Bayer MaterialScience innovation favors Shanghai TDI plant

15 April 2011 16:05  [Source: ICB]

Bayer MaterialScience draws on a tradition of innovation to secure its place in the PU markets of tomorrow

Wave of the future: BMS says its gas-phase phosgenation technology transforms the production economics of PU


Bayer MaterialScience could become China's low-cost producer of the polyurethane (PU) feedstock toluene di-isocyanate (TDI) when a new 250,000 tonne/year production facility in Shanghai, China, goes online in the next few months.

The scenario might seem unlikely in a market crowded with cut-rate competition, but Bayer says its new gas-phase phosgenation (GPP) technology completely transforms the economics of production. If the venture prospers, as seems likely, considerable credit will go to the development of GPP - one in a long series of PU innovations that include the material's invention in 1937.

"We are proud to be 'the inventor company,' and we will continue to invest in R&D in our sustainable business," remarks Ralf Guether, head of communications for polyurethanes.

Bayer MaterialScience spends heavily on research and development to keep the pipeline flowing, he says - €231m ($335m) last year, up from €207m in 2009. The sum is independent of revenues, which totaled €10.1bn in 2010. Parent Bayer, which also includes the Bayer HealthCare and Bayer CropScience businesses, reported revenues of €35.1bn in 2010 and a total R&D budget of €3.1bn.

Megatrends feature prominently in the company's R&D program, Guether notes. "Within the context of these megatrends, we develop technologies and solutions to tackle problems."

For example, the megatrends of environmental sustainability and personal mobility are behind a range of applications that Bayer has developed to enable cleaner, more energy-efficient transportation.

They include polyurethane composite materials for the roof modules of cars and Makrolon polycarbonate (PC) for automotive glazing. Both require less energy to manufacture and contribute less weight to the finished vehicle than the steel and glass components they replace.

Another technology, PU sandwich construction, can reduce the weight of trunk floors and cargo beds by up to 80%. Manufacturing entails impregnating the "sandwich" - a paper honeycomb core between glass fiber mats - with a two-component PU spray system, followed by press molding.

In the realm of railroad transportation, Bayer has developed a flexible PU foam system to tackle two persistent problems: maintenance of the track bed and noise reduction. The result, the Durflex track superstructure system, entails injecting a PU foam into the ballast stones of the track bed, completely filling the cavities between them. When trains pass over the track, the foam ensures the ballast stones remain in their original position. By absorbing vibrations, the foam can also reduce noise by three decibels.

Test tracks are currently in operation in both China and Germany.

The TDI pilot plant at Chempark, Germany

Megatrends lie behind innovations in production technology, as well. For example, the "Dream Production" project, a partnership between Bayer, German energy firm RWE and Aachen University, has developed a process for making polyether polycarbonate polyols (PPPs) from carbon dioxide (CO2) - the ubiquitous greenhouse gas regarded by many as the most serious environmental threat of our time. These PPPs can, in turn, be combined with isocyanates to manufacture polyurethanes.

This way, CO2 feedstocks captured from power plants and incorporated into lightweight materials that help cut back energy consumption and the consequent energy production can be used to reduce CO2 emissions.

Based on a breakthrough in catalysis technology, the PPP process is currently being scaled up in a new pilot plant at Chempark Leverkusen, where Bayer is headquartered.

Polyurethanes do more than minimize the energy consumption; they also significantly contribute to its conservation. In the form of rigid foams, PUs offer unusually high thermal efficiency and are widely used as insulation in buildings and refrigerators. Demand in this application is high and growing. In the US alone, it is expected to reach 1.7bn pounds (771,000 tonnes) in 2014, according to US-based Freedonia. The firm estimates that annual demand growth during 2009-2014 will average 5.3%.

The largest market opportunity for PU foam insulation is in China, however, where energy scarcity is a matter of national security, and anything that can help solve the problem is strongly encouraged.

China presents a huge opportunity for polyurethanes, not only in rigid foam insulation, but also in flexible foam cushions, coatings, molded parts and myriad other applications associated with manufacturing and construction.

One consequence is the proliferation of local producers offering the isocyanates and polyols that are polyurethane's feedstocks. Another is the arrival of Western producers. US-based Huntsman, in a joint venture with Germany's BASF, has a 240,000 tonne/year methylene diphenylene diisocyanate (MDI) plant at the Shanghai Chemical Industrial Park (SCIP), and it is pursuing approval to build a second in the same location. BASF also has a 160,000 tonne/year TDI plant at SCIP, and recently won approval to build a 400,000 tonne/year MDI plant in the inland city of Chongqing.

Bayer has had a 350,000 tonne/year MDI plant at SCIP since 2008, and recently announced plans to increase the site's MDI capacity to 1m tonnes/year by 2016. It also plans to build a €65m unit to produce isophorone diisocyanate (IPDI), a feedstock for specialty PUs used in coatings. Bayer's TDI unit based on gas-phase phosgenation is in the same location.

The new TDI unit, which is expected to go on stream mid-year, will enter a field crowded with local competition. Many existing players intend to add capacity, according to a report in China Chemical Reporter. Gansu Yinguang Chemical Industry Group plans to add 200,000 tonnes/year; Cangzhou Dahua, 100,000 tonnes/year; BlueStar Chemical, 150,000 tonnes/year; Yantai Juli Fine Chemical, 100,000 tonnes/year; and CNGC Liaoning Beifang Jinhua Polyurethane, 100,000 tonnes/year.

Other companies also plan to enter the market: Fujian Southeast Electrochemical with 100,000 tonnes/year capacity; Yantai Wanhua Polyurethanes with 300,000 tonnes/year; and Shaanxi Yanchang Petroleum with 300,000 tonnes/year.

For a company to profit in such a competitive environment, it should have more than efficient operations - it should also have an unusual advantage. For Bayer, that is gas-phase phosgenation.

TDI is produced from toluene in three steps. First, toluene is nitrated. The product, an 80/20 mixture of 2,4- and 2,6-dinitrotoluene (DNT), is then reduced to the corresponding isomers of toluene diamine (TDA). In the last step, TDA is converted to the isomeric mixture of diisocyanates by reaction with phosgene.

Typically, the phosgenation is carried out in the liquid phase: a solution of phosgene, usually in ortho-dichlorobenzene (ODB), is added to a solution of TDA, also in ODB. The result is a slurry of the intermediate toluene dicarbamoyl chloride, which releases hydrogen chloride during distillation, yielding the diisocyanate.

The GPP process is quite different. Neither TDA nor phosgene is in the form of a solution. Instead, both are heated above 300 degrees celcius. The reactants, now in the gaseous phase, are then brought together and mixed in the reactor. A nozzle designed by Bayer engineers specifically for the purpose ensures proper mixing, which is critical. At this point, ODB is added, and distillation of the resulting slurry again produces the diisocyanate.

The GPP process features several advantages over the conventional approach, says the company. Solvent consumption is reduced by 80%, energy consumption is consequently reduced by 40-60%, and the initial investment required is lowered by 20%.

The speed of the reaction is dramatically increased, as well: whereas residence time for the conventional process is 50 minutes, for the GPP process it is a mere 20 seconds. The resulting benefits include greater selectivity and higher yield, while the excess of phosgene necessary to ensure reaction is reduced. The process is also quick and easy to start up and shut down, increasing safety.

Bayer has not been more specific about the overall cost advantage the Shanghai TDI plant will enjoy over competitors, but it will clearly be significant.

Meanwhile, the Bayer R&D program will not rest. Around the world, rivals eye markets that could be theirs, plot to take a share and marshall resources for the assault, confident of their own advantages.

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By: Clay Boswell
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