Integrated Process for Conversion of Waste Plastics to Final Petrochemical Products

Abstract

An integrated process for the conversion of waste plastics to high value products. The integrated process allows for operation with a hydroprocessing reactor which provides simultaneous hydrogenation, dechlorination, and hydrocracking of components of a hydrocarbon stream to specifications which meet steam cracker requirements.

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;   contacting the hydrocarbon stream with a hydroprocessing catalyst in the presence of hydrogen to yield a 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 hydrocarbon product; and   feeding the treated hydrocarbon stream or a blended hydrocarbon stream comprising the treated hydrocarbon stream to a steam cracker to yield the high value product,   wherein the treated hydrocarbon stream or blended hydrocarbon stream meets steam cracker feed requirements for chloride content, olefin content, and boiling end point.   
     
     
         2 . The process of  claim 1 , 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, wherein the treated hydrocarbon stream comprises the one or more chloride compounds in a concentration of less than 5 ppm based on a total weight of the treated hydrocarbon stream. 
     
     
         3 . 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. 
     
     
         4 . 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.   
     
     
         5 . The process of  claim 1 , further comprising:
 before the step of contacting, contacting a catalyst activating stream comprising one or more sulphides with the hydroprocessing catalyst, and wherein the one or more sulphides of the catalyst activating stream are present in an amount such that a sulphur content of the catalyst activating stream is about 0.5 wt % to about 5 wt % based on the total weight of the catalyst activating stream.   
     
     
         6 . The process of  claim 1 , wherein the step of contacting 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. 
     
     
         7 . The process of  claim 1 , wherein the treated hydrocarbon stream comprises the one or more chloride compounds in a concentration of less than 3 ppm based on a total weight of the treated hydrocarbon stream, and wherein the treated hydrocarbon stream is fed directly to the stream cracker. 
     
     
         8 . The process of  claim 1 , further comprising:
 blending the treated hydrocarbon stream with a non-chlorinated hydrocarbon stream to yield the blended hydrocarbon stream comprising the one or more chloride compounds in a concentration of less than 3 ppm based on a total weight of the blended hydrocarbon stream, wherein the blended hydrocarbon stream is fed to the steam cracker.   
     
     
         9 . The process of  claim 1 , wherein the hydroprocessing catalyst comprises cobalt and molybdenum on an alumina support, nickel and molybdenum on an alumina support, tungsten and molybdenum on an alumina support, or nickel and molybdenum sulphides. 
     
     
         10 . The process of  claim 9 , wherein contacting the hydrocarbon stream with the hydroprocessing catalyst comprises:
 contacting one or more sulphides contained in or added to the hydrocarbon stream with the hydroprocessing catalyst.   
     
     
         11 . The process of  claim 10 , wherein the one or more sulphides are contained in or added to the hydrocarbon stream in an amount such that a sulphur content of the hydrocarbon stream is about 0.5 wt % to about 5 wt % based on the total weight of the hydrocarbon stream. 
     
     
         12 . The process of  claim 1 , wherein the high value products are ethylene, propylene, butene, butadiene, aromatic compounds, or combinations thereof. 
     
     
         13 . The process of  claim 1 , wherein the step of converting comprises:
 subjecting the waste plastics to a pyrolysis process to produce one or more plastic pyrolysis oil in the hydrocarbon stream.   
     
     
         14 . The process of  claim 13 , wherein the step of subjecting comprises a first stage and a second stage fluidly connected downstream of the first stage, wherein the first stage utilizes thermal cracking of the waste plastics and the second stage utilizes catalytic cracking of the waste plastics to yield the hydrocarbon stream flowing from the second stage. 
     
     
         15 . The process of  claim 13 , wherein the step of subjecting comprises a first stage and a second stage fluidly connected downstream of the first stage, wherein the first stage utilizes catalytic cracking of the waste plastics and the second stage utilizes thermal cracking of the waste plastics to yield the hydrocarbon stream flowing from the second stage. 
     
     
         16 . The process of  claim 1 , wherein recovering a treated hydrocarbon stream from the hydrocarbon product comprises:
 separating a treated product from a sulphur and chlorine-containing gas in a separator; and   flowing the treated product in the treated hydrocarbon stream from the separator.   
     
     
         17 . 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 ppm 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. 
     
     
         18 . The process of  claim 1 , further comprising:
 converting the waste plastics to C 1  to C 4  pyrolysis gases;   wherein the C 1  to C 4  pyrolysis gases and the C 1  to C 4  gases yielded in the step of contacting are fed to the steam cracker.   
     
     
         19 . The process of  claim 18 , wherein the C 1  to C 4  pyrolysis gases are treated to remove sulphur and chlorine-containing gases before the C 1  to C 4  pyrolysis gases are fed to the steam cracker. 
     
     
         20 . The process of  claim 1 , wherein 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.