Study on the Structure and Catalytic Performance of Catalyst Fe7S8 for Direct Coal Liquefaction

Abstract

In order to study the relationship between the direct coal liquefaction performance and the structure of Fe7S8 catalysts prepared by different methods, Fe7S8 catalysts with different crystal structures were prepared by calcination and solvothermal method separately. The results of characterization (XRD, Raman, and SEM) and liquefaction performance evaluation of catalysts show that the monoclinic and hexagonal Fe7S8 were obtained by calcination and solvothermal method, respectively. The yield of liquefied oil was 15.84%, 36.18% and the conversion was 67.97%, 70.94%, respectively. The solvothermal method was suitable for the preparation of liquefaction catalyst. Elemental analysis of liquefaction products, thermogravimetry differential thermal analysis (TG-DTA) and in situ Raman spectroscopy and X-ray diffraction (XRD) analyses of Fe7S8-R prepared by solvothermal method show that the catalysts played a role in activating hydrogen to produce active hydrogen and regulating the distribution of hydrogen and oxygen in the products. Fe7S8-R gradually formed Fe1-xS with the change of temperature and atmosphere during liquefaction, which is the active species of direct coal liquefaction.

Keywords

• direct coal liquefaction
• fe7s8
• monoclinic
• hexagonal
• pyrrhotite