Process for removing ash and heavy hydrocarbons from coal tar

Abstract

A process for removing ash and heavy hydrocarbon compounds from coal is described. The coal feed, the coal tar stream, or a coal tar fraction is contacted with a solvent to dissolve a soluble portion of the coal tar stream, the ash and heavy hydrocarbons being insoluble in the solvent, the solvent selected from the group consisting of dimethyl sulfoxide, sulfolane, dimethyl formamide, glyme, diglyme, ionic liquids, and combinations thereof, with the proviso that an anion of the ionic liquid is not a dialkylphosphate.

What is claimed is: 
     
         1 . A process for removing ash and heavy hydrocarbon compounds from coal comprising:
 pyrolyzing a coal feed into a coal tar stream and a coke stream;   separating the coal tar stream into at least two fractions;   contacting one or more of the coal tar stream, or one of the fractions with a solvent to dissolve a soluble portion of the coal tar stream, or one of the fractions, the ash and heavy hydrocarbons being insoluble in the solvent, the solvent selected from the group consisting of dimethyl sulfoxide, sulfolane, dimethyl formamide, glyme, diglyme, ionic liquids, and combinations thereof, with the proviso that an anion of the ionic liquid is not a dialkylphosphate.   
     
     
         2 . The process of  claim 1  further comprising separating the ash and heavy hydrocarbons from the solvent. 
     
     
         3 . The process of  claim 2  wherein the ash and heavy hydrocarbons are separated from the solvent by one or more of settling, decantation, filtration, centrifugation, and using a filter column. 
     
     
         4 . The process of  claim 1  wherein the solvent is the ionic liquid and wherein the ionic liquid comprises imidizolium-based ionic liquids, pyridinium-based ionic liquids, pyrrolidinium-based ionic liquids, ammonium-based ionic liquids, sulphonium-based ionic liquids, phosphonium-based ionic liquids, caprolactam-based ionic liquids, or combinations thereof. 
     
     
         5 . The process of  claim 1  wherein the solvent is the ionic liquid and wherein the anion of the ionic liquid comprises halides, sulfates, acetates, tosylates, phosphates, antimonates, borates, aluminates, imides, thiocynates, dicyanimides, or combinations thereof. 
     
     
         6 . The process of  claim 1  further comprising regenerating the used solvent and recycling the regenerated solvent. 
     
     
         7 . The process of  claim 6  wherein the solvent is dimethyl sulfoxide, sulfolane, dimethyl formamide, or combinations thereof, and further comprising purifying the regenerated solvent before recycling the regenerated solvent. 
     
     
         8 . The process of  claim 6  wherein the solvent is the ionic liquid and wherein regenerating the used solvent comprises stripping the used solvent with steam or nitrogen at a temperature of about 50° C. or above, or extracting with a solvent. 
     
     
         9 . The process of  claim 1  further comprising removing at least one contaminant from the coal tar stream or one of the fractions by solvent extraction, adsorption with an adsorbent, or oxidation to form a treated stream having a reduced level of the at least one contaminant, the at least one contaminant comprising nitrogen containing compounds, sulfur containing compounds, and metals. 
     
     
         10 . The process of  claim 9  wherein the contaminant is the sulfur containing compounds and wherein removing at least one contaminant from the coal tar stream or one of the fractions comprises oxidizing the sulfur containing compounds and extracting the oxidized sulfur containing compounds by solvent extraction. 
     
     
         11 . The process of  claim 9  wherein removing the at least one contaminant comprises contacting the coal tar stream or the one of the fractions with an adsorbent, and wherein the adsorbent comprises a metal deposited on a support selected from the group consisting of molecular sieves, alumina, activated carbons, amorphous silica-alumina, clay, and silica gel; silver impregnated zeolite selected from the group consisting of faujasites (13X, CaX, NaY, CaY, and ZnX), chabazites, clinoptilolites and LTA (3A, 4A, 5A) zeolites; sulfur or a metal sulfide on an activated carbon support or an activated alumina support; or a metal sulfide, metal oxide, or metal carbonate on a support, the metal is selected from the group consisting of copper, silver, gold, antimony, lead, and manganese, and the support selected from the group consisting of alumina, silica, clay, or carbon. 
     
     
         12 . The process of  claim 1  further comprising processing at least one of the fractions to produce at least one product. 
     
     
         13 . The process of  claim 12  wherein the at least one fraction is processed by at least one of hydrotreating, hydrocracking, fluid catalytic cracking, alkylation, and transalkylation. 
     
     
         14 . A process for removing ash and heavy hydrocarbon compounds from coal comprising:
 pyrolyzing a coal feed into a coal tar stream and a coke stream;   separating the coal tar stream into at least two fractions;   contacting one or more of the coal tar stream, or one of the fractions with a solvent to dissolve a soluble portion of the coal tar stream or one of the fractions, the ash and heavy hydrocarbons being insoluble in the solvent, the solvent selected from the group consisting of dimethyl sulfoxide, sulfolane, dimethyl formamide, glyme, diglyme, ionic liquids, and combinations thereof, with the proviso that an anion of the ionic liquid is not a dialkylphosphate;   separating the ash and heavy hydrocarbons from the solvent; and   processing at least one of the fractions to produce at least one product.   
     
     
         15 . The process of  claim 14  wherein the ash and heavy hydrocarbons are separated from the solvent by one or more of settling, decantation, filtration, centrifugation, and using a filter column. 
     
     
         16 . The process of  claim 14  wherein the solvent is the ionic liquid and wherein the ionic liquid comprises imidizolium-based ionic liquids, pyridinium-based ionic liquids, pyrrolidinium-based ionic liquids, ammonium-based ionic liquids, sulphonium-based ionic liquids, phosphonium-based ionic liquids, caprolactam-based ionic liquids, or combinations thereof. 
     
     
         17 . The process of  claim 14  wherein the solvent is the ionic liquid and wherein the anion of the ionic liquid comprises halides, sulfates, acetates, tosylates, phosphates, antimonates, borates, abominates, imides, thiocynates, dicyanimides, or combinations thereof. 
     
     
         18 . The process of  claim 14  further comprising regenerating the used solvent and recycling the regenerated solvent. 
     
     
         19 . The process of  claim 14  further comprising removing at least one contaminant from the coal tar stream or one of the fractions by solvent extraction, adsorption with an adsorbent, or oxidation to form a treated stream having a reduced level of the at least one contaminant, the at least one contaminant comprising nitrogen containing compounds, sulfur containing compounds, and metals. 
     
     
         20 . The process of  claim 14  wherein the at least one fraction is processed by at least one of hydrotreating, hydrocracking, fluid catalytic cracking, alkylation, and transalkylation.