Correlation of Plasma Properties with Gas Phase Products in Nonthermal Plasma-Assisted Pyrolysis/Hydrogenolysis of Polymers

Plastic disposal is of global concern, and upcycling plastics via pyrolysis is limited by high bulk temperature requirements and low product selectivity. The use of nonthermal plasma can mitigate these problems. This work provides an exploratory study of plasma properties and correlated gas phase products in a nanosecond pulsed nonthermal plasma spark discharge over a bed of common polymer powders, in argon, hydrogen (to promote hydrogenolysis), and nitrogen gas mixtures. Optical emission spectroscopy is used to determine plasma density, electron, and gas temperatures and Fourier Transform infrared absorption is used to determine the concentrations of gas phase products. The work provides insight into the design of plasma reactors for depolymerization and highlights the importance of hydrogen gas and heat addition in the reaction chemistry.