Combined urea hydrolysis and selective catalytic reduction for emissions control

A catalyst aftertreatment system, comprising:

• a dosing compartment comprising a doser configured to introduce a diesel exhaust fluid (DEF) comprising urea into a diesel exhaust;
• a mixing chamber subsequent to the doser configured to mix the DEF with the diesel exhaust, the mixing chamber including a static metallic mixer, and a catalyst substrate having a binary catalyst coated thereon;
• wherein the binary catalyst comprises a zeolite having a crystal lattice comprising a metal oxide, wherein the metal oxide is covalently bound to elements within the crystal lattice;
• or a plurality of metal oxide nanoparticles hybridized to a zeolite, wherein the metal oxide nanoparticle has a maximum dimension of from 0.1 to 50 nm;
• or any combination thereof;
• and
• wherein the binary catalyst is configured to simultaneously hydrolyze urea to generate ammonia, store NH3, and reduce NOx within 60 seconds of a cold start event, with no visible urea deposit formation on the catalyst substrate over a period of at least 40 test runs;
• a SCR unit subsequent to the mixing chamber unit, comprising an SCR catalyst configured to facilitate reduction of nitrogen oxide (NOx) in the diesel exhaust with NH3.