dynamic Simulation of Lurgi-type Reactor for Methanol Synthesis

The purpose of this work is to develop a reasonably detailed dynamic model of a Lurgitype industrial methanol synthesis reactor so as to determine important simplifications, to identify application/operating model limits, and to preliminary check the feasibility for the Nonlinear Model Predictive Control (NMPC) methodology. To do so, a Partially Differential Equation (PDE) system is formulated and integrated to characterize the main phenomena occurring in this shell and tube boiler-reactor. The PDE numerical solution is performed via certain very performing algorithms (BzzMath library).

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.

Optimization of Methanol Yield from a Lurgi Reactor

AbstractMethanol is an important chemical with the potential to become an alternative fuel. An optimization study was performed for a Lurgi methanol synthesis reactor using the commercial process simulator Aspen Plus. The optimization routine is coupled with a steady‐state model of the methanol synthesis reactor. Syngas inlet temperature, steam drum pressure, and cooling water volumetric flow rate were optimized so that methanol production in the reactor outlet was maximized. The methanol yield increased by 7.04 %.

Methanol synthesis in a novel axial-flow, spherical packed bed reactor in the presence of catalyst deactivation

Since in the foreseeable future liquid hydrocarbon fuels will play a significant role in the transportation sector, methanol might be used potentially as a cleaner and more reliable fuel than the petrochemical-based fuels in the future. Consequently, enhancement of methanol production technology attracts increasing attention and, therefore, several studies for developing new methanol synthesis reactors have been conducted worldwide. The purpose of this research is to reduce the pressure drop and recompression costs through the conventional single-stage methanol reactor. To reach this goal, a novel axial-flow spherical packed bed reactor (AF-SPBR) for methanol synthesis in the presence of catalyst deactivation is developed. In this configuration, the reactor is loaded with the same amount of catalyst in the conventional single-stage methanol reactor. The reactants are flowing axially through the reactor. The dynamic simulation of the spherical reactors has been studied in the presence of long-term catalyst deactivation for four reactor configurations and the results are compared with the achieved results of the conventional tubular packed bed reactor (CR). The results show that the three and four stages reactor setups can improve the methanol production rate by 4.4% and 7.7% for steady state condition. By utilizing the spherical reactors, some drawbacks of the conventional methanol synthesis reactors such as high pressure drop, would be solved. This research shows how this new configuration can be useful and beneficial in the methanol synthesis process.

Reduction in CO emissions along a two-stage hydrogen-permselective membrane reactor in methanol synthesis process

Carbon monoxide (CO) is a scentless and invisible gas that is quite poisonous. It is also known to be a major environmental pollutant. Industrial chemical processes contribute to CO pollution levels in the atmosphere. One of the most important processes for controlling the carbon monoxide content is conversion of CO to methanol by catalytic hydrogenation. The present work investigates enhancement of CO conversion in a conventional two-stage methanol synthesis reactor using a hydrogen-permselective membrane. For this membrane system, a one-dimensional dynamic plug flow model was proposed in the presence of long-term catalyst deactivation. This model compares CO removal in a membrane two-stage methanol synthesis reactor with a conventional two-stage methanol synthesis reactor. A conventional two-stage reactor is a vertical shell and tube in which the first reactor coolant is saturated water and the second one is cooled with synthesis gas. In a membrane two-stage reactor, the wall of the tubes in the gas-cooled reactor is coated with a Pd–Ag membrane, which only permits the diffusion of hydrogen. For validation of the recommended dynamic model, the measured daily process data of a methanol plant recorded for a period of 4 years were used and a good agreement was obtained.

The applications of metal supported chromia-alumina catalysts in C1 reactions

The aim of this work was to determine the catalytic properties of metal (Ni, Cu, Pt) supported catalysts in C1 reactions. Catalytic activity of Cr x Al y O z binary oxides alone and Me/Cr x Al y O z samples were determined in: CO oxidation (by water vapor or oxygen), methanol synthesis (MS) reaction as well as partial oxidation of methane (POM) to synthesis gas.

