Patent ID: 8087235

Claim:
A process for removing NO R from exhaust gas of a combustion engine, comprising: (i) storing NO x , by a NO x sorbent, under lean exhaust gas conditions; (ii) catalyzing, by a NO x -reducing catalyst, in situ reduction of the stored NO x to produce NH 3 under rich exhaust gas conditions; (iii) storing, by a NH 3 sorbent, under rich exhaust gas conditions, the produced NH 3 ; and (iv) catalyzing, by a NH 3 selective catalytic reduction (SCR) catalyst, reaction of the stored NH 3 with NO x under lean exhaust gas conditions to yield N 2 ; steps (i)-(iv) occurring simultaneously, with the NO x sorbent, the NO x -reducing catalyst, the NH 3 sorbent and the SCR catalyst being in physical contact with each other in the form of a mixture of said sorbents and catalysts; and the mixture further including at least one material from group (1) and at least one material from group (2), with the amount of the material from group (2) being in the range of 10-75 weight-% of the total mixture and functioning as an acidic solid for absorbing ammonia, in which: group (1) consists of palladium on a carrier oxide, with the carrier oxide consisting of at least one of zirconium oxide, cerium oxide, aluminum oxide and silica alumina oxide; and group (2) consists of zeolites, heteropoly acids, sulfated zirconium oxides, zirconium phosphates.