A novel Pd-doped perovskite-based LaCo0·9Pd0·1O3–Ba/Al2O3 catalyst enhances NOx to ammonia reaction.

The effect of Pd doping on the NOx removal efficiency and NH 3 selectivity was studied over lean NOx trap LaCo 1- x Pd x O 3 -Ba/Al 2 O 3 -type catalysts. Two catalysts were prepared by the sequential impregnation of 15 wt% of LaCo 1- x Pd x O 3 -type perovskites and 20 wt% of barium over alumina. The results of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, temperature programmed techniques, UV–vis diffuse reflection absorption spectroscopy, and X-ray photoelectron spectroscopy demonstrated that perovskite and barium grains uniformly distribution over the alumina surface. Cobalt partial substitution by palladium changed the chemical coordination environment, thus leading to the redox properties of perovskites getting different. Moreover, the LaCoO 3 –Ba/Al 2 O 3 catalyst exhibited a high reduction on NOx by H 2 between 450 and 550 °C. Whereas Pd-doped LaCo 0·9 Pd 0·1 O 3 –Ba/Al 2 O 3 catalyst decreased the best activity interval around 100 °C, as well as improved the NH 3 selectivity. The NOx reduction conversion of the LaCo 0·9 Pd 0·1 O 3 –Ba/Al 2 O 3 catalyst increased significantly from 72.9% to around 100% at H 2 /NO ratio = 1, and the production of NH 3 was increased from 20.1% to 58.6% at H 2 /NO ratio = 3. • Novel perovskite-based catalysts were synthesized for excellent textural properties. • Pd changes the chemical environment of the cobalt metal ions and enhances the redox properties of LaCoO 3. • Pd enhances H 2 dissociation thus offering more H ions to promote the NH 3 generation. [ABSTRACT FROM AUTHOR]