Torrefaction of hydrotreated palm kernel shell and mesocarp fiber mixture

Abstract

This paper examines the torrefaction of a hydrotreated mixture of palm shell and mesocarp fiber and its physicochemical and thermal properties after torrefaction. The weight ratio was fixed at 60:40 (palm shell to mesocarp fiber) for the untreated and hydrotreated mixture of palm shell and mesocarp fiber. The untreated and hydrotreated mixture was subsequently torrefied from 250 to 300°C. The results revealed that the physical appearance of the untreated and hydrotreated mixture darkened after torrefaction. Higher torrefaction temperature increased the mass loss, fixed carbon, ash and heating value of torrefied products. The ash content of torrefied hydrotreated mixture decreased by 42% (maximum) if compared to the torrefied untreated mixture. Likewise, the heating value of the torrefied hydrotreated mixture (23 MJ/kg) was higher than the untreated mixture. However, the moisture content and volatile matter gradually decreased with increasing torrefaction temperature. The mass loss and volatile matter of the torrefied hydrotreated mixture were considerably improved compared to the torrefied untreated mixture. Overall, the results showed that hydrotreatment resulted in a promising torrefaction end-products. Therefore, combined hydrotreatment and torrefaction is a practical and promising technique for producing low-ash oil palm biomass.