Almost all energy (and hence most fuels and organic chemicals) derive from fossil fuels (natural gas, oil or coal) that in turn derive from solar energy. However the fuels must first be converted and refined (purified) into easily usable forms. For transportation (ca. 27% of global energy use) the fuel should be in a convenient liquid form. The Second Law of Thermodynamics .indicates that conversion can involve large losses which should be minimised The most usual technology involves reforming the fossil fuel into syngas, CO H2. The syngas is then converted into largely n-alkanes and n-1-alkenes over heterogeneous catalysts (metallic Fe or Co, 250-350oC) in the very exothermic Fischer-Tropsch (FT) reaction. The precise processes that occur on the FT catalyst are still not completely clear, but the Dual Path mechanism seems to answer most questions. Here the reaction paths are determined by the interplay of the metal and support surfaces and the surface organics. In the (classical) Dissociative Mechanism the surface is regarded as neutral and only neutral organic / species, eg., {C}, {CH}, {CHn}, etc are involved. In the Associative Mechanism, more polar steps involving electrophiles and nucleophiles, eg., {CHOH}; {CHδ } occur,
The key building block in the normal FT process is CO, but 1Cclimate change 1D considerations indicate that CO2 would be a very useful raw material. Can this work?