Catalysts for Pyrolysis

Abstract

Disclosed herein are processes, systems, and catalysts for improving pyrolysis technology. The disclosed processes and systems utilize a catalyst to increase pyrolysis gas (py-gas) and decrease bio-oil yields in pyrolysis reactions. The disclosed catalysts may include biochar derived from pyrolysis of industrial residuals, such as pyrolysis of wastewater biosolids (WB) and paper mill sludge (PMS). The disclosed catalysts also may include ash derived from incineration of wastewater biosolids (“biosolids incineration ash” (BIA)).

We claim: 
     
         1 . A method comprising performing pyrolysis of a biomass or biosolids in the presence of a catalyst, the catalyst comprising a biochar obtained from pyrolysis of wastewater biosolids (WB-biochar), a biochar obtained from pyrolysis of paper mill sludge (PMS-biochar), or ash obtained from biosolids incineration (BIA). 
     
     
         2 . The method of  claim 1 , wherein the catalyst comprises a metal or a salt or oxide thereof selected from calcium, iron, and magnesium. 
     
     
         3 . The method of  claim 1 , wherein the catalyst comprises the metal or the salt or oxide thereof at a concentration of at least about 1% by dry weight. 
     
     
         4 . The method of  claim 1 , wherein the catalyst is WB-biochar produced by pyrolyzing dried biosolids material comprising waste activated sludge, raw primary sludge, anaerobically digested sludge, aerobically digester sludge, lime-stabilized sludge, or a mixture thereof. 
     
     
         5 . The method of  claim 1 , wherein the WB-biochar or PMS-biochar is a recycled product of pyrolysis. 
     
     
         6 . A method comprising treating a product of pyrolysis by heating the product in the presence of a catalyst comprising the solid product obtained from pyrolysis of wastewater biosolids (WB-biochar), a biochar obtained from pyrolysis of paper mill sludge (PMS-biochar), or ash obtained from biosolids incineration (BIA). 
     
     
         7 . The method of  claim 6  comprising:
 (a) pyrolyzing a biomass or biosolids in a first reactor vessel to generate the pyrolysis product, wherein the pyrolysis product comprises a vapor comprising bio-oil; 
 (b) passing the vapor through a second reactor vessel comprising the catalyst; and 
 (c) condensing the vapor to separate a liquid product comprising bio-oil and a gaseous product comprising py-gas. 
 
     
     
         8 . The method of  claim 7 , wherein the second reactor vessel is heated to a temperature of at least about 500 ° C. 
     
     
         9 . The method of  claim 7 , wherein the catalyst and the pyrolysis product are present in the second reactor vessel at a concentration ratio by weight of (0.01-1):1. 
     
     
         10 . The method of  claim 6 , wherein the catalyst comprises metal or a salt or oxide thereof. 
     
     
         11 . The method of  claim 10 , wherein the metal is selected from calcium, iron, and magnesium. 
     
     
         12 . The method of  claim 10 , wherein the catalyst comprises the metal or the salt or oxide thereof at a concentration of at least about 1% by dry weight. 
     
     
         13 . The method of  claim 6 , wherein the catalyst is WB-biochar produced by pyrolyzing dried biosolids material comprising waste activated sludge, raw primary sludge, anaerobically digested sludge, or a mixture thereof. 
     
     
         14 . The method of  claim 6 , wherein the catalyst is a recycled product of pyrolysis. 
     
     
         15 . The method of  claim 7 , wherein catalyst is produced in step (a) and recycled for use in step (b). 
     
     
         16 . A system for performing pyrolysis comprising a heated reactor vessel for pyrolyzing a biomass or biosolids, the heated reactor vessel comprising a catalyst, the catalyst comprising a biochar obtained from pyrolysis of wastewater biosolids (WB-biochar), a biochar obtained from pyrolysis of paper mill sludge (PMS-biochar), or ash obtained from biosolids incineration (BIA). 
     
     
         17 . The system of  claim 16 , wherein the catalyst comprises metal or a salt or oxide thereof. 
     
     
         18 . The system of  claim 17 , wherein the metal is selected from calcium, iron, and magnesium. 
     
     
         19 . The system of  claim 17 , wherein the catalyst comprises the metal or the salt or oxide thereof at a concentration of at least about 1% by dry weight. 
     
     
         20 . A system for performing pyrolysis comprising:
 (a) a first heated reactor vessel for pyrolyzing a biomass or biosolids to generate a pyrolysis product, wherein the pyrolysis product comprises a vapor;   (b) a second heated reactor vessel configured for receiving and treating the pyrolysis product, the second heated reactor vessel comprising a catalyst, the catalyst comprising a biochar obtained from pyrolysis of wastewater biosolids (WB-biochar), a biochar obtained from pyrolysis of paper mill sludge (PMS-biochar), or ash obtained from biosolids incineration (BIA); and   (c) a condenser configured for receiving the treated pyrolysis product and separating the vapor to obtain a liquid product comprising bio-oil and a gaseous product comprising py-gas.