(582u) Methanol to Propylene Conversion: Recent Development Trends

The conversion of methanol to propylene (MTP) is a value-added process and has gained extreme significance because of high demand of propylene in the production of petrochemicals. The demand for propylene is increasing due to increasing usage of polypropylene. The catalytic materials used in MTP conversion include SAPO-34 (small-pore molecular sieves), ZSM-5 (medium-pore zeolites) and its modified forms. Limited research has also been found using large pore zeolites such as mordenite and EU-1. MTP research has been carried using structured catalysts including ceramic based honeycomb or monolith and silicon carbide (SiC) foam. The major difference in process design between SAPO-34 and H-ZSM-5 is that the SAPO-34 is used in fluidized bed process while H-ZSM-5 catalyst is used in fixed bed process. SAPO-34 is a selective catalyst for olefins but deactivates fast and thus requires frequent regeneration. The H-ZSM-5 is less selective for olefins but shows less deactivation and thus quite stable. A number of structured supports such as monolith, foam and mesh are being research for coating the active zeolite based catalysts. The structured catalysts are used to reduce the diffusional limitations of pellet catalyst system and have exhibited excellent results in terms of activity and selectivity.