New process development of natural gas conversion technology to liquid fuels via OCM reaction

The conversion of methane via oxidative coupling of methane (OCM) to transportable liquid fuel has been investigated to utilize remote natural gas effectively. A conceptual view of this new process for gasoline production was developed on the basis of reviews of other conventional OCM processes and sensitivity analyses. The process developed, referred to herein as ''original'', is characterized as follows: (1) application of a circulating fluidized bed with a riser reactor to the OCM process because of its high efficiency of heat removal, temperature controllability, and ability to deal with high space velocity reaction; (2) application of a bubbling fluidized bed reactor with an internal heat exchanger for the control of heat generated to oligomerization process; (3) design of split feed of recycled gas, which is composed of recycled unconverted methane with byproducts, into the reaction process (the CO2 to be methanated by H-2 skips over the CO2 absorber and is directly fed to the methanation reactor); (4) direct feed of the OCM/pyrolysis reader effluent to the oligomerization reactor without separation of ethylene from coupling products. Olefins in the effluents, which contain unreacted CH4, C2H4, and other components, can be sufficiently converted into liquid fuels using a newly developed oligomerization catalyst. Economic comparisons between this original process and the conventional OCM technology were carried out. The evaluation showed that the optimal performance of the OCM catalyst is 30% methane conversion and 80% C-2+ selectivity under some inverse correlation of conversion and selectivity and that our original process is more economical than the existing co-feed mode process.