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An improved hydrotreating process for removing sulfur from distillate boiling range feedstreams. This improved process utilizes a two stage hydrotreating process scheme, each stage associated with an acid gas removal zone wherein one of the stages utilizes a rapid cycle pressure swing adsorption zon

An improved hydrotreating process for removing sulfur from distillate boiling range feedstreams. This improved process utilizes a two stage hydrotreating process scheme, each stage associated with an acid gas removal zone wherein one of the stages utilizes a rapid cycle pressure swing adsorption zone to increase the concentration of hydrogen in the process.

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1. A process for hydrotreating a heteroatom-containing distillate boiling range feed, which process comprises a) contacting said distillate boiling range feed in a first hydrotreating zone in the presence of hydrogen, with a catalytically effective amount of a hydrotreating catalyst at hydrotreating

1. A process for hydrotreating a heteroatom-containing distillate boiling range feed, which process comprises a) contacting said distillate boiling range feed in a first hydrotreating zone in the presence of hydrogen, with a catalytically effective amount of a hydrotreating catalyst at hydrotreating conditions to result in a first liquid phase product having a reduced amount of sulfur, and a first vapor phase, which vapor phase contains hydrogen, light hydrocarbons, hydrogen sulfide and ammonia;b) separating the first liquid phase and the first vapor phase;c) removing hydrogen sulfide and ammonia from said first vapor phase with a basic scrubbing solution in order to form a scrubbed first vapor phase;d) removing light hydrocarbons from said scrubbed first vapor phase thereby increasing its hydrogen concentration, in a rapid cycle pressure swing adsorption unit containing a plurality of adsorbent beds and having a total cycle time of less than about 30 seconds and a pressure drop within each adsorbent bed of greater than about 5 inches of water per foot of bed length;e) feeding at least a portion of the scrubbed first vapor phase having an increased concentration of hydrogen to a second hydrotreating zone;f) contacting said first liquid phase product in a second hydrotreating zone in the presence of hydrogen at least a portion of which is obtained from the scrubbed first vapor phase of step d) above, with a catalytically effective amount of a hydrotreating catalyst at hydrotreating conditions to result in a second liquid phase product having a reduced amount of sulfur, and a second vapor phase product, which second vapor phase product contains light hydrocarbons, hydrogen sulfide and hydrogen;g) separating the second liquid phase product from the second vapor phase;h) removing hydrogen sulfide from said second vapor phase with a basic scrubbing solution in order to form a scrubbed second vapor phase; andi) feeding at least a portion of the scrubbed second vapor phase product to said first hydrotreating zone,wherein said removing step d) results in a recovery of a purified hydrogen-containing gas stream, relative to said hydrogen-containing make-up treat gas, said vapor phase product, or both, so as to exhibit (iv) a rate of recovery (R%) greater than 80% for a product purity to feed ratio (P%/F%) greater than 1.1, (v) a rate of recovery (R%) greater than 90% for a product purity to feed ratio (P%/F%) less than 1.1 but greater than 0, or (vi) both (iv) and (v). 2. The process of claim 1 wherein the feed is selected from the group consisting of Fischer-Tropsch liquids; atmospheric gas oils; atmospheric pipestill sidestreams selected from diesel, light diesel, and heavy diesel; vacuum gas oils; deasphalted vacuum and atmospheric residua; mildly cracked residual oils; coker distillates; straight run distillates; solvent-deasphalted oils; pyrolysis-derived oils; high boiling synthetic oils, cycle oils and cat cracker distillates. 3. The process of claim 2 wherein the hydrotreating catalyst contains one or more components selected from the group consisting of cobalt, nickel, tungsten, alumina, a zeolite, silica, silica-alumina, and molecular sieve. 4. The process of claim 2 wherein the total cycle time of rapid cycle pressure swing adsorption is less than about 15 seconds. 5. The process of claim 4 wherein the total cycle time is less than about 10 seconds and the pressure drop of each adsorbent bed is greater than about 10 inches of water per foot of bed length. 6. The process of claim 5 wherein the total cycle time is less than about 5 seconds. 7. The process of claim 6 wherein the pressure drop of greater than about 20 inches of water per foot of bed length. 8. The process of claim 1 wherein the cycle time of rapid cycle pressure swing adsorption is less than about 10 seconds and the pressure drop in each adsorbent bed is greater than about 10 inches of water per foot of bed length. 9. The process of claim 8 wherein the cycle time is less than about 5 seconds and the pressure drop if greater than about 20 inches of water per foot of bed length. 10. The process of claim 1 wherein a hydrogen-containing make-up gas is introduced into said first hydrotreating zone, which hydrogen-containing make-up gas contains hydrogen and light hydrocarbons. 11. The process of claim 10 wherein, before said hydrogen-containing make-up gas is introduced into said first hydrotreating zone, light hydrocarbons are removed therefrom in a rapid cycle pressure swing adsorption unit containing a plurality of adsorbent beds and having a total cycle time of less than about 30 seconds and a pressure drop within each adsorbent bed of greater than about 5 inches of water per foot of bed length. 