Iron ore as precursor for preparation of highly active χ-Fe5C2 core-shell catalyst for Fischer-Tropsch synthesis

Abstract

This work describes a novel method for the preparation of active and stable Fe-based catalyst from an iron ore, which was chemically treated with oxalic acid to obtain a mixture of iron oxides and oxalate. It was found that under CO atmosphere at 350 °C, this mixture can be effectively transformed into active iron carbide phase (χ-Fe5C2), which is highly desirable for FTS. The catalysts were characterized by SEM, TEM, TGA, Raman, XRD, BET, and CO-TPR-MS. The catalytic performance was evaluated under FTS conditions (280 °C, H2 / CO = 1, P =20 bar) and GHSV = 12 N L gcat−1 h−1 for 100 h. The results showed that the CO conversion (66.8%) was higher on the oxalic acid-treated iron ore than in the untreated iron ore (46.5%), obtaining a high C5+ hydrocarbon selectivity (> 60.0%) in all cases. The proposed method significantly reduced the catalyst preparation steps using an inexpensive and abundant raw material for the sustainable preparation of very active and stable Fe-based catalysts for the FTS.