Liquid phase methanol synthesis

In industrial practice, three-phase catalytic reactors are often used, with gases like such as H2, H2O, NH3 or O2 as reactants. The process can be classified on the basis of these gases as hydrogenation, hydration, amination, oxidation, etc [3]. Among these processes, hydrogenation is by far the most important multiphase catalytic reaction. Recently, liquid- -phase methanol synthesis and the Fischer-Tropsch process were commercialized respectively... 

Cybulski et al. [39] have studied the performance of a commercial-scale monolith reactor for liquid-phase methanol synthesis by computer simulations. The authors developed a mathematical model of the monolith reactor and investigated the influence of several design parameters for the actual process. Optimal process conditions were derived for the three-phase methanol synthesis. The optimum catalyst thickness for the monolith was found to be of the same order as the particle size for negligible intraparticle diffusion (50-75 p.m). Recirculation of the solvent with decompression was shown to result in higher CO conversion. It was concluded that the performance of a monolith reactor is fully commensurable with slurry columns, autoclaves, and trickle-bed reactors. 

A. Cybulski, R.K. Edvinsson, S. Irandoust, and B. Andersson, Liquid-phase methanol synthesis Modelling of a monolithic reactor, Chem. Eng. Sci. 48(20) 3463 (1993). 

Development of stable catalysts for liquid-phase methanol synthesis from CO2 and H2... 

This work focuses on the investigation of the stability of catalytic activity in the liquid phase methanol synthesis process. Novel catalysts with a long-term stability have been developed by the addition of hydrophobic materials. The addition of hydrophobic materials were effective for slowing down the crystallite size growth and inhibition of deactivation of catalyst as compared with the original catalyst without modification. 

Methanol synthesis from CO2 and H2 has received much attention as one of the most promising processes to convert C02 into chemicals. Gas-phase methanol synthesis process should recycle a large quantity of unconverted gas and furthermore the single pass conversion is limited by the large heat release in the reaction. Liquid-phase methanol synthesis in solvent has received considerable attention, since temperature control is much easier in the liquid phase than in the gas phase. 

Several types of reactors have been proposed such as the liquid entrained reactor(l) and the Trickle bed reactor(2). The authors have been studying a liquid-phase methanol synthesis process in order to develop a new technology as an alternative for a gas-phase process, and reported that a new process employing liquid-liquid separation of the products from the solvent has several advantages in practical methanol synthesis(3). 

Figure 2 shows X-ray diffraction patterns of the catalysts after the liquid-phase methanol synthesis. The crystallite size of the catalyst modified with the special silicone oil was lower than that of the original catalyst without modification. The crystallite size of the catalyst modified with the hydrophilic silica B was a little lower than that of the original catalyst. And also the formation of Zn2Si04 phase was detected in the catalysts modified with the special silicone oil and the hydrophilic silica B after the liquid-phase methanol synthesis. The catalyst modified with the hydrophilic silica B was more stable than the original catalyst without... 

Figure 2. X-ray diffraction patterns of catalysts after the liquid-phase methanol synthesis...

The catalysts with a long-term stability for the liquid-phase methanol synthesis process have been developed. The addition of hydrophobic materials to the catalyst could suppress the sintering of Cu particles in the catalyst and then result in a long-term stability of the catalyst. The modification of Cu/ZnO-based catalyst by the hydrophobic treatment is very uscfiil for improving a long-term stability of the catalyst for the liquid-phase methanol synthesis from C02 and H2. 

Vijayaraghavan, P. Kulik, C.J. Lee, S. Modelling of a liquid entrained reactor for liquid phase methanol synthesis process. Fuel Sci. Technol. Int. 1992, 10 (9), 1501-1521. 

Uztiirk S, Shah YT, Deckwer W-D (1988) Comparison of Gas and Liquid Phase Methanol Synthesis Processes. Chem Eng J 37 177-192... 

The ICI patents (ref. 20) describe the use of intermetallics (similar to those in Tabel 2 above) in liquid-phase methanol synthesis. The reaction was conducted at 70°C and 5 MPa using a syngas of 67 /33 CO which was contacted with a sample of ground catalyst suspended in 10 times its mass of octane. Although no details of activity are given it is claimed that high methanol yields were produced under those conditions. Therefore, the copper-based intermetallic catalysts may have application in the Chem Systems process. 

In addition, new and novel methanol production processes are being developed, and the patent literature is very active. Many of the contributions to this conference describe the forefront of these technologies. Liquid-phase methanol synthesis via the Chem Systems process has been demonstrated in a large semi-works unit since 1984 (ref. 5). And a new methanol production process which uses air partial oxidation has been proposed by Brookhaven National Laboratory (ref. 6). 

Lee, S., Research support for liquid phase methanol synthesis process development, Electric Power Research Report. AP-4429, pp. 1-312, Palo Alto, CA, February 1986. 

Cybulski, A., Liquid-phase methanol synthesis Catalysts, mechanism, kinetics, chemical equilibria, vapor-liquid equilibria, and modeling—A review, Catal. Rev.-Sci. Eng. 36(4) 557-615 (1994). 

An important relatively recent achievement is the development of the so-called liquid entrained reactor (LER) for liquid phase methanol synthesis. To assess the performance of these reactors, much simultaneous work has been done on MARs, comparing the performance of the two types of reactors for this reaction. A good discussion of this can be found in a paper by Vijayaraghavan et a. (1993). An equation developed for the overall gas-liquid mass transfer coefficient (see Ko, 1987 Lee et al., 1988 Parameswaran et al., 1991) is... 

Ko. M.K. Mass Transfer Analysis of the Liquid Phase methanol Synthesis process, Ph.D. dissertation. University of Skron, Akron, OH, 1987. 

Lee, S., Parameswaran, E.R., and Sawant, A.V. Mass Transfer in the Liquid Phase Methanol Synthesis (LPMeOH ) Process, Ap-5758, Electric Power Research Institute, Palo Alto, CA, 1988. 

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