Michalis Vasiliades

Abstract:

During the last decades, several natural gas (NG) reservoirs were found to be rich in CO₂ (> 40 vol%), and this led to an intense effort for the development of a dry reforming of methane (DRM) catalytic technology (CH₄ + CO₂ to 2 CO + 2 H₂) with a favorable H₂/CO gas ratio for liquid fuels (Gas To Liquid, GTL) and other useful chemicals (e.g., DME, MeOH, acetic acid) by the catalysis research community and related industries [1]. Biogas (a renewable energy source) can also be a suitable feedstock for the DRM catalytic technology [2].
Practical problems related to the irreversible coking phenomena, especially on the less-costly attractive Ni-based catalysts, remain one of the main obstacles for the catalytic DRM technology to find industrial applications. It is well known that an in-depth understanding of the elementary steps related to carbon deposition and removal chemistry on Ni or other relevant metal supported catalytic systems along with their micro-kinetic analysis is a key factor for the future development of highly active and
carbon - resistant DRM catalytic systems, preferably at temperatures lower than 750 ^oC.
This keynote lecture will present the use of various transient and isotopic experiments (use of ¹⁸O₂, ¹³CO₂ and ¹³CH₄) to elucidate the role of metal cation dopant in Ce_1-xM_xO₂ (M = Ti⁴⁺, Pr³⁺) used as support of Ni, and the use of Pt in the NiPt alloy supported on Ce_0.8Pr_0.2O₂, in reducing the carbon accumulation to a remarkable extent during DRM at 750^oC. In particular, the importance of carbon gasification by labile oxygen of support to the formation of CO(g), the contribution of oxygen vacant sites of support to the CO₂ dissociation rate and re-oxidation of support, and the quantification of the origin of carbon accumulation (CH₄ vs CO₂ activation route) will be elucidated [3, 4]. Other experimental approaches reported in the literature for the understanding of carbon deposition and removal chemistry on supported Ni and other metals will be presented. Experimental results from the SSITKA technique (use of ¹³CO₂ or ¹³CH₄) will be presented to demonstrate the effect of metal dopant on support and Pt on the active carbon that is strictly associated with the rate of reaction.

[1] S. Afzal, D. Sengupta, A. Sarkar, M. El-Halwagi, N. Elbashir, ACS Sustainable Chem. Eng. 6 (2018) 7532-7544.
[2] Ch. Papadopoulou, H. Matralis, X. Verykios, in:, L. Guczi, A. Erdohelyi (Eds.), Catal. Altern. Energy Gener., Springer New York, New York, NY, 2012, pp. 57-127.
[3] C.M. Damaskinos, M.A. Vasiliades, A.M. Efstathiou, Appl. Catal. A: Gen., in press (doi.org/10.1016/j.apcata.2019.04.023).
[4] M.A. Vasiliades, C.M. Damaskinos, K.K. Kyprianou, M. Kollia, A.M. Efstathiou, Catal. Today, in press (doi.org/10.1016/j.cattod.2019.04.022).