Metal-supported material and ammonia synthesis catalyst

A metal-supported material in which ruthenium particles are supported on a composite oxide expressed by General Formula (2):

• AnX1−nOx (2)
• where A represents an element selected from the group consisting of Ce, Pr, and Tb, that is in a trivalent state at least partially, and a ratio of moles of the element in the trivalent state to total moles of the element in both a tetravalent state and the trivalent state is 0.1 to 0.9,
• X represents an element selected from the group consisting of Ca, Sr, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and that is different from A,
• n satisfies 0<n<1, and
• x represents the number of oxygen atoms necessary for the composite oxide to keep neutral electrically;
• wherein the composite oxide includes a solid solution that is a tetragonal crystal or a cubic crystal,
• wherein a ratio of a value (Dads) of a ruthenium dispersion degree obtained by an H2 pulse chemical adsorption method to a value (DTEM) of a ruthenium dispersion degree expected from an average particle diameter of ruthenium particles obtained from a TEM image satisfies 0<Dads/DTEM<1, and
• wherein the metal-supported material is manufactured by:
• mixing an A precursor including A and an X precursor including X to obtain a mixture;
• calcinating the mixture at 600° C. or more to obtain a carrier including the composite oxide;
• supporting a compound including ruthenium on the composite oxide to prepare a before-reducing process supporting material;
• and
• performing a reducing process on the before-reducing process supporting material at 400° C. or more.