A catalyst comprising a zeolite loaded with copper ions and at least one trivalent metal ion other than Al+3, wherein the catalyst decreases NOx emissions in diesel exhaust. The trivalent metal ions are selected from, for example, trivalent transition metal ions, trivalent main group metal ions, and/or trivalent lanthanide metal ions. In particular embodiments, the catalysts are selected from Cu—Fe-ZSM5, Cu—La-ZSM-5, Fe—Cu—La-ZSM5, Cu—Sc-ZSM-5, and Cu—In-ZSM5. The catalysts are placed on refractory support materials and incorporated into catalytic converters.