Aluminum Doped Titania as a Support of Copper Catalysts for SCR of Nitrogen Oxides.

Wojciech Guziewicz,Jacek Gurgul,Małgorzata Zimowska,Bogna D Napruszewska,Anna Białas

doi:10.3390/ma14206021

Abstract

Aluminum doped titania samples were synthesized as supports of copper oxide catalysts for NO reduction with ammonia. Samples were prepared by the sol-gel method with various ratios of aluminum to titanium. Their thermal stability was examined by TG/DSC methods which revealed that precursors were decomposed at 450 °C. The XRD measurements showed that aluminum caused the diminishing of titania crystallites and was built into the anatase structure or formed an amorphous phase. The admixture of aluminum in titania resulted in a significant increase in specific surface area of mesoporous supports as determined by low temperature sorption of nitrogen. Results of the catalytic tests over copper/aluminum-titania samples obtained by impregnation pointed out that the addition of aluminum broadened the temperature window of high catalytic activity. The increase in Al concentration shifted the temperature of maximum activity to higher values, and at the same time lowered nitrous oxide formation as well. Better catalytic efficiency could result from high copper dispersion on the catalysts surface, as well as the synergistic interaction between Ti and Cu causing reduction in CuO species as confirmed by XPS measurements. It was shown that copper was present as Cu+ species mainly, forming Cu-O-Ti bonds on the catalysts surface.

Highlights

Among the catalysts used in selective catalytic reduction (SCR) of nitrogen oxides (NOx ) with ammonia, copper oxide is regarded as a highly efficient active phase
Aluminum doped titania precursors were obtained by the sol-gel method
XRD results showed that titania crystallized as anatase

Summary

Introduction

Among the catalysts used in selective catalytic reduction (SCR) of nitrogen oxides (NOx ) with ammonia, copper oxide is regarded as a highly efficient active phase. The main challenge in preparing copper oxide catalysts is to widen the temperature window of their high activity [1] It can be attained by elaborating the materials which enable good dispersion of copper species on the support and which are cheaper than zeolites. It is worth noting that alumina supported copper catalysts are active at higher temperatures and less nitrous oxide is formed than over titania ones [4]. This is a huge advantage because N2 O is a greenhouse gas which damages the ozone layer [4]

Methods

Results

Conclusion