Production of paraffinic fuel from renewable feedstocks
A process has been developed for producing fuel from renewable feedstocks such as plant and animal oils and greases. The process involves treating a first portion of a renewable feedstock by hydrogenating and deoxygenating in a first reaction zone and a second portion of a renewable feedstock by hydrogenating and deoxygenating in a second reaction zone to provide a diesel boiling point range fuel hydrocarbon product. If desired, the hydrocarbon product can be isomerized to improve cold flow properties. A portion of the hydrocarbon product is recycled to the first reaction zone to increase the hydrogen solubility of the reaction mixture.
1. A process for producing a hydrocarbon product comprising paraffins from at least a first and a second portion of renewable feedstock said process comprising; treating the first portion of renewable feedstock in a first reaction zone by hydrogenating and deoxygenating the first portion of feedstock at reaction conditions to provide a first effluent comprising paraffins; passing at least a portion of the first effluent to a second reaction zone and treating the second portion of renewable feedstock in the second reaction zone by hydrogenating and deoxygenating the second portion of renewable feedstock at reaction conditions to provide a second effluent comprising paraffins; and recycling a recycle stream comprising a portion of at least one of the reaction zone effluents to the first reaction zone wherein the volume ratio of recycle stream to first portion of renewable feedstock is in the range of about 2:1 to about 8:1, and wherein the renewable feedstock is selected from the group consisting of poultry fat, babassu oil, used cooking oil, camelina oil, carinata oil, oleaginous yeast oil, palm kernel oil, palm fatty acid distillate, and mixtures thereof.
2. The process of claim 1 wherein the first portion and the second portion of renewable feedstock are generated by separating a feedstock into two portions.
3. The process of claim 1 wherein the first portion and the second portion of renewable feedstock have different compositions.
4. The process of claim 1 wherein the first reaction zone and the second reaction zone are housed in separate vessels.
5. The process of claim 1 wherein the first reaction zone and the second reaction zone are housed in a single vessel.
6. The process of claim 1 wherein the recycle stream comprises both a portion of the first effluent and a portion the second effluent.
7. The process of claim 1 further comprising isomerizing at least a portion of the paraffins in the second effluent by contacting the second effluent with an isomerization catalyst at isomerization conditions to isomerize at least a portion of the paraffins to branched-paraffins.
8. The process of claim 1 further comprising passing at least a portion of the second effluent and a third portion of renewable feedstock to a third reaction zone and treating the third portion of renewable feedstock in the third reaction zone by hydrogenating and deoxygenating the third portion of the feedstock at reaction conditions to provide a third effluent comprising paraffins.
9. The process of claim 8 wherein the recycle stream comprises a portion of the third effluent.
10. The process of claim 8 further comprising isomerizing at least a portion of the paraffins in the third effluent by contacting the third effluent with an isomerization catalyst at isomerization conditions to isomerize at least a portion of the paraffins to branched-paraffins.
11. The process of claim 8 further comprising passing at least a portion of the third effluent and a fourth portion of renewable feedstock to a fourth reaction zone and treating the fourth portion of renewable feedstock in the fourth reaction zone by hydrogenating and deoxygenating the fourth portion of the feedstock at reaction conditions to provide a fourth effluent comprising paraffins.
12. The process of claim 11 wherein the recycle stream comprises a portion of the fourth effluent.
13. The process of claim 11 further comprising isomerizing at least a portion of the paraffins in the fourth effluent by contacting the fourth effluent with an isomerization catalyst at isomerization conditions to isomerize at least a portion of the paraffins to branched-paraffins.
14. The process of claim 1 further comprising pre-treating at least one portion of the renewable feedstock in a pretreatment zone at pretreatment conditions to remove at least a portion of contaminants.
15. The process of claim 1 where the pretreatment step comprises contacting with an acidic ion exchange resin or with an acid solution.
16. The process of claim 1 where the first reaction zone comprises a hydrogenation and deoxygenation catalyst at a temperature of about 200° C. to about 300° C. and a pressure of about 1379 kPa absolute (200 psia) to about 4826 kPa absolute (700 psia).
17. The process of claim 1 where deoxygenation comprises at least one of decarboxylation, decarbonylation, and hydrodeoxygenation.
18. The process of claim 1 further comprising treating a petroleum hydrocarbon feedstock in the first reaction zone or the second reaction zone.