Lower-Cost Route to Acrylic Acid Nears

Novomer recently received a $5-million grant from the Clean Energy Manufacturing Initiative of the U.S. Department of Energy (DOE) to aid its efforts in developing a new process to make acrylic acid. Instead of relying on propylene, the typical feedstock, the new route uses ethylene oxide, thereby leveraging cost-advantaged North American shale gas. The Waltham, Mass.-based company's two-stage process can produce chemicals such as acrylic acid, butanediol, tetrahydrofuran and succinic acid (Figure 1). Products made via Novomer's technology are expected to be 20–40% lower in cost, partly because of the use of lower-cost starting materials compared to current production processes.

Initial efforts will focus on acrylic acid, a 4.4-million-metric-ton/year global petrochemical business worth around $7 billion in 2011. Global demand for crude acrylic acid should increase at a rate of 4.8% annually from 2010 to 2015, according to a 2011 forecast by IHS Chemical. This strong growth stems from rising demand for super-absorbent polymers, adhesives and sealants. Moreover, increase in construction and building activities in emerging economies should keep driving acrylic-acid demand in the coming years.

TWO-STAGE PROCESS
In the first stage of the process, a novel catalyst spurs the reaction of carbon monoxide and shale-gas-based ethylene oxide to form propiolactone. This then is converted into acrylic acid in the second stage using established technology.

The core catalyst that enables the technology is a homogeneous cobalt-based compound first developed at Cornell University, Ithaca, N.Y., by Professor Geoffrey Coates and further optimized by Novomer. This catalyst is 99% selective, so almost no raw materials are wasted in the process. Moreover, it functions at only 30–50°C, compared to current acrylic-acid processing catalysts that typically operate at 200–250°C. The combination of high selectivity and moderate temperature mean that Novomer's process will have a lower carbon and energy footprint than the propylene oxidation process to make acrylic acid.

MULTIPLE POTENTIAL PRODUCTS

Figure 1. New process can make a variety of chemicals that have large, established markets.

In the 1970s, Celanese operated a commercial acrylic acid process using propiolactone as an intermediate. The firm used ketene and formaldehyde as starting materials to produce propiolactone. However, this process was shut down because the front-end reaction was energy intensive and had poor yields. Novomer's process to make propiolactone from carbon monoxide and ethylene oxide avoids these limitations, and will be coupled to the process Celanese used to convert the propiolactone (Figure 2). CURRENT STATUSTo validate the economics of the catalyst and manufacturing process, Novomer currently is building a 5-kg/day laboratory-scale unit, funded in part by the $5-million DOE grant. This unit is scheduled to fully begin operations by the end of 2015.Novomer has partnered on this project with a major industrial gas producer, which will supply the carbon monoxide from waste carbon dioxide using a solid oxide electrolyzer. The unit also will be able to run on on-purpose carbon monoxide from a steam methane reformer or gasified biomass. However, opting for CO2 as a raw material could significantly reduce the carbon footprint, which in turn adds to the "green" value of the process.At the conclusion of the project, by early 2016, Novomer will build a 2,000-metric-ton/year pilot plant with an industrial partner to further de-risk the technology. Negotiations are underway with chemical partners interested in hosting the pilot-scale facility. Interest is high due to the economic and environmental advantages. Potential partners include companies that produce acrylic acid today and want a lower-cost route, and those that have ethylene oxide and want to make higher-value derivatives beyond monoethylene glycol.

MARRYING OLD AND NEW

Figure 2. Process couples new catalytic process for producing propiolactone with established technology to convert that intermediate.

The first commercial-scale plant most likely will be located on the U.S. Gulf Coast, where it would draw upon shale-advantaged ethylene. (New ethylene units, representing about a 30% increase in capacity, already have been announced for the region.) Novomer's technology could result in the construction of the first acrylic acid plant in the U.S. in more than ten years. It also would enable U.S. producers to become global low-cost leaders in chemical intermediates and reduce dependencies on crude oil markets. Besides the DOE, a number of leading institutions have recognized Novomer's efforts. The company has received various awards such as MIT Technology Review's 50 Most Innovative Companies and a 2012 ICIS Award for Innovation by a Small or Medium Enterprise.

MIKE SLOWIK is director of chemicals for Novomer, Inc., Waltham, Mass. HARSHAL SAWANT is a business development associate for Novomer. E-mail them at [email protected] and [email protected].