Use of phosphate and thiophosphate esters neutralized with water soluble amines as ethylene furnace anti-coking antifoulants

An improved method of reducing fouling and corrosion in ethylene cracking furnaces using petroleum feedstocks, the improvement comprising admixing the petroleum feedstock with at least 10 ppm of a compound chosen from the group consisting of phosphite esters, phosphate esters, thiophosphite esters, thiophosphate esters and mixtures thereof, said esters being characterized by the formulas:

• ##STR9## where X equals S or O, and R.sub.1, R.sub.2, and R.sub.3, are each independently selected from the group consisting of hydrogen, water soluble amine, alkyl, aryl, alkaryl, cycloaklyl, alkenyl, and arylalkyl group provided that in at least one and not more than two of each R.sub.1, R.sub.2, and R.sub.3 are water soluble amines having partition coefficients greater than about 3.0 and at least one of R.sub.1, R.sub.2, and R.sub.3 is selected from the group consisting of alkyl, aryl, alkaryl, cycloaklyl, alkenyl, and arylalkyl.