Dow to Use Russian Process in PO/Styrene Plant

Dow Chemical Co. (Midland, MI) will build a new world-scale propylene oxide/styrene monomer (POSM) plant at one of its integrated sites on the US Gulf Coast. It will be the first Dow plant to use a coproduct POSM process. Other companies, notably Arco Chemical (now part of BP Amoco plc, currently operate POSM plants.

When it comes on stream in mid-2004, the new POSM facility will have capacity for 650,000 mt/yr of ethylbenzene, 250,000 mt/yr of propylene oxide, and 575,000 mt/yr of styrene monomer. The new plant positions Dow as the sole global PO producer with both chlorohydrin and POSM capacity.

Dow, which licenses POSM technology from the Russian chemical company Nizhnekamskneftekhim (NKNK), plans to use the process in a 250,000 mt/yr PO plant slated to open at its Tianjin, China, complex later in the decade.

Dow, however, has not abandoned its chlorohydrin-based propylene oxide capacity. It plans to expand existing chlorohydrin units "wherever it is deemed appropriate to meet market demand."

Dow's chlorohydrin route reacts propylene and chlorine in the presence of water to yield propylene chlorohydrin. It reacts this intermediate product with caustic soda to form propylene oxide. The route is economical where Dow has inexpensive sources of electricity and chloralkalis.

The POSM process starts with ethylbenzene, which reacts with oxygen and propylene over a proprietary catalyst to form propylene oxide and intermediates that can be converted to styrene.

The economics are especially attractive to Dow. It claims it is the world's largest producer of polyether polyols, propylene glycol, and P-series glycol ethers, which comprise a large proportion of the global PO demand. Dow also says it is the world's largest consumer and producer of styrene.

Dow's ability to consume both coproducts gives the company a competitive advantage in managing the large volumes of styrene produced by POSM plants.

"The addition of new POSM technology to Dow's manufacturing options is an important step in maintaining Dow's leadership position as a low-cost producer of PO derivatives," says Bob Wood, business group president for polyurethanes, polyurethane systems, propylene oxide and propylene glycol, epoxy resins and intermediates, and Concepture.

"The capability to use either chlorohydrin or POSM technology globally provides Dow with the flexibility to practice the most appropriate technology on a site-by-site basis around the world," says Dow business group president says Bob Wood.

Dow purchased an exclusive license to use NKNK POSM technology outside the Commonwealth of Independent States in 1998.

By Alan S. Brown