Contribution of nitrogen oxides (NOx) to global warming, acid rain formation and the production of smog and ground level ozone has led to many attempts to reduce their emission. Among various approaches, selective catalytic reduction of NO with hydrocarbon (HC-SCR) has been known as an effective and the simplest method for NO reduction.

This study was aimed to develop the catalytic system that active for the selective reduction of NO with C₃H₈ under lean-burn condition. A high Zr-loaded SBA-15 mesoporous material (32.1 wt%) with high surface area (548m².g^-1), well-ordered structure and high surface acidity (136 μmol. g^-1) was prepared by a novel direct-post synthesis technique (DP).

Different catalytic systems were prepared by loading of various metals such as Ni, Co, Fe, Cu, G...[ Read more ]

Contribution of nitrogen oxides (NOx) to global warming, acid rain formation and the production of smog and ground level ozone has led to many attempts to reduce their emission. Among various approaches, selective catalytic reduction of NO with hydrocarbon (HC-SCR) has been known as an effective and the simplest method for NO reduction.

This study was aimed to develop the catalytic system that active for the selective reduction of NO with C₃H₈ under lean-burn condition. A high Zr-loaded SBA-15 mesoporous material (32.1 wt%) with high surface area (548m².g^-1), well-ordered structure and high surface acidity (136 μmol. g^-1) was prepared by a novel direct-post synthesis technique (DP).

Different catalytic systems were prepared by loading of various metals such as Ni, Co, Fe, Cu, Ga, Ag and Fe on the developed support. Among them, Ni and Co catalysts supported on Zr-SBADP2 exhibited promising results for NO reduction. Ni5/Zr-SBADP2 exhibited 17%, 34% and 47% N₂ yield at 350, 400 and 450℃, respectively, in the absence of the water vapor. However, the presence of the water vapor caused a slight decrease in NO reduction. The NO conversion to N2 decreased from 47% to 29% in the presence of 7 vol% of water vapor at 450℃. Moreover, a complete conversion of NO was achieved over Ni2.5/Zr-SBADP2 at 450℃ when propane concentration was increased from 500 ppm to 1750 ppm. Co catalysts supported on Zr- SBA-15 showed better activity compared to those observed over the Ni5/Zr-SBADP2 catalyst. The NO reduction activity improved significantly at low temperatures and the active temperature window broadened as well. Co2/Zr-SBADP2 exhibited 54%, 70 % and 60% N₂ yield in the absence of water vapor at 350, 400 and 450℃, respectively. Presence of water vapor not only did not suppress the NO conversion efficiency, but also significantly increased the N₂ yield at relatively low temperatures. In the presence of water vapor, the catalyst performance increased from 18% to 34% and 54% to 70% at 300 and 350℃, respectively. Furthermore, hydrothermal and long-term stability study indicated that both catalysts could retain their performances after being used under hydrothermal condition and maintain the efficiency of NOx reduction for a prolonged period without considerable deactivation.