Production method of liquid hyrdocarbons from natural gas

摘要

In a so-called GTL process comprising producing synthesis gas from natural gas, producing a Fischer-Tropsch oil from the resultant synthesis gas by Fischer-Tropsch synthesis, and upgrading the oil to produce liquid hydrocarbons containing a fuel oil, the synthesis gas produced in the synthesis gas production step is partly led into a branch line before being introduced into the Fischer-Tropsch oil production step. High-purity hydrogen is produced by separating the hydrogen from the synthesis gas which has entered the branch line. This high-purity hydrogen separated is wholly supplied to the upgrading reaction step and used as hydrogen for upgrading reaction. Furthermore, use may be made of a method comprising causing the synthesis gas which has entered the branch line to undergo a water gas shift reaction to heighten the hydrogen concentration thereof, thereafter producing high-purity hydrogen by separating the hydrogen from the gas, circulating the gas remaining after the separation to the synthesis gas production step, and using the circulated gas as a raw material for synthesis gas production.