Biphasic Plasma Microreactor for Oxyfunctionalization of Liquid Hydrocarbons

• Published in: Industrial & engineering chemistry research 2024-05, Vol.63 (20), p.9008-9017
• Main Authors: Nguyen, Darien K., Cameli, Fabio, Dimitrakellis, Panagiotis, Vlachos, Dionisios G.
• Format: Article
• Language: English
• Subjects: Kinetics, Catalysis, and Reaction Engineering
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/acs.iecr.4c00605

Oxyfunctionalization of linear alkanes is important but challenging to achieve. Herein, we demonstrate a biphasic gas–liquid modular plasma microreactor utilizing Ar/O2 gas to selectively oxidize liquid n-dodecane (C12) in an electrified, catalyst-free fashion. C12 secondary alcohols and ketones are the major products, with selectivities of 45–60% and a maximum yield of 23%. Fine-tuning gas and liquid flow rates enhance the plasma–liquid interfacial area, leading to a conversion of >50%. Difunctional and oligomerized oxygenates, alongside lighter hydrocarbons stemming from carbon–carbon cleavage, form at higher conversions. The energy efficiency (0.189 μmol/J) of the modular microreactor is the highest reported among plasma systems. Alkane conversion can be further improved by increasing the length of the plasma region while maintaining excellent energy efficiencies. Similarly, sequential processing/recirculation can enhance the extent of the reaction. This system is also amenable to treating mixtures of liquid n-alkanes, where smaller hydrocarbons are oxidized preferentially to a certain extent. The vapor pressure and liquid temperature are the key parameters. The chemistry occurs primarily in the gas phase for the lighter hydrocarbons and switches to interfacial reactions for the larger ones.