Influence of Molten Salt Torrefaction Pretreatment on Upgrading of Bio-Oil from Camellia Oleifera Shell

As an excellent reaction medium, molten salt had large heat capacity, high thermal conductivity and stable chemical properties. Therefore, a new pretreatment method, molten salt pyrolysis (MT) pretreatment, was studied to pretreat Camellia oleifera shell (COS). The effect of temperature (160~280°C) on MT was mainly studied and compared with conventional dry and hydrothermal torrefaction. Furthermore, the physicochemical and pyrolysis characteristics of COS and torrefied biochar were also studied. The analysis of pyrolysis characteristics indicated that the energy of activation of biochar was reduced after MT, which was conducive to the occurrence of pyrolysis reaction. The content of phenols compounds rose considerably with MT pretreatment. The relative content of phenols at MT-240°C was 74.11%, which was higher than that of hydrothermal and dry torrefaction. In this study, an innovative and successful pretreatment process for converting COS into high-value phenols was proposed.