Catalytic routes to transportation fuels utilizing natural gas hydrates

Gas hydrates hold >50% of earth's total combustible carbon. To make this va st but dilute (CH(4)similar to 3.9 wt%) energy source available, an economi cal three-step route is outlined. A major technological challenge is enviro nmentally-benign mining of gas hydrates that releases "Aqueous CH4" and mak es it available at the surface (Step 1). Step 2 involves a cost-effective p artial oxidation (POX) with air route that eliminates the O-2-separation pl ant (conventional POX with O-2) to produce synthesis gas. In Step 3, techno logies that affect catalytic conversion of synthesis gas to Fischer-Tropsch (F-T) diesel, MeOH, and dimethylether (DME) transportation fuels are consi dered. The selection of MeOH and DME energy liquids is justified based on s even criteria: (1) low temperature; (2) low pressure; (3) high gas conversi on per pass to eliminate recycle; (4) high spacetime-yield; (5) high produc t selectivity; (6) robust catalyst; (7) overall high process efficiency. A Ni/Base catalyst system, presently undergoing pilot testing at Brookhaven N ational Laboratory (BNL), is described that by virtue of its homogeneous li quid phase operation selectively (>95%) produces methanol with unprecedente d single pass conversion (>95%) at T<150 degrees C and P=2-5 MPa essentiall y satisfies these set-forth process requirements. A preliminary kinetic stu dy on the original BNL catalyst system is presented and a limited kinetic r ate expression is deduced. Several areas for further research are identified that will allow economica l production of MeOH or DR IE in the skid-mounted unit/flexible product opt ion concept applicable to both on-land and off-short: gas hydrates. (C) 199 9 Elsevier Science B.V. All rights reserved.