(A) Introduction(B)Methods of producing(a) Polymerisation(b) Fischer– Tropsch process(c) Bergius Process
Synthetic fuel or synfuel is a liquid fuel obtainedfrom coal, natural gas, oil shale, or biomass.It may also refer to fuels derived from other solids suchas plastics or rubber waste. It may also (less often) referto gaseous fuels produced in a similar way.Common use of the term "synthetic fuel" is to describefuels manufactured via Fischer Tropschconversion, methanol to gasoline conversion, ordirect coal liquefaction.
Methods of producing synthetic petrol:• Polymerisation• Fischer- Tropsch method• Bergius processPoiymerisation:In this method, smaller molecules of hydrocarbons arecombined to form heavier molecule resembling gasoline.It is of two type:(a)Thermal polymerisation(b)Catalytic polymerisation
(a)THERMAL POLYMERISATION:Thermal polymerisation is carried out attemperature about500-600 C and pressureabout 70-350 kg/cm.cm(b)CATAIYTIC POLYMERISATION:It is carried out at a lower temperature of 150-200 C ,in alow pressure and in presence of catalyst like posphoricacid. The rate of reaction is increased. The gasolineobtained is of improved quality andpossess high antiknock properties than the gasolineobtained from thermal polymerisation process.
The Fischer– Tropsch process (or Fischer– Tropsch synthesis) is acollection of chemical reactions that converts a mixture of carbonmonoxide and hydrogen into liquid hydrocarbons. The process, akey component of gas to liquids technology, produces a syntheticlubrication oil and synthetic fuel, typically from coal, natural gas,or biomass. The F–T process has received intermittent attentionas a source of low-sulfur diesel fuel and to address the supply orcost of petroleum-derived hydrocarbons.
Fischer- Tropsch processThe water gas is varied with hydrogen and the combination is purifiedby transitory from side to side Fe2O3 and then into a mixture ofFe2O3+Na2CO3. The cleanse gas is dense to 5 to 25 atm and then led fromside to side a converter, which is preserve at a temperature of 200 –300oC.The converter is provided with a catalyst bed consisting of amixture of 100 parts cobalt, 5 parts thoria, 8 parts magnesia and 200parts keiselghur earth.The outcoming gaseous mixture is led to a condenser, where theliquid crude oil is obtained. The crude oil is fractionated to yield gasolineand heavy oil. The heavy oil is used for cracking to get more gasoline.
:Bergius processOne of the main methods of direct conversion of coal toliquids by hydrogenation process is the Bergius process.In this process, coal is liquefied by mixing it with hydrogengas and heating the system (hydrogenation). Dry coal ismixed with heavy oil recycled from the process. Catalyst istypically added to the mixture. The reaction occurs atbetween 400 °C (752 °F) to 5,000 °C (9,030 °F)and 20 to70 MPa hydrogen pressure. The reaction can be summarizedas follows:
Bergius Process - Synthetic Petrol:In this process, the finely powdered coal is completed keen on a paste throughheavy oil and a catalyst powder (tin or nickel oleate) is mixed with it. The paste ispumped along with hydrogen gas into the converter, where the synthetic paste is heatedto 400 - 450°C under a pressure of 200 - 250 atm.During this process hydrogen combines with coal to form saturated higherhydrocarbons, which experience additional decay at superior temperature to acquiescecombination of lesser hydrocarbons. The mix is led to a condenser, where the crude oilis attained. The crude oil is then fractionated to yield:(a)Gasoline (b)Middle oil (c)Heavy oil