Analysis of Methanol Production from Biomass Gasification

AbstractA biomass‐based methanol production process was investigated. The process consists of a biomass gasifier, steam reformer, and methanol synthesis reactor as the main units. Reactors were simulated by applying the kinetic models previously developed and the process was analyzed based on the simulation results. The key parameters, the equivalence ratio in biomass gasification, the temperature in steam reforming, and the recycle of hydrogen in methanol synthesis were identified. These parameters affect the methanol production. The process analysis indicates that the optimal combinations of the parameters can greatly enhance the methanol production and the thermodynamic efficiency. Finally, the elemental analysis for carbon and hydrogen along the process was carried out.

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.

Process integration and economic analysis of bio-oil platform for the production of methanol and combined heat and power

Process to process material and heat integration strategies for bio-oil integrated gasification and methanol synthesis (BOIG-MeOH) systems were developed to assess their technological and economic feasibility. Distributed bio-oil generations and centralised processing enhance resource flexibility and technological feasibility. Economic performance depends on the integration of centralised BOIG-MeOH processes, investigated for cryogenic air separation unit (ASU) and water electrolyser configurations. Design and operating variables of gasification, heat recovery from gases, water and carbon dioxide removal units, water-gas shift and methanol synthesis reactors and CHP network were analysed to improve the overall efficiency and economics. The efficiency of BOIG-MeOH system using bio-oil from various feedstocks was investigated. The system efficiency primarily attributed by the moisture content of the raw material decreases from oilseed rape through miscanthus to poplar wood. Increasing capacity and recycle enhances feasibility, e.g.1350MWBOIG-MeOH with ASU and 90% recycle configuration achieves an efficiency of 61.5% (methanol, low grade heat and electricity contributions by 89%, 7.9% and 3% respectively) based on poplar wood and the cost of production (COP) of methanol of 318.1 Euro/t for the prices of bio-oil of 75 Euro/t and electricity of 80.12 Euro/MWh, respectively. An additional transportation cost of 4.28e8.89 Euro/t based on 100 km distance between distributed and centralised plants reduces the netback of bio-oil to 40.9e36.3 Euro/t.

A Novel once-through Process for Methanol and DME Synthesis from Syngas

A novel process for methanol and dimethyl ether(DME) synthesis was developed, in which two methanol-synthesis fixed-bed reactors were followed by an identical one for DME synthesis with cooling sections in between. Self-made Cu-Zn-Al catalyst for methanol synthesis and DME synthesis were used in this process. Tests of catalysts showed that both of them had activity and favorable stability and wound be capable of long-term industrial operation under the conditions. The investigation of processing parameters and stability led us safely to ensure the optimal condition: T1-200oC,T2-190 °C,T3-210 °C,5Mpa,total Space Velocity-1000h-1(T1,T2,T3 defined as temperature of catalytic beds in three serial reactors). Under that the catalytic system kept stable during the investigated hours.

Methanol production from CO2 using solar-thermal energy: process development and techno-economic analysis

We describe a novel solar-based process for the production of methanol from carbon dioxide and water. The system utilizes concentrated solar energy in a thermochemical reactor to reenergize CO2 into CO and then water gas shift (WGS) to produce syngas (a mixture of CO and H2) to feed a methanol synthesis reactor. Aside from the thermochemical reactor, which is currently under development, the full system is based on well-established industrial processes and component designs. This work presents an initial assessment of energy efficiency and economic feasibility of this baseline configuration for an industrial-scale methanol plant. Using detailed sensitivity calculations, we determined that a break-even price of the methanol produced using this approach would be 1.22 USD/kg; which while higher than current market prices is comparable to other renewable-resource-based alternatives. We also determined that if solar power is the sole primary energy source, then an overall process energy efficiency (solar-to-fuel) of 7.1% could be achieved, assuming the solar collector, solar thermochemical reactor sub-system operates at 20% sunlight to chemical energy efficiency. This 7.1% system efficiency is significantly higher than can currently be achieved with photosynthesis-based processes, and illustrates the potential for solar thermochemical based strategies to overcome the resource limitations that arise for low-efficiency approaches. Importantly, the analysis here identifies the primary economic drivers as the high capital investment associated with the solar concentrator/reactor sub-system, and the high utility consumption for CO/CO2 separation. The solar concentrator/reactor sub-system accounts for more than 90% of the capital expenditure. A life cycle assessment verifies the opportunity for significant improvements over the conventional process for manufacturing methanol from natural gas in global warming potential, acidification potential and non-renewable primary energy requirement provided balance of plant utilities for the solar thermal process are also from renewable (solar) resources. The analysis indicates that a solar-thermochemical pathway to fuels has significant potential, and points towards future research opportunities to increase efficiency, reduce balance of plant utilities, and reduce cost from this baseline. Particularly, it is evident that there is much room for improvement in the development of a less expensive solar concentrator/reactor sub-system; an opportunity that will benefit from the increasing deployment of concentrated solar power (electricity). In addition, significant advances are achievable through improved separations, combined CO2 and H2O splitting, different end products, and greater process integration and distribution. The baseline investigation here establishes a methodology for identifying opportunities, comparison, and assessment of impact on the efficiency, lifecycle impact, and economics for advanced system designs.

Copper-supported catalysts in methanol synthesis and water gas shift reaction

The comparative studies of physicochemical properties of Cu-support catalysts (support = ZnO, Al2O3, Cr2O3, ZnAl2O4, FeAlO3, or CrAl3O6) and their catalytic activity in methanol synthesis and water gas shift reaction were the main goal of this work. The promotion effect of copper addition in both reaction was proved. The formation of spinel type structure CuCr2O4, ZnAl2O4 and binary oxide CrAl3O6, FeAlO3 during calcination process was confirmed by XRD technique. Results showed that 20% Cu/FeAlO3 had the best performance in water gas shift reaction. The best selective and active catalyst in methanol synthesis was 20% Cu/ZnAl2O4.

Optimization of methanol synthesis reaction on Cu/ZnO/Al2O3/ZrO2 catalyst using genetic algorithm: Maximization of the synergetic effect by the optimal CO2 fraction

A kinetics model that takes the synergetic effect of carbon dioxide fraction on the methanol production rate into account is applied to the development of a mathematical model for the bench-scale reactor. A comparison between the simulation results and the experimental data corroborates the validity of the model. Several optimization strategies are suggested to maximize the methanol yield, among which the utilization of piecewise trajectories for wall temperature along the reactor axis as well as the optimal CO2 fraction at the inlet of the reactor is found to be the best strategy in the sense of methanol production per unit amount of the feed, in such a way that the optimization strategy considers the variation of the reaction temperature in the reactor and maximizes the synergetic effect on the production rate by the addition of carbon dioxide.

Copper crystallite size and methanol synthesis catalytic property of Cu-based catalysts promoted by Al, Zr and Mn

Five Cu-based catalysts with different promoters (Al, Zr and Mn) were prepared by uniform coprecipitation and evaluated in a laboratory fixed bed reactor for methanol synthesis at 463–513 K and a pressure of 4 MPa. These catalysts were characterized by X-ray diffraction (XRD) and the data showed that they had similar crystal phase and copper crystallite sizes. The most active catalyst comprised fibrous particles with a ring structure. Zirconium, aluminum and manganese additives caused no evident change in the main active phase of the catalysts but gave rise to different copper crystallite sizes. The different Cu0 crystallite sizes resulted in different amounts of active sites, but the activation energies of methanol synthesis on these catalysts were all about 104 kJ/mol and turnover frequencies (TOFs) were about the same values, indicating the close relationship between methanol productivity and microstructure of Cu-based catalyst.

Preparation of Cu/ZnO/Al2O3 catalyst under microwave irradiation for slurry methanol synthesis

Cu/ZnO/Al2O3 catalysts with Cu/Zn/Al ratios of 6/3/1 were precipitated and aged by conventional and microwave heating methods and tested in the slurry phase reactor for methanol synthesis. The effect of technological condition of precipitation and aging process under microwave irradiation on the catalytic performance was investigated to optimize the preparing condition of Cu/ZnO/Al2O3 catalyst. The results showed that the microwave irradiation during precipitation process could improve the activity of the catalyst, but had little effect on the stability. While the microwave irradiation during aging process has a great benefit to both the activity and stability of the catalyst, the catalyst aged at 80°C for 1 h under microwave irradiation possessed higher methanol space time yield (STY) and more stable catalytic activity. The activity and stability of the catalyst was further enhanced when microwave irradiation was used in both precipitation and aging processes; the optimized condition for the catalyst precursor preparation was precipitation at 60°C and aging at 80°C under microwave irradiation.