Process to prepare adsorbents from organic fertilizer and their applications for removal of acidic gases from wet air streams

Abstract

The invention is directed to an adsorbent comprising: a) 20-30% porous carbon with incorporated organic nitrogen species; and b) 70-80% inorganic matter. The invention is directed to a method of making an adsorbent which comprises: a) thermally drying dewatered sewage sludge to form granulated organic fertilizer; and b) pyrolyzing said the organic fertilizer at temperatures between 600 and 1000° C. The invention is additionally directed to the process of removing acidic gases from wet air streams comprising putting an adsorbent in contact with the wet air stream and allowing the adsorbent to adsorb the acidic gases.

1 .- 28 . (canceled) 
     
     
         29 . The process of removing acidic gases from wet air streams comprising putting an adsorbent comprising 20-30% porous non-activated carbon; and 70-80% inorganic matter, wherein the adsorbent has a basic pH, and wherein the adsorbent maintains a basic pH after hydrogen sulfide adsorption to a breakthrough capacity in contact with the wet air stream and allowing the adsorbent to adsorb the acidic gases. 
     
     
         30 . The process of  claim 29 , wherein the acidic gases are one or more of hydrogen sulfide, sulfur dioxide, hydrogen cyanide, and nitrogen dioxide. 
     
     
         31 . The process of  claim 29 , wherein the acidic gas is hydrogen sulfide which reacts with inorganic matter to be oxidized to sulfur dioxide or elemental sulfur and salt forms thereof. 
     
     
         32 . The process of  claim 29 , wherein the wet air stream is effluent from a sewage treatment plant, gaseous fuel, or gases from hydrothermal vents. 
     
     
         33 . The process of removing acidic gases from wet air streams comprising forming an adsorbent by thermally drying and granulating dewatered sewage sludge and pyrolyzing said organic fertilizer at temperatures between 600-1000° C., wherein said temperature is reached at a heating rate between 5 and 10° C./minute and hold time for the pyrolysis is between 60 and 90 minutes, said adsorbent maintains a basic pH after hydrogen sulfide adsorption to a breakthrough capacity, and the above are conducted only with heat and physical processing, putting said adsorbent in contact with the wet air stream, and allowing the adsorbent to adsorb the acidic gases. 
     
     
         34 . The process of  claim 33 , wherein the acidic gases are one or more of hydrogen sulfide, sulfur dioxide, hydrogen cyanide, and nitrogen dioxide. 
     
     
         35 . The process of  claim 33 , wherein the temperature of pyrolysis is between 800 and 1000° C. 
     
     
         36 . The process of  claim 35 , wherein the temperature of pyrolysis is between 900 and 1000° C. 
     
     
         37 . The process of  claim 33 , wherein the temperature of pyrolysis is between 600 and 900° C. and the adsorbent is further treated with 15-20% HCl. 
     
     
         38 . The process of  claim 37 , wherein the temperature of pyrolysis is between 800 and 900° C. 
     
     
         39 . The process of  claim 33 , wherein the adsorbent may be regenerated by heating to 300-500° C. to remove elemental sulfur and sulfur dioxide.