Patent ID: 7414009

Claim:
Photocatalyst particles comprising composite particles of titanium dioxide and a compound inactive as a photocatalyst, produced by a method comprising the steps of preparing a water based slurry of pH 3 to 5 comprising titanium dioxide, preparing a water based solution comprising a compound inactive as a photocatalyst, and reacting said slurry and said water based solution together at a pH of 4 to 10, wherein said photocatalyst particles achieve a ratio of decomposition of acetaldehyde (DWA) value of at least 20%, wherein said DWA value is measured after 3.5 g of said photocatalyst particles are spread uniformly across a flat surface of diameter 9 cm, placed within 5 L of dry air containing 20 ppm by volume of acetaldehyde, and irradiated for one hour with a day white fluorescent lamp producing an ultraviolet light intensity of 6 μW/cm 2 at a wavelength of 365 nm.