Simplified direct pyrolysis method for preparation of nanocrystalline iron based catalysts for H۲ purification via high temperature water gas shift reaction

چکیده مقاله

The high-temperature water gas shift reaction is an important step in industrial processes and gas purification. Although the chromium promoted Fe2O3 catalysts have been widely used in this reaction, but preparation of catalyst directly in the active phase (Fe3O4) is of great importance from technical viewpoint. In this paper, facile direct pyrolysis method was employed for synthesis of nanocrystalline Fe3O4 based catalysts with different Fe/Cr and Fe/Cu ratios for high temperature water gas shift reaction. The prepared samples were characterized by X-ray diffraction (XRD), N2 adsorption (BET), temperature-programmed reduction (TPR), thermal gravimetric and differential thermal analyses (TGA/DTA) and scanning electron microscopy (SEM) techniques. XRD analysis showed that this simple preparation method allows obtaining the catalyst directly in the active phase with chromium and copper incorporated into magnetite lattice. Moreover, the effect of chromium and copper contents on the structural properties and catalytic performance of the catalysts was investigated. It was found that, among the catalysts evaluated the catalyst with Fe/Cr = 10 and Fe/Cu = 20 ratio possessed higher activity compared to commercial catalyst and showed high stability during 10 h time on stream. In addition, the effect of reduction and calcination temperatures, GHSV and steam/gas ratio on the catalytic performance was evaluated.