Patent ID: 8821818

Claim:
A method of cleaning stack gases comprising the steps of: (a) providing in a stack adapted to pass stack gases through a first catalytic flow-through bed of calcium zeolite comprising zeolite particles of a majority between 44 μm and 64 μm in size adapted to reduce carbon oxides from the stack gases, (b) providing in the stack adapted to pass stack gases positioned adjacent the first catalytic flow-through bed, a second catalytic flow-through bed of a blend between 25 and 75% of sodium zeolite and calcium zeolite comprising zeolite particles of a majority between 65 μm and 125 μm in size adapted to reduce nitrogen oxides from the stack gases, (c) providing in the stack adapted to pass stack gas positioned adjacent the second catalytic flow-through bed, a third catalytic flow-through bed of calcium zeolite comprising zeolite particles of a majority between 78 μm and 204 μm adapted to reduce sulfur oxides in the stack gases, and (d) passing stack gases selected from the group consisting of volatiles from combustion of coal or from combustion of natural gas or propane or from a cement kiln sequential through the first catalytic bed, the second catalytic bed, and the third catalytic bed each collecting solids in the catalytic beds and providing gas exiting the third catalytic bed with at least 90% reduction in sulfur oxides, nitrogen oxides, and carbon oxide.