Bridging Dehydrogenation and Hydrogenation in Heterogeneous Catalysis: A Demonstration of a Unified Catalytic Approach

• Published in: Chemistry : a European journal 2024-08, Vol.30 (47), p.e202400980-n/a
• Main Authors: Jangir, Jyothi, Jagirdar, Balaji R.
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Cascade chemical reactions; Catalysis; Catalysts; Catalytic activity; Chemical reactions; Chemical synthesis; Dehydrogenation; Endothermic reactions; Heterogeneous catalysis; Heterostructures; Hydrogen; Hydrogenation; Liquid organic hydrogen carriers; Nanoparticles; Noble metals; Palladium; Pd−Ru heterostructure; Recyclability; Ruthenium; Thermal stability
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202400980

In the pursuit of enhancing the applications of hydrogen as an energy carrier, this research delved into the utilization of a singular hybrid catalyst capable of performing both dehydrogenation and hydrogenation processes for Liquid Organic Hydrogen Carriers (LOHCs). This study presents the synthesis and characterization of a hybrid catalyst, combining an organometallic pincer complex with Pd−Ru heterostructures supported on γ‐alumina. Unlike conventional transition and noble metal nanoparticles, the use of a pincer complex offers exceptional thermal stability due to its aryl backbone, which is advantageous for various endothermic dehydrogenation reactions of hydrocarbons in LOHCs. This pioneering hybrid catalyst is a novel approach, demonstrating a proof of concept. In this study, we utilized the hybrid catalyst to investigate the dehydrogenation and hydrogenation of a lower enthalpic system, specifically the cyclooctane−cyclooctene system. The dehydrogenation of cyclooctane was conducted at 443 K using tertiary butyl ethylene as a sacrificial hydrogen acceptor, while the hydrogenation of cyclooctene reaction catalyzed by Pd−Ru nanostructures occurred at 298 K and 1 atm H2. The results showed successful tandem dehydrogenation‐hydrogenation reactions. However, challenges were noted in terms of catalytic activity and recyclability, providing valuable insights for further refinement and optimization. The research showcases the dual dehydrogenation and hydrogenation capabilities of an innovative hybrid catalyst, illustrated through the cyclooctane−cyclooctene model. This hybrid catalyst combines a pincer iridium complex with Pd−Ru heterostructures, both supported on solid γ‐alumina, serving as a compelling proof of concept for tandem dehydrogenation‐hydrogenation processes.