An alkylation catalyst having a zeolite catalyst component and a binder component providing mechanical support for the zeolite catalyst component is disclosed. The binder component is an ion-modified binder that can include metal ions selected from the group consisting of Co, Mn, Ti, Zr, V, Nb, K, Cs, Ga, B, P, Rb, Ag, Na, Cu, Mg, Fe, Mo, Ce, and combinations thereof. The metal ions reduce the number of acid sites on the zeolite catalyst component. The metal ions can range from 0.1 to 50 wt % based on the total weight of the ion-modified binder. Optionally, the ion-modified binder is present in amounts ranging from 1 to 80 wt % based on the total weight of the catalyst.

The present disclosure provides catalyst compositions for NO.sub.x conversion and wall-flow filter substrates comprising such catalyst compositions. Certain catalyst compositions include a zeolite with sufficient Cu exchanged into cation sites thereof to give a Cu/Al ratio of 0.1 to 0.5 and a CuO loading of 1 to 15 wt. %; and a copper trapping component (e.g., alumina) including a plurality of particles having a D.sub.90 particle size of about 0.5 to 20 microns in a concentration of about 1 to 20 wt. %. The zeolite and copper trapping component can be in the same washcoat layer or can be in different washcoat layers (such that the copper trapping component serves as a pre-coating on the wall-flow filter substrate).

To be able to produce an SCR catalyst (2), in particular one having a zeolite fraction (Z) as catalytically active fraction, in a reliable process and at the same time achieve good catalytic activity of the catalyst (2), an inorganic binder fraction (B) which is catalytically inactive in the starting state and has been treated to develop catalytic activity is mixed into a catalyst composition (4). The inorganic binder component for the binder fraction (B) is, in the starting state, preferably porous particles (10), in particular diatomaceous earth, which display mesoporosity. To effect catalytic activation, the individual particles (10) are either coated with a catalytically active layer (12) or transformed into a catalytically active zeolite (14) with maintenance of the mesoporosity.

A cold start catalyst is disclosed. The cold start catalyst comprises a zeolite catalyst and a supported platinum group metal catalyst. The zeolite catalyst comprises a base metal, a noble metal, and a zeolite. The supported platinum group metal catalyst comprises one or more platinum group metals and one or more inorganic oxide carriers. The invention also includes an exhaust system comprising the cold start catalyst. The cold start catalyst and the process result in improved NO.sub.x storage and NO.sub.x conversion, improved hydrocarbon storage and conversion, and improved CO oxidation through the cold start period.

The current invention refers to the LNT and the SCR catalysts designed for combined LNT-SCR applications. LNT catalysts are based on proton-conducting oxides of fluorite structure, namely Ca (Sr)LaCe (Zr, Pr) mixed oxides in which up to 40 mol-% of lanthanum is replaced by calcium and/or strontium, and up to 66 mol-% of cerium is replaced by zirconium and/or praseodymium, further combined with PtPd or PtPdRh precious metal components. SCR catalysts are Cu/zeolite modified by citrate treatment or CuCe, MnCe or CoCe/modified zeolite.

Provided is a system for treating an exhaust gas comprising a first SCR catalyst zone comprising vanadium loaded on a metal oxide selected from TiO.sub.2, ZrO.sub.2, SiO.sub.2, CeO.sub.2, and Al.sub.2O.sub.3; and a second SCR catalyst zone comprising a copper loaded small-pore molecular sieve, wherein the first SCR catalyst zone is disposed upstream of the second SCR catalyst zone with respect to normal exhaust gas flow through the system. Also provided is a method for using the system to treat exhaust gas.