What are the main production routes for propylene and how do their cost structures compare?

What are the main production routes for propylene and how do their cost structures compare?
Propylene supply comes from three main routes: steam cracking of naphtha, refinery FCC units, and on-purpose PDH. Naphtha cracking remains cost-sensitive, with naphtha accounting for about 75% of propylene costs and closely tracking crude oil. FCC is the lowest-cost route due to minimal depreciation allocation, but output depends on refinery configuration and product slate. PDH is growing fastest in China — 15 units totaling 7.06 million tons — yet construction is complex and operations demanding. Coal-to-olefins, another route, sees coal costs representing 79% of propylene costs, with consumption now below 7 tons per ton of olefin. During the 14th Five-Year Plan, PDH is expected to overtake FCC as China's second-largest production route, driven by low oil prices and carbon trading pressures on coal-based processes.