Method of making phosphate-based ceramic filters

A method of making a ceramic body, the method comprising:

• a) forming a mixture comprising:
• NZP-forming raw material powders selected from the group consisting of metal oxide sources capable of reacting to form a reaction product comprising an NZP phase having the general formula R1+(y/2)Zr4P6−ySiyO24 where 0≦y≦1.0 and R is one or more of the metals Ca, Sr, and Ba, pre-reacted powder having said general formula, and mixtures thereof;
• and,
• a precursor additive selected from the group consisting of silica precursor, zirconia precursor, and mixtures thereof;
• wherein the precursor additive results in improved strength during binder removal in the subsequent firing;
• b) shaping the mixture into a green structure;
• and,
• c) firing the green structure to produce a ceramic body, wherein the ceramic body has an open porosity of at least 35% by volume, a median pore size of at least 8 micrometers and a permeability of at least 0.30×10−12 m2.