Fuel for diesel engines
The invention concerns a fuel to operate Diesel engines, in particular in cars, wherein the fuel contains an antioxidant. To achieve that the discoloration of the water white Diesel fuel during longer storage and/or incident light radiation is prevented at least for longer periods, the fuel contains a para-substituted, sterically hindered phenol (I) as antioxidant, the substituent of which in the para position is different from a tertiary butyl group.
1. A Diesel fuel formulation having a stabilized water white color, comprising:
a. a Diesel fuel consisting of a mixture of water white refinery products; and
b. a sterically hindered phenolic antioxidant consisting of (i) a para-substituted, sterically hindered phenol (I), wherein the substituent in the para position is not a tertiary butyl group and wherein the phenol (I) is substituted in the para position with an n-alkyl group with a C number 1 to 4 and in both ortho positions with a tertiary alkyl group, and (ii) a para-substituted sterically hindered phenol (II) selected from the group consisting of para-substituted sterically hindered phenols wherein the para position and both ortho positions of the phenol (II) are substituted with a tertiary alkyl group, wherein the ratio of phenol (I) to phenol (II) is from about 5:1 to about 15:1, wherein phenol (I) is present in a concentration of 10 to 200 mg/kg, and wherein the antioxidant hinders or prevents discoloration of the fuel, and wherein the diesel fuel formulation has a cetane number greater than 55 and up to only 15 weight percent of aromatic compounds.
2. The fuel of claim 1 wherein the tertiary alkyl group of the phenol (I) is a tertiary butyl group.
3. The fuel of claim 1 wherein the n-alkyl group of the phenol (I) is a methyl group.
4. The fuel of claim 1 wherein the phenol (I) is present in a concentration of 50 to 100 mg/kg.
5. The fuel of claim 1 wherein both ortho positions and the para position of the phenol (II) are substituted by the same tertiary alkyl group each.
6. The fuel of claim 1 wherein the tertiary alkyl group of the phenol (II) is a tertiary butyl group.
7. The fuel of claim 1 wherein the fuel remains at 100 Hazen or less for at least 3 days if the fuel is exposed to light or 3 months if the fuel is not exposed to light.
8. The fuel of claim 1 wherein a n-paraffin contents does not exceed 10% by volume.
9. The fuel of claim 1 wherein the fuel formulation has the following properties:
Sulfur content: <10 mg/kg
Density: 0.825 kg/L to 0.840 kg/L
Contents of polyaromatic compounds: max. 2% by weight.