Chapter 13 - Propylene Epoxidation via Shell's SMPO Process: 30 Years of Research and Operation

Abstract

Shell has coproduced propylene oxide (PO) and styrene using its proprietary styrene monomer propylene oxide (SMPO) process for three decades. Research, development, and plant trials have been performed on a continuous basis in order to improve its efficiency and cost competitiveness. This chapter discusses the some of the key fundamental and technological learnings gathered over various parts of the process. The heart of the process is formed by the catalytic epoxidation of propylene with ethylbenzene hydroperoxide using a silica-supported titanium catalyst. Fundamental studies have provided models for the active sites, the reaction mechanism, and the cause of catalyst deactivation. Other process elements have been investigated and improved as well. Minor by-products have been tracked across the process to unravel their impact on the various process steps. Computational flow dynamic studies of the air-oxidation step, as well as broad catalytic studies of the dehydration step, have led to significant performance improvements.