Comparative Economic and Environmental Assessments of H2O2-based and Tertiary Butyl Hydroperoxide-based Propylene Oxide Technologies

Until a decade ago, the industrial technologies for producing propylene oxide from propylene were predominantly based on variations of the venerable chlorohydrin and organic hydroperoxide processes. Within the past decade, highly selective H2O2-based propylene epoxidation technologies have been developed by Dow-BASF (HPPO process) and the University of Kansas Center for Environmentally Beneficial Catalysis (CEBC-PO process). We present comparative economic and environmental impact analyses based on plant scale simulations of the processes for an assumed 200,000 tonnes/yr of PO production capacity and employing relevant process data from the literature. The predicted capital costs for the CEBC-PO process ($228 million) and HPPO process ($275 million) are lower than the conventional PO/TBA process ($372 million). The PO production costs via the conventional PO/TBA and HPPO processes are 150.4c/lb PO (profit 87.9c/lb, assuming a market value of 41c/lb for the TBA co-product and 42c/lb for the enriched propane co-product) and 107.1c/lb PO (profit 36.1c/lb, assuming a market value of 42c/lb for the enriched propane co-product), respectively. For the CEBC-PO process, the production cost is 90.6c/lb PO (profit 30.4c/lb), assuming a life of one year for the methyltrioxorhenium catalyst and a catalyst leaching rate of 9.3 x 10(-2) lb/h (or 1.6 ppm Re in the reactor effluent). The comparative economic analysis suggests that the CEBC-PO process has potential for being economically competitive and establishes quantitative catalyst performance metrics for achieving the same. Quantitative cradle-to-gate LCA shows that the environmental impacts of producing PO by the conventional PO/TBA, HPPO, and CEBC-PO processes are of the same order of magnitude. The lower GHG emissions predicted for the HPPO and CEBC-PO technologies, compared to the PO/TBA process, lie within the prediction uncertainty of this analysis. This comparative LCA analysis traces the adverse environmental impacts to sources outside the propylene oxide plant in all three processes: fossil fuel-based energy (natural gas, transportation fuel) utilization during raw material (i-butane, propylene and hydrogen peroxide) production.