Pressure methanol synthesis

The alkalized zinc oxide—chromia process developed by SEHT was tested on a commercial scale between 1982 and 1987 in a renovated high pressure methanol synthesis plant in Italy. This plant produced 15,000 t/yr of methanol containing approximately 30% higher alcohols. A demonstration plant for the lEP copper—cobalt oxide process was built in China with a capacity of 670 t/yr, but other higher alcohol synthesis processes have been tested only at bench or pilot-plant scale (23). 

Thermal chlorination of methane was first put on an industrial scale by Hoechst in Germany in 1923. At that time, high pressure methanol synthesis from hydrogen and carbon monoxide provided a new source of methanol for production of methyl chloride by reaction with hydrogen chloride. Prior to 1914 attempts were made to estabHsh an industrial process for methanol by hydrolysis of methyl chloride obtained by chlorinating methane. 

Figure 9.6.5 Experimentally measured Van Heerden diagram for low pressure methanol synthesis. ...

The low-pressure methanol synthesis process utilizes ternary catalysts based on copper, zinc oxide, and another oxide, such as alumina or chromia, prepared by coprecipitation. Cu-Zn0-Al203 and Cu-Zn0-Cr203 are usually the most important industrial catalysts. A significant advance was made when a two-stage precipitation was suggested in which ZnAl2C>4, a crystalline zinc aluminate spinel, was prepared prior to the main precipitation of copper-zinc species.372 This alteration resulted in an increase in catalyst stability for long-term performance with respect to deactivation. Catalyst lifetimes industrially are typically about 2 years. 

Schuth, F., High-throughput screening under demanding conditions Cu/ZnO catalysts in high pressure methanol synthesis as an example, J. Catal. 2003, 216, 110-119. 

Low-pressure methanol synthesis relies almost exclusively on catalysts based on copper, zinc oxide, and alumina. The catalysts are produced by ICI (now Johnson Matthay), Siidchemie (now Clariant), Haldor Topsoe, in the past also by BASF, and other chemical enterprises and contain 50-70 atomic % CuO, 20%-50% ZnO, and 5%-20% Al203. Instead of alumina, chromium oxide and rare earth oxides have also been used. The mixed oxide catalysts are usually shipped as 4-6 mm cylindrical pellets with specific surface area of 60-100 m2/g. The catalysts are activated in situ with dilute hydrogen, often derived from off-gases from synthesis gas... 

Many studies of simultaneous adsorption of hydrogen or water and CO or C02 have been carried out on the high-pressure methanol synthesis catalysts based on zinc oxide and one or several other oxides, but only three investigations (104, 113, 114) dealt with catalysts containing copper, and two of these were made in reference to the mechanism of the low-temperature shift reaction. 

Figure 1.2 A few illustrative examples of chemicals and classes of chemicals that are manufactured by homogeneous catalytic processes. In 1.6 low-pressure methanol synthesis by a heterogeneous catalyst is one of the steps. In 1.9 it is ethylene that is converted to acetaldehyde. In 1.7 all the available building blocks may be used.

Synetix Methanol (LPM) Natural gas, refinery offgas, naphtha oil Proven low-pressure methanol synthesis technology and catalysts 58 1999... 

Catalysts based on CuO-ZnO are of great industrial interest because they exhibit high activity for the low temperature-pressure methanol synthesis and the water-gas-shift reactions. It is known that the activity and useful life of catalysts depend mainly on the activation process and the thermal history they experience during the operation. In the low temperature water gas shift (LTWGS) process, prior to reaction, the catalyst is activated by gas reduction to convert copper oxide into metallic copper [1]. It has been observed that reduction conditions affect the activity and the stability of Cu-ZnO catalysts. For instance, sintering and formation of alloys must be avoided in the reduction step because they deactivate the catalyst [2-3] for the water-gas-shift reaction. 

Then, the surface species were investigated under high-pressure methanol synthesis conditions by DRIFT spectroscopy. DRIFT spectra were recorded as a fimction of time when the sulfided Ca/Pd/SiO2 (Ca/Pd=0.5) was exposed to the stream of syngas at 613 K and S.l MPa (Figure 5 (a)). 

