Acid-impregnated activated carbon and methods of forming and using the same
An acid-impregnated activated carbon matrix is formed from a carbonaceous material by the addition of a mineral acid, and may be used to chemisorb ammonia from a gas stream. The ammonia reacts with the acid to form a fertilizer salt. The spent matrix may be used as a fertilizer, or the fertilizer salt may be elutriated from the matrix.
1. A method of chemisorbing ammonia from a gas stream comprising the steps of:
(a) reacting liquid acid with a carbonaceous biomass material under ambient conditions to convert the biomass to a porous carbon matrix impregnated with the liquid acid, and without a heat treatment, washing or neutralization step;
(b) flowing an ammonia-containing gas over or through the porous carbon matrix impregnated with a mineral acid in a reactor, such that the ammonia reacts with the mineral acid, to produce ammonium salt.
2. The method of claim 1 wherein the liquid acid comprises sulphuric acid, phosphoric acid, nitric acid or hydrochloric acid.
3. The method of claim 2 wherein the liquid acid comprises concentrated sulphuric acid.
4. The method of claim 1 wherein the porous carbon matrix impregnated with the mineral acid is disturbed during gas flow.
5. The method of claim 1 comprising the further step of pelletizing or granulating the porous carbon matrix impregnated with the mineral acid prior to chemisorption.
6. The method of claim 5 wherein the porous carbon matrix pellets or granules are disturbed during gas flow.
7. A method of producing a fertilizer product comprising the steps of:
(a) reacting liquid acid with a carbonaceous biomass material under ambient conditions to convert the biomass to a porous carbon matrix impregnated with the liquid acid, and without a heat treatment, washing or neutralization step;
(b) flowing an ammonia-containing gas over or through the porous carbon matrix impregnated with a mineral acid in a reactor, such that the ammonia reacts with the mineral acid, to produce an ammonium salt fertilizer.
8. The method of claim 7 further comprising the step of screening, pelletizing or granulating the porous carbon matrix to a desired particle size range.
9. The method of claim 7 , further comprising the step of elutriating the ammonium salt fertilizer from the porous carbon matrix.
10. The method of claim 7 wherein the liquid acid comprises sulphuric acid, phosphoric acid, nitric acid or hydrochloric acid.
11. The method of claim 10 wherein the mineral acid comprises concentrated sulphuric acid.