Method for the treatment of plastic pyrolysis oils including two-stage hydrocracking

Abstract

The present invention relates to a process for treating a plastics pyrolysis oil, comprising: a) the selective hydrogenation of said feedstock to obtain a hydrogenated effluent; b) hydrotreatment of said hydrogenated effluent to obtain a hydrotreatment effluent; c) a first step of hydrocracking of said hydrotreated effluent to obtain a first hydrocracked effluent; d) separation of the hydrocracked effluent in the presence of an aqueous stream, to obtain a gaseous effluent, an aqueous liquid effluent and a hydrocarbon-based liquid effluent; e) fractionation of the hydrocarbon-based liquid effluent to obtain at least one gas stream and at least one naphtha cut and a heavier cut; f) a second step of hydrocracking of the heavier cut to obtain a second hydrocracked effluent; g) recycling of at least a portion of said second hydrocracked effluent into the separation step d).

1 . Process for treating a feedstock comprising a plastics pyrolysis oil, comprising:
 a) a selective hydrogenation step performed in a reaction section fed at least with said feedstock and a gas stream comprising hydrogen, in the presence of at least one selective hydrogenation catalyst, at a temperature of between 100 and 280° C., a partial pressure of hydrogen of between 1.0 and 10.0 MPa abs. and an hourly space velocity of between 0.3 and 10.0 h −1 , to obtain a hydrogenated effluent;   b) a hydrotreatment step performed in a hydrotreatment reaction section, using at least one fixed-bed reactor containing n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrotreatment catalyst, said hydrotreatment reaction section being fed at least with said hydrogenated effluent obtained from step a) and a gas stream comprising hydrogen, said hydrotreatment reaction section being used at a temperature of between 250 and 430° C., a partial pressure of hydrogen of between 1.0 and 10.0 MPa abs. and an hourly space velocity of between 0.1 and 10.0 h −1 , to obtain a hydrotreatment effluent;   c) a first hydrocracking step performed in a hydrocracking reaction section, using at least one fixed-bed reactor containing n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed at least with said hydrotreated effluent obtained from step b) and a gas stream comprising hydrogen, said hydrocracking reaction section being used at a temperature of between 250 and 480° C., a partial pressure of hydrogen of between 1.5 and 25.0 MPa abs. and an hourly space velocity of between 0.1 and 10.0 h −1 , to obtain a first hydrocracked effluent;   d) a separation step, fed with the hydrocracked effluent obtained from step c) and an aqueous solution, said step being performed at a temperature of between 50 and 370° C., to obtain at least one gaseous effluent, an aqueous effluent and a hydrocarbon-based effluent;   e) a step of fractionating all or a portion of the hydrocarbon-based effluent obtained from step d), to obtain at least one gas stream and at least two liquid hydrocarbon-based streams, said two liquid hydrocarbon-based streams being at least one naphtha cut comprising compounds with a boiling point of less than or equal to 175° C. and one hydrocarbon cut comprising compounds with a boiling point of greater than 175° C.;   f) a second step of hydrocracking performed in a hydrocracking reaction section, using at least one fixed-bed reactor containing n catalytic beds, n being an integer greater than or equal to 1, each comprising at least one hydrocracking catalyst, said hydrocracking reaction section being fed with at least a portion of said hydrocarbon cut comprising compounds with a boiling point of greater than 175° C. obtained from step e) and a gas stream comprising hydrogen, said hydrocracking reaction section being operated at a temperature of between 250 and 480° C., a partial pressure of hydrogen of between 1.5 and 25.0 MPa abs. and an hourly space velocity of between 0.1 and 10.0 h −1 , to obtain a second hydrocracked effluent;   g) a step of recycling at least a portion of said second hydrocracked effluent obtained from step f) into the separation step d).   
     
     
         2 . Process according to  claim 1 , which also comprises a recycling step h) in which a fraction of the hydrocarbon-based effluent obtained from the separation step d) or a fraction of the naphtha cut with a boiling point of less than or equal to 175° C. obtained from the fractionation step e) is sent into the selective hydrogenation step a) and/or the hydrotreatment step b). 
     
     
         3 . Process according to  claim 1 , in which the amount of the recycle stream from step h) is adjusted so that the weight ratio between the recycle stream and the feedstock comprising a plastics pyrolysis oil is less than or equal to 10. 
     
     
         4 . Process according to  claim 1 , comprising a step a0) of pretreating the feedstock comprising a plastics pyrolysis oil, said pretreatment step being performed upstream of the selective hydrogenation step a) and comprising a filtration step and/or a step of washing with water and/or an adsorption step. 
     
     
         5 . Process according to  claim 1 , in which the reaction section of step a) or b) uses at least two reactors functioning in permutable mode. 
     
     
         6 . Process according to  claim 1 , in which a stream containing an amine is injected upstream of step a). 
     
     
         7 . Process according to  claim 1 , in which said selective hydrogenation catalyst comprises a support chosen from alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof and a hydro-dehydrogenating function comprising either at least one group VIII element and at least one group VIB element, or at least one group VIII element. 
     
     
         8 . Process according to  claim 1 , in which said hydrotreatment catalyst comprises a support chosen from the group consisting of alumina, silica, silica-aluminas, magnesia, clays and mixtures thereof and a hydro-dehydrogenating function comprising at least one group VIII element and/or at least one group VIB element. 
     
     
         9 . Process according to  claim 1 , in which said hydrocracking catalyst of step c) or of step f) comprises a support chosen from halogenated aluminas, combinations of boron and aluminum oxides, amorphous silica-aluminas and zeolites and a hydro-dehydrogenating function comprising at least one group VIB metal chosen from chromium, molybdenum and tungsten, alone or as a mixture, and/or at least one group VIII metal chosen from iron, cobalt, nickel, ruthenium, rhodium, palladium and platinum. 
     
     
         10 . Process according to  claim 1 , in which said zeolite is chosen from Y zeolites, alone or in combination, with other zeolites from among beta, ZSM-12, IZM-2, ZSM-22, ZSM-23, SAPO-11, ZSM-48 and ZBM-30 zeolites, alone or as a mixture. 
     
     
         11 . Process according to  claim 1 , in which the naphtha cut comprising compounds with a boiling point of less than or equal to 175° C. obtained from step e), is sent, totally or partly, into a steam cracking step i) performed in at least one pyrolysis furnace at a temperature of between 700 and 900° C. and at a pressure of between 0.05 and 0.3 MPa relative. 
     
     
         12 . Process according to  claim 1 , in which the naphtha cut comprising compounds with a boiling point of less than or equal to 175° C. obtained from step e) is fractionated into a heavy naphtha cut comprising compounds with a boiling point of between 80 and 175° C. and a light naphtha cut comprising compounds with a boiling point of less than 80° C., at least a portion of said heavy cut being sent into an aromatic complex including at least one naphtha reforming step. 
     
     
         13 . Process according to  claim 12 , in which at least a portion of the light naphtha cut is sent into the steam cracking step i). 
     
     
         14 . Product which may be obtained via the process according to  claim 1 .