A process for making cerium dioxide nanoparticles containing at least one transition metal (M) utilizes a suspension of cerium hydroxide nanoparticles prepared by mechanical shearing of an aqueous mixture containing an oxidant in an amount effective to enable oxidation of cerous ion to ceric ion, thereby forming a product stream that contains transition metal-containing cerium dioxide nanoparticles, Ce.sub.1-xM.sub.xO.sub.2, wherein x has a value from about 0.3 to about 0.8. The nanoparticles thus obtained have a cubic fluorite structure, a mean hydrodynamic diameter in the range of about 1 nm to about 10 nm, and a geometric diameter of less than about 4 nm. The transition metal-containing crystalline cerium dioxide nanoparticles can be used to prepare a dispersion of the particles in a nonpolar medium.

The present invention relates to use of Perovskite type of materials as combustion improver in gaseous and liquid fuels. Structurally, the Perovskite material consists of ABO.sub.3, A.sub.xB.sub.1-xC.sub.yO.sub.3 or A.sub.xB.sub.1-xC.sub.yO.sub.3 kind of material with stoichiometric deficiency and oxygen deficient sites. More particularly, the present invention relates to the nanosized perovskite materials stably dispersed in hydrocarbon medium and compatible to the fuel has been used to improve the combustion process and generate more heat output.

A diesel fuel additive includes a cetane number improver and an at least one organometallic combustion catalyst in solution and/or at least one metal-oxide combustion catalyst in suspension.

An additive composition for a marine fuel or a heating oil comprising a stabilized colloidal dispersion of catalytic metal particles, a neutral or overbased alkaline earth metal detergent and a carrier fluid miscible with a marine fuel oil, a heavy fuel oil, a marine distillate fuel, and/or a residual fuel oil. Also provided are marine fuel and/or heating oil compositions having the additive composition described above and associated methods and uses.

Fuel additive compositions include a plurality of metal nanoparticles and a carrier that is dispersible in a hydrocarbon fuel. The metal nanoparticles can be spherical-shaped and/or coral-shaped metal nanoparticles. The carrier can be liquid, gel or solid and can be readily miscible or soluble in a hydrocarbon fuel such as gasoline, diesel, jet fuel, or fuel oil. The carrier can be a solid carrier configured to allow the hydrocarbon fuel to dissolve the solid carrier in order to release and disperse the metal nanoparticles within the hydrocarbon fuel.

The present invention relates to an additized blended fuel composition comprising of 97 to 50 weight % of liquified petroleum gas (LPG); 3 to 50 weight % of dimethyl ether (DME); and a nanocatalyst. More particularly, the present invention relates to an improvement in the combustion efficiency of the DME blended LPG fuel by using catalytic amount of the nano-catalyst, when introduced in ppm level enhances the combustion properties, thereby increasing the flame temperature and reducing the consumption of fuel gas mixture.