Low pressure methanol processes

Supp. E., Technology of Lurgi s Low Pressure Methanol Process, Chem. Tech., 3 430, 1973. 

High pressure processes P > 150 atm) are catalyzed by copper chromite catalysts. The most widely used process, however, is the low pressure methanol process that is conducted at 503—523 K, 5—10 MPa (50—100 atm), space velocities of 20, 000-60,000 h , and H2-to-CO ratios of 3. The reaction is catalyzed by a copper—zinc oxide catalyst using promoters such as alumina (31,32). This catalyst is more easily poisoned than the older copper chromite catalysts and requites the use of sulfiir-free synthesis gas. 

Several other important commercial processes need to be mentioned. They are (not necessarily in the order of importance) the low pressure methanol process, using a copper-containing catalyst which was introduced in 1972 the production of acetic add from methanol over RhI catalysts, which has cornered the market the methanol-to-gasoline processes (MTG) over ZSM-5 zeolite, which opened a new route to gasoline from syngas and ammoxidation of propene over mixed-oxide catalysts. In 1962, catalytic steam reforming for the production of synthesis gas and/or hydrogen over nickel potassium alumina catalysts was commercialized. 

LCM [Leading Concept for Methanol] A process for making methanol, combining the ICI Low Pressure Methanol process with the steam reforming section of the LCA ammonia process. Developed by ICI in 1990 and piloted in Melbourne, Australia, from 1994. Envisaged for floating factories in off-shore gas fields. 

Naphtha was the initial feedstock for the ICI low pressure methanol process because it was available to ICI at the time they developed the process. However, it is also the most ideal feedstock from a stoichiometric viewpoint as evidenced by the following reaction. 

Application The One Synergy process is improved low-pressure methanol process to produce methanol. The new method produces methanol from natural or associated gas using two-stage steam reforming followed by compression, synthesis and distillation. Capacities, ranging from 5,000 to 7,000 mtpd, are practical in a single stream. Carbon dioxide (C02) can be used as a supplementary feedstock to adjust the stoichiometric ratio of the synthesis gas. 

Schiller A predecessor of the ICI Low Pressure Methanol process, developed by IG Farben. 

Anonymous, The ICI Low Pressure Methanol Process, Agricultural Division, Imperial Chemical Industries, Bilingham, England, No date. 

Winkler process, the Koppers-Totzek process, and the Texaco process. Downstream adjustment and treatment of the raw product gases is required when these processes are used to supply feedstock or cofeedstock to a typical low-pressure methanol process operating at 220 to 270°C and 5.066 to 10.132 MPa (50 to 100 atm). A few of the operating details of these and other commercial coal gasification processes are presented here. 

The GTM plant employs the ICI low-pressure Methanol Process sub-licensed from Davy McKee, and incorporates two methanol trains each capable of producing 2200 tonnes per day of methanol. 

In the two decades since I.C.I. introduced the low-pressure methanol process others have gained increasing shares of the market. Major competitors include Lurgi, Mitsubishi Gas Chemicals and Haldor Topsoe. All have their own variations of the co-precipitated Cu-ZnO catalysts. Recently, Alberta Gas Chemicals has constructed several 1200 tonne/day plants one at Medicine Hat, Alberta and the other at Taranaki near the Synfuels methanol-to-gasoline plant in New Zealand. The Alberta Gas Chemicals plants use catalysts under licence. 

The reactor configuration most prevalent for methanol synthesis from syngas is the gas-phase fixed-bed reactor. It is a two-phase system in which the reacting gas flows through a bed of catalyst particles. ICI introduced its low pressure methanol process in low tonnage plants. This process typically operates at temperatures of 220-28CTC and pressures of 5—10 MPa. The exothermic nature of the methanol synthesis reaction makes the temperature control difficult. The reactor operates adiabatically and the temperature rise... 

Figure 3.14 A schematic of the ICI Katalco low pressure methanol process. Source [14,134],...

Figure 2.4 displays the simplified flowsheet of a low-pressure methanol process (Ullmann, 2001). The graphical user interface of a modem simulation packages could tempt a novice user to enter a simulation problem directly, without analysis. Examine the modelling issues that simulation of this process could arise. 

A side stream of gas is bypassed around the shift unit to achieve the correct Hj CO ratio for the methanol synthesis process. Methanol synthesis itself operates at about 80 bar using the Lurgi Low Pressure Methanol Process followed by a distillation step to achieve the required product quality specification. 

The requirements on purity and composition of the synthesis gas are the same for all modem low-pressure methanol processes in which copper-based catalysts are used. S3oithesis gases are required to fulfill the following conditions ... 

Tests with catalysts containing copper were carried out by Imperial Chemical Industries Ltd., England, from about 1958 to 1962 and eventually a practical copper catalyst for methanol synthesis and the first Low-pressure Methanol Processes were brought onto the market. In the process developed by ICI the quench reactor, in which the reaction heat is removed by quenching with cold gases and which is known from high-pressure methanol synthesis, is used. 

The two low-pressure methanol processes to which currently more than 90% of the world methanol production is manufactured, the Imperial Chemical Industries, Ltd. (ICI) one and the LURGI one, differ considerably in the reactor section. 

The LURGI Octamix Process developed in the years 1978 to 1983 also applies a synthesis loop highly similar to that for the LURGI low-pressure methanol process. As in the case of this process, the tubular reactor is also used to produce fuel methanol. A modified variant of the LURGI methanol catalyst is used operating optimally at a temperature range between 260 and 290° C and at pressures below l(X)bar. 

If the LURGI Low-Pressure Methanol Process discussed in this paper is replaced by another methanol process, the pros and cons of the individual process steps may of course be different... 

Methanol is manufactured from syn. gas by passing the latter at 230-270°C/50-100atm over a copper oxide catalyst (CuO.ZnO or CuO.ZnO.Al Oj) (ICI Low Pressure Methanol process). (The copper oxide is reduced to metal.)... 

First conmereial methanol pioeess by destructive distillation of wood Synflietic methanol route su sted by French chemist Paul Sabatier First synthetic methanol plant commericalizBd by BASF Synthetic methanol process introduced in United States Late 1940s Conversion from water g3s to natural g3s as source of synthetic g s for feed to methanol reactors 1966 Low-pressure methanol process announced by ICl... 

It is clear that the mixed copper oxide/zinc oxide/alumina formulation is an excellent catalyst in the low-pressure methanol process. There has been much debate in explaining the role of copper in the reaction and how methanol is pro-dnced. The group that invented the catalyst examined a number of possibih-... 

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