Catalytic Gasification Process with Recovery of Alkali Metal from Char

Abstract

Processes are described for the extraction and recovery of alkali metal from the char that results from catalytic gasification of a carbonaceous material. Among other steps, the processes of the invention include a hydrothermal leaching step in which a slurry of insoluble particulate comprising insoluble alkali metal compounds is treated with carbon dioxide and steam at elevated temperatures and pressures to effect the conversion of insoluble alkali metal compounds to soluble alkali metal compounds. Further, processes are described for the catalytic gasification of a carbonaceous material where a substantial portion of alkali metal is extracted and recovered from the char that results from the catalytic gasification process.

1 . A process for extracting and recovering alkali metal from a char, the char comprising (i) one or more soluble alkali metal compounds and (ii) insoluble matter comprising one or more insoluble alkali metal compounds, the process comprising the steps of:
 (a) providing a char at an elevated temperature ranging from 50° C. to 600° C.;   (b) quenching the char in an aqueous medium to fracture the char and form a quenched char slurry;   (c) separating the quenched char slurry into a first liquid stream and an insoluble matter stream, the first liquid stream comprising at least a portion of the soluble alkali metal compounds from the char, and the insoluble matter stream comprising residual soluble alkali metal compounds and a first insoluble matter comprising insoluble alkali metal compounds;   (d) recovering the first liquid stream;   (e) contacting the first insoluble matter with an alkali metal hydroxide and calcium oxide, calcium hydroxide, or both, under suitable pressure and temperature so as to convert at least a portion of the insoluble alkali metal compounds in the first insoluble matter to one or more soluble alkali metal compounds and produce a first leached slurry comprising soluble alkali metal compounds and a partially extracted insoluble matter, wherein the partially extracted insoluble matter comprises insoluble alkali metal compounds;   (f) contacting the first leached slurry with carbon dioxide under suitable pressure and temperature so to convert at least a portion of the insoluble alkali metal compounds in the partially extracted insoluble matter to one or more soluble alkali metal compounds and produce a second leached slurry comprising soluble alkali metal compounds and a residual insoluble matter;   (g) separating the second leached slurry into a second liquid stream and a residual insoluble matter stream, the second liquid stream comprising a predominant portion of the soluble alkali metal compounds from the second leached slurry, and the residual insoluble matter stream comprising residual soluble alkali metal compounds and residual insoluble alkali metal compounds;   (h) recovering the second liquid stream; and   (i) washing the residual insoluble matter stream to recover substantially all of the residual soluble alkali metal compounds in the residual insoluble matter stream as a first wash stream,   
     wherein the quenching and contacting are performed in the substantial absence of gaseous oxygen. 
   
   
       2 . The process according to  claim 1 , wherein the char is a solid residue derived from gasification of a carbonaceous material in the presence of an alkali metal. 
   
   
       3 . The process according to  claim 2 , wherein the carbonaceous material comprises one or more of coal, petroleum coke, asphaltene, liquid petroleum residue or biomass. 
   
   
       4 . The process according to  claim 1 , further comprising the step of recovering the first wash stream for use as the aqueous medium. 
   
   
       5 . The process according to  claim 1 , wherein the alkali metal comprises sodium and/or potassium. 
   
   
       6 . The process according to  claim 1 , wherein the alkali metal is potassium. 
   
   
       7 . The process according to  claim 1 , wherein the source of alkali metal is an alkali metal salt selected from the group consisting of carbonate, hydroxide, acetate, halide and nitrate salts. 
   
   
       8 . The process according to  claim 1 , wherein the source of alkali metal is potassium carbonate. 
   
   
       9 . The process according to  claim 1 , wherein the contacting of the first insoluble matter with an alkali metal hydroxide and calcium oxide, calcium hydroxide, or both is performed at a temperature ranging from about 150 to about 250° C. 
   
   
       10 . The process according to  claim 1 , further comprising the step of degassing the second leached slurry under suitable pressure and temperature so as to remove excess carbon dioxide and hydrogen sulfide. 
   
   
       11 . The process according to  claim 1 , wherein the char is a solid residue derived from gasification of a carbonaceous material in the presence of an alkali metal; the carbonaceous materials comprises one or more of coal, petroleum coke, asphaltene, liquid petroleum residue or biomass; and the alkali metal comprises sodium and/or potassium, and wherein the process further comprises the step of degassing the second leached slurry under suitable pressure and temperature so as to remove excess carbon dioxide and hydrogen sulfide. 
   
   
       12 . The process according to  claim 4 , wherein the char is a solid residue derived from gasification of a carbonaceous material in the presence of an alkali metal; the carbonaceous materials comprises one or more of coal, petroleum coke, asphaltene, liquid petroleum residue or biomass; and the alkali metal comprises sodium and/or potassium, and wherein the process further comprises the step of degassing the second leached slurry under suitable pressure and temperature so as to remove excess carbon dioxide and hydrogen sulfide. 
   
   
       13 . The process according to  claim 9 , wherein the char is a solid residue derived from gasification of a carbonaceous material in the presence of an alkali metal; the carbonaceous materials comprises one or more of coal, petroleum coke, asphaltene, liquid petroleum residue or biomass; and the alkali metal comprises sodium and/or potassium, and wherein the process further comprises the step of degassing the second leached slurry under suitable pressure and temperature so as to remove excess carbon dioxide and hydrogen sulfide. 
   
   
       14 . A process for catalytically converting a carbonaceous composition, in the presence of an alkali metal gasification catalyst, into a plurality of gaseous products and recovering a gasification catalyst, the process comprising the steps of:
 (a) supplying a carbonaceous composition to a gasification reactor, the carbonaceous composition comprising an ash;   (b) reacting the carbonaceous composition in the gasifying gasification reactor in the presence of steam and an alkali metal gasification catalyst under suitable temperature and pressure to form (i) a char comprising the alkali metal from the alkali metal gasification catalyst in the form of one or more soluble alkali metal compounds and one or more insoluble alkali metal compounds, and (ii) a plurality of gaseous products comprising methane and at least one or more of hydrogen, carbon monoxide, carbon dioxide, hydrogen sulfide, ammonia, and other higher hydrocarbons, the gasification catalyst comprising an alkali metal;   (c) removing a portion of the char and from the gasification reactor;   (d) extracting and recovering a substantial portion of the alkali metal from the char according to the process of  claim 1 ; and   (e) at least partially separating the plurality of gaseous products to produce a stream comprising a predominant amount of one of the gaseous products.   
   
   
       15 . The process according to  claim 14 , wherein the carbonaceous composition comprises one or more of coal, petroleum coke, asphaltene, liquid petroleum residue or biomass. 
   
   
       16 . The process according to  claim 14 , wherein the stream comprises a predominant amount of methane.