Observation and rationalization of nitrogen oxidation enabled only by coupled plasma and catalyst

Area of Science:

• Chemical Engineering
• Plasma Science
• Catalysis

Background:

• Non-thermal plasmas (NTP) coupled with heterogeneous catalysts can enhance reaction yields.
• Understanding the synergistic mechanisms between NTP and catalysts is challenging due to non-negligible individual contributions.
• Nitrogen (N2) oxidation to nitric oxide (NO) is a key industrial process.

Purpose of the Study:

• To demonstrate and rationalize the synergistic effect of platinum (Pt) catalysts with NTP for N2 oxidation.
• To identify the specific features of NTP and Pt that lead to enhanced NO production.
• To develop a modeling approach for optimizing plasma-catalyst systems.

Main Methods:

• Experimental demonstration of Pt-catalyzed N2 oxidation in an RF plasma afterglow.
• Development of reactor models incorporating reduced NTP and surface-microkinetic mechanisms.
• Analysis of radical reactions and N2 dissociation barriers under experimental conditions.

Main Results:

• Significant NO production was achieved only when Pt catalyst and NTP were combined.
• NTP and thermal catalytic NO production were suppressed individually.
• Pt catalyzed NTP-generated radicals and vibrationally excited molecules to produce NO.
• Synergistic effects were observed under conditions where individual components showed minimal activity.

Conclusions:

• Unambiguous evidence of synergism between NTP and Pt catalysts for N2 oxidation was established.
• The study identified the origins of this synergy, involving catalysis of plasma-generated species.
• A modeling framework was presented to guide the optimization of plasma-catalyst systems for productivity and energy efficiency.