Method for making a middle distillate

Abstract

Hydrocracking processes for the selective production of middle distillates are disclosed. The hydrocracking catalyst contains a low acidity, highly dealuminated USY zeolite having a zeolite acid density of from 1 to 100 micromole/g, a catalyst support, and one or more metals. The hydrocracking process can maximize middle distillate yield while providing for effective impurity removal and enhanced aromatics saturation.

1 . A method making a middle distillate, comprising
 (a) contacting a hydrocarbon feedstock with a hydrocracking catalyst under hydrocracking conditions sufficient to attain a conversion level of at least 50% below 700° F. (371° C.), so as to form a hydrocracked product; and   (b) separating the hydrocracked product into a converted product having a boiling range maximum of 700° F. (371° C.) and an unconverted product having a boiling range minimum of 700° F. (371° C.);   wherein the hydrocracking catalyst comprises (1) a USY zeolite component having a SiO 2 /Al 2 O 3  mole ratio of at least 50, an alpha value of not more than 5, and a zeolite acid site density of from 1 to 100 micromole/g; (2) an amorphous cracking component; and (3) at least one hydrogenation metal component selected from the group consisting of a Group VIB metal, a Group VIII metal, and mixtures thereof.   
     
     
         2 . The method of  claim 1 , wherein the conversion level is from 55% to 90%. 
     
     
         3 . The method of  claim 1 , wherein the converted product has a boiling range of from 280° F. to 525° F. (138° C. to 274° C.). 
     
     
         4 . The method of  claim 1 , wherein the converted product has a boiling range of from 550° F. to 700° F. (288° C. to 371° C.). 
     
     
         5 . The method of  claim 1 , wherein the converted product contains less than 10 ppm sulfur and less than 10 ppm nitrogen. 
     
     
         6 . The method of  claim 1 , wherein the converted product contains less than 1 ppm nitrogen. 
     
     
         7 . The method of  claim 1 , wherein the zeolite component has a SiO 2 /Al 2 O 3  mole ratio of from 80 to 150. 
     
     
         8 . The method of  claim 1 , wherein the zeolite component has an alpha value of from 0.01 to 3. 
     
     
         9 . The method of  claim 1 , wherein the zeolite component has a zeolite acid site density of from 1 to 50 micromole/g. 
     
     
         10 . The method of  claim 1 , wherein the amorphous cracking component is a silica-alumina containing SiO 2  in an amount of from 10 to 70 wt. % of the bulk dry weight of the carrier as determined by ICP elemental analysis and having a mean mesopore diameter of from 7 to 13 nm, a BET surface area of from 450 to 550 m 2 /g, and a total pore volume of from 0.57 to 1.05 mL/g. 
     
     
         11 . The method of  claim 1 , wherein deposition of the hydrogenation metal component on the catalyst is achieved in the presence of at least one organic oxygen-containing ligand. 
     
     
         12 . The method of  claim 11 , wherein the at least one organic oxygen-containing ligand is selected from the group consisting of carboxylic acids, amino acids, esters, ketones, polyols, amino alcohols, and mixtures thereof. 
     
     
         13 . The method of  claim 12 , wherein the at least one organic oxygen-containing ligand is a carboxylic acid selected from the group consisting of formic acid, acetic acid, glyoxylic acid, oxalic acid, glycolic acid, lactic acid, malonic acid, succinic acid, malic acid, tartaric acid, citric acid, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), ethylene glycol tetraacetic acid (EGTA), salicylic acid, and mixtures thereof.