Citation: Modisha, P.; Garidzirai, R.; Güne¸ s, H.; Bozbag, S.E.; Rommel, S.; Uzunlar, E.; Aindow, M.; Erkey, C.; Bessarabov, D. A Promising Catalyst for the Dehydrogenation of Perhydro-Dibenzyltoluene: Pt/Al 2 O 3 Prepared by Supercritical CO 2 Deposition. Catalysts 2022, 12, 489. https://doi.org/10.3390/ catal12050489 Academic Editors: Vincenzo Vaiano and Olga Sacco Received: 4 April 2022 Accepted: 26 April 2022 Published: 28 April 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). catalysts Article A Promising Catalyst for the Dehydrogenation of Perhydro-Dibenzyltoluene: Pt/Al 2 O 3 Prepared by Supercritical CO 2 Deposition Phillimon Modisha 1, * , Rudaviro Garidzirai 1 , Hande Güne¸ s 2 , Selmi Erim Bozbag 2 , Sarshad Rommel 3 , Erdal Uzunlar 4,5 , Mark Aindow 3 , Can Erkey 2,6 and Dmitri Bessarabov 1, * 1 HySA Infrastructure Centre of Competence, Faculty of Engineering, North-West University, Private Bag X6001, Potchefstroom Campus, Potchefstroom 2520, South Africa; 31831435@nwu.ac.za 2 Department of Chemical and Biological Engineering, Koç University, Sarıyer, 34450 Istanbul, Turkey; hande.gunesakinciturk@arcelik.com (H.G.); sbozbag@ku.edu.tr (S.E.B.); cerkey@ku.edu.tr (C.E.) 3 Department of Materials Science and Engineering, Institute of Material Science, University of Connecticut, Storrs, CT 06269-3136, USA; sarshad.rommel@uconn.edu (S.R.); m.aindow@uconn.edu (M.A.) 4 Department of Chemical Engineering, Izmir Institute of Technology, Urla, 35430 Izmir, Turkey; erdaluzunlar@iyte.edu.tr 5 Iongenics Electrochemical Technologies, Teknopark Izmir, Urla, 35430 Izmir, Turkey 6 Koç University Tüpra¸ s Energy Center (KUTEM), Koç University, Sarıyer, 34450 Istanbul, Turkey * Correspondence: phillimon.modisha@nwu.ac.za (P.M.); dmitri.bessarabov@nwu.ac.za (D.B.); Tel.: +27-18-285-2460 (D.B.) Abstract: Pt/Al 2 O 3 catalysts prepared via supercritical deposition (SCD), with supercritical CO 2 , wet impregnation (WI) methods and a selected benchmark catalyst, were evaluated for the dehydrogena- tion of perhydro-dibenzyltoluene (H18-DBT) at 300 ◦ C in a batch reactor. After ten dehydrogenation runs, the average performance of the catalyst prepared using SCD was the highest compared to the benchmark and WI-prepared catalysts. The pre-treatment of the catalysts with the product (dibenzyltoluene) indicated that the deactivation observed is mainly due to the adsorbed H0-DBT blocking the active sites for the reactant (H18-DBT). Furthermore, the SCD method afforded a catalyst with a higher dispersion of smaller sized Pt particles, thus improving catalytic performance towards the dehydrogenation of H18-DBT. The particle diameters of the SCD- and WI-prepared catalysts varied in the ranges of 0.6–2.2 nm and 0.8–3.4 nm and had average particle sizes of 1.1 nm and 1.7 nm, respectively. Energy dispersive X-ray spectroscopy analysis of the catalysts after ten dehydrogena- tion runs revealed the presence of carbon. In this study, improved catalyst performance led to the production of more liquid-based by-products and carbon material compared to catalysts with low catalytic performance. Keywords: supercritical deposition; wet impregnation; supercritical CO 2 ; liquid organic hydrogen carriers; dibenzyltoluene; dehydrogenation 1. Introduction The establishment of a cost-competitive and efficient infrastructure for hydrogen stor- age and distribution is required to promote a hydrogen economy. This is important, as governments and industries are working towards implementing decarbonization strategies, such as utilizing hydrogen as a vector for clean energy. Hydrogen storage and distribution in the form of liquid organic hydrogen carriers (LOHCs) has become a ‘hot topic’ recently. This is because LOHCs can store large volumes of hydrogen for long periods and without self-discharge at ambient temperature and pressure. Traditional hydrogen storage tech- nologies require high-pressure steel tanks, expensive composite cylinders, energy-intensive gaseous compression and liquefaction processes [1–6]. Unlike in traditional technologies, Catalysts 2022, 12, 489. https://doi.org/10.3390/catal12050489 https://www.mdpi.com/journal/catalysts