Microwave assisted versus conventional pyrolysis of MDF: characterization of the biochars by FT-IR and solid-state 13C-NMR

Abstract

Biochars produced by microwave assisted pyrolysis and conventional pyrolysis from Medium Density Fibreboard were characterized by FT-IR and 13C solid-state NMR spectroscopy. The influence of different pyrolysis parameters, including microwave power, pyrolysis temperature and presence/absence of microwave absorbers is evaluated in relation to the biochar yield and properties, Whereas FT-IR and NMR are both indispensable tools to identify the functional groups of the biochars, solid-state 13C-NMR spectroscopy further allows to obtain quantitative data as a function of the conversion degree, and especially regarding the aromaticity. ln general microwave assisted pyrolysis yields biochars with a higher degree of aromaticity, and therefore improved stability, at lower temperatures as compared to conventional pyrolysis. lt is demonstrated that pyrolysis is a viable option to transform MDF into a value added product at the end of its lifetime.