METHOD FOR REGENERATION OF EXHAUST GAS TREATMENT CATALYST, AND EXHAUST GAS TREATMENT CATAYLST PRODUCED USING THE METHOD
A regenerated exhaust gas treatment catalyst regenerated by: a used catalyst coarse grinding step (S 1 ) for coarsely grinding a used exhaust gas treatment catalyst; a separation step (S 2 ) separating a coarsely ground material into coarse pieces and a fine powder; a used catalyst fine grinding step (S 3 ); steps (S 4 ) to (S 7 ) for kneading the fine powder together with other raw materials, molding a kneaded material, and drying and burning a molded material to produce a base material; a fresh catalyst grinding step (S 8 ); a slurry formation step (S 9 ); a slurry coating step (S 10 ) coating the surface of the base material with the slurry solution; and a coating drying step (S 11 ) and a coating burning step (S 12 ) for drying the base material that has been coated with the slurry solution and burning the base material at a temperature higher than that employed in the production of the exhaust gas treatment catalyst.
1 . An exhaust gas treatment catalyst regenerated by a method of regenerating an exhaust gas treatment catalyst having ash adhering to a surface thereof, the exhaust gas treatment catalyst regenerated by performing:
a used catalyst crushing step of crushing the exhaust gas treatment catalyst that has been used;
a separating step of separating the crushed exhaust gas treatment catalyst into coarse pieces having a size exceeding a threshold size S and fine particles having a size not larger than the threshold size S;
a used catalyst pulverizing step of pulverizing the separated coarse pieces into a fine powder;
a molding step of molding the pulverized fine powder as a raw material into an exhaust gas treatment catalyst;
a precursor calcining step of calcining a molded precursor of the exhaust gas treatment catalyst;
a newly-made catalyst crushing step of crushing the exhaust gas treatment catalyst that has been newly made;
a slurrying step of slurrying the crushed newly-made exhaust gas treatment catalyst;
a slurry coating step of coating a surface of a base obtained by the calcination in the precursor calcining step with the slurry liquid; and
a coating calcining step of calcining the base coated with the slurry liquid at a higher temperature than a calcination temperature during production of the crushed newly-made exhaust gas treatment catalyst, wherein
the threshold size S has a value not smaller than 0.105 mm.
2 . The exhaust gas treatment catalyst according to claim 1 , wherein the coating calcining step is a calcining step at a higher temperature by 25° C. or above than the calcination temperature during the production of the crushed newly-made exhaust gas treatment catalyst.
3 . The exhaust gas treatment catalyst according to claim 2 , wherein the coating calcining step is a calcining step at a temperature of 700° C. or less.
4 . The exhaust gas treatment catalyst according to claim 1 , wherein the crushed and slurried newly-made exhaust gas treatment catalyst has an average particle diameter of 3 to 8 μm.
5 . The exhaust gas treatment catalyst according to claim 1 , wherein a main raw material of the exhaust gas treatment catalyst is titanium oxide.
6 . The exhaust gas treatment catalyst according to claim 5 , wherein the exhaust gas treatment catalyst is used to treat exhaust gas from a burned coal.
7 . The exhaust gas treatment catalyst according to claim 6 , wherein the exhaust gas treatment catalyst is used to treat nitrogen oxide in the exhaust gas.
8 . The exhaust gas treatment catalyst according to claim 1 , wherein the used catalyst crushing step is a step in which the exhaust gas treatment catalyst that has been used is crushed such that 70 to 95 wt % of the whole exhaust gas treatment catalyst that has been used becomes the coarse pieces having a size exceeding the threshold size S.
9 . The exhaust gas treatment catalyst according to claim 8 , wherein the threshold size S has a value not larger than 1.0 mm.
10 . The exhaust gas treatment catalyst according to claim 1 , wherein the used catalyst pulverizing step is a step in which the coarse pieces are pulverized such that the fine powder has an average particle diameter not larger than 0.1 mm.