Combined solid adsorption-hydrotreating process for whole crude oil desulfurization

Abstract

A whole crude oil desulfurization system and process includes a combination of an adsorption zone and a hydroprocessing zone. This combined process and system reduces the requisite throughput for the hydroprocessing unit, conventionally a very costly and process both in terms of energy expenditures and catalyst depletion. By first contacting the whole crude oil feedstock with an adsorbent for the sulfur-containing compounds, the adsorption effluent having a relatively lower sulfur content can be collected and provided to refiners without further treatment. The adsorbates, including adsorbed organosulfur compounds, are solvent desorbed resulting in a stream containing high levels of organosulfur compounds and a solvent. Following recovery of the solvent, the volume of the sulfur-containing feedstream that remains to be desulfurized in the hydroprocessing zone is substantially less than the original amount of whole crude oil feedstock.

What is claimed is: 
     
         1 . A process for treating whole crude oil containing organosulfur compounds comprising:
 a. contacting, upstream of a crude distillation unit, a whole crude oil feed stream containing organosulfur compounds with a solid porous adsorbent material having average pore diameter in the mesoporous range to about 50 nanometers, wherein organosulfur compounds are adsorbed by the adsorbent material;   b. recovering a treated effluent stream having a reduced level of organosulfur compounds;   c. desorbing at least a portion of the organosulfur compounds from the adsorbent material, and recovering a purge stream having an increased level of organosulfur compounds from the adsorbent material; and   d. hydroprocessing the purge stream and recovering a hydroprocessed stream having a reduced level of organosulfur compounds.   
     
     
         2 . The process as in  claim 1 , wherein the adsorbent material is contained in at least one fixed bed. 
     
     
         3 . The process of  claim 1 , wherein the hydroprocessed stream is combined with the treated effluent stream. 
     
     
         4 . The process of  claim 1 , wherein the treated effluent stream is further subjected to a fractionation process to remove a gas phase that contains at least hydrogen sulfide gas. 
     
     
         5 . The process of  claim 1 , wherein the treated effluent stream contains at least about 5 to 53 weight percent less organosulfur compounds than the whole crude oil stream. 
     
     
         6 . The process of  claim 1 , wherein the treated effluent stream contains at least about 30 to 53 weight percent less organosulfur compounds than the whole crude oil stream. 
     
     
         7 . The process of  claim 1 , wherein the desorbing step employs a stripping solvent. 
     
     
         8 . The process of  claim 7 , wherein the purge stream contains at least a portion of the stripping solvent, and organosulfur compounds, and wherein at least a portion of the stripping solvent in the desorbed purge stream is distilled and recycled. 
     
     
         9 . The process of  claim 7 , wherein the stripping solvent comprises a solvent selected from the group consisting of toluene, hexane, butane, pentane and combinations comprising at least one of the foregoing solvents. 
     
     
         10 . The process of  claim 7 , wherein the stripping solvent comprises toluene. 
     
     
         11 . The process of  claim 1 , wherein the desorbing step employs a supercritical fluid. 
     
     
         12 . The process of  claim 11 , further comprising recovering the desorbed purge stream containing at least a portion of the supercritical fluid and the increased organosulfur compound purge stream, and wherein at least a portion of the supercritical fluid in the desorbed purge stream is compressed and reused as the stripping solvent. 
     
     
         13 . The process of  claim 11 , wherein the supercritical fluid comprises a supercritical fluid selected from the group consisting of supercritical carbon dioxide, ethane, supercritical ethylene, supercritical propane, supercritical butane and combinations comprising at least one of the foregoing supercritical fluids. 
     
     
         14 . The process of  claim 11 , wherein the supercritical fluid comprises supercritical carbon dioxide. 
     
     
         15 . The process of  claim 1 , wherein the adsorbent material has an adsorbent capacity, and wherein contacting comprises:
 passing the whole crude oil feed stream through a first adsorbing bed containing adsorbent material until the adsorbent material in the first adsorbing bed has reached a predetermined percentage of its adsorbent capacity; and   passing the whole crude oil feed stream through a second adsorbing bed containing adsorbent material when the adsorbent material in the first adsorbing bed has reached the predetermined percentage of its adsorbent capacity.   
     
     
         16 . The process of  claim 15 , further comprising desorbing the first adsorbing bed while the whole crude oil feed stream is passed through the second adsorbing bed. 
     
     
         17 . The process of  claim 15 , wherein the predetermined percentage is greater than at least 95%. 
     
     
         18 . The process of  claim 1 , wherein the adsorbent material is selective to organosulfur compounds including benzothiophenes dibenzothiophenes, other multi-ring thiophenes, and combinations comprising at least one of the foregoing organosulfur compounds. 
     
     
         19 . The process of  claim 1 , wherein the adsorbent material is selected from the group of materials consisting of Y-zeolites, active carbon powders and a combination comprising at least one of the foregoing materials. 
     
     
         20 . The process of  claim 1 , wherein hydroprocessing is selected from the group consisting of hydrodesulfurization, hydrocracking, hydrodenitrification, hydrodealkylation and hydrotreating.