Fluid for purifying heat engines and methods for preparing said fluids by emulsification

A fluid for the decontamination of heat engines in order to be able to carry out, at the same time, both the selective catalytic reduction of oxides of nitrogen contained in exhaust gases as well as assisting in the regeneration of the particulate filter (PF) by catalytic combustion of particles of soot deposited in the particulate filter, the fluid comprising:

• an oil-in-water emulsion comprising:
• an aqueous solution of at least one reducing compound or precursor of a reducing compound, the aqueous solution of at least one reducing compound or precursor of a reducing compound being a solution of urea, 32.5±0.7% by weight in solution in demineralized water or being a solution of at least one of ammonium formate, ammonium carbamate, and guanidine salts in water,
• a dispersion of metal oxides in a hydrocarbon or a mixture of hydrocarbons, and
• a surfactant or a mixture of surfactants enabling the production and stabilization of a stable oil-in-water type emulsion, the surfactant or mixture of surfactants comprising a nonionic surfactant soluble in water and having an HLB (hydrophilic/lipophilic balance) in the range 7 to 16 selected from any mixture produced from the chemical families sorbitan esters, ethoxylated sorbitan esters, ethylene oxide (EO)/propylene oxide (PO) block copolymers, ethoxylated fatty acids or alcohols, ethoxylated fatty acid esters, ethoxylated octylphenols, alkylpolyglucosides or APG, alone or as a mixture.