A method and a system for a treatment of a NOx- and soot-containing exhaust gas

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The invention proposes a method and system for treating exhaust gas from internal combustion engines (especially diesel engines) that contains both nitrogen oxides (NOx) and soot. This is achieved by first increasing the amount of nitrogen dioxide (NO2) in the exhaust gas, injecting ammonia (or a precursor like urea), and passing the gas through a soot filter. The soot filter traps soot particles, on which a selective catalytic reduction (SCR) reaction occurs, converting NOx into harmless nitrogen and water using the ammonia. This approach enables effective simultaneous removal of NOx and soot with reduced size and weight of the after-treatment system.

Use CasesContent extracted from patent full text and abstract with AI.

• Automotive exhaust after-treatment systems for diesel and lean-burn gasoline vehicles.
• Emissions control for heavy-duty vehicles, buses, trucks, and commercial fleets.
• Retrofitting emission control in existing engines to meet stricter environmental standards.
• Stationary power generation engines (e.g., generators) burning diesel or similar fuels.
• Marine diesel engines for ships requiring cleaner exhaust emissions.
• Industrial machinery operating with internal combustion engines in regulated environments.

BenefitsContent extracted from patent full text and abstract with AI.

• Enables simultaneous reduction of both NOx and soot from engine exhaust in a compact system.
• Reduces the size, complexity, and weight of exhaust after-treatment systems.
• Utilizes the soot layer on the filter to facilitate NOx reduction, removing the need for complex catalytic coatings in some cases.
• Improves overall system efficiency, reducing both maintenance requirements and costs.
• Allows flexible control of the NO2/NOx ratio for optimal SCR performance.
• Minimizes unreacted ammonia emissions (ammonia slip), contributing to cleaner output.
• Offers better thermal durability and applicability at a range of operating temperatures.
• Facilitates compliance with increasingly stringent emission regulations.

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Inventors & Applicants

Patent Abstract

It is the aim of the present invention to provide a method and a system for the treatment of a NO x - and soot-containing exhaust gas stemming from an internal combustion engine that combines soot filtration/deposition and selective catalytic reduction of NO x in a new way to foster the overall system efficiency and to reduce system size and weight. This aim is achieved according to the present invention by a method and a system for a treatment of a NO x - and soot-containing exhaust gas stemming from an internal combustion engine (4); comprising the steps of: a) providing NO 2 in the NO x - and soot-containing exhaust gas by an internal combustion measure and/or by bringing at least a part of the NO x - and soot-containing exhaust gas into contact with an oxidation catalyst (6); b) injecting at least into a part of the NO x - and soot-containing exhaust gas a predetermined amount of ammonia, either as neat ammonia or as a precursor compound for ammonia, such as urea, a liquid solution of urea, ammonium carbamate, isocyanic acid, cyanuric acid, methanamide, etc. or combinations of them, downstream and/or parallel to the controlling of the amount of the NO 2 as seen in the flow direction of the NO x - and soot-containing exhaust gas; c) bringing the ammonia-enriched NO x - and soot-containing exhaust gas into contact with a support structure (16) filtering and thereby depositing soot particles (14) from the NO x - and soot-containing exhaust gas on its surface thereby initiating a selective catalytic reduction of at least a part of the NO x -molecules with ammonia to nitrogen and water.