Engineering MDI Technology Benchmark for Production of Methylene Diisocyanate (MDI)

Author / Editor: Anke Geipel-Kern* / Anke Geipel-Kern

With a new MDI technology, Covestro aims to improve efficiency and environmental protection. Everyone is talking about sustainability — including the chemical industry. With the quartet of regenerative energies, alternative raw materials, recycling solutions and CO2-saving technologies, Covestro wants to become a front runner. A completely new MDI technology should also help.

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Promising greater resource efficiency in Brunsbüttel: the pilot plant for MDI production using the Adip process.
Promising greater resource efficiency in Brunsbüttel: the pilot plant for MDI production using the Adip process.
(Source: Covestro)

You could be forgiven for thinking that Klaus Schäfer, Chief Technology Officer at Covestro, is the only person to be addressing the topics of the circular economy and energy transformation in the chemical industry. As the front man of Covestro’s sustainability strategy, he made one public appearance after another last year.

But you can also see him as a Dechema board member, chairman of the VCI committee on energy, climate and raw materials, as a keynote speaker at the Raw Materials Summit, and now as a member of the National Hydrogen Council — this busy man is on the road tirelessly to represent the interests of the chemical industry and explain the transformation of the sector.

He is also serious about his own company. As a technical strategist, he and CEO Markus Steilemann are steering the plastics group towards greenhouse gas neutrality and the circular economy.

From 2005 to 2025, we want to reduce CO2 emissions per tonne of product by 50 percent.

Klaus Schäfer, Chief Technology Officer at Covestro

Linear was yesterday; today we manage circularly

This goal seems realistic: So far, the company has achieved a 40 percent reduction in CO2 emissions from 2005. The new vision of the polyurethane producer is as clear as it is technically demanding: out of the linear economy and into the circular one. Covestro, according to the will of the company’s leaders, is to become the spearhead and pioneer of the plastics industry in terms of the circular economy. With the recycling of stack-gas CO2 as a raw material for polyurethane (PUR) production, the first step towards circularity has already been taken, explains Schäfer. Other steps are to follow, including bio-based raw materials, for example in a pilot project with Borealis, which is investigating the use of biophenol in polycarbonate and is to be transferred to large-scale production at some point.

Through a cooperation with Ørsted, the company wants to secure electricity from offshore wind power plants from 2025 onwards in order, according to Schäfer, to “increasingly include electricity from renewable energies in the energy portfolio”. And last but not least, it is about new recycling technologies, such as chemolysis, with which PUR foams are to be turned back into raw materials for polymer synthesis.

MDI technology at the heart of PUR production

But for now it’s down to the nitty-gritty: the production of methylene diisocyanate (MDI) is now set to make a leap in efficiency. For more than 50 years, Covestro has claimed technology and cost leadership for this important component of rigid polyurethane foams. And this is becoming increasingly important for market success: according to market researchers, the global MDI market was around 7,500 kilo tons in 2019 and will grow by 3.6 percent annually until 2026, or by as much as 5 percent when broken down into individual sectors, such as the automotive industry.

Economy of scale: important, but there’s more to it

Everyone is talking about sustainability — including the chemical industry. With the quartet of regenerative energies, alternative raw materials, recycling solutions and renewable energy sources, competition in the consolidated market is fierce. BASF, for example, is currently building a world-scale plant at its Verbund site in Geismar (Lousiana) that will double production capacity in the USA from 300,000 to 600,000 tons.

In addition to the German and international competition, which includes Dow Du Pont, Huntsman and Tosoh, Asian producers are now also gaining strength, throwing capacity into the market and thus depressing prices. Wanhua has meanwhile moved into the top group. According to analysts at Fitch Rating, the Chinese group has the largest MDI capacity in the world and produced 2.1 million tons per year at the end of 2019, which corresponds to a quarter of global capacity. This puts the Chinese ahead of BASF and Covestro. The efficiency of the German chemical companies is likely to be their biggest defence: The analysts explicitly highlight the low MDI cash costs, which are the lowest among competitors in Asia and are mainly due to the use of integrated plants and technology by German manufacturers.

Yet it will hardly be possible to meet the challenges of the future with just economies of scale and interconnected systems, especially if CO2 emissions are subject to levies in the future. “If we manage to arrive at a uniform CO2 pricing, it won't worry us at Covestro because we are investing in CO2-saving technologies,” explains Schäfer.

New process tames the production of phosgene

This lead is underlined by the new pilot plant in Brunsbüttel, Germany whose technology Covestro is celebrating as a breakthrough. 20 years of conceptual work went into the plant, says Schäfer. “Adip” is a technology that has been developed intensively across all the company’s sites.

The abbreviation Adip stands for adiabatic isothermal phosgenation, a completely new phosgene process that does not require any external heat supply and is therefore much more efficient than the one currently used. Up to 40 percent water vapor and 25 percent electricity per ton of rigid foam precursor produced could be saved by the new process, the engineers have calculated — and up to 35 percent less CO2 is emitted to the atmosphere. Another advantage of the process is that the reactor is smaller, which means that plants can be smaller but still have higher capacities — Covestro is talking about increases of up to 50 percent.

Innovation hotbed for the MDI process

The fact that the plant was built in Brunsbüttel ties in with the site’s history: Covestro has been producing MDI in the far north of Germany since 1988. In February 2020, the go-ahead was given for the commissioning of an MDI plant that will double production capacity at the site, to 400,000 metric tons per year. This puts Brunsbüttel in the top three European MDI producers. Four years ago, Covestro decided to convert a decommissioned TDI plant to MDI production. "Now the production in Brunsbüttel is the most modern in the world and Adip is the icing on the technology cake", says site manager Dr Uwe Arndt.

He expects the pilot phase to take 12 months. The project will be successful if Covestro can show that this technology can also be used to build the next world-scale plant. Will that also be in Brunsbüttel? Yes, if you take Schäfer for his word, though the climate would not be helped if certain products were no longer to be manufactured in Germany or Europe but in the Arab or Asian regions, and then imported.

* * The author is a senior editor at PROCESS. Contact: