Chemical engineers discuss green research and education
HELD for the first time in Northern Ireland, and hosted by Queen’s University Belfast, this year’s ChemEngDayUK saw around 145 delegates gather to experience a rich programme focussed on sustainability, featuring more than 100 contributions of posters, presentations, and workshops.
Presenters shared research targeting sustainability and tackling global challenges, ranging from using digitalisation to optimise carbon capture and use, to advancing bio-based solutions such as biomass use in hydrogen production.
Haresh Manyar, event co-organiser, said: “One of the things I tell [my students] is to feel proud about what we are doing, because what we are doing is problem solving. We are providing solutions for all the global challenges we are facing at the moment.”
Sam McCalmont, a PhD student in the Moura Group at Queen’s University Ionic Liquid Laboratories (QUILL), presented work on developing ionic liquid (IL) technology for separating ethylene and ethane, essential for achieving the high purities required.
He said that traditionally separation on ethylene/ethane gas produced in refining is via well-established but energy intensive cryogenic distillation. Using ILs is a potential alternative.
ILs are compounds composed completely of ions – an anion and a cation – with a melting point below 100°C. McCalmont aims to develop them as a bridge between physiosorbent and chemisorbent materials used for separation. He told The Chemical Engineer that to date ILs have been a physiosorbent method.
“As you move from physiosorbent to chemisorbent, you gain the possibility of forming stronger separations between the gases, if one gas favours the IL and the other does not. The better the separation, the more efficient it is in regard to energy and less IL is needed.”
His group chose cyanopyridinium-based ILs as a possible material to improve separation. As previously in QUILL, these were developed to include nitrile groups to the pyridinium ring to increase affinity for electron rich pi-systems to test if interactions could be formed with ethylene (pi-system) compared to ethane (saturated molecule).
McCalmont first tested interactions indirectly using a pressure volume temperature (pVT) method. Gas was added to a vessel containing the IL, and the amount that had entered the IL was calculated by measuring the amount of gas in the system before and after equilibration with the IL.
Through pVT screening, McCalmont identified two ILs to use in a gas solubility system (GSS) pVT, from this ultimately calculating that each had selectivity for ethylene of about 1.3. To put this into context, McCalmont said that the best selectivity so far reported for ILs in ethylene/ethane separation is 2.1.
To promote ethylene interaction, he decided to add another IL to each developed to act as a diluent and allow ethylene more free volume to interact. This was to avoid adding silver/copper which can make ILs chemisorbent, but raise issues regarding reaction with contaminants, for example leading to formation of explosive silver acetylene.
McCalmont created 50/50 mixtures of the cyanopyridinium-based ILs with a standard, imidazolium-based IL, pushing selectivities to 1.5, higher than previously found for the developed ILs as well as the diluent alone (1.4).
Using nuclear magnetic resonance (NMR), he directly confirmed interaction between the gas and mixed ILs. However, 2D NMRs showed an increase in the self-diffusion coefficients of the mixtures compared with the unmixed ILs, indicating weakened interaction. He said the observation could be due to the gas acting like a lubricant, allowing the IL to flow more easily.
McCalmont concluded that the ILs developed have similar ideal selectivities to those of physiosorbent ILs, further confirmed with NMR showing a lack of strong interaction with the gas. In the final months of his PhD, he will explore increasing the number of nitrile groups in the IL, conduct 2D NMRs on different IL mixtures and look for observable interaction, and move to molecular dynamic simulations to observe interactions at the molecular level with the Wilken Group at QUB.
In a workshop run by IChemE’s Education Special Interest Group (EdSIG), chemical engineers explored development of graduate skills for sustainable and responsible engineering practice.
The panellists considered the question: How is success perceived/measured?
Peter Robertson, expert in energy and environmental engineering and professor at QUB, said that the first thing that’s critical is wide engagement with stakeholders and listening to them to ensure that no one is marginalised and there is agreement on what success is. He said people in particular disciplines can strugglenwith this.
“We can quite often have a perception that what we think we’re doing is particularly right, and others, when they raise their issues, it’s because they don’t understand. Well, if they don’t understand, we haven’t been explaining it well.”
Ed Byrne, professor at University College Cork, discussed the need to broaden what chemical engineering is about and understand society’s values and perspective.
“If we broaden our import, our meaning, our value towards society, and [show] that we really are making a positive difference, working with people as opposed to imposing solutions we feel are best, then we’re making progress, we’re being successful.”
Elias Condy, a final-year MEng student, argued that “it really just comes down to the numbers” and whether we achieve net zero by 2050.
Ademola Odunsi, lecturer at University College London, said that measuring success requires considering many different indices and at different points.
“Whether it’s students in a classroom and how they get on with the tasks that they are set, or whether it is graduates when they are leaving the four walls of the university and how they actually apply that knowledge to wherever they find themselves. And the entire society at large, how we take on sustainability, how we view it, how we understand it.”
Marta Granollers Mesa, EdSIG vice chair and deputy department head at Aston University, said the success of delivering sustainability skills to students could be assessed though feedback from placement employers, and assessment of which sectors graduates enter and the careers they pursue.
Highlighting that through his experience he has discovered that “most” chemical engineering students aim to pursue finance careers, an audience member asked the panel how they could be encouraged into paths where sustainability skills and knowledge are relevant.
Granollers Mesa said that “just because you don’t go into a sector that is technical, it doesn’t mean that you cannot embed in your decisions, sustainable thinking” adding that sustainability is an umbrella goal that encompasses both technical and non-technical areas.
Byrne said: “We need to do better as engineers. The 20th century engineer is not fit-for-purpose for purpose for 21st century problems…We do need the [core] competencies…but we need beyond that. We need to go way beyond that to make ourselves relevant. And then our graduates will work in the sectors.”
He said that sustainability is a key issue in “the world of work”.
“If we’re not up to speed in our programmes and embedding that in developing the type of graduate that needs to be working towards 2050 and beyond, then we’re failing and we’re not going to be attracting those graduates.”
Closing the conference, Manyar stressed that after two days of “intensive and extensive interactions between so many different colleagues from everywhere – from the UK, from Ireland, we have colleagues from India as well – these interactions, these conversations should never stop, they should go on and on and on”.
“Let the conversations continue. The conference stops...[but it] doesn’t mean science and technology stops.”
Next year’s ChemEngDayUK will be hosted by Imperial College London.
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