Integrated hydrocracking and dewaxing of hydrocarbons
An integrated process for producing naphtha fuel, diesel fuel and/or lubricant base oils from feedstocks under sour conditions is provided. The ability to process feedstocks under higher sulfur and/or nitrogen conditions allows for reduced cost processing and increases the flexibility in selecting a suitable feedstock. The sour feed can be delivered to a catalytic dewaxing step without any separation of sulfur and nitrogen contaminants. The integrated process includes an initial dewaxing of a feed under sour conditions, optional hydrocracking of the dewaxed feed, and a separation to form a first diesel product and a bottoms fraction. The bottoms fraction is then exposed to additional hydrocracking and dewaxing to form a second diesel product and optionally a lubricant base oil product. Alternatively, a feedstock can be hydrotreated, fractionated, dewaxed, and then hydrocracked to form a diesel fuel and a dewaxed, hydrocracked bottoms fraction that is optionally suitable for use as a lubricant base oil.
1. A method for producing a diesel fuel and a lubricant basestock, comprising:
contacting a feedstock with a hydrotreating catalyst under effective hydrotreating conditions to produce a hydrotreated effluent;
fractionating the hydrotreated effluent to produce at least a first diesel product fraction and a bottoms fraction;
hydrocracking the bottoms fraction under effective hydrocracking conditions;
dewaxing the bottoms fraction under effective catalytic dewaxing conditions, the dewaxing catalyst including at least one non-dealuminated, unidimensional, 10-member ring pore zeolite, and at least one Group VI metal, Group VIII metal, or combination thereof;
and fractionating the hydrocracked, dewaxed bottoms fraction to form at least a second diesel product fraction and a lubricant base oil product fraction.
2. The method of claim 1 , wherein at least a portion of the first diesel product fraction is fed to the dewaxing step.
3. The method of claim 1 , further including combining the first diesel product fraction and the second diesel product fraction.
4. The method of claim 1 , wherein the effective hydrotreating conditions include a temperature of from 200° C. to 450° C., hydrogen partial pressure of from 1.8 MPa to 34.6 MPa (250 psi to 5000 psi), a liquid hourly space velocity of from 0.2 to 10 hr −1 , and a hydrogen circulation rate of from 35.6 to 1781 m 3 /m 3 (200 to 10,000 scf/B).
5. The method of claim 1 , wherein the effective hydrocracking conditions include a temperature of 200° C. to 450° C., a hydrogen partial pressure of 250 psig to 5000 psig (1.8 MPa to 34.6 MPa), a liquid hourly space velocity of 0.2 h −1 to 10 h −1 , and a hydrogen treat gas rate of 35.6 m 3 /m 3 to 1781 m 3 /m 3 (200 SCF/B to 10,000 SCF/B).
6. The method of claim 1 , wherein the effective dewaxing conditions include a temperature of from 200° C. to 450° C., a hydrogen partial pressure of from 1.8 MPa to 34.6 MPa (250 psi to 5000 psi), a liquid hourly space velocity of from 0.2 to 10 hr −1 , and a hydrogen circulation rate of from 35.6 to 1781 m 3 /m 3 (200 to 10,000 scf/B).
7. The method of claim 1 , wherein a hydrogen gas introduced as part of effective hydrotreating conditions, effective dewaxing conditions, or effective hydrocracking conditions is chosen from a hydrotreated gas effluent, a clean hydrogen gas, a recycle gas and combinations thereof.
8. The method of claim 1 , wherein the dewaxing catalyst comprises a molecular sieve having a SiO 2 :Al 2 O 3 ratio of 200:1 to 30:1 and comprises from 0.1 wt % to 3.33 wt % framework Al 2 O 3 content, the dewaxing catalyst including from 0.1 to 5 wt % platinum.
9. The method of claim 8 , wherein the molecular sieve is EU-1, ZSM-35, ZSM-11, ZSM-57, NU-87, ZSM-22, EU-2, EU-11, ZBM-30, ZSM-48, ZSM-23, or a combination thereof.
10. The method of claim 9 , wherein the molecular sieve is ZSM-48, ZSM-23, or a combination thereof.
11. The method of claim 1 , wherein the dewaxing catalyst comprises at least one low surface area metal oxide, refractory binder, the binder being silica, alumina, titania, zirconia, or silica-alumina.
12. The method of claim 11 , wherein the metal oxide, refractory binder further comprises a second metal oxide, refractory binder different from the first metal oxide, refractory binder.
13. The method of claim 11 , wherein the dewaxing catalyst comprises a micropore surface area to total surface area ratio of greater than or equal to 25%, wherein the total surface area equals the surface area of the external zeolite plus the surface area of the binder, the surface area of the binder being 100 m 2 /g or less.
14. The method of claim 1 , wherein the hydrocracking catalyst is a zeolite Y based catalyst.
15. The method of claim 1 further including hydrofinishing the hydrocracked, dewaxed bottoms fraction under effective hydrofinishing conditions prior to the second fractionating step.
16. The method of claim 1 , wherein fractionating to form a lubricant base oil product fraction comprises forming a plurality of lubricant base oil products, including a lubricant base oil product having a viscosity of at least 2cSt, and a lubricant base oil product having a viscosity of at least 4 cSt suitable for use in engine oils made according to SAE J300 in 0W-, 5W-, or 10W- grades.