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

Abstract

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 H 2 O 2 -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 150.4¢/lb PO (profit 87.9¢/lb, assuming a market value of 41¢/lb for the TBA co-product and 42¢/lb for the enriched propane co-product) and 107.1¢/lb PO (profit 36.1¢/lb, assuming a market value of 42¢/lb for the enriched propane co-product), respectively. For the CEBC-PO process, the production cost is 90.6¢/lb PO (profit 30.4¢/lb), assuming a life of one year for the methyltrioxorhenium catalyst and a catalyst leaching rate of 9.3 × 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.

Environmental impacts of ethylene production from diverse feedstocks and energy sources

“…3 Block diagram describing the various processes included in the cradle-to-gate life-cycle assessment for the production of ethylene from ethanol obtained from corn reported emissions. This trend is similar to what we have reported elsewhere [35][36][37].…”

The effects of impregnation of precious metals on the catalytic activity of titanium silicate (TS-1) in epoxidation of propene using hydrogen peroxide

“…In several liquid-phase epoxidation routes to convert propene into propene oxide, much attention has been directed to heterogeneous catalytic oxidation using hydrogen peroxide as a more environmentally benign and profitable chemical process [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Titanium silicalite (TS-1) catalyst has been extensively investigated for this route because propene oxide can be produced with a high selectivity in methanol under mild conditions [4,5,[10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The direct epoxidation process based on hydrogen peroxide (oxidant) and TS-1 (catalyst) was commercialized and referred to as "hydrogen peroxide-to-propene oxide" (HPPO) process.…”

A spray reactor concept for catalytic oxidation of p-xylene to produce high-purity terephthalic acid

“…The costs associated with utilities and raw materials labor are obtained from specified current sources. Finally, comparative gate-to-gate LCA (life cycle assessment) and cradle-to-gate LCA of both processes are performed to evaluate the relative environmental impacts [127,128].…”

“…They found that a subcritical HTW-based process was equally capital intensive, less energy intensive, and more environmentally benign than the current acetic-acidbased process (MC process). [128], all of which were developed by CEBC researchers. The work presented herein is a relatively thorough quantitative evaluation of the CEBC spray technology for TPA production, from both economic and environmental points of view.…”

“…It can also offer a link between the environmental impacts and economics of processes to help select an optimized application. CEBC researchers have employed LCA methodology for performing comparative environmental impacts of process concepts (ethylene and propylene epoxidations) developed at CEBC with conventional processes [127,128].…”