Gasification/Fischer-Tropsch conversion

Sasol Fischer-Tropsch Process. 1-Propanol is one of the products from Sasol s Fischer-Tropsch process (7). Coal (qv) is gasified ia Lurgi reactors to produce synthesis gas (H2/CO). After separation from gas Hquids and purification, the synthesis gas is fed iato the Sasol Synthol plant where it is entrained with a powdered iron-based catalyst within the fluid-bed reactors. The exothermic Fischer-Tropsch reaction produces a mixture of hydrocarbons (qv) and oxygenates. The condensation products from the process consist of hydrocarbon Hquids and an aqueous stream that contains a mixture of ketones (qv) and alcohols. The ketones and alcohols are recovered and most of the alcohols are used for the blending of high octane gasoline. Some of the alcohol streams are further purified by distillation to yield pure 1-propanol and ethanol ia a multiunit plant, which has a total capacity of 25,000-30,000 t/yr (see Coal conversion processes, gasification). 

Consequently, two semicommercial pilot plants have been operated for 1.5 years. One plant, designed and erected by Lurgi and South African Coal, Oil, and Gas Corp. (SASOL), Sasolburg, South Africa, was operated as a sidestream plant to a commercial Fischer-Tropsch synthesis plant. Synthesis gas is produced in a commercial coal pressure gasification plant which includes Rectisol gas purification and shift conversion so the overall process scheme for producing SNG from coal could be demonstrated successfully. The other plant, a joint effort of Lurgi and El Paso Natural Gas Corp., was operated at the same time at Petrochemie Schwechat, near Vienna, Austria. Since the starting material was synthesis gas produced from naphtha, different reaction conditions from those of the SASOL plant have also been operated successfully. 

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]. 

Thermochemical biomass-to-liquid (BtL) conversion, involving thermal gasification of the biomass and subsequent synthesis of biofuels by the Fischer-Tropsch process. Various aspects of the use of catalysis in this process are discussed in the several chapters. 

Recent research in homogeneous catalysis emphasized the identification and development of transition metal complexes for the conversion of synthesis gas (CO -I- H2) , which is produced from natural gas or from coal and other hydrocarbon sources by gasification. Solid catalysts are known for conversion of CO + H2 into methanol, into mixtures of hydrocarbons (Fischer-Tropsch products), or into other products (see... 

General Synthesis Scheme. A schematic diagram of a plant producing synthetic liquid fuels and chemicals from coal via the Fischer-Tropsch synthesis is shown in Fig. 11-3. Gasification of coal with steam and oxygen is followed by a purification step to eliminate solids, sulfur compounds, and most of the carbon dioxide. Two stages of synthesis are employed to attain a high conversion of the synthesis gas. Recovery and treatment of primary... 

With the increasing costs of petroleum, the gasification-based coal refinery is another concept for the production of fuels, electricity, and chemical products (Speight, 2011). Coal gasification has also been used for production of liquid fuels (Fischer-Tropsch diesel and methanol) via a catalytic conversion of synthesis gas into liquid hydrocarbons (Speight, 2008 and references cited therein Chadeesingh, 2011). 

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