12. The process of claim 11 wherein the total cycle time or rapid cycle pressure swing adsorption is less than about 10 seconds and the pressure drop in each adsorbent bed is greater than about 10 inches of water per foot of bed length. 13. The process of claim 12 wherein the total cycle time is less than about 5 seconds. 14. The process of claim 13 wherein the pressure drop of greater than about 20 inches of water per foot of bed length. 15. A process for hydrotreating distillate boiling range feed, which comprises: a) contacting said distillate boiling range feed in a first hydrotreating zone and contacting it, in the presence of hydrogen, with a catalytically effective amount of a hydrotreating catalyst at hydrotreating conditions to result in a first liquid phase having a reduced amount of sulfur, and a first vapor phase, which vapor phase product is comprised of hydrogen, light hydrocarbons, hydrogen sulfide and ammonia;b) separating the first liquid phase and the first vapor phase;c) removing hydrogen sulfide from said first vapor phase with a basic scrubbing solution in order to form a scrubbed first vapor phase;d) feeding at least a portion of the scrubbed first vapor phase to a second hydrotreating zone;e) contacting said first liquid phase in a second hydrotreating zone and contacting it, in the presence of hydrogen at least a portion of which is obtained from the scrubbed first vapor phase of step d) above, with a catalytically effective amount of a hydrotreating catalyst at hydrotreating conditions to result in a second liquid phase having a reduced amount of sulfur, and a second vapor phase product, which vapor phase product contains light hydrocarbons, hydrogen sulfide and hydrogen;f) separating the second liquid phase from the second vapor phase;g) removing hydrogen sulfide from said second vapor phase with a basic scrubbing solution in order to form a scrubbed second vapor phase;h) removing light hydrocarbons from said scrubbed second vapor phase thereby increasing its hydrogen concentration, in a rapid cycle pressure swing adsorption unit containing a plurality of adsorbent beds and having a total cycle time of less than about 30 seconds and a pressure drop within each adsorbent bed of greater than about 5 inches of water per foot of bed length; andi) feeding at least a portion of the scrubbed second vapor phase having an increased concentration of hydrogen to said first hydrotreating zone,wherein said removing step h) results in a recovery of a purified hydrogen-containing gas stream, relative to said hydrogen-containing make-up treat gas, said vapor phase product, or both, so as to exhibit (iv) a rate of recovery (R%) greater than 80% for a product purity to feed ratio (P%/F%) greater than 1.1, (v) a rate of recovery (R%) greater than 90% for a product purity to feed ratio (P%/F%) less than 1.1 but greater than 0, or (vi) both (iv) and (v). 16. The process of claim 15 wherein the feedstream is selected from the group consisting of Fischer-Tropsch liquids; atmospheric gas oils; atmospheric pipestill sidestreams selected from diesel, light diesel, and heavy diesel; vacuum gas oils; deasphalted vacuum and atmospheric residua; mildly cracked residual oils; coker distillates; straight run distillates; solvent-deasphalted oils; pyrolysis-derived oils; high boiling synthetic oils, cycle oils and cat cracker distillates. 17. The process of claim 16 wherein the cycle time of rapid cycle pressure swing adsorption is less than about 10 seconds and the pressure drop in each adsorbent bed is greater than about 10 inches of water per foot of bed length. 18. The process of claim 17 wherein the cycle time is less than about 5 seconds and the pressure drop is greater than about 20 inches of water per foot of bed length. 19. The process of claim 15 wherein the total cycle time of rapid cycle pressure swing adsorption if less than about 15 seconds. 20. The process of claim 19 wherein the total cycle time is less than about 10 seconds and the pressure drop of each adsorbent is greater than about 10 inches of water per foot of bed length. 21. The process of claim 20 wherein the total cycle time is less than about 5 seconds. 22. The process of claim 21 wherein the pressure drop of greater than about 20 inches of water per foot of bed length. 23. The process of claim 15 wherein a hydrogen-containing make-up gas is introduced into said second hydrotreating zone, which hydrogen-containing makeup gas contains hydrogen and light hydrocarbons. 24. The process of claim 23 wherein, before said hydrogen-containing make-up gas is introduced into said second hydrotreating zone, light hydrocarbons are removed therefrom in a rapid cycle pressure swing adsorption unit containing a plurality of adsorbent beds and having a total cycle time of less than about 30 seconds and a pressure drop within each adsorbent bed of greater than about 5 inches of water per foot of bed length. 25. The process of claim 24 wherein the total cycle time or rapid cycle pressure swing adsorption is less than about 10 seconds and the pressure drop in each adsorbent bed is greater than about 10 inches of water per foot of bed length. 26. The process of claim 25 wherein the total cycle time is less than about 5 seconds. 27. The process of claim 26 wherein the pressure drop of greater than about 20 inches of water per foot of bed length.