Production of high-cetane diesel fuel from low-quality biomass-derived feedstocks
A method is taught for producing diesel fuels of high cetane value from a triglyceride feedstock, comprising pretreating the triglyceride feedstock by thermal cracking to partially convert the triglycerides and produce a middle distillates stream, and catalytically hydrotreating the middle distillate fraction to produce high cetane value diesel fuels. A biomass-derived diesel fuel is also taught having sulphur content below 10 ppm, a cetane-value of at least 70, a cloud point below 0° C. and a pour point of less than −4° C. A blended diesel fuel is also taught comprising 5 to 20 vol. % of the biomass-derived diesel fuel of the present invention and 80 to 95 vol. % of a petroleum diesel, based on total volume of the blended diesel fuel.
1. A method of producing diesel fuels of high cetane value from a triglyceride feedstock, comprising:
a. pretreating the triglyceride feedstock by thermal cracking to partially convert the triglycerides and produce a middle distillates fraction; and subsequently
b. catalytically hydrotreating the middle distillate fraction to produce high cetane value diesel fuels.
2. The method of claim 1 wherein the triglycerides feedstock is selected from the group consisting of restaurant trap grease, animal fats, waste greases, low-quality vegetable oils and combinations thereof.
3. The method of claim 1 wherein the middle distillates have a boiling point in the range of from 160° C. to 345° C.
4. The method of claim 1 wherein thermal cracking is conducted at a temperature in the range of from 390° C. to 460° C.
5. The method of claim 1 wherein thermal cracking is conducted at a temperature in the range of from 410° C. to 430° C.
6. The method of claim 1 wherein catalytic hydrotreating consumes less than 2.0 kg of hydrogen per 100 kg of middle distillate fed to the hydrotreating step.
7. The method of claim 1 wherein catalytic hydrotreating is conducted