Method for making a catalyst comprising a phosphorous modified zeolite and use of said zeolite

A method to make a phosphorus modified zeolite comprising:

• (a) providing a zeolite comprising at least one ten member ring in the structure thereof;
• (b) mixing the zeolite of step a) with at least one binder and/or shaping additive, and then shaping the mixture to form a catalyst precursor;
• (c) calcining the catalyst precursor of step (b);
• (d) performing steaming on at least one of:
• the zeolite before step (b), the catalyst precursor before step (c), the catalyst precursor after step (c), or combinations thereof, wherein 60 to 95% of the tetrahedral aluminum is retained in the zeolite or catalyst precursor after steaming, wherein the zeolite or catalyst precursor is not leached with acid;
• (e) introducing phosphorus on the catalyst precursor to introduce at least 0.1 wt % of the phosphorus to form a phosphate catalyst, wherein the introduction is made by incipient wetness impregnation at 30 to 100° C.;
• (f) introducing calcium on to the phosphate catalyst by incipient wetness impregnation, wherein the calcium is introduced to the phosphate catalyst in a solubilized form, optionally simultaneously with step e);
• and
• (g) steaming the catalyst, wherein the steaming in step (d), step (g), or both is performed at a steaming severity (X) of at least about 2.