Econic: making good use of carbon dioxide

Using carbon dioxide (CO₂) to make polyols appears to be an undeniably good thing to do with the greenhouse gas. Here we look at Econic Technologies, one of the growing innovative companies that are helping to drive this technology forward.

Rowena Sellens, CEO of Econic Technologies, is a clear evangelist for the use of carbon dioxide to make polyols. The company, spun out of London’s Imperial College and now located in the science park on the former AstraZeneca site at Alderley Park just south of Manchester, has a strong patent portfolio comprising catalyst technologies that can produce polycarbonate and polyether carbonate polyols with tuneable amounts of carbon dioxide in their backbone.

Not only is it possible to use different amounts of CO₂ with Econic’s technology, but this makes it possible to produce polyols which span a wide spectrum of physical properties without blending, she said.

‘CO₂ is a big issue,’ said Sellens. Although using CO₂ in polyol technology will not solve the CO₂ greenhouse gas problem, she says it represents a small bite out of it. ‘It encourages innovation and investment in the area.’

One good way to reduce the impact of greenhouse gases such as CO₂ is to reduce the amount of carbon used in industrial processes. Sellens explains, ‘If you use less petrochemical feedstock it fundamentally reduces emissions.’

Her assertion is backed up in research by Niklas von der Assen and Andre Bardow, who published a report, ‘Life cycle assessment of polyols for polyurethane production using CO₂ as feedstock: insights from an industrial case study’. They demonstrated that for every tonne of CO₂ used in making polyol, a further two tonnes of CO₂, which would be generated if a petrochemical route were used, are not created. ‘There’s a triple whammy, it’s great,’ she said.

CO₂ is a big issue

The polyurethane industry could make an impact on carbon dioxide levels in the atmosphere, though, Sellens explained. ‘If there is 30% market adoption of CO₂ to polyol technology at an average of 25% CO₂ content in the finished polyol, then by 2026 that would reduce CO₂ generated by around 3.5 MT/Year. That’s the equivalent of taking 2 million cars off the road. According to IHS Markit, that equates to reducing US auto production by 10% in 2016’

Econic started to look at polyols because they represent a large and growing market, and there is a desire for ‘green’ polyurethane. ‘To be frank, the concept of CO₂ polyols has been thought about for quite some time, so the foundations of the technologies developed by Covestro, and also Novomer, which is now part of Aramco, all emerged in a narrow period of time,’ Sellens said.

She continued that putting CO₂ into polyols is one of the few areas where it can be used directly as a reagent, rather than having to be transformed into a starting material using an energy-intensive step.

Symmetry

‘There is a symmetry about it,’ she added. ‘You take it straight into the polymer, there’s a CO₂ unit in the backbone of the polymer and, it is made from CO₂. You really are creating value out of CO₂ and, potentially, turning something useless and harmful into something very useful.’

The cost profile of CO₂ is also very attractive: there are a number of cost scenarios associated with capturing CO₂, but they are all an order of magnitude below the cost of the polyol without considering carbon-trading advantages that there could be, Sellens added.

Econic’s Business Development Director, Richard French, claimed, ‘CO₂ generated in petrochemical plants can be obtained with around 98% purity.’ This implies that if this technology were bolted on to existing processes, there would be little cleaning necessary before the CO₂ could be used.

Econic has two catalyst systems, both homogeneous, and Econic anticipates that they will be able to recycle the catalysts, and reuse them.

‘The first technology, Econic’s Alternating Catalyst system, produces alternating polyols and inserts a carbonate group between each of the epoxide molecules, giving a polymer backbone with a very regular array,’ he said. This catalyst allows up to 50% of conventional petrochemical feedstock to be replaced with CO₂.

He claimed that reactions using the catalyst systems proceed under very industry-appropriate pressures. ‘You don’t have to ramp up the pressure very high to drive the reaction. It can operate at pressures below 10 bar, giving the customer the opportunity to retrofit the system to their existing assets, and not have to buy a new set of reactors,’ he said.

The highly regular polyols produced give a fairly hard polymer, which can be advantageous in some applications. ‘This can be disadvantageous for other applications for example flex foam,’ he conceded

Understanding this, Econic has developed a Tuneable Catalyst System, where the amount of CO₂ can be selected and controlled to fit the final PU property requirements.

French said this system will operate at 6 bar, well within the industrial range for polyol production.

Playing tunes with CO₂

Econic believes other existing catalyst systems for incorporation of CO₂ into polyols generally require much higher pressures to operate effectively, with some catalyst systems leading to the incorporation of low percentages of CO₂ in polyols, while others can only incorporate high levels of carbon dioxide.

‘The Econic catalyst is an organic ligand with a metal centre,’ Sellens said. ‘Our systems are unique. We believe we have clear IP space, and we’ve been building into that space.’

‘If you can go from 0 to 100% CO₂, then you can match any potential application. If you can only go low or high, then you are limited. That was always our drive around tuneability. Once you are working in the high CO₂ area, polyols on their own are not going to meet all the application needs without blending [with other less viscous polymers]. Being able to dial-up [CO₂ content] is really fantastic.’

She added that the viscosity of the polyol drops exponentially as the CO₂ content is reduced. ‘If there is a product that can get into the middle-range of CO₂ and viscosity, then opening up the range of CO₂ containing materials opens up the application spectrum,’ she said.

When I visited the site in early November 2017, Econic was constructing a demonstrator plant at The Heath, a business and technical facility in nearby Runcorn.

‘Although we intend to be a catalyst technology provider, it’s very hard to sell a product if you can’t prove your claims,’ Sellens said. ‘The focus of our portfolio is on the catalysts, not on the work on polyols containing CO₂. The demonstration unit is about the validity and credibility of this technology, and the ability to supply small samples of polyol in the 10-20 kg range. For us, the challenge is to find the right people who will move swiftly, and take this technology forward.’

Not as viscous as you think

French added: ‘With Econic Alternating and Tuneable catalyst systems, we believe we can cover the whole polyol market requirement.’

Currently, French said, the company is working on hot-melts. ‘These look good. Metal coatings, rigid foams and elastomers are all areas of interest too.’ The company is also investigating polyols for flexible foams.

Econic presented papers at the recent CPI meeting in New Orleans about both catalyst technologies, as well as work on water-borne polyurethane dispersions.

‘We analysed these dispersions, prepared using 2000 MW diols containing different CO₂ contents. We took three industry control standards and used a variety of tests [to characterise the resulting dispersions],’ said French.

He added that some were aged in the dark and in the light for a week at room temperature then subjected to a range of US test methods. The viscosities and physical and chemical properties of the dispersions were well within the acceptable operating windows, with the exception of those containing the alternating polyol.

‘Sometimes, people have the impression that CO₂-based polyols are going to be very viscous, and they can be if you go for high CO₂ content, but if you can tune the CO₂ content, then you can get what you need. Lower CO₂ polyols would be applicable for flexible fabric coatings. The polyols were stable in terms of heat stability and yellowness. It is possible to tune the glass transition temperature of polyols by tuning the amount of CO₂ present in them,’ he added.

‘We are in different stages of evaluation with a range of people in the industry and we’re quite well into process and product development with a couple of them,’ Sellens concluded. ‘We don’t have any exclusive arrangements. Time and pace can give people the edge.’