Reaction process for ZnCl2 activation of phenol liquefied wood fibers

Abstract

In this study, ZnCl₂ activation of phenol liquefied wood fibers at different temperatures was conducted to investigate the reaction mechanisms during the activation process. By combining Fourier transform infrared (FTIR) spectroscopy, thermogravimetric-FTIR-mass spectrometry (TG-FTIR-MS) and elemental analysis, the reaction mechanisms during the ZnCl₂ activation were deduced. Below 327 °C, dehydration of the hydroxyl groups and fracturing of molecular chains occurred inside the fiber. At 327–700 °C was the main stage of activation, where molecular structure was rearranged due to intramolecular condensation, crosslinking reactions and scission of molecular chains. A carbon net-like structure was preliminarily formed at 402 °C. Due to the removal of pyrolysis products such as H₂, H₂O, CO, CO₂, benzene and phenol, surface defects were filled in molten ZnCl₂. Pores would be left on the fiber surface after activation, cooling and cleaning. Above 700 °C, the aromatization degree and the degree of aromatic ring gradually improved.