Catalytic hydrogenolysis of As-enriched Pteris vittata L. into high quality biofuel and study on the migration of heavy metals

Abstract As-enriched Pteris vittata L. (PVL, a kind of hyper-accumulator biomass) was converted into high-quality biofuel by the catalytic hydrogenolysis, aiming to achieve effective treatment and high-value utilization of hyper-accumulators. After pretreatment of PVL to remove lipids and lignin, more than 64% of heavy metals were transferred into water, and the As content in the solid biomass was reduced from 1328 mg/kg to 483 mg/kg. The multifunctional catalysts RhCl3/NaI/HCl/H2 were used in a biphasic reaction system to convert PVL into biofuel with high selectivity. The main products are C5 and C6 furans and low oxygen content ketones, which have a high heating value (HHV) and can be directly used as biofuel. The highest yields of C5 and C6 products were obtained with 60.2% and 61.1% (based on the corresponding hemicellulose and cellulose) under the optimal reaction conditions (160 °C, 4 h, 300 psi H2, 4 mmol NaI, H2O/toluene = 1:1). The total biofuel yield based on dry PVL was 18.8 wt.%. After the reaction, more than 50% heavy metals (Cu, Pb, Zn, Cd, As) remained in the bio-char, while the heavy metals in the biofuel were less than 20% (As content was less than 55 mg/kg). Therefore, catalytic hydrogenolysis was perceived as a promising technique for PVL treatment to obtain high-quality biofuel and arsenic recovery.