Patent ID: 7838460

Claim:
A nanoporous metal oxide material comprising two or more metal oxides, wherein the nanoporous metal oxide material has a ceria content of 10 to 60 weight %, a zirconia content of 20 to 90 weight %, and an alumina content of 70 weight % or less, and has nanopores whose diameters are 10 nm or less, and the metal oxides are homogeneously dispersed in a wall constituting the nanopores; and wherein when spectra for all metal elements of metal oxides whose content in the nanoporous metal oxide material is 10 at % or more are measured by energy dispersive X-ray spectroscopy at measuring points in a region where a sample thickness can be regarded as almost constant using transmission electron microscope with an electron beam diameter of 1.0 nm and an accelerating voltage of 200 kV, a mean X m of relative intensity ratio X derived by converting integrated intensity of fluorescent X-ray peak of each metal element in obtained spectra to relative ratio, and a second moment ν 2 around the mean X m satisfy a condition expressed by a formula (I) for all the metal elements: ν 2 /X m 2 ≦0.02 (1) wherein X m is the mean of relative intensity ratio X and is described by an equation X m =(ΣX)/N (N being the number of measuring points), ν 2 is the second moment around the mean X m and is described by an equation ν 2 ={Σ(X−X m ) 2 }/N, and ν 2 /X m 2 is a second moment normalized to the square of the mean X m , in the formula (1).