Recent developments in low pressure methanol synthesis processes result from improvements in energy efficiency obtained in various parts of the plant including converter, separator, and heat exchange operations. There is also the on-going development of improved co-precipitated catalysts. However, there have been no major advancements to rival that achieved by I.C.I. in the mid 1960 s. 

This section of the review considers several recent developments in catalysts for low to medium pressure methanol synthesis that could be used in existing converters. These include the Raney copper-zinc catalysts, which have similar compositions and properties to co-precipitated catalysts, thorium-copper and cesium-copper intermetallics and supported noble metals... 

Several processing alternatives have been proposed for converting synthesis gas to methanol. The main incentives are reduced energy costs due to the ability to operate at lower temperatures, lower pressures or both. The most notable of these alternatives (in terms of recent interest) have been the alkyl formate process (ref. 27) and the Chem Systems three-phase reactor approach (ref. 28). A very recent development is the use of a gas-solid-solid trickle flow reactor.which it is proposed can be retrofitted in conventional low pressure methanol synthesis plants (ref. 29). These three alternatives will be reviewed in turn. 

The Mitsubishi Gas Chemical Low-Pressure Methanol Synthesis Process. A schematic flow diagram of the process developed by the Mitsubishi Gas Chemical Company [27] is shown in Figure 3.16. This process also uses a copper-based methanol-synthesis catalyst and is operated at temperatures of 200-280°C over a pressure range of 50-150 atm. The temperature in the catalyst bed is kept under control by using a quench-type converter design, as well as by recovering some of the reaction heat in an intermediate stage boiler. The process uses hydrocarbon feedstock. The feed is desulfurized and... 

Flow sheet of the Lurgi low pressure methanol synthesis process. 

Haldor Topsoe A/S Low Pressure Methanol Synthesis Process. Figure 3.19 shows a schematic of Haldor Topsoe A/S process [9], starting from natural gas or associated gas feedstocks using two-step reforming. The syn-... 

Figure 3.19 Flow diagram of the Haldor Topsoe A/S low pressure methanol synthesis process. (1) desulfurizer, (2) process steam generation unit, (3) primary reformer, (4) oxygen-blown secondary reformer, (5) superheated high-pressure steam generator, (6) distillation section, (7) single-stage syngas compressor, (8) synthesis loop, and (9) is recirculator compressor for recycle gas. Source [9,14],...

Figure 3.20 A schematic of the M. W. Kellogg low pressure methanol synthesis process. Source. [9,134].

Uhde GmbH Methanol Natural gas, LPG and heavy naphtha Process uses steam-reforming synthesis gas generation and a low-pressure methanol synthesis loop technology 11 NA... 

Fig. 7-1 Chemical processing flow chart of the Lurgi low-pressure methanol synthesis, from [38]... 

The presence of Cu in the active catalysts has been further confirmed by reduction studies performed by Ruggeri et al. They demonstrated clearly that ZnO slows down the reduction of Cu to Cu . Driessen has shown that, at 1 atm pressure, methanol synthesis on a Cu/ZnO catalyst has an induction period of several hours, and that this can be substantially shortened if the catalyst is preoxidized under mild conditions and then used without further reduction. This result also points to Cu" as an active centre. 

Figure 3.14 for a three-stage converter with two quenches. This type of converter is used for Id s low-pressure methanol synthesis [6]. 

A block flow diagram for production of fuel grade methanol from biomass is depicted in Figure I. The gasification step is based upon the Purox process and is followed by shift conversion and gas purification steps. The clean gas, which is shifted to a H2/CO ratio of approximately 2/1, is converted to methanol in the ICI low-pressure methanol synthesis process. The process yields approximately 98% pure methanol with the remaining 2% consisting of water and some higher carbon number alcohols. 

Example 11.9 m-1 Simulation of a Fauser-Montecatini Reactor for High-Pressure Methanol Synthesis... 

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. 

Villa P, Forzatti P, Buzzi-Ferraris G, Garone G, Pasquon I (1985) Synthesis of alcohols from carbon oxides and hydrogen. 1. Kinetics of the low-pressure methanol synthesis. Ind Eng Chem Process Des Dev 24 (1) 12-19... 

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