Sustaining metal-organic frameworks for water-gas shift catalysis by non-thermal plasma
Authors: Shaojun Xu, Sarayute Chansai, Cristina Stere, Burapat Inceesungvorn, Alexandre Goguet, Kanlayawat Wangkawong, S F Rebecca Taylor, Nadeen Al-Janabi, Christopher Hardacre, Philip A Martin, Xiaolei Fan
Journal: Nature Catalysis
Publication Date: 14 January, 2019
Department of: Chemical Engineering and Analytical Science
Low-temperature plasma activates metal-organic frameworks for catalytic reactions
Metal-organic frameworks (MOFs) are crystalline porous materials constructed by connecting metal ions/clusters with organic linkers (such as multi-dentate carboxylates). The highly dispersed and uniformly distributed metal sites can be tailored in MOFs, endowing them the great yet versatile capacity for various applications such as catalysis. However, to date, MOFs have found limited practical applications in catalysis primarily due to their poor thermal and hydrolytic stability. This severely restricts their applications in conventional catalysis involving thermal treatment and/or use of water.
Now, chemical engineers at The University of Manchester together with colleagues in Belfast and Chiang Mai University (Thailand) have proposed and developed innovative low-temperature plasma processes to activate the intrinsic catalytic properties of MOFs. In addition, they sustained the stability of MOFs for challenging catalysis of the water-gas shift reaction for hydrogen production which normally only occurs at high temperatures. Importantly, the stability of MOFs is sustained under plasma activation and in the presence of water. The method has been proven to be generic, and therefore has the potential to be a platform technology enabling the utilisation of MOFs for a wider range of catalysis, such as catalytic reduction of nitrogen oxides (NOx) for emission control.
- The limited thermal and water stability of metal-organic frameworks (MOFs) often restricts their applications in conventional catalysis involving thermal treatment and/or use of water.
- A challenging feature of using MOFs with open metal sites (OMSs, i.e. coordinatively unsaturated metal sites) in heterogeneous catalysis lies in the role of OMSs, which have to provide a balance between activity and stability during the reaction under heating, in the presence of water or both.
- Low-temperature plasma (i.e. non-thermal plasma, NTP) is a promising technique which can overcome the stability barriers of MOFs in conventional catalysis.
- An example of NTP-activated water-gas shift reaction over a MOF (HKUST-1 with copper OMSs) is presented. Significantly, the exceptional stability of HKUST-1 has been sustained under NTP activation and in the presence of water, leading to a high specific rate.