Alternative fuel and chemicals from synthesis gas

Development of a reliable and cost-effective method of wax/catalyst separation is a key step toward a commercially viable slurry reactor process with iron oxide-based catalyst for Fischer-Tropsch (F-T) synthesis of hydrocarbon transportation fuels. Although a variety of suitable catalysts (including, for example, cobalt-based catalysts) are available, iron oxide-based catalysts are preferred for coal-derived, CO-rich syngas because, in addition to catalyzing the F-T reaction, they simultaneously catalyze the reaction stifling CO to H{sub 2}, obviating a separate shift process block and associated costs. Because of the importance of development of this wax/catalyst separation, a study was initiated in February 1991. P. Z. Zhou of Burns and Roe reviewed the status of F-T wax/catalyst separation techniques. This led to the selection of a filtration system for the separation. Pilot tests were conducted by Mott Porous Metal Products in 1992 to develop this system. Initial results were good, but problems were encountered in follow-up testing. As a result of the testing, a filter was selected for use on the pilot plant. In LaPorte, Texas, APCI has been operating a pilot plant for the development of various synthesis gas technologies with DOE and industry support. The APCI F-T program builds on the DOE-sponsored laboratory-scale work by Mobil, reported in the mid-1980s, which used an iron oxide catalyst to produce high-quality F-T liquids in relatively compact reactors. Separation of the catalyst solids from the wax still represents a challenge. In the summer of 1992, testing of the selected filter was begun as part of the pilot plant testing. The filter performed poorly. Separation of the catalyst was primarily by sedimentation. It was recommended that the wax/catalyst separation be developed further