Heterogeneous Cu-Fe oxide catalysts for preferential CO oxidation (PROX) in H2-rich process streams.

Venkata D. B. C. Dasireddy,Darko Hanzel,Blaž Likozar,Krish Bharuth-Ram

doi:10.1039/d0ra06969h

Abstract

The influence of Fe loading in Cu–Fe phases and its effect on carbon monoxide (CO) oxidation in H2-rich reactant streams were investigated with the catalyst material phases characterized by Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD) studies and Mössbauer Spectroscopy (MS). There was no change in the oxidation state of the Fe ions with copper or iron loading. The catalytic activity was examined in the feed consisting of H2, H2O and CO2 for the preferential CO oxidation (PROX) process. These catalysts showed an optimized performance in converting CO in WGS streams in the temperature range of 80–200 °C. In addition to the formation of the CuFe2O4 phase, the Fe and Cu were found to be incorporated into a Cu–Fe supersaturated solid solution which improved CO oxidation activity, with carbon dioxide and water produced selectively with high catalytic activity in depleted hydrogen streams. Relatively high conversion of CO was obtained with high Fe metal loading. In addition to their catalytic efficiency, the employed heterogeneous catalysts are inexpensive to produce and do not contain any critical raw materials such as platinum group metals.

Highlights

The production of clean hydrogen for hydrogen-fuelled polymer electrolyte membrane fuel cells (H2-PEM) is gaining importance in recent days
It can be observed that supporting of metal oxide on the Al2O3 resulted in an apparent decrease of the surface area and pore volume which could be due to the blocking of some micropores and mesopores of the Al2O3 supports by Cu and Fe particles
The activities, compare as follows at T50: Fe/CuFe2O4 (120 C) > CuFe2O4/Al2O3 (140 C) > CuFe2O4 (140 C) > Cu/CuFe2O4. These results indicate that the introduction of Fe into CuFe2O4 catalysts can promote the oxidation of carbon monoxide (CO)

Summary

Introduction

In a supported catalyst system, phase-speci c mixed metal oxides have recently attracted great interest for use as catalyst and catalyst supports,[7,8] since these materials give rise to well dispersed and stable metal particles on the surface of the support materials and improved catalytic performance. In searches for an alternative, recent studies have found that Fe3+ had a promotional effect on the activity of Cu–Ce catalysts used for CO oxidation.[12] The Cu-based oxide catalysts have good catalytic performances for CO-PROX, which coupled with their low fabrication costs make them an efficient alternative to the precious metal catalysts. Cu–Fe/Al2O3 and Cu and Fe loaded CuFe2O4, were synthesized (with a 5 wt% of Cu and 5 wt% of Fe loading) and the role of Fe species on the active phase and in the activity of the catalyst were investigated using Mossbauer spectroscopy and X-ray diffraction

Experimental

Characterisation

Catalytic testing

Results and discussion

Conclusion