CARBON NANOTUBES AND NANO-Ce–Zr OXIDES SUPPORTED H3PW12O40 FOR EFFECTIVE ADSORPTION–DECOMPOSITION OF NOx

Abstract

Surface-modified carbon nanotubes (CNTs) and nano- Ce–Zr mixed oxides (CZO) were prepared and employed initially as supports of H3PW12O40 (HPW) for NO x adsorption–decomposition. Both CNTs and nano-CZO are favorable supports for HPW. After loading with HPW, the NO x adsorption efficiency increases, especially for HPW/CZO in which the highest adsorption efficiency can achieve 98% at the HPW loading of 70%, much higher than that of single HPW. NO x adsorption efficiency can be influenced considerably by catalyst preparing conditions, in particularly, ethyl alcohol is superior to water as solvent for HPW loading onto CNTs; the –OH containing CNTs shows better promotion effect on the adsorption of NO x than that containing –COOH when using absolute ethyl alcohol as solvent; mechanical grinding method is superior to incipient impregnation method in loading HPW onto the support of CZO. For both catalysts of HPW/CNTs and HPW/CZO, with the increase of HPW loading, the NO x adsorption efficiency tends to reach a peak value before dropping down. Heated from 150°C to 450°C at a rate of 50°C/min, the adsorbed NO was found to decompose into N2 , O2 and N2O , and yields of N2 being 21.8% and 27.3%, respectively for HPW/CNTs and HPW/CZO were obtained.