Direct and real-time analysis in a plasma reactor using a compact FTICR/MS: degradation of acetone in nitrogen and by-products formation

Abstract

Methods for reduction of Volatile Organic Compounds (VOCs) content in air depend on the 10 application considered. For low concentration and low flux, non-thermal plasma methods are often considered as efficient. However, the complex chemistry involved is still not well understood as there is a lack of datasets of byproducts formation. So as to overcome this issue, rapid analytical methods are needed. We present the coupling of a rapid chemical ionization mass spectrometer (CIMS) for the real-time analysis of the VOCs formed during a degradation experiment. The high resolution instrument used 15 allows for chemical ionization and direct quantification of non-targeted compounds. We present degradation experiments of acetone in a photo-triggered nitrogen plasma discharge. Two regimes were highlighted: efficient conversion at low concentrations (<100ppm) and moderate efficiency conversion at higher concentrations (>100ppm). Those two regimes were clearly delimited as the sum of two exponential curves occuring at respectively low and high concentrations. Many by-products were detected, in 20 particular HCN presented a significantly high yield. Nitrile compounds (acetonitrile, propionitrile,...) are formed as well. To a lower extent, ketene, acetaldehyde and formaldehyde are observed. The association of the high resolution mass spectrometer to the plasma reactor will allow further insights into the plasma chemistry and comparison to modelisation.