Patent ID: 8883668

Claim:
A method of making a phosphorous modified zeolite, comprising: selecting a zeolite having a Si:Al atomic ratio of 30 or less, wherein the zeolite is selected from the group consisting of MFI, MEL, FER, MOR, and clinoptilolite, and wherein the selected zeolite is in the H + or NH 4 + form; steaming the zeolite at a temperature ranging from 400° C. to 870° C. for 0.01 h to 200 h; leaching the zeolite with an aqueous acid solution containing a source of P at conditions effective to remove a substantial amount of Al from the zeolite and to introduce more than 0.3 wt % of P, wherein the aqueous acid solution containing the source of P comprises a salt of a phosphate ([PO 4 ] 3− ), an acid or a corresponding salt of a phosphite ([HPO 3 ] 2− ), an acid or a corresponding salt of a hypophosphite ([H 2 PO 2 ] 1− ), an acid or a corresponding salt of a diphosphate, or an acid or a corresponding salt of a polyphosphate; separating the zeolite from the aqueous acid solution; and calcining the zeolite.