Fischer methanol synthesis

Its appeal Hes in the fact that synthesis gas can be produced from trash, municipal sewage, scrap wood, sawdust, newsprint, or other waste. The early work of Fischer and Tropsch on methanol synthesis showed that ethanol could be obtained in the process (165) and that by certain modifications the proportion of ethanol in the product could be increased (166). The Hterature concerning this method is extensive (167—176). The conditions that favor ethanol formation are 125—175°C and 1.42 MPa (14 atm) in the presence of reduction catalysts such as powdered iron. 

Ruthenium is a known active catalyst for the hydrogenation of carbon monoxide to hydrocarbons (the Fischer-Tropsch synthesis). It was shown that on rathenized electrodes, methane can form in the electroreduction of carbon dioxide as weU. At temperatures of 45 to 80°C in acidihed solutions of Na2S04 (pH 3 to 4), faradaic yields for methane formation up to 40% were reported. On a molybdenium electrode in a similar solution, a yield of 50% for methanol formation was observed, but the yield dropped sharply during electrolysis, due to progressive poisoning of the electrode. 

In this energy chain, coal is gasified to generate synthesis gas. The H2 CO ratio required for an optimum efficiency is adjusted via the CO shift reaction of a part of the carbon monoxide (CO) contained in the synthesis gas. The remaining synthesis gas is converted to liquid hydrocarbons via Fischer-Tropsch synthesis or via methanol synthesis with a downstream MtSynfuels (trademark by Lurgi) process (see beginning of Section 7.3.4). The liquid hydrocarbon yield amounts to about 0.40 MJ per MJ of hard coal, which is of the same order of magnitude as in the case of BTL ( 0.40 MJ/MJ) to calculate the thermal process efficiency, the electricity export must also be taken into account (see Table 7.12). 

The resulting synthesis gas can subsequently be converted into methanol (Reaction 3) or polymerized to a mixture of hydrocarbons via the Fischer-Tropsch synthesis (Reaction 4) [37, 38]. These conversions usually require a H2/CO molar ratio close to 2 (Reactions 3 and 4), which contrasts with the H2/CO ratio of 0.5 that is delivered upon biomass gasification (Reaction 2). It can therefore be suitable to adjust the H2/CO ratio through the water-gas shift reaction (Reaction 5) ... 

Conversion of lignocellulose into transportation fuels via pyrolysis and subsequent oil upgrading [72], via gasification and subsequent Fischer-Tropsch or methanol synthesis [3], via hydrolysis and subsequent fermentation to ethanol or subsequent conversion into ethyl levulinate [45, 46, 73]. 

For production of liquid hydrocarbons and oxygenated compounds other than methanol, shifting is usually carried to C0 H2 ratios in the range 1.8-2.4 and use is made of variants of Fischer-Tropsch synthesis ). 

If the gasifier product stream is intended for downstream use as the feedstock for further upgrading such as methanation, methanol or Fischer Tropsch synthesis, very thorough desulphuri-sation is essential since the catalysts in these upgrading processes are highly sensitive to sulphur poisoning. The methanation catalysts normally cannot tolerate more than 0.05 ppm of sulphur in the feedstock. In addition to H2S sulphur values in the gasifier product it may contain COS, CS2, mercaptans and thiophenes. These are normally removed by activated carbon or zinc oxide filters ahead of the sensitive synthesis catalyst beds. 

Notably, once the oxygenated hydrocarbons have been converted into synthesis gas, it is then possible to carry out the subsequent conversion of synthesis gas into a variety of liquid products by well-established catalytic processes, such as the production of long-chain alkanes by Fischer-Tropsch synthesis and/or the production of methanol. 

Stage 3 shifts the source of hydrocarbon for transportation and chemicals to methane. Methane currently is reformed at elevated temperatures and pressures to synthesis gas. This mixture of hydrogen and carbon monoxide can then be converted via the well-known technologies of methanol synthesis and Fischer-Tropsch synthesis to eventually produce a variety of chemicals and fuels. In this stage, focus... 

Coal liquefaction Fischer-Tropsch synthesis Synthesis of methanol Hydrogenation of oils Alkylation of methanol and benzene Polymerization of olefins Hydrogenation of coal oils, heavy oil fractions, and unsaturated fatty acids Adsorption of S02 in an aqueous slurry of magnesium oxide and calcium carbonate S02 or removal from tail gas Wet oxidation of waste sludge Catalytic desulfurization of petroleum fractions Wastewater treatment... 

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