MSSI researchers invent new gas sponges
Bernal Scientists from MSSI at the University of Limerick, as part of an international research team, have invented a new approach for purifying gases using sponge-like materials that could result in lower global energy use, emissions and pollution.
In an article published on May 19th 2016 in Science, Prof. Michael Zaworotko, SFI Research Professor and Bernal Chair of Crystal Engineering and Dr. Kai-Jie Chen, post-doctoral researcher, both at the University of Limerick, have discovered that a sieve-like structure known as SIFSIX-2-Cu-i serves as a sponge for acetylene. This means that gas mixtures such as those generated in the petrochemical industry can be purified more efficiently, more specifically and without high energy demands. This is important because commodity purification alone currently accounts for between 10-15% of the world’s energy consumption. If the processes currently used, typically distillation, were replaced with more energy efficient technologies like these sponges, then the US alone could save 100 million tonnes of carbon dioxide emissions and US$4 billion in energy costs annually.
The new invention is relevant to the production of ethylene, the largest and one of the most energy demanding processes in the petrochemical industry. Ethylene, a simple molecule of hydrogen and carbon, is a vital component in a multi-billion Euro industry, spanning the production of common day plastics (polyethylene), to controlling the process of ripening fruit. Alternatives to the current process such as separating molecules according to their size, structure or properties are much less energy intensive but do not work well for the final step in ethylene production, i.e. removal of acetylene impurities. The approach that has been developed by Prof. Zaworotko, Dr. Chen and their international collaborators uses a class of material called Hybrid Ultramicroporous Materials or HUMs. SIFSIX-2-Cu-i (below, first reported by Zaworotko’s group in collaboration with Dr. M. Eddaoudi of KAUST in Nature in 2013) is a HUM with tiny, atomic-sized sieves of less than 1 nanometre in size. This means that in principle they can sieve and separate gas molecules based upon size alone. In 2015, Dr. Chen and Zaworotko thought that SIFSIX-2-Cu-i and related materials could be useful as acetylene sieves but unexpectedly discovered that they behave more like sponges, especially SIFSIX-2-Cu-i. Speaking about the discovery, Prof. Zaworotko, whose research into HUMs started in 1995, commented that, “in a way this was a glorious failure, where the outcome was so much better than expected.” At this point Zaworotko communicated with an international team of researchers including Prof. Banglin Chen (University of Texas at San Antonio, USA) and Prof. Huabin Xing (Zhejiang University, China) and discovered that they were also exploring SIFSIX compounds for ethylene purification and that they had made similar observations. Rather than compete with each other, the teams then decided to work together on patenting and publishing this exciting invention.
This new invention offers an entirely more environmentally friendly, cost effective way to purify ethylene, the most intensively produced organic chemical in the world. In the bigger picture, similar approaches could work for other important purification processes such as carbon capture and water desalination leading to significantly reduced global consumption of energy and release of greenhouse gases. As noted by Zaworotko, “we are not dealing with incremental improvements in performance, but big leaps forward. This is because of the special nature of the nanoscale features of SIFSIX materials and our ability to control them”.
This discovery also highlights the quality of research that is taking place at the University of Limerick. “We pride ourselves on a reputation for delivering translational research that makes an impact on industry, society and the wider community”, comments Prof. Edmond Magner, Dean of Faculty of Science and Engineering at UL. “This research, which has been supported by Science Foundation Ireland, is a prime example of how knowledge and expertise developed at UL has presented a real solution to a very real challenge in a traditional industry that has impact far beyond our shores”.
Professor Michael Zaworotko is SFI Research Professor and Bernal Chair of Crystal Engineering at the University of Limerick. This material is based upon works supported by the Science Foundation Ireland under Grant No. [13/RP/B2549].