Methanol Synthesis Process Research Articles

Neural Net Based Hybrid Modeling of the Methanol Synthesis Process

A Hybrid modeling approach, combining an analytical model with a radial basis function neural network is introduced in this paper. The modeling procedure is combined with genetic algorithm based feature selection designed to select informative variables from the set of available measurements. By only using informative inputs, the model's generalization ability can be enhanced. The approach proposed is applied to modeling of the liquid–phase methanol synthesis. It is shown that a hybrid modeling approach exploiting available a priori knowledge and experimental data can considerably outperform a purely analytical approach.

液相メタノールにおける一酸化炭素ガスの輸送過程に関する研究

To estimate the effect of transport process of carbon monoxide gas in liquid methanol in a two-step methanol synthesis process which starts with carbonylation of methanol to methyl formate, solution and diffusion process of CO gas and its single bubbles in liquid phase methanol were theoretically and experimentally studied under various pressures and temperatures. Diffusion coefficients of dissolved CO gas in methanol were obtained by comparing the experimental data of CO gas solution in methanol within a small glass tube with theoretical solutions based on one dimensional diffusion model. The diffusion coefficients are between 4.0×10-9 m2/s and 7.6×10-9 m2/s for the temperatures ranged from 30 to 80 °C, and become higher as temperature increases. In the theoretical analysis for the solution of single CO bubbles in methanol accompanying chemical absorption, the single CO bubble was assumed to be stationary and surrounded by infinite liquid methanol. The rate of solution of bubble in liquid is affected strongly by various parameters, such as solubility, diffusion coefficient, chemical reaction constant, bubble radius, especially temperature. The theoretical results show that the rate of solution of CO bubble in liquid methanol was enhanced by chemical reaction, and the total reaction rate can be improved by enhancing the transport process of gas in the liquid. They also show that the reaction constant can be obtained by comparing the experimental data of the variation of bubble radius with time with the theoretical solutions. It was understood that the theoretical nondimensional times for complete solution of the single bubbles in methanol without reaction agree well with the experimental data for the initial diameters around 0.25 mm, and the times become shorter for larger bubble diameters due to the increasing effect of nature convection induced by density difference around the bubble.

Kinetics and modelling of dimethyl ether synthesis from synthesis gas

The kinetics of the dual catalytic methanol and dimethyl ether (DME) synthesis process over a commercial CuO/ZnO/Al 2O 3 (methanol forming) and a γ-alumina (dehydration) catalyst have been investigated at 250°C and 5 MPa using a gradientless, internal-recycle-type reactor. A kinetic model for the combined methanol+DME synthesis based on a methanol synthesis model proposed by Vanden Bussche and Froment (1996) J. Catal., 161, 1–10) and a methanol dehydration model by Bercic and Levec (1993) Ind. Engng Chem. Res., 31, 1035–1040) has been tested using results obtained from a wide range of CO 2 : CO feed ratios. Results at different CO x : H 2 ratio and catalyst loading ratios were also obtained. Catalyst deactivation was observed during DME synthesis at high space velocities and a large ratio of dehydration catalyst.

Carbon Dioxide Hydrogenation To Form Methanol via a Reverse-Water-Gas-Shift Reaction (the CAMERE Process)

The CAMERE process (carbon dioxide hydrogenation to form methanol via a reverse-water-gas-shift reaction) was developed and evaluated. The reverse-water-gas-shift reactor and the methanol synthesis reactor were serially aligned to form methanol from CO2 hydrogenation. Carbon dioxide was converted to CO and water by the reverse-water-gas-shift reaction (RWReaction) to remove water before methanol was synthesized. With the elimination of water by RWReaction, the purge gas volume was minimized as the recycle gas volume decreased. Because of the minimum purge gas loss by the pretreatment of RWReactor, the overall methanol yield increased up to 89% from 69%. An active and stable catalyst with the composition of Cu/ZnO/ZrO2/Ga2O3 (5:3:1:1) was developed. The system was optimized and compared with the commercial methanol synthesis processes from natural gas and coal.

