Syngas, conversion into methanol

For the conversion of syngas into methanol, the pressure is raised from 25 to 100 bar. The gas mixture is catalytically converted at temperatures between 250 and 300 °C. The synthesis of methanol is exothermic and strongly equilibrium limited. In conventional operation, the conversion of hydrogen typically does not exceed 30%. In the large-scale plant, methanol and the by-product, water, are flashed off and the unconverted gas is recompressed and recycled to extinction. 

The compressed syngas reaches the synthesis loop where it is converted into methanol via the Casale plate-cooled converter (12), characterized by the highest conversion per pass and mechanical robustness. The heat of reaction is used to generate directly medium-pressure steam. The gas is cooled (13), and the raw methanol is condensed and separated (14), while the unreacted syngas is circulated back to the converter. The inerts (15) contained in the synthesis gas are purged from the loop, and the hydrogen contained is recovered in a hydrogen... 

Conversion of biomass-based syngas to alcohols. Micro-channel reactors for converting the gas from biomass into methanol and higher alcohols are described by Hu etal in the US, (2007). 

Scheme 3.17 Ru-catalyzed conversion of H2 + CO methyl formate into methanol and syngas.

Processes for catalytic conversion of syngas into methanol can be divided into three classes according to reaction pressure, temperature, and catalyst composition. Today, high-pressure processes (250-350 bar, 300-450 °C, Cr/Zn) are no longer economic. Medium-pressure (100-250 bar, 220-300 °C, Cu/Zn) and low-pressure (50-100 bar, 200-300 °C, Cu/Zn) processes are operated, with the latter being much more attractive owing lower investment and operating cost... 

The partial oxidation of methane in catalytic monoliths at short contact-times is another example with several empty routes illustrating importance of thermodynamic consistency in selection of kinetic parameters. This reaction offers a promising route for the conversion of natural gas into more useful chemicals such as synthesis gas (syngas), a mixture of hydrogen and carbon monoxide. Syngas can subsequently be converted into methanol or higher hydrocarbons. The kinetic model for partial oxidation of methane on Rh includes 19 reversible reactions with six-gas phase species and 11 adsorbed species [5]. Presence of 19 steps, one balance equation (which relates coverage of surface species) and... 

Current biodiesel can not be considered as a 100% biomass-based fuel as long as methanol is derived from petrochemical resources. A clean way to solve the biorelated problem is the conversion of glycerol waste from the transesterification process into syngas. In this context, glycerol reforming is a suitable target reaction worthy of study. 

The reaction of methane and carbon dioxide in thermal plasma conditions leads mostly to the production of syngas. While non-thermal plasma can also be apphed for effective conversion of the CH4-CO2 mixture into syngas (see Chapter 10), non-equihbrium plasma conditions can also lead to the direct formation of methanol in the following process (Rusanov Fridman, 1984) ... 

The first of these new cobalt catalysts were made in 1986 by coprecipitation techniques using aqueous solutions with ammonium bicarbonate as the precipitant in a similar way to the methods used for methanol synthesis catalysts. The new catalysts were immediately found to be very active and selective catalysts for the conversion of syngas into hydrocarbons. A particularly attractive feature was their low methane make and tolerance of CO2 The CO2 tolerance was ascribed to the interplay between the support and the cobalt phase both in the oxidized and reduced forms. The general belief is that the support stabilizes the cobalt phase such that the catalyst can be operated at the higher temperatures, required to maintain activity despite competitive adsorption by CO2, without any loss in stability. Other investigators e.g. Shell have used similar strategies [2]. 

As indicated, the process can be directed towards ethylene production and hence chemical synthesis. The use of ZSM-5 catalysts for direct conversion of syngas into hydrocarbons (i.e., without the need to produce methanol first) and selective preparation of benzene, toluene, and xylene aromatics only are already being actively investigated. 

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