Process for treatment of pitch from coal tar

Abstract

A process for treating a pitch fraction from coal tar is described. The pitch fraction is contacted with a solvent, an extraction agent, or an adsorbent to remove at least one contaminant, such as oxygenate compounds, nitrogen containing compounds, and sulfur containing compounds. The solvent can be an ionic liquid, the extraction agent can be at least one of amphiphilic block copolymers, cyclodextrins, functionalized cyclodextrins, and cyclodextrin-functionalized polymers, and the adsorbent can be exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds.

What is claimed is: 
     
         1 . A process for processing a pitch fraction from coal tar comprising:
 providing a coal tar stream;   separating the coal tar stream into at least two fractions, one fraction comprising pitch;   contacting the pitch fraction with a solvent, an extraction agent, or an adsorbent to remove at least one contaminant forming a treated pitch stream having a reduced level of the at least one contaminant, the solvent comprising an ionic liquid, the extraction agent comprising at least one of amphiphilic block copolymers, cyclodextrins, functionalized cyclodextrins, and cyclodextrin-functionalized polymers, the adsorbent comprising exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds, and wherein the at least one contaminant comprises oxygenate compounds, nitrogen containing compounds, and sulfur containing compounds;   processing the treated pitch fraction.   
     
     
         2 . The process of  claim 1  wherein the ionic liquid comprises imidizolium-based ionic liquids, pyridinium-based ionic liquids, pyrolidinium-based ionic liquids, ammonium-based ionic liquids, sulphonium-based ionic liquids, phosphonium-based ionic liquids, caprolactam-based ionic liquids, or combinations thereof. 
     
     
         3 . The process of  claim 1  wherein an anion of the ionic liquid comprises halides, sulfates, acetates, tosylates, phosphates, antimonates, borates, aluminates, imides, thiocynates, dicyanimides, or combinations thereof. 
     
     
         4 . The process of  claim 1  wherein the extraction agent comprises the amphiphilic block copolymer, and wherein the amphiphilic block copolymer comprises at least two blocks selected from polyethylene oxide blocks, polypropylene oxide blocks, butylene oxide blocks, silicone blocks, urethane blocks, polyurethane ionomer blocks, acrylate ionomer blocks, polymethylacryate blocks, polyacrylic acid blocks, and polyvinylidene chloride blocks. 
     
     
         5 . The process of  claim 1  wherein the extraction agent further comprises an ionic liquid, or a supercritical fluid, or both. 
     
     
         6 . The process of  claim 5  wherein the extraction agent further comprises the ionic liquid, and wherein the ionic liquid is selected from imidazolium-based ionic liquid, pyrrolidinium-based ionic liquid, pyridinium-based ionic liquid, sulphonium-based ionic liquids, phosphonium-based ionic liquids, and ammonium-based ionic liquids. 
     
     
         7 . The process of  claim 5  wherein the extraction agent further comprises the supercritical fluid, and wherein the supercritical fluid comprises supercritical carbon dioxide, supercritical ammonia, supercritical ethane, supercritical propane, supercritical butane, or supercritical water. 
     
     
         8 . The process of  claim 7  wherein the supercritical fluid is the supercritical ammonia, wherein one of the fractions comprises ammonia, and wherein the ammonia in the fraction is processed into the supercritical ammonia. 
     
     
         9 . The process of  claim 7  wherein the supercritical fluid is the supercritical carbon dioxide, wherein one of the fractions comprises carbon dioxide, and wherein the carbon dioxide in the fraction is processed into the supercritical carbon dioxide. 
     
     
         10 . The process of  claim 1  wherein at least two contaminants are removed, and wherein the first contaminant is removed using a first solvent, extraction agent, or adsorbent and wherein the second contaminant is removed using a second solvent, extraction agent, or adsorbent after the removal of the first contaminant and before processing the treated pitch fraction. 
     
     
         11 . The process of  claim 1  further comprising contacting the treated pitch fraction with a second adsorbent or an oxidant to remove at least one additional contaminant, the at least one additional contaminant comprising arsenic, metal compounds, mercury halides, elemental mercury, inorganic halides, organic halides, and coal tar insolubles, and wherein the second adsorbent comprises a noble metal deposited on a support selected from the group consisting of molecular sieves, alumina, activated carbons, 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 activated alumina, clay, or activated carbon. 
     
     
         12 . The process of  claim 1  further comprising reducing a viscosity of the pitch fraction before removing the at least one contaminant. 
     
     
         13 . The process of  claim 10  wherein the viscosity is reduced by mixing the pitch fraction with a solvent. 
     
     
         14 . The process of  claim 1  further comprising processing at least one of the fractions to produce at least one product. 
     
     
         15 . The process of  claim 14  wherein the at least one fraction is processed by at least one of hydrotreating, hydrocracking, fluid catalytic cracking, alkylation, transalkylation, oxidation, or hydrogenation. 
     
     
         16 . A process for processing a pitch fraction from coal tar comprising:
 pyrolyzing a coal feed into a coal tar stream and a coke stream;   separating the coal tar stream into at least two fractions, one fraction comprising pitch;   contacting the pitch fraction with a solvent, an extraction agent, or an adsorbent to remove at least one contaminant forming a treated pitch stream having a reduced level of the at least one contaminant, the solvent comprising an ionic liquid, the extraction agent comprising at least one of amphiphilic block copolymers, cyclodextrins, functionalized cyclodextrins, and cyclodextrin-functionalized polymers, the adsorbent comprising exfoliated graphite oxide, thermally exfoliated graphite oxide or intercalated graphite compounds, and wherein the at least one contaminant comprises oxygenate compounds, nitrogen containing compounds, and sulfur containing compounds;   processing the treated pitch fraction.   
     
     
         17 . The process of  claim 16  wherein the ionic liquid comprises imidizolium-based ionic liquids, pyridinium-based ionic liquids, pyrolidinium-based ionic liquids, ammonium-based ionic liquids, sulphonium-based ionic liquids, phosphonium-based ionic liquids, caprolactam-based ionic liquids, or combinations thereof. 
     
     
         18 . The process of  claim 16  wherein the extraction agent comprises the amphiphilic block copolymer, and wherein the amphiphilic block copolymer comprises at least two blocks selected from polyethylene oxide blocks, polypropylene oxide blocks, butylene oxide blocks, silicone blocks, urethane blocks, polyurethane ionomer blocks, acrylate ionomer blocks, polymethylacryate blocks, polyacrylic acid blocks, and polyvinylidene chloride blocks. 
     
     
         19 . The process of  claim 16  wherein the extraction agent further comprises an ionic liquid, or a supercritical fluid, or both, and wherein the ionic liquid is selected from imidazolium-based ionic liquid, pyrrolidinium-based ionic liquid, pyridinium-based ionic liquid, sulphonium-based ionic liquids, phosphonium-based ionic liquids, and ammonium-based ionic liquids, and wherein the supercritical fluid comprises supercritical carbon dioxide, supercritical ammonia, supercritical ethane, supercritical propane, supercritical butane, or supercritical water.