Porous particulates

Patent Granted Disclosed are particulates of calcium oxide and calcium hydroxide which are suitably used for filling a gas fixing unit (32) of a fixation device (3) for a halide gas. Particularly disclosed are those particulates highly reactive with a halide gas or a decomposition product thereof. Specifically disclosed is a porous calcium oxide particulate composed of spherical porous calcium oxide particles, which has a BET specific surface area of not less than 50 m<2>/g. The total pore volume of pores having a diameter of 2-100 nm contained in all the porous particles is within the range of 0.40-0.70 mL/g.