Robust Integrated Process for Conversion of Waste Plastics to Final Petrochemical Products

Abstract

A robust integrated process for the conversion of waste plastics to high value products. The robust integrated process allows for operation with a single hydroprocessing reactor which provides simultaneous hydrogenation, dechlorination, and hydrocracking of components of a hydrocarbon stream to specifications which meet steam cracker requirements, with the option to further dechlorinate the treated hydrocarbon stream in a polishing zone.

What is claimed is: 
     
         1 . A process for converting waste plastics to a high value product comprising:
 converting the waste plastics to a hydrocarbon stream in a liquid phase, wherein the hydrocarbon stream comprises one or more chloride compounds in a concentration of 5 ppm or more based on a total weight of the hydrocarbon stream;   contacting the hydrocarbon stream with a first hydroprocessing catalyst in the presence of hydrogen to yield a first hydrocarbon product comprising C 1  to C 4  gases and C 5 + liquid hydrocarbons;   recovering the C 5 + liquid hydrocarbons in a treated hydrocarbon stream from the first hydrocarbon product, wherein the treated hydrocarbon stream comprises the one or more chloride compounds in a concentration of 3 to 5 ppm based on a total weight of the treated hydrocarbon stream;   dechlorinating the treated hydrocarbon stream to yield a polished hydrocarbon stream comprising one or more chloride compounds in a concentration of less than 3 ppm based on a total weight of the polished hydrocarbon stream; and   feeding the treated hydrocarbon stream or polished hydrocarbon stream to a steam cracker to yield the high value product,   wherein the treated hydrocarbon stream or polished hydrocarbon stream meets steam cracker feed requirements for chloride content, olefin content, and boiling end point.   
     
     
         2 . The process of  claim 1 , wherein the step of dechlorinating comprises contacting the treated hydrocarbon stream with a second hydroprocessing catalyst in the presence of hydrogen to yield a second hydrocarbon product. 
     
     
         3 . The process of  claim 1 , wherein the step of dechlorinating comprises removing at least a portion of the one or more chloride compounds via adsorptive dechlorination to yield the polished hydrocarbon stream. 
     
     
         4 . The process of  claim 1 , wherein the polished hydrocarbon stream comprises the one or more chloride compounds in a concentration of less than 1 ppm based on the total weight of the polished hydrocarbon stream, wherein the hydrocarbon stream comprises the one or more chloride compounds in a concentration of greater than 200 ppmw based on a total weight of the hydrocarbon stream. 
     
     
         5 . The process of  claim 1 , wherein the hydrocarbon stream comprises one or more olefins, wherein the treated hydrocarbon stream comprises the one or more olefins in a concentration of less than 1 wt. % based on the total weight of the treated hydrocarbon stream, and wherein the one or more olefins are present in the hydrocarbon stream in a concentration of 20 wt % or more based on the total weight of the hydrocarbon stream. 
     
     
         6 . The process of  claim 1 , wherein the hydrocarbon stream comprises heavy hydrocarbon molecules, and further comprising:
 hydrocracking at least a portion of the heavy hydrocarbon molecules during the step of contacting the hydrocarbon stream with a first hydroprocessing catalyst.   
     
     
         7 . The process of  claim 1 , further comprising:
 before the step of contacting the hydrocarbon stream with a first hydroprocessing catalyst, contacting a catalyst activating stream comprising one or more sulphides with the first hydroprocessing catalyst, and wherein the one or more sulphides are in an amount of about 0.5 wt % to 5 wt % based on the total weight of the catalyst activating stream.   
     
     
         8 . The process of  claim 1 , wherein the one or more sulphides of the hydrocarbon stream are present in a concentration of about 2 wt % based on the total weight of the hydrocarbon stream. 
     
     
         9 . The process of  claim 1 , wherein the step of contacting the hydrocarbon stream with a first hydroprocessing catalyst is performed at a weight hourly space velocity of 0.1 to 10 hr −1 , at a hydrogen to hydrocarbon ratio of 10 to 3,000 NL/L, and at a pressure of 1 to 200 barg. 
     
     
         10 . The process of  claim 1 , wherein the first hydroprocessing catalyst comprises cobalt and molybdenum on an alumina support, nickel and molybdenum on an alumina support, tungsten and molybdenum on an alumina support, nickel sulphide, molybdenum sulphides, a combination of nickel and molybdenum sulphides, or combinations thereof. 
     
     
         11 . The process of  claim 10 , wherein contacting the hydrocarbon stream with the first hydroprocessing catalyst comprises:
 contacting one or more sulphides contained in or added to the hydrocarbon stream with the first hydroprocessing catalyst.   
     
     
         12 . The process of  claim 2 , wherein the second hydroprocessing catalyst comprises cobalt and molybdenum on an alumina support, nickel and molybdenum on an alumina support, tungsten and molybdenum on an alumina support, nickel sulphide, molybdenum sulphides, a combination of nickel and molybdenum sulphides, or combinations thereof. 
     
     
         13 . The process of  claim 12 , wherein contacting the treated hydrocarbon stream with the second hydroprocessing catalyst comprises:
 contacting one or more chloride compounds contained in the treated hydrocarbon stream with the second hydroprocessing catalyst.   
     
     
         14 . The process of  claim 1 , wherein the high value products are ethylene, propylene, butene, butadiene, aromatic compounds, or combinations thereof. 
     
     
         15 . The process of  claim 1 , wherein the step of converting comprises:
 subjecting the waste plastics to a pyrolysis process to produce one or more of plastic pyrolysis oil and tire pyrolysis oil in the hydrocarbon stream.   
     
     
         16 . The process of  claim 1 , wherein recovering a treated hydrocarbon stream from the first hydrocarbon product comprises:
 separating the first hydrocarbon product into a treated product from a first chlorine-containing gas in a first separator; and   flowing the treated product in the treated hydrocarbon stream from the first separator to an adsorption unit or to a steam cracker.   
     
     
         17 . The process of  claim 2 , wherein the step of dechlorinating further comprises:
 separating the second hydrocarbon product into a polished product and a second chlorine-containing gas in a second separator; and   flowing the polished product in the polished hydrocarbon stream from the second separator to a steam cracker.   
     
     
         18 . The process of  claim 1 , wherein the step of converting the waste plastics to a hydrocarbon stream in a liquid phase is performed in the presence of a head space purge gas fed to a pyrolysis unit, wherein the head space purge gas comprises hydrogen, nitrogen, steam, product gases, or combinations thereof. 
     
     
         19 . The process of  claim 1 , further comprising:
 converting the waste plastics to C 1  to C 4  pyrolysis gases,   wherein one or more of the C 1  to C 4  pyrolysis gases, the C 1  to C 4  gases yielded in the step of contacting, and C 1  to C 4  gases yielded in the step of dechlorinating is fed to the steam cracker.   
     
     
         20 . The process of  claim 1 , wherein the step of contacting includes simultaneous i) dechlorination of the hydrocarbon stream such that the treated hydrocarbon stream comprises one or more chloride compounds in a concentration less than 1 ppmw based on the total weight of the treated hydrocarbon stream, ii) hydrogenation of the hydrocarbon stream such that the treated hydrocarbon stream comprises one or more olefins in a concentration less than 1 wt % based on the total weight of the treated hydrocarbon stream, and iii) reduction of heavy hydrocarbon molecules of the hydrocarbon stream.