Process for renewable fuels using a multistage approach
The invention relates to a method to reduce the formation of high molecular weight compounds and catalyst coking in the production of renewable diesel. Renewable diesel is produced using hydrogenation, decarboxylation, decarbonylation, and/or hydrodeoxygenation of renewable feedstocks such as animal and/or plant fats, oils, and/or greases (FOG). By first reacting the most reactive species in the FOG in an initial reaction zone prior to the main reaction zone, maximum reaction temperatures and side reactions that lead to the formation of high molecular weight compounds are reduced. This reduces catalyst coking (extends catalyst life) and improves product quality.
1. A method for processing plant and/or animal FOG in a reaction zone to form paraffins comprising:
providing a first feed to a reaction zone comprising a plurality of reactors or beds;
partially reacting the FOG within a first of the plurality of reactors or beds at temperatures less than about 648° F.;
providing a second feed to a second of the plurality of reactors or beds;
reacting a remaining quantity of the FOG from the first of the plurality of reactors or beds within the second of the plurality of reactors or beds;
wherein the first feed includes an unreacted fresh feed component and a first recycled component which is obtained from a point downstream of the reaction zone and the ratio of the first recycled component to the fresh feed component is less than 4:1;
wherein the second feed includes a product component from the first of the reactors or beds and a second recycled component which is obtained from a point downstream of the reaction zone and the ratio of a combination of all recycle streams to the fresh feed component is greater than 8:1; and
wherein a ratio of the first recycled component to the first feed is less than a ratio of the second recycled component to the second feed.
2. The method according to claim 1 , wherein the LHSV to the first of the plurality of reactors or beds is more than 2 hr −1 on a total feed basis.
3. The method according to claim 1 , wherein the LHSV to the first of the plurality of reactors or beds is more than 5 hr −1 on a total feed basis.
4. The method according to claim 1 , wherein it an outlet temperature of the first plurality of reactors or beds is greater than an inlet temperature of the second of the plurality of reactors or beds.
5. The method according to claim 1 , wherein the free fatty acid concentration of the product component from the first reactor is less than free fatty acid concentration of the first feed.
6. The method according to claim 5 , wherein the free fatty acid concentration is reduced in the reaction zone to no more than 5 wt % on a fresh feed basis.
7. The method according to claim 1 , wherein FOG saturation is more than 25% in the first of the plurality of reactors or beds.
8. The method according to claim 1 , wherein FOG saturation is more than 50% in the first of the plurality of reactors or beds.
9. The method according to claim 1 , wherein FOG saturation is more than 75% in the first of the plurality of reactors or beds.
10. The method according to claim 1 , wherein FOG conversion to paraffin is less than 50 wt % in the first of the plurality of reactors or beds.
11. The method according to claim 1 , wherein FOG conversion to paraffin is less than 25 wt % in the first of the plurality of reactors or beds.
12. The method according to claim 1 , wherein FOG conversion to paraffin is less than 10 wt % in the first of the plurality of reactors or beds.
13. The method according to claim 1 , wherein a product stream from the reactor zone is further processed in an isomerization step.
14. The method according to claim 1 , wherein a product stream from the reactor zone is further processed in an isomerization and/or cracking step to produce a lighter boiling point range product.
15. The method according to claim 14 , wherein the product stream from the reactor zone is further processed in an isomerization and/or cracking step to produce a jet/kerosene boiling range product.
16. The method according to claim 14 , wherein the product stream from the reactor zone is further processed in an isomerization and/or cracking step to produce a naphtha/gasoline boiling range product.
17. The method according to claim 1 , wherein a product stream from the reactor zone is further processed in an isomerization and/or cracking step to produce a fuel gas boiling range product.