Probing the Role of a Non-Thermal Plasma (NTP) in the Hybrid NTP Catalytic Oxidation of Methane
Authors: Emma K Gibson, Cristina E Stere, Bronagh Curran-McAteer, Wilm Jones, Giannantonio Cibin, Diego Gianolio, Alexandre Goguet, Peter P. Wells, Richard A. Catlow, Paul Collier, Peter Hinde, Christopher Hardacre
Journal: Angewandte Chemie
Publication Date: 06 July, 2017
Department of: Chemical Engineering and Analytical Science
Probing the workings of a emission control catalyst under plasma activation
Catalytic methane combustion is of critical environmental importance due to its high global warming potential and increasing use in dual-fuel vehicles; however, conventional emission control technologies are not active enough to thermally oxidise the methane to carbon dioxide in the exhaust.
Non-thermal plasma (NTPs) can be used to assist catalytic reactions that otherwise only take place at high temperatures. However, while a number of hypotheses have been put forward as to the action of NTPs in these reactions, there has been little evidence to back them up. Now, researchers at the University of Manchester have directly probed what”s happening during a hybrid NTP-catalytic reaction using a technique called in-situ core X-ray Absorption Spectroscopy (XAS) which provides insight into the structure of the catalyst under reaction conditions. This is the first use of this technique to examine the catalytic oxidation of methane by palladium supported on alumina. NTP-activated catalysts have high activity at the temperatures which are present in the exhaust of methane-powered vehicles. The researchers have shown that whilst the NTP plays a role in increasing the temperature of the catalyst, this is not sufficient to activate the thermal reaction. The in-situ XAS also indicates no change in the structure of the metal nanoparticles present during the application of the NTP, so the NTP must also lower the activation energy by offering an alternative pathway for the reaction to proceed. The work addresses a number of the fundamental questions regarding the role of the NTP in activating catalytic processes and opens up the opportunity to design new catalytic systems under NTP for more efficient emission control in the future.
- The plasma changes the temperature of the nanoparticle
- The plasma provides a new reaction pathway lowering the activation barrier
- No significant structural change of the catalyst occurs on application of the plasma