Mathematical Model for Simulating Behavior of Fauser-Montecatini Industrial Reactors for Methanol Synthesis

Abstract

This paper describes a mathematical model for design and simulation of Fauser Montecatini reactors for methanol synthesis. The model considers the reaction of CO2 conversion, the phenomena of mass and heat transfer between the gas phase and the catalyst surface, and the diffusion of reactants and products within the catalyst pores. It has been used to prepare a computer simulation program to check operation of various industrial reactors. Agreement between experimental data and calculation results is generally very satisfactory.This paper describes a mathematical model for design and simulation calculations of Fauser-Montecatini reactors for the synthesis of methanol. A sketch of this type of reactor is reported in Figure 1. The kinetics of the reaction are CO + 2H2 CH3OH on ZnO-and Cr203-based catalysts and with pure reagents was determined by Xatta et al. (1953Xatta et al. ( , 1955, Cappelli and Dente (1965), using Montecatini-Edison catalyst having the following characteristics: Chemical composition ZnO Cr203 Real density Density of particle Specific surface Porosity <75 A 75-75,000 A >75,000 A Total porosity 75.3% 11.6% 5.36 g/cm3 2.35 g/cm3 70 m!/g 0.0602 cm3/g 0.1837 cm3/g 0.0014 cms/g 0.2453 cm3/gThe model also takes into consideration the reaction C02 + H2 ^CO + H20

Methanol synthesis in a trickle‐bed reactor

“…Gas-phase fixed-bed reactors (GPFBR) such as Fauser-Montecantini reactors offer many advantages for methanol synthesis (Cappelli et al, 1972). Fixed-bed reactors can have high catalyst loadings, which enable high synthesis gas feed rates per unit weight of catalyst (WHSV).…”

“…The kinetics and mechanism for gas-phase methanol synthesis from natural-gas-derived synthesis gas have been studied extensively (Strelzoff, 1970;Fajula et al, 1982;Klier et al, 1982;Cappelli et al, 1972). Rates on liquid-phase methanol synthesis in a slurry reactor using a coal-derived synthesis gas feed are also available, although not as extensive as the gas-phase synthesis reaction (Frank, 1980;Frank and Mednick, 1982;Weimer et al, 1987;Air Products, 1988).…”

“…Rate equations have been published by Cappelli et al (1972) for methanol synthesis over the ZnO-Cr20, catalyst (a hightemperature and high-pressure system) and by Dybkjaer et al (1981), Klier et al (1982), and Murchison et al (1988) for the Cu-Zn-Cr oxide-based catalyst. However, the rate equations do not fit the published data very well and Dybkjaer et al and Klier et al do not report all of the parameters in their rate expressions.…”

Geometry Effects on the Concentration and Reaction Rate Profile in Methanol Production Catalyst. 1. Neglecting External Diffusion

“…It is known (Cappelli et al, 1972) that, under the temperature conditions used in industrial reactors for methanol synthesis, the conversion reaction rate of reaction 2 is very high. It is therefore assumed that equilibrium conditions are reached at the external surface of the catalytic particles, and therefore the material balance for only methanol within the isothermal and isobaric catalyst pellets is derived.…”

Accurate Effective Diffusivities in Multicomponent Systems

“…The effective diffusivities are calculated for the system at 573.15 K and 10 MPa with 100 moles initially present in the mixture (n T0 = 100 mol). The initial mole fractions of the mixture are taken from Cappelli et al [18] representing a typical feed for a methanol synthesis reactor operating at high pressure. After normalization to exclude N 2 they are: 12.14% CO, 0.12% CH 3 OH, 70.94% H 2 , 0.16% H 2 O, 14.90% CH 4 (inert) and 1.74% CO 2 .…”