Abstract
The addition of urea was studied as one of the preparation methods for porous phosphate particles. Urea was added to the preparation of lanthanum polyphosphate from lanthanum nitrate and sodium polyphosphate solutions. The precipitations prepared in various concentration of urea and their thermal products were estimated from the view of the chemical composition, powder and acidic properties. The addition of urea on preparation of lanthanum polyphosphate produced the increase of about 20 nm-radius pores without the change of chemical composition of phosphates. The large amount of urea covered the pore of lanthanum polyphosphate. The amount of included urea in lanthanum polyphosphate was estimated from NH3-TPD curves. The adsorption of trimethylamine decreased on lanthanum polyphosphate because of the remaining of urea.
