Recent research efforts have focused on changing base catalyst formulations instead of developing entirely new catalysts. These efforts have included doping of catalysts with different metals, novel catalyst preparation techniques, optimizing process conditions, and new catalyst support materials. While many of these research efforts have improved catalyst performance, an evaluation of the economics of each improvement needs to be performed. The tolerance of modified methanol and

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... catalysts to sulfur remains very low (<1 ppm). Sulfided catalysts represent an improvement in this area, but it is unclear if this improves the economics of the process. If required to maintain between 50 and 100 ppm of sulfur in the syngas, only very small improvements in the overall process economics are possible. In addition, low sulfur requirements, especially to H 2 S and mercaptans, for transportation and chemicals applications of the mixed alcohol product may require additional cleanup anyway, potentially eliminating any economic advantage. The technical and economic risks include feasibility to produce the desired product slate, scale-up considerations, designing for severe process conditions, catalyst sensitivities, competitiveness versus petroleum fuels, and catalyst prices. Studies have shown that current mixed alcohol technologies can compete with wholesale gasoline prices at $1.25 to $1.70 per gallon, assuming $0/ton feedstock prices and no production credits. Consideration must be made for the impacts this product will have on transportation fuel specifications, especially octane, volatility, sulfur, and corrosion. Fluctuations in price for rare and high demand metals also add considerable risk to the commercial feasibility of this process.