High temperature antioxidant additives and methods that improve a liquid fuel composition's thermal oxidative stability are disclosed. A liquid fuel composition may comprise a liquid fuel and a high temperature antioxidant additive. The high temperature antioxidant additive may comprise an aromatic carbocyclic ring that is monocyclic and comprises substituents comprising a hydroxyl group and an iminomethyl group positioned in an ortho relationship.

High temperature antioxidant additives and methods that improve a liquid fuel composition's thermal oxidative stability are disclosed. A liquid fuel composition may comprise a liquid fuel and a high temperature antioxidant additive. The high temperature antioxidant additive may comprise an aromatic carbocyclic ring that is monocyclic and comprises substituents comprising a hydroxyl group and an iminomethyl group positioned in an ortho relationship.

Disclosed herein is a fuel composition having (1) greater than 50 wt % of a hydrocarbon fuel boiling in the gasoline or diesel range and (2) a minor amount of a low-speed pre-ignition (LSPI)-reducing additive having one or more of an amidine, or a beta-amino alkanol having the structure

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R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are each independently selected from hydrogen, aromatic ring, and a C.sub.1-C.sub.20 alkyl group and R.sub.5 is hydrogen or an alcohol having the structure (CH)R.sub.6OH. R.sub.6 is hydrogen, a C.sub.1-C.sub.10 alkyl group, or a C.sub.1-C.sub.10 alkenyl group, or a salt thereof.

The invention provides a method of removing or lowering amounts of hydrogen sulfide in a crude oil, the method comprising adding to the crude oil an imine compound represented by the formula R.sup.1C(CH.sub.3).sub.2NCH.sub.2, wherein R.sup.1 represents a (1-5C)alkyl group.

The invention provides a method of removing or lowering amounts of hydrogen sulfide in a crude oil, the method comprising adding to the crude oil an imine compound represented by the formula R.sup.1C(CH.sub.3).sub.2NCH.sub.2, wherein R.sup.1 represents a (1-5C)alkyl group.

The present invention discloses a homogenous cerium (Ce) catalyst composition comprising Ce(IV) complex alone, or Ce(IV) complex in a mixture with Ce(III) complex, that can significantly improve both LPG and soot combustion, resulting in higher flame temperatures, faster heating, reduced cooking time and reduced fuel consumption. The cerium(III) complex is cerium(III) 2-ethylhexanoate and the cerium(IV) complex is aqua(2-N-(2-hydroxyethylimino)-4-pentanoate) dinitrocerium(IV) [Ce(L1)(H.sub.2O)(NO.sub.3).sub.2], wherein L1 is 2-N-(2-hydroxyethylimino)-4-pentanone.

The present invention discloses a homogenous cerium (Ce) catalyst composition comprising Ce(IV) complex alone, or Ce(IV) complex in a mixture with Ce(III) complex, that can significantly improve both LPG and soot combustion, resulting in higher flame temperatures, faster heating, reduced cooking time and reduced fuel consumption. The cerium(III) complex is cerium(III) 2-ethylhexanoate and the cerium(IV) complex is aqua(2-N-(2-hydroxyethylimino)-4-pentanoate) dinitrocerium(IV) [Ce(L1)(H.sub.2O)(NO.sub.3).sub.2], wherein L1 is 2-N-(2-hydroxyethylimino)-4-pentanone.

Fuel and lubricant compositions are provided that contain a primary low-speed pre-ignition (LSPI)-reducing additive comprising (i) an amino additive, (ii) an amine additive, (iii) a triazole additive, (iv) a benzamidinium additive, (v) a benzoxazole additive, or (vi) a NCX motif additive. Methods for preventing or reducing low speed pre-ignition events in spark-ignited engines using these compositions are also provided.

The present invention discloses a homogenous cerium (Ce) catalyst composition comprising Ce(IV) complex alone, or Ce(IV) complex in a mixture with Ce(III) complex, that can significantly improve both LPG and soot combustion, resulting in higher flame temperatures, faster heating, reduced cooking time and reduced fuel consumption. The cerium(III) complex is cerium(III) 2-ethylhexanoate and the cerium(IV) complex is aqua(2-N-(2-hydroxyethylimino)-4-pentanoate) dinitrocerium(IV) [Ce(L1)(H.sub.2O)(NO.sub.3).sub.2], wherein L1 is 2-N-(2-hydroxyethylimino)-4-pentanone.

The present invention discloses a homogenous cerium (Ce) catalyst composition comprising Ce(IV) complex alone, or Ce(IV) complex in a mixture with Ce(III) complex, that can significantly improve both LPG and soot combustion, resulting in higher flame temperatures, faster heating, reduced cooking time and reduced fuel consumption. The cerium(III) complex is cerium(III) 2-ethylhexanoate and the cerium(IV) complex is aqua(2-N-(2-hydroxyethylimino)-4-pentanoate) dinitrocerium(IV) [Ce(L1)(H.sub.2O)(NO.sub.3).sub.2], wherein L1 is 2-N-(2-hydroxyethylimino)-4-pentanone.