Process for hydrocracking into a stage of hydrocarbon feedstocks

Abstract

This invention relates to an improved process for hydrocracking into a stage of hydrocarbon feedstocks, using in a first reaction zone a pretreatment catalyst that exhibits a low acidity according to a standard activity test and an amorphous acid catalyst for hydrocracking that is free of zeolite in a second reaction zone that is located downstream from the first. The objective of the process is essentially the production of middle distillates, i.e., fractions with an initial boiling point of at least 150° C. and a final boiling point that goes just up to the initial boiling point of the residue, for example less than 340° C., or else 370° C. and optionally oil bases.

1 . Process for hydrocracking that comprises the following successive stages: 
 A hydrorefining stage in which the feedstock is brought into contact with at least one hydrorefining catalyst that exhibits in the standard activity test a conversion rate of the methylcyclohexane that is less than 10% by mass;    A hydrocracking stage in which at least a portion of the effluent that is obtained from the hydrocracking stage is brought into contact with at least one non-zeolitic hydrocracking catalyst that in the standard activity test exhibits a conversion rate of methylcyclohexane that is higher than 10% by mass:    
     
     
         2 . Process according to  claim 1 , in which the hydrocracking catalyst contains 10-95% by weight of silica.  
     
     
         3 . Process according to one of the preceding claims, in which the hydrocracking catalyst comprises a substrate that is selected from the group that is formed by the silica-aluminas, the titanium silica-alumina-oxide compositions, the zirconia silica-alumina-oxide compositions, and their mixtures with a binder.  
     
     
         4 . Process according to one of the preceding claims, in which the hydrocracking catalyst comprises: 
 0-20% by weight of at least one promoter element that is selected from the group that is formed by boron, phosphorus and silicon;    0-20% by weight of at least one element of group VIIA;    0-20% by weight of at least one element of group VIIB;    0-60% by weight of at least one element of group VB;    5-40% by weight of at least one metal of group VIB and at least one metal of group VIII that is not noble (expressed in oxide).    
     
     
         5 . Process according to one of the preceding claims, in which all of the effluent that is obtained from the hydrorefining zone is sent into the hydrocracking zone.  
     
     
         6 . Process according to one of the preceding claims, in which the proportion of the hydrorefining catalytic volume represents 10-60% of the total catalytic volume.  
     
     
         7 . Process according to one of the preceding claims in which the hydrotreatment catalyst does not contain silica.  
     
     
         8 . Process according to one of  claims 1  to  6 , in which the hydrotreatment catalyst contains silicon as a promoter element that is deposited on the matrix, whereby its silica content is less than 10% by weight.  
     
     
         9 . Process according to one of the preceding claims, in which the feedstock contains at least 20% by volume of compounds that boil above 340° C.; it exhibits a nitrogen content that is higher than 500 ppm and a sulfur content of between 0.01 and 5% by weight.