Advanced methanol to olefins process
This factsheet decribes the advanced methanol to olefins process, which is a combination of both licensed technologies UOP (Universal Oil Products)/Hydro Methanol to Olefins and Olefin Cracking Process (OCP) by Total. UOP/Hydro MTO technology consists of a methanol to olefin reaction, product purification and separation. The reaction for MTO can be described by two steps.The first step is the conversion of methanol to dimethyl ether (DME) and water:
2 CH3OH → CH3OCH3+ H2O
The second step is the conversion of DME to both ethylene and propylene:
CH3OCH3 → C2H4 + H2O
3 CH3OCH3 → 2 C3H6 + 3 H2O
The production ratio between ethylene and propylene varies depending on the catalyst employed, the reaction conditions and the technology. Both reaction steps above occur in a catalytic fluidized-bed reactor. Coke formed via unwanted reactions can accumulate in the catalyst over time, which can reduce its performance. For this reason, portions of the catalyst are continuously removed from the reactor to a regeneration unit. The coke is removed from the catalyst with the help of air or oxygen in the regeneration reactor. The ratio between propylene and ethylene produced by the reaction can also be adjusted by the operational conditions: the range is 1.3 to 1.8.
The product stream from the conversion reactor is fed to a separation section to remove water and to recover non-reacted DME. The olefin-rich stream is directed to a fractionation section in which the desired products ethylene and propylene are recovered. Residual gas and a stream that consists of medium boiling hydrocarbons are also recovered in the separation section. The hydrocarbon mix coming from the separation section is fed into a cracking reactor to provide another source for ethylene and propylene production. The cracking product is rich in olefins, which is sent to the separation section to recover ethylene and propylene. The byproduct from the cracking section is a mix of C4 olefins (‘high boiling point hydrocarbons’ in the picture) (Jasper, S., El-Halwagi, M.M, 2015).