流通式反応装置における液相メタノール合成反応速度の実験的測定

To achieve reduction of primary energy consumption and prevent deterioration of global environment, a liquid-phase methanol synthesis process was investigated to recover wasted or unused discharged heat from industrial sources for the thermal energy demands of residential and commercial areas. The chemical reaction rate of methanol synthesis by hydrogenolysis of methyl formate was measured using a plate-type of Raney copper catalyst in a reactor with circulating flow. The contents of methanol in the liquid were analyzed by gas chromatographs, then the reaction rate was calculated by the measured increases in methanol due to reaction. The reaction characteristics were investigated by carrying the experiments at various temperatures, flow velocities and at various catalyst development conditions. It was obtained that the reaction rate increases with the temperature due to the enhancement of activation of the catalyst and the increases of solubility of hydrogen gas in methyl formate. It increases also at higher flow velocity for the higher diffusion effect. The reaction rate showed little dependence on the catalyst thickness under the present experimental condition for the catalyst thickness ranging from 64 to 70μm.

種々圧力・温度下の液相ギ酸メチル及びメタノールにおける―酸化炭素ガスの溶解度

Solution process of CO gas in liquid phase methyl formate and methanol was experimentally studied under various pressures and temperatures to evaluate the transport effect of CO gas in the liquids in a two-step methanol synthesis process which starts with carbonylation of methanol to methyl formate, then followed by the hydrogenolysis of the formate. The solubility of carbon monoxide in liquid phase methyl formate and methanol were measured by the decrease in pressure due to absorption at pressures up to 1700 kPa and temperatures form 20 to 140°C. It was obtained that the solubilities were between 3.1×10-3 and 11.5×10-3 for CO in methyl formate, and between 4×10-4 and 10.7×10-3 for CO in methanol. The Henry's law constant was about 160 MPa at a temperature of 20°C for CO in methyl formate, and about 250 MPa at temperatures under 100°C and pressures under 1000 kPa for CO in methanol. The Henry's law constant decreased with the increase of temperature. Empirical correlations for solubility at various temperatures and pressures were given based on the experimental data.

Direct methanol synthesis using non-thermal pulsed plasma generated by a solid state pulse generator

Conversion of hydrocarbon fuels to methanol will promote their efficient utilization since methanol can easily be converted to hydrogen using low temperature heat energy, which would otherwise be disposed. Conventional process for methanol synthesis requires large amount of energy, therefore it can not be applied in the energy utilization system. The non-thermal plasma process can induce chemical reactions that do not occur under usual condition, and attempts have been made to apply a pulsed discharge plasma for direct methanol synthesis. A solid state pulse generator has been developed to increase frequency of pulse. A pulsed voltage of 1 ∼ 2 μ s rise time and 4 ∼ 5 μ s pulse width can be generated with frequency of 10 kHz. It was found that voltage and current characteristics was different with type of the reactor. The pulse generator was used for the methanol synthesis. Methanol with concentration of up to 0.7% could be obtained at 5 kHz pulse frequency and 6.7 sec gas residence time, when CH4 O2 (96:4) mixture was used at room temperature.

97/00840 Comparison of two-phase and three-phase methanol synthesis processes

97/00840 Comparison of two-phase and three-phase methanol synthesis processes

97/00132 Comparison of two-phase and three-phase methanol synthesis processes

97/00132 Comparison of two-phase and three-phase methanol synthesis processes

Liquid phase methanol synthesis catalyst

Abstract This work focuses on the investigation of the stability of catalyst activity in the liquid phase methanol synthesis process. The effects of various kinds of metfhods to inhibit the deactivation of catalyst have been experimentally examined. The activity of catalyst was stabilized without lowering of activity by a suitable hydrothermal treatment, although the activity of the untreated catalyst decreased gradually with time. The additive and coating of hydrophobic material were effective for slowing down the crystallite size growth and inhibition of deactivation of catalyst. It was considered that hydrophobic material inhibited the adsorption of produced water onto the hydrophilic catalyst. Hydrophobic treatment of catalyst was found to be effective for liquid phase methanol synthesis from CO2 and H2 using hydrophobic solvent.

Methanol synthesis from CO2 and H2 over a multicomponent catalyst

Abstract The optimum operation conditions for preparing a Cu ZnO-based gd multicomponent catalyst (Cu/ZnO/ZrO2/Al2O3/Ga2O3) by a coprecipitation method were established. The operation conditions for preparing the precipitate rarely affect the activity of the catalyst, whereas thoroughly washing the precipitate with distilled water to remove Na in the catalyst is greatly important for improving the activity of the catalyst. The Cu ZnO-based multicomponent catalyst prepared under the optimum preparation conditions was highly active and stable for a long period in a continuous methanol synthesis operation at 523 K with a total pressure of 5 MPa. In the case of the methanol synthesis over the multicomponent catalyst using a recycle reactor employed as a model reactor for a practical methanol synthesis process, the conversion of CO2 in a make-up gas to methanol was more than 99.9%, indicating that the methanol synthesis over the multicomponent catalyst is extremely selective.

Comparison of two-phase and three-phase methanol synthesis processes

A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The basic kinetic and thermodynamic data were taken from previous studies carried out in our laboratory. The results show that both reactor systems produce comparable methanol yields under the same process conditions except for the reactor temperature. Carbon conversion to methanol values close to 100% can be achieved. The three-phase process is more efficient in terms of heat recovery and power consumption. This is primarily caused by the fact that the three-phase process generates high-pressure steam and the ICI two-phase process yields boiler feed water of 90°C. Furthermore, the pressure drop in the three-phase reactor is smaller than in the two-phase reactor, resulting in a smaller duty of the recycle compressor. However, for the present low energy prices, the annual financial savings, coupled with these energetic aspects, are not sufficient to compensate for the higher capital investment of the three-phase reactor system relative to the ICI two-phase reactor system. A relatively high natural gas price of US $4.1 per gigajoule is needed to reach the economical break-even point between the two processes. More active catalysts may be developed in the near future. Our results show that a relative increase in the catalyst activity by a factor of 1.5 or more (for both processes) will make the three-phase process of economic interest at a natural gas price of US $2.5 per gigajoule.

STATISTICAL MODEL FOR SLURRY PHASE METHANOL SYNTHESIS PROCESS IN AN ENTRAINED REACTOR

ABSTRACT The process feasibility analysis on the liquid phase methanol synthesis (LPMeOH) process was performed in an entrained slurry reactor system. In this three phase mini-pilot plant system, finely powdered catalyst is slurried in the inert oil phase and this catalyst-oil slurry is continuously recirculated through the entrained reactor, where it is contacted with the cocurrent flow of syngas to form the product methanol The effect of various operating conditions which included the reactor temperature, the reactor pressure, the flow rate of catalyst-oil slurry, the flow rate of syngas, the slurry holdup tank pressure, the syngas composition, and the catalyst loadings in slurry, on the productivity of methanol in the reactor was studied. Using the operating conditions, a statistical reaction rate model not based on the kinetic mechanism, was developed to predict the productivity of methanol in an entrained reactor. The rate of production of methanol predicted by this model agreed well with the experim...

METHANOL PRODUCTIVITY COMPARISON BETWEEN AN AGITATED SLURRY REACTOR AND AN ENTRAINED REACTOR

ABSTRACT The effect of various operating conditions including the catalyst loading in slurry, on the productivity of methanol in an agitated slurry reactor were studied. The modeling of the mechanically agitated slurry reactor was performed with the aid of the reaction rate expression and the gas-liquid mass transfer correlation that were developed, to predict the rate of methanol production for any inlet condition The equilibrium limitation encountered in the liquid phase methanol synthesis process in an agitated slurry reactor can be alleviated by conducting this process in an entrained reactor, where the product methanol formed is continuously flashed out of the system. After developing a kinetic rate expression and a gas-liquid mass transfer correlation, the modeling of the entrained reactor was performed to predict the reactor productivity for any process condition. The rate of methanol production predicted for nominally identical operating conditions in an entrained reactor and in a mechanically agi...

ROLE OF IN-SITU PRODUCED METHANOL ON THE CATALYST DEACTIVATION IN THE LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT The role of methanol produced in-situ in the liquid phase methanol synthesis process has been experimentally examined. The catalyst crystallite size is found to be more stable when the produced water and methanol are consistently removed from the catalyst active sites. The experimental evidence shows that in-situ produced water is not the only culprit for the catalyst crystallite size growth, rather, methanol is also responsible for contributing to crystallite growth and therefore catalyst deactivation Hydrothermal leaching of the catalyst was also determined to be an active participant in catalyst deactivation. Two experimental designs were run to assess the influence of temperature, leaching solution concentration and pretreatment conditions on the extent of leaching of the methanol synthesis catalyst. Water and methanol were found to be active participants in the reduction of catalyst activity. Hence, the methanol/water solutions serve as potentially harmful agents in the leaching of aluminum ...

Effective liquid-phase methanol synthesis utilizing liquid-liquid separation

New liquid phase methanol synthesis process is proposed in that methanol is ejected with hydrocarbon solvent exclusively as a liquid phase, while gaseous components are not practically discharged from the reactor. Methanol is obtained in 95% yield with trace amount of feed gas by liquid-liquid separation from hydrophobic solvent. The advantage of the present process is that the gas recycle can be virtually eliminated.

KINETIC RATE EXPRESSION FOR METHANOL SYNTHESIS IN A LIQUID ENTRAINED REACTOR

Abstract In the three phase entrained reactor for the liquid phase synthesis of methanol, the catalyst-inert oil slurry is pumped through the tubular reactor and syngas is fed to the reactor cocurrently with the upward flow of slurry. According to an elaborate experimental design plan, the effect of different operating conditions on the liquid phase synthesis of methanol in an entrained reactor, was studied. The parameters of this experimental study included reactor temperature, reactor pressure, slurry flow rate, syngas flow rate, slurry holdup tank pressure, and syngas composition. The data obtained from the experiments at low catalyst loading in slurry, were used to develop a kinetic rate expression for the liquid phase methanol synthesis process in an entrained reactor. This in turn helps the scale-up and commercialization of the methanol synthesis process in an entrained reactor.

MODELING OF A MECHANICALLY AGITATED SLURRY REACTOR FOR LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT In the liquid phase methanol synthesis process in a mechanically agitated slurry reactor (MASR), catalyst particles in powder form are slurried in the oil phase, and this catalyst-oil slurry is continuously agitated by the impeller in the reactor. Syngas, which is fed to the reactor, reacts in the presence of the activated catalyst-oil slurry, to form the product, methanol. A computer model was developed based on the experimental results, for the liquid phase methanol synthesis process, in a mechanically agitated slurry reactor. This computer program accurately predicts the multicomponent phase equilibria, ultimate chemical equilibria, and the compositions of each reactant and product species exiting in the agitated slurry reactor The results of the modeling predictions, agree well with the experimental data collected from the agitated slurry reactor.

CATALYST EFFECTIVENESS FACTORS UNDER GAS-TO-LIQUID MASS TRANSFER LIMITING REGIME IN LIQUID PHASE METHANOL SYNTHESIS PROCESS

ABSTRACT The effectiveness factors of methanol synthesis catalyst were experimentally measured under condition of gas-to-liquid mass transfer limiting regime in the liquid phase methanol synthesis process, where the synthesis catalyst is slurried in an inert liquid phase. The experimental measurements of effectiveness factors were based on an intrinsic methanol synthesis rate per unit mass of catalyst (gmol/kg cat.h) which is not limited by external mass transfer. The experiments were carried out under well-defined conditions of temperature, pressure, syngas feed flow rate, and impeller speed. The experiments were carried out in a 1-L stirred autoclave. The catalyst slurry ratios were varied from 10 g in 550 mL of Witco-40 oil (corresponding to a slurry ratio of 2.2%) to 150 g in 550 mLof Witco-40 oil (corresponding to a slurry ratio of 25.1%). The experimental measurements have been summarized in one single plot as generalized catalyst effectiveness factor as a function of catalyst slurry ratio. The resu...

Methanol Synthesis from Blast Furnace Off Gas.

Carbon dioxide emission from the blast furnace can be suppressed by the establishment of the blast furnace operation with natural gas injection and methanol synthesis process from the off gas. Natural gas injection leads to the decrease in concentrations of CO and CO2 and to the increase in H2, which are advantageous to the methanol synthesis reaction. Catalysts of Cu-ZnO/Al2O3 system were found active in the methanol synthesis from the off gas, although the composition of a Cu-ZnO/Al2O3 catalyst used in the conventional methanol synthesis industry showed the formation of only a small amount of methanol. The catalysts of Cu-ZnO/Al2O3 system with the higher concentrations of Cu and ZnO were highly active and selective to methanol where the selectivity reached 90%. The reduction temperture of the catalysts exerted remarkable influence on the methanol yield. The Cu-ZnO/Al2O3 catalyst with the optimal composition of Cu, ZnO, and Al2O3 demonstrated excellent stability in the methanol synthesis during a long time run.