Insight into the effect of ZnCl2 on analytical pyrolysis behavior of cellulolytic enzyme corn stover lignin

- Effect of ZnCl2 on pyrolysis of cellulolytic enzyme corn stover lignin was studied.
- ZnCl2 promoted the formation of solid char and non-condensable gases.
- Pyrolysis of lignin with ZnCl2 exhibited higher activation energies (114-236 kJ/mol).
- Formation of monomeric phenols was substantially suppressed with ZnCl2.
- A possible mechanism of ZnCl2 on lignin pyrolysis was proposed.

The target of this work is to investigate the effect of impregnated ZnCl2 on the analytical pyrolysis behavior of waste cellulolytic enzyme corn stover lignin (CECL). Pyrolysis of CECL in a thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FTIR) exhibited that ZnCl2 promoted the formation of solid product, resulted in high activation energies (114-236 kJ/mol). The evolution amount of CO2 and H2O increased 2-3 times with ZnCl2. Pyrolysis in a pyrolyzer coupled with gas chromatography/mass spectrometry (Py-GC/MS) showed that 4-vinylphenol and 4-vinylguaiacol exhibited high peak areas, and the formation of most monomeric phenols was substantially suppressed by ZnCl2. A possible mechanism was provided considering that ZnCl2 promoted the formation of char and non-condensable gases while suppressed the formation of bio-oil. The substantial evolution of gases could be responsible for the highly porous structure of activated carbon prepared with ZnCl2. Our work provides a foundation towards understanding the effect of ZnCl2 on lignin pyrolysis.