Catalytic thermal decomposition of the fungicide chlorothalonil and derivatives over different modified zeolites and metal surfaces

Abstract

Homogeneous and heterogeneous gas-phase static thermolysis of chlorothalonil (CT, 1) and four derivatives are presented. After thermal decomposition, many interesting products are formed. Chlorothalonil yielded principally carbonaceous residues and dehalogenated compounds, while all the derivatives also afforded a condensed dihydrophenazine (17). Relevant information from pyrolysis states that: CT is quantitatively decomposed when compared to its aromatic derivatives; in all cases some potential toxic compounds (which were detected with the help of NMR, GC–MS and IR) are produced; the best catalysts to perform the decomposition are the acidic zeolite H–Y and metallic Cu; the two zeolites used, (H-ZSM-11 and H–Y) are able to adsorb the substrates, but only H–Y is capable of decomposing CT in carbonaceous residues.