EFFECTS OF PRESSURE ON LIGNOCELLULOSIC BIOMASS FAST PYROLYSIS

The present work focuses on the effects of pressure on the quality of char and primary tar produced from fast pyrolysis of lignocellulosic biomass. Heat treatment has been carried out in a heated strip reactor (HSR) at 1573 K in nitrogen at 2, 4, 8 bar, with holding times of 3 s and heating rate of 104 K/s. The equipment allows quenching the volatiles as soon as they are emitted from the particles and collecting them for further chemical analyses. The char samples are also collected for thermogravimetric analysis in air. The DTG curves in air of char prepared at 2 bar shows two resolved peaks. Increasing the pressure of heat treatment from 2 to 4 bar has a minor effect on char reactivity, whereas further increase to 8 bar drastically changes the char combustion patterns, and the DTG curves exhibit only one well defined peak. For all the process conditions investigated, Oxo-aromatics are the dominant species in the tar. Benzendiol prevails in the 2 bar tar, followed by oxo-aromatic compounds related to lignin structure, while PAHs are mainly present as Fluorene. When pressure increases, Phenols compounds drastically prevail, and PAHs as Anthracene and Pyrene appear.