A system and method for the reduction of NOx emissions from combustion sources are provided. The system includes a fuel tank, fuel converter unit, condensor unit, selective catalytic reduction (SCR) unit and an engine. The condenser unit includes a generally cylindrical inner wall defining a cavity having a first lower end and a second upper end, the first lower end is configured to include a gas inlet for receiving a gas mixture from the fuel converter and the second upper end is configured to include a gas outlet in fluid communication with the SCR unit. A heat exchanger is disposed within the cavity of the condensor unit to contact the gas mixture and separate heavy hydrocarbons from light hydrocarbons, wherein the light hydrocarbons are fed to the SCR unit and the heavy hydrocarbons are condensed and either send back to the fuel tank or directly to the engine for combustion.