Cellulose modified iron catalysts for enhanced light olefins and linear C5+ α-olefins from CO hydrogenation

Abstract

Abstract Cheap and renewable cellulose used for surface modification was adopted in iron catalysts for CO hydrogenation. Fe3O4 were first prepared by solvothermal method and then modified by hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC), respectively, which were employed as model catalysts to investigate the modification effect on olefin formation in Fischer-Tropsch synthesis. The catalysts were characterized by SEM, N2 adsorption, XRD, TG, FT-IR, H2O-TPD-MS, CO-TPD, H2-TPR, XPS, Zeta potential and contact angle measurements. Results demonstrated that on Fe3O4/HEC, light olefins (C2=–C4=) and linear C5+ α-olefins were highly produced with an olefin/paraffin (O/P) ratio of 4.4. Compared with Fe3O4, the linear α-olefin selectivity was increased from 5% to 61.5%, and the methane selectivity was reduced to 14.7%. The CO conversion was higher on Fe3O4/CMC (50.8%) than on Fe3O4/HEC (8.8%) due to the electronic effect of –COONa. High olefin selectivity was mainly caused by the iron surface modification, which inhibited the secondary hydrogenation of primary olefins. The hydroxyl on HEC promoted the chain growth resulting in higher C5+ hydrocarbons. Surface hydroxyl groups played an improtant role in tuning the product distribution and promoting the formation of linear α-olefins in CO hydrogenation.