Catalytic processes and systems for base oil production using zeolite ssz-32x

Abstract

Processes and catalyst systems are provided for dewaxing a hydrocarbon feedstock to form a lubricant base oil. A layered catalyst system of the present invention may comprise a first hydroisomerization dewaxing catalyst disposed upstream from a second hydroisomerization dewaxing catalyst. Each of the first and second hydroisomerization dewaxing catalysts may be selective for the isomerization of n-paraffins. The first hydroisomerization catalyst may have a higher level of selectivity for the isomerization of n-paraffins than the second hydroisomerization dewaxing catalyst. At least one of the first and second hydroisomerization dewaxing catalysts comprises small crystallite zeolite SSZ-32x.

What is claimed is: 
     
         1 . A process for catalytically dewaxing a waxy hydrocarbon feedstock, comprising:
 a) contacting the hydrocarbon feedstock in a first hydroisomerization zone under first hydroisomerization dewaxing conditions with a first hydroisomerization catalyst comprising SSZ-32x to provide a first isomerization stream; and   b) contacting at least a portion of the first isomerization stream in a second hydroisomerization zone under second hydroisomerization dewaxing conditions with a second hydroisomerization catalyst which comprises a molecular sieve and a Group VIII metal to provide a second isomerization stream.   
     
     
         2 . The process according to  claim 1 , wherein the second hydroisomerization catalyst comprises a 1-D, 10-ring molecular sieve. 
     
     
         3 . The process according to  claim 1 , wherein the first hydroisomerization catalyst comprises SSZ-32x doped with a metal modifier selected from the group consisting of Mg, Ca, Sr, Ba, K, La, Pr, Nd, Cr, and combinations thereof. 
     
     
         4 . The process according to  claim 3 , wherein the first hydroisomerization catalyst has a first level of selectivity for the isomerization of n-paraffins in the feedstock, the second hydroisomerization catalyst has a second level of selectivity for the isomerization of n-paraffins in the feedstock, and wherein the first level of selectivity is higher than the second level of selectivity. 
     
     
         5 . The process according to  claim 3 , wherein the metal modifier comprises Mg at a concentration in the range from about 0.5 to about 2.5 wt. %. 
     
     
         6 . The process according to  claim 3 , wherein the second hydroisomerization catalyst at least substantially lacks a metal modifier. 
     
     
         7 . The process according to  claim 1 , wherein at least about 80% of the feedstock components have a boiling point below about 900° F. (482° C.). 
     
     
         8 . The process according to  claim 1 , wherein each of the first hydroisomerization catalyst and the second hydroisomerization catalyst is doped with a metal modifier selected from the group consisting of Mg, Ca, Sr, Ba, K, La, Pr, Nd, Cr, and combinations thereof. 
     
     
         9 . The process according to  claim 1 , wherein the first hydroisomerization catalyst and the second hydroisomerization catalyst are disposed within a single reactor. 
     
     
         10 . The process according to  claim 1 , further comprising:
 c) prior to step a), contacting the hydrocarbon feedstock in a hydrotreating zone under hydrotreating conditions with a hydrotreating catalyst, wherein the hydrotreating catalyst occupies a volume in the range from about 3% to about 30% of the total volume of the hydrotreating catalyst, the first hydroisomerization catalyst, and the second hydroisomerization catalyst.   
     
     
         11 . The process according to  claim 1 , wherein the ratio of the volume of the first hydroisomerization catalyst to the volume of the second hydroisomerization catalyst is in the range from about 3:2 to about 2:3. 
     
     
         12 . The process according to  claim 1 , further comprising:
 c) contacting the second isomerization stream with a hydrofinishing catalyst in the presence of hydrogen to provide a base oil product having a pour point of not more than about −12° C., and a pour-cloud spread of not more than about 5° C.   
     
     
         13 . The process according to  claim 1 , wherein the first hydroisomerization catalyst comprises from about 5 to about 95 wt. % SSZ-32x and from about 0.1 to about 1.0 wt. % of Group VIII metal. 
     
     
         14 . A process for catalytically dewaxing a waxy hydrocarbon feedstock, comprising:
 a) contacting the hydrocarbon feedstock in a first hydroisomerization zone under first hydroisomerization dewaxing conditions with a first hydroisomerization catalyst comprising SSZ-32x to provide a first isomerization stream; and   b) contacting at least a portion of the first isomerization stream in a second hydroisomerization zone under second hydroisomerization dewaxing conditions with a second hydroisomerization catalyst to provide a second isomerization stream, wherein the first hydroisomerization catalyst further comprises a Group VIII metal, the second hydroisomerization catalyst comprises a 1-D, 10-ring zeolite and a Group VIII metal, at least one of the first hydroisomerization catalyst and the second hydroisomerization catalyst is doped with a metal modifier selected from the group consisting of Mg, Ca, Sr, Ba, K, La, Pr, Nd, Cr, and combinations thereof; and the first and second hydroisomerization catalysts are disposed in the same reactor.   
     
     
         15 . The process according to  claim 14 , further comprising:
 c) contacting the second isomerization stream with a hydrofinishing catalyst in the presence of hydrogen to provide a base oil product having a pour point of not more than about −12° C., and a pour-cloud spread of not more than about 5° C.   
     
     
         16 . The process according to  claim 14 , wherein the first hydroisomerization catalyst is doped with the metal modifier, the first hydroisomerization catalyst has a first level of selectivity for the isomerization of n-paraffins in the feedstock, the second hydroisomerization catalyst has a second level of selectivity for the isomerization of n-paraffins in the feedstock, and wherein the first level of selectivity is higher than the second level of selectivity. 
     
     
         17 . A layered catalyst system, comprising:
 a first hydroisomerization zone comprising a first hydroisomerization catalyst comprising SSZ-32x; and   a second hydroisomerization zone comprising a second hydroisomerization catalyst, wherein each of the first and second hydroisomerization catalysts comprises a molecular sieve and a Group VIII metal, and the molecular sieve of at least one of the first hydroisomerization catalyst and the second hydroisomerization catalyst is doped with a metal modifier selected from the group consisting of Mg, Ca, Sr, Ba, K, La, Pr, Nd, Cr, and combinations thereof.   
     
     
         18 . The layered catalyst system according to  claim 17 , wherein the first hydroisomerization catalyst comprises SSZ-32x doped with the metal modifier, the first hydroisomerization catalyst is disposed upstream from the second hydroisomerization catalyst, and wherein the first hydroisomerization catalyst has a first level of selectivity for the isomerization of n-paraffins, the second hydroisomerization catalyst has a second level of selectivity for the isomerization of n-paraffins, and wherein the first level of selectivity is higher than the second level of selectivity. 
     
     
         19 . The layered catalyst system of  claim 17 , wherein the molecular sieve of the second hydroisomerization catalyst comprises SSZ-32 or SSZ-32x. 
     
     
         20 . The layered catalyst system of  claim 17 , wherein the molecular sieve of the second hydroisomerization catalyst comprises SSZ-32x.