Preparation, characterization, and activity of SnO 2 nanoparticles supported on Al 2 O 3 as a catalyst for the selective reduction of NO with C 3 H 6

SnO 2 nanoparticles were prepared using the hydrothermal method. The particle size was gradually increased with increasing the hydrothermal temperature and period. The size of SnO 2 nanoparticles was successfully controlled in the range of 2.3–5.9 nm. The deposition of SnO 2 nanoparticles on to Al 2 O 3 was made through impregnation process. TEM and XRD measurements revealed that SnO 2 nanoparticles are highly dispersed on the surface of Al 2 O 3 without changing the particle size. When SnO 2 nanoparticles prepared at 150 °C for 3 h were deposited on to Al 2 O 3 (denoted as SnO 2 - 150 - 3 /Al 2 O 3 ), a part of SnO 2 nanoparticles was suspected to be dispersed inside of the pores of Al 2 O 3 . This is probably due to a small size of SnO 2 nanoparticles compared with the pore diameter of Al 2 O 3 . On the other hand, SnO 2 nanoparticles with relatively large size were found to be predominantly present on the outer surface of Al 2 O 3 . H 2 -TPR measurements suggest the presence of SnO 2 –Al 2 O 3 interaction in SnO 2 /Al 2 O 3 catalysts. Especially, SnO 2 - 150 - 3 /Al 2 O 3 was considered to include SnO 2 nanoparticles interacting more strongly with Al 2 O 3 . SnO 2 /Al 2 O 3 catalysts showed higher catalytic activity for the selective reduction of NO with C 3 H 6 than Al 2 O 3 , suggesting that the SnO 2 /Al 2 O 3 prepared using SnO 2 nanoparticles is effective to develop highly active catalyst.