PNNL

Abstract

Integration of biofuels produced via hydrothermal liquefaction (HTL) into the aviation fuel market is hindered by the high nitrogen content of these fuel products. Traditional hydrocracking requires high energy and hydrogen use. To this end, adsorption-based processes offer similar nitrogen removal with significantly reduced energy costs. In this work, we demonstrate a scalable energy-efficient packed bed adsorption column system using silica gel as a high surface area adsorbent with adequate surface acidity for nitrogen containing compounds (NCCs) removal from biofuel. Effects of feed flow rate, particle size, and thermal regeneration/treatment on adsorption capacity and product purity are quantified. Effects of feed complexity through use of a known reference fuel with added NCCs in the packed column system are also investigated. Sorbent characterization was done via thermogravimetric analysis (TGA) and BET nitrogen sorption measurements. The results presented in this work demonstrate up to 99.8% removal of NCCs from a model fuel fraction at an original NCC concentration of ~1500ppm to single digit ppm after treatment and examine thermal regeneration of the sorbent materials for their reuse. This successful proof-of-concept indicates a potentially economically viable method for ensuring the stability of bioderived sustainable aviation fuel, as well as minimization of NOx compound release and integrability of HTL fuels into the current infrastructure.