Method for producing diesel fuel by moderate pressure hydrocracking

Abstract

The invention concerns a process for moderate pressure hydrocracking (i.e., at a hydrogen partial pressure of more than 70 bars and at most 100 bars) with a conversion of at least 80% by volume, of a feed with a T 5 temperature in the range 250° C. to 400° C. and a T 95 temperature of at most 470° C. (T 5 and T 95 measured in accordance with ASTM-D2887), to produce a diesel with a 95% distillation point of less than 360° C., a sulphur content of at most 50 ppm and a cetane number of more than 51. The process operates with or without a recycle of the liquid effluent. Highly advantageously, it can be integrated into a refinery layout comprising catalytic cracking. The invention also concerns a unit for carrying out said process.

1 . A process for producing a diesel having a 95% distillation point of less than 360° C., a sulphur content of at most 50 ppm and a cetane number of more than 51, said process treating hydrocarbon feeds with a Ts temperature in the range 250° C. to 400° C. and a T 95  temperature of at most 470° C., said process comprising hydrotreatment which produces an effluent having an organic nitrogen content below 10 ppm followed by moderate pressure hydrocracking with a hydrocracking catalyst comprising at least one Y zeolite, at least one matrix and at least one hydro-dehydrogenating function said hydrocracking being carried out at a hydrogen partial pressure of more than 70 bars and at most 100 bars, at a temperature of at least 320° C., with a H 2  feed volume ratio of at least 200 Ni/Ni, and at an hourly space velocity of 0.15-7 h −1 , the process being carried out with a conversion of at least 80% by volume and the liquid effluent obtained by hydrocracking being distilled to separate the diesel.  
     
     
         2 . A process according to  claim 1 , in which the conversion is at least 95% by volume.  
     
     
         3 . A process according to any one of the preceding claims, in which the hydrocarbon feed has a T 95  temperature in the range 390-430° C.  
     
     
         4 . A process according to any one of the preceding claims, in which the hydrocarbon feed has a T 5  temperature in the range 320° C. to 370° C.  
     
     
         5 . A process according to any one of the preceding claims, in which the hydrocarbon feed is selected from the group formed by heavy atmospheric gas oils or light vacuum gas oils, light vacuum distillates, mixtures of said feeds and mixtures of said feeds with a diesel fraction.  
     
     
         6 . A process according to any one of the preceding claims, in which hydrotreatment and hydrocracking are carried out in the same reactor and without intermediate separation of the gases produced by hydrotreatment.  
     
     
         7 . A process according to any one of the preceding claims, in with the hydrocracking residue is recycled to the process after purging.  
     
     
         8 . A process according to any one of the preceding claims, in which the diesel obtained has a 95% point of at most 340° C., a sulphur content of at least 10 ppm and a cetane number of at least 54.  
     
     
         9 . A process according to any one of the preceding claims, in which the hydrotreatment catalyst contains: 
 5% to 40% by weight of at least one element from group VIB and non noble group VIII (% oxide);    0-20% of at least one promoter element selected from phosphorus, boron, silicon (% oxide)    0-20% of at least one group VIIB element    0% of group VIIA element    0-60% of at least one group VB element    0.1-95% of at least one matrix    and the hydrocracking catalyst contains    0.1-80% by weight of Y zeolite;    0.1-40% by weight of at least one element from group VIB and group VIII (% oxide);    0.1-99.8% by weight of matrix (% oxide);    0-20% by weight of at least one element selected from the group formed by P, B, Si (% oxide)    0% by weight of group VIIA element    0-20% by weight of at least one group VIIB element    0-60% by weight of at least one group VB element.    
     
     
         10 . A process according to any one of the preceding claims, in while the feed with a T 5  temperature of 250° C. to 400° C. and a T 95  temperature of at most 470° C. is a light fraction from vacuum distillation of an atmospheric residue.  
     
     
         11 . A process according to  claim 10 , in which the vacuum distillation also produces a vacuum residue with a boiling point of at least 535° C. and at least one heavy fraction located between said light fraction and the residue, at least a portion of said heavy fraction undergoing catalytic cracking.  
     
     
         12 . A process according to any one of the preceding claims, in which the hydrocarbon feed to be treated by moderate pressure hydrocracking is a heavy atmospheric gas oil from atmospheric distillation, the atmospheric residue boiling above said gas oil being vacuum distilled to produce at least one heavy vacuum distillate fraction that undergoes catalytic cracking and a vacuum residue.  
     
     
         13 . A process according to any one of the preceding claims, in which the moderate pressure hydrocracking purge undergoes catalytic cracking.  
     
     
         14 . A process according to any one of the preceding claims in which, before undergoing catalytic cracking, the heavy vacuum distillate is hydrotreated under a hydrogen partial pressure of 25-90 bars, at a temperature of 350-430° C., with a conversion of at least 10% and less than 40% by volume, to products boiling below 350° C.  
     
     
         15 . A process according to any one of the preceding claims, in which the vacuum residue undergoes a treatment by a process selected from the group formed by visbreaking, residue hydroconversion, and coking processes.  
     
     
         16 . A process for treatment of a crude hydrocarbonated feed, comprising the following steps: 
 atmospheric distillation of the crude hydrocarbonated feed, producing at least one naphta fraction, at least one kerosene fraction, at least one diesel fraction and an atmospheric residue,    vacuum distillation of the atmospheric residue to separate at least one light distillate fraction, at least one heavy distillate fraction and a vacuum residue,    treatment of said light fraction by the process according to any one of the  claims 1  to  15  with production of hydrocracking residue,    catalytic cracking of at least one heavy fraction, optionally added with at least a part of the hydrocracking residue.    
     
     
         17 . A process for treatment of a crude hydrocarbonated feed, comprising the following steps: 
 atmospheric distillation of the crude hydrocarbonated feed, producing at least one naphta fraction, at least one kerosene fraction, at least one diesel fraction, a heavy atmospheric gasoil and an atmospheric residue,    vacuum distillation of the atmospheric residue to separate at least one heavy distillate fraction and a vacuum residue,    treatment of said heavy gasoil cut by the process according to any one of the  claims 1  to  15  with production of hydrocracking residue,    catalytic cracking of at least one heavy fraction, optionally added with at least a part of the hydrocracking residue.    
     
     
         18 . A process according to  claim 16  in which atmospheric distillation also produces a heavy atmopsheric gasoil cut, said cut being also treated with the said light fraction by the process according to any one of the  claims 1  to  15 .  
     
     
         19 . A process according to any one of the  claims 16  to  18  also comprising the treatment of vacuum residue by viscoreduction.  
     
     
         20 . A unit for producing diesel, comprising: 
 a column for distilling a hydrocarbon feed to separate at least one fraction with a T 5  temperature in the range 250° C. to 400° C. and a T 95  temperature of at most 470° C.;    at least one zone for hydrotreating said feed or said fraction;    at least one zone for moderate pressure hydrocracking of said reaction, said pressure being more than 70 bars and at most 100 bars;    at least one zone for separating products to obtain a diesel with a 95% distillation point of less than 360° C., a sulphur content of at most 50 ppm and a cetane number of more than 51.    
     
     
         21 . A unit for producing diesel according to  claim 20 , from a crude hydrocarbon feed, comprising: 
 a column for atmospheric distillation of said crude feed to separate at least naphtha, diesel and an atmospheric residue;    a vacuum distillation column to treat said atmospheric residue, and to separate at least one vacuum distillate and a vacuum residue;    in which unit the atmospheric distillation column or vacuum distillation column comprises at least one line recovering a fraction with a T 5  temperature in the range 250° C. to 400° C. and a T 95  temperature of at most 470° C.;    the unit also comprising at least one zone for hydrotreating said fraction followed by at least one moderate pressure hydrocracking zone and at least one zone for separating products to obtain a diesel with a 95% distillation point of less than 360° C., a sulphur content of at most 50 ppm and a cetane number of more than 51.    
     
     
         22 . A unit according to  claim 20  or  claim 21 , comprising a hydrotreatment zone prior to the hydrocracking zone and located in the same reactor.  
     
     
         23 . A unit according to any one of  claims 20  to  22 , in which the product separation zone separates a hydrocracking residue with a boiling point of more than at least 535° C. and comprises a purge line for said residue and optionally a line for recycling said purged residue towards the hydrocracking zone or reactor.  
     
     
         24 . A unit according to any one of  claims 20  to  23 , comprising a catalytic cracking zone for treating at least one vacuum distillate fraction located between the fraction with a T 95  temperature of at most 470° C. and the vacuum residue.  
     
     
         25 . A unit according to any one of  claims 20  to  24 , comprising a line supplying the purge to the catalytic cracking zone.  
     
     
         26 . A unit according to any one of  claims 20  to  25 , comprising a hydrotreatment zone prior to the catalytic cracking zone.