Mixed metal catalyst additive and method for use in hydrocarbonaceous fuel combustion system

1. A method of improving the combustion of and the slag resulting from the combustion of a hydrocarbonaceous fuel composition, the method comprising the steps of:

providing a hydrocarbonaceous fuel composition comprising a transition metal-containing organometallic compound, at least one alkali metal compound, and a magnesium-containing compound, the amount of magnesium-containing compound is an amount sufficient to supply about 60 to 600 ppm magnesium metal to the fuel composition;

combusting the fuel composition in a combustion system, wherein the combustion of the fuel composition causes the formation of slag;

wherein the amount of transition metal, alkali metal and magnesium contained in the fuel composition is in an amount effective to improve the combustion of the fuel composition and improve the slag resulting from combustion of the fuel;

whereby the slag is improved and the improvement to the slag is selected from the group comprising slag that is more easily removed, is less built up, and is more friable.

2. The method as described in claim 1 , wherein the transition metal-containing compound, alkali metal compound, and magnesium-containing compound are included in the additive in a ratio of about one part manganese, one part alkali metal, and three parts magnesium of the respective metals.

3. The method as described in claim 1 , wherein the organometallic compound is a compound with a stabilizing ligand containing a functional group selected from the group consisting of alcohols, aldehydes, ketones, esters, anhydrides, sulfonates, phosphonates, chelates, phenates, crown ethers, naphthenates, carboxylic acids, amides, acetyl acetonates and mixtures thereof.

4. The method as described in claim 1 , wherein the organometallic compound comprises manganese.

5. The method as described in claim 4 , wherein the manganese-containing compound is selected from the following group: cyclopentadienyl manganese tricarbonyl, methylcyclopentadienyl manganese tricarbonyl, dimethylcyclopentadienyl manganese tricarbonyl, trimethylcyclopentadienyl manganese tricarbonyl, tetramethylcyclopentadienyl manganese tricarbonyl, pentamethylcyclopentadienyl manganese tricarbonyl, ethylcyclopentadienyl manganese tricarbonyl, diethylcyclopentadienyl manganese tricarbonyl, propylcyclopentadienyl manganese tricarbonyl, isopropylcyclopentadienyl manganese tricarbonyl, tert-butylcyclopentadienyl manganese tricarbonyl, octylcyclopentadienyl manganese tricarbonyl, dodecylcyclopentadienyl manganese tricarbonyl, ethylmethylcyclopentadienyl manganese tricarbonyl, indenyl manganese tricarbonyl, and mixtures of two or more such compounds.

6. A method as described in claim 1 , wherein the alkali metal compound contains an alkali metal selected from the group consisting of lithium, sodium, potassium and rubidium.

7. A method as described in claim 1 , wherein the magnesium-containing compound is selected from the group of compounds derived from sulfonic acids, carboxylic acids, alkylphenols, sulfurized alkylphenols, and organic phosphorus acids and mixtures thereof.

8. A method as described in claim 1 , wherein the amount of transition metal-containing organometallic compound is an sufficient amount to supply about 0.1 to 40 ppm transition metal to the fuel composition.

9. A method as described in claim 1 , wherein the amount of alkali metal is an amount sufficient to supply about 0.1 to 40 ppm alkali metal to the fuel composition.