Facet-Dependent Performance of Hydroxylated Anodic Boehmite for Catalyzing Gaseous Formaldehyde Oxidation

Structured mesoporous anodic AlOOH (a-AlOOH) with dominant facets were developed and investigated in terms of the catalytic performance in formaldehyde oxidation. The activity of mesh-type a-AlOOH in the elimination of formaldehyde was compared with those of commercial AlOOH, a-gamma-Al2O3 (calcined AlOOH), commercial gamma-Al2O3, and AAO. The results show that a-AlOOH exhibit the highest catalytic activity toward the decomposition of gaseous formaldehyde. It was found that at the lower temperature range (< 50 A degrees C), CO2 were only detected over a-AlOOH, which indicated that formaldehyde oxidation reaction was carried out at low temperature over a-AlOOH but not just adsorption as reported. To clarify the phenomenon, XRD, SEM, HRTEM, XPS and TGA were performed, and the results show that a-AlOOH crystallized in the form of thin films could be due to the predominance of well-developed {031} {200} {002} facets containing exposed numerous reactive surface hydroxyls, which are preferred for the formaldehyde oxidation reaction. Furthermore, these hydroxyls enhanced the removal efficiency and contributed to the fast recovery ability and stability of the catalyst in water vapor environment. [GRAPHICS] .