Chemical Technology: Methanol to Olefins

What is Methanol to Olefins?

Methanol to Olefins is a technology which can convert methanol to olefins (ethylene, propylene, butylenes, isobutylenes, and heavier olefins). Methanol to Olefins (MTO) technology can be considered as new technology in petrochemical processing since propylene and ethylene are usually obtained through conventional processes such as steam cracking, FCC and other available options.

Chemical Information and Process Technology

The process is to produce selective production of ethylene and propylene from methanol. MTO process converts methanol to ethylene and propylene at nearly 80% carbon selectivity in a fluidized bed reactor. The MTO reaction is exothermic.

Carbon or coke accumulates on the catalyst and must be removed to maintain catalyst activity. The coke is removed by combustion with air in a catalyst regenerator system. Other co-products include very small amounts of C1-C4 paraffins, hydrogen, CO and CO2, as well as ppm levels of heavier oxygenates that are removed to ensure that the product olefins meet polymer-grade specifications.

The ratio of propylene/ethylene product can range from less than 0.8 to more than 1.3. When combined with the Total Petrochemicals/UOP Olefin Cracking process (to be discussed later) to convert the heavier olefins, the overall yields of ethylene plus propylene increase to between 85 to 90 % and propylene/ethylene product ratios of more than 1.5 are achievable. MTO is part of a two-step process, which converts natural gas or coal to methanol followed by the conversion of methanol to light olefins.

Market Information/ Economics

MTO projects are driven by the desire to monetize natural gas or coal and the market demands for ethylene and propylene and their derivatives. Stranded natural gas prices are generally independent of crude oil and naphtha market prices so MTO provides another means for olefin derivative producers to diversify the cost structure for their feedstocks. MTO can provide much lower costs of production and higher returns on investment than naphtha crackers especially when crude oil market prices are high. MTO can also provide much lower costs of production and higher returns on investment than ethane crackers using ethane or natural gas liquids extracted from natural gas at prices above $3 to 4 per million Btu (e.g. North America). MTO plants can be located near or integrated with a methanol plant or they can be located separately with a methanol plant located near the gas source and the MTO plant located near the olefin markets or olefin derivative plants. In either case the methanol plant is located with access to low cost natural gas or coal. If there is local demand for a portion of the light olefins or their derivatives, then it can be desirable to locate the MTO unit at the same location as the methanol unit. If all of the light olefins or their derivatives are to be exported, then it may be preferable to ship methanol to an MTO unit that is located near the olefin or olefin derivative markets.