Method for reducing NOx in the exhaust streams of internal combustion engines

Claim 1

A method of reducing the concentration of NO x in the exhaust stream of an internal combustion engine capable of combusting an air/fuel mixture in the interior of a piston-cylinder assembly, wherein air is fed into the interior of a piston-cylinder assembly by an air feed stream and fuel is fed into the interior of the piston-cylinder assembly by a fuel feed stream, comprising the steps of: introducing an effective NO x reducing amount of a solution of a selective reducing agent that decomposes upon combustion consisting essentially of a compound selected from the group consisting of cyanuric acid; cyanuric acid in which one or more hydroxyl groups are substituted by --NH 2 , --NHR, or --NR 2 where R is a C 1-4 alkyl group; isocyanuric acid; and mixtures thereof, and a solvent which is soluble in the fuel feed stream into a fuel feed stream; introducing said air feed stream and said fuel feed stream into the interior of the piston-cylinder assembly to form an air/fuel mixture which initiates a premixed flame phase of combustion, such that said selective reducing agent is present during the initiation of said premixed flame phase of combustion; combusting said air/fuel mixture, wherein said selective reducing agent reduces the concentration of NO x present in the exhaust stream, and wherein said selective reducing agent is introduced into said fuel feed stream in an effective NO x reducing amount up to a molar ratio of 1:2 with respect to the molar amount of NO x which would be present in the exhaust stream in the absence of said selective reducing agent.

Claim 2

A method of reducing the concentration of NO x in the exhaust stream of an internal combustion engine capable of combusting an air/fuel mixture in the interior of a piston-cylinder assembly, wherein air is fed into the interior of a piston-cylinder assembly by an air feed stream and fuel is fed into the interior of the piston-cylinder assembly by a fuel feed stream, comprising the steps of: introducing an effective NO x reducing amount of a solution of a selective reducing agent that decomposes upon combustion consisting essentially of a compound selected from the group consisting of cyanuric acid; cyanuric acid in which one or more hydroxyl groups are substituted by --NH 2 , --NHR, or --NR 2 where R is a C 1-4 alkyl group; isocyanuric acid; and mixtures thereof, and a solvent which is soluble in the fuel feed stream into a fuel feed stream; introducing said air feed stream and said fuel feed stream into the interior of the piston-cylinder assembly to form an air/fuel mixture which initiates a premixed flame phase of combustion, such that said selective reducing agent is present during the initiation of said premixed flame phase of combustion; combusting said air/fuel mixture, wherein said selective reducing agent reduces the concentration of NO x present in the exhaust stream, and wherein said selective reducing agent is introduced into said fuel feed stream in an effective NO x reducing amount up to a molar ratio of 1:2 with respect to the molar amount of NO x which would be present in the exhaust stream in the absence of said selective reducing agent.

Claim 9

A method of reducing the concentration of NO x in an exhaust stream of a compression ignition engine having lean operating conditions, wherein air is fed into the interior of a piston cylinder assembly of the compression ignition engine by an air-feed stream and fuel is fed into the interior of the piston cylinder assembly by a fuel feed stream, comprising the steps of: providing a compression ignition engine having the piston-cylinder assembly and the fuel feed stream, the piston-cylinder assembly having an interior wherein combustion of an air and fuel mixture may occur; providing a selective reducing agent that decomposes upon combustion consisting essentially of a compound selected from the group consisting of cyanuric acid; cyanuric acid in which one or more hydroxyl groups are substituted by --NH 2 , --NHR, or --NR 2 where R is a C 1-4 alkyl group; isocyanuric acid; and mixtures thereof; dissolving said selective reducing agent in a solvent which is soluble in the fuel feed stream to form a treatment agent solution; mixing a NO x reducing amount of said treatment agent solution into the fuel feed stream, so as to produce a treated fuel mixture; and introducing a NO x reducing amount of said treated fuel mixture into said interior of the piston-cylinder assembly, such that said treated fuel mixture mixes with the air from the air feed stream to form an air and fuel mixture which initiates a premixed flame phase of combustion, wherein said treated fuel mixture is present during initiation of the premixed flame phase of combustion; combusting said air and fuel mixture, wherein said cyanuric acid reacts with one or more products of combustion to reduce the concentration of NO x present in the exhaust stream, and wherein said selective reducing agent is introduced into said fuel feed stream in an effective NO x reducing amount up to a molar ratio of 1:2 with respect to the molar amount of NO x which would be present in the exhaust stream in the absence of said selective reducing agent.

Claim 10

A method of reducing the concentration of NO x in an exhaust stream of a compression ignition engine having lean operating conditions, wherein air is fed into the interior of a piston cylinder assembly of the compression ignition engine by an air-feed stream and fuel is fed into the interior of the piston cylinder assembly by a fuel feed stream, comprising the steps of: providing a compression ignition engine having the piston-cylinder assembly and the fuel feed stream, the piston-cylinder assembly having an interior wherein combustion of an air and fuel mixture may occur; providing a selective reducing agent that decomposes upon combustion consisting essentially of a compound selected from the group consisting of cyanuric acid; cyanuric acid in which one or more hydroxyl groups are substituted by --NH 2 , --NHR, or --NR 2 where R is a C 1-4 alkyl group; isocyanuric acid; and mixtures thereof; dissolving said selective reducing agent in a solvent which is soluble in the fuel feed stream to form a treatment agent solution; mixing a NO x reducing amount of said treatment agent solution into the fuel feed stream, so as to produce a treated fuel mixture; and introducing a NO x reducing amount of said treated fuel mixture into said interior of the piston-cylinder assembly, such that said treated fuel mixture mixes with the air from the air feed stream to form an air and fuel mixture which initiates a premixed flame phase of combustion, wherein said treated fuel mixture is present during initiation of the premixed flame phase of combustion; combusting said air and fuel mixture, wherein said cyanuric acid reacts with one or more products of combustion to reduce the concentration of NO x present in the exhaust stream, and wherein said selective reducing agent is introduced into said fuel feed stream in an effective NO x reducing amount up to a molar ratio of 1:2 with respect to the molar amount of NO x which would be present in the exhaust stream in the absence of said selective reducing agent.