Abstract: The invention relates to systems and methods for treating oxygen-rich NOx-containing exhaust. The systems and methods comprise using first and second NOx reducing catalysts. According to one aspect of the invention, the first catalyst reduces NOx in oxygen-rich exhaust primarily through reaction with a first reductant species and the second catalyst reduces NOx in oxygen-rich exhaust primarily through reaction with a second reductant species. Collectively, the two catalysts are substantially more effective than either of the catalysts individually in reducing the concentration of NOx in the exhaust. According to another aspect of the invention, an exhaust system is configured to inject a first reductant species primarily at a first location upstream of the first NOx reducing catalyst, and is configured to inject a second reductant species primarily at a second location downstream of the first NOx reducing catalyst, but upstream of the second NOx reducing catalyst.

Abstract: One aspect of the invention relates to a process for synthesizing ammonia from hydrogen and nitrogen in which an adsorbant is provided to adsorb ammonia as it is being produced. Adsorption of the product drives the ammonia synthesis reaction and allows the process to be carried out at pressures where the gas phase equilibrium conversion is too low for a conventional system to be practical. The invention is applicable to both small and large scale ammonia synthesis. A small scale ammonia synthesis plant can be a stationary or vehicle-mounted plant used to supply reducing agent for selective catalytic reduction of NOx in diesel exhaust. Ammonia can be desorbed from the adsorbant, extracted from the adsorbant, or stored and transported in its adsorbed state.

Abstract: The invention relates to systems for removing NOx from exhaust. In one aspect of the invention, after adsorption, an NOx adsorber is isolated from the main exhaust flow and desorption induced by raising the temperature. The desorbed NOx is combined with a reductant and reduced over a catalyst. Preferably, the reductant is syn gas produced in an on-board reformer. The catalyst need never be exposed to the main exhaust flow, which is particularly advantageous for catalysts sensitive to water, oxygen, or sulfur. In another aspect of the invention, a recirculating flow is induced through an NOx adsorber during a regeneration cycle. Recirculation can induce greater desorption at a given temperature, provide a source of heat for the adsorber, and allow a higher conversion rate with a fixed amount of catalyst. A further aspect of the invention relates to a vehicle-mounted adsorbers with provisions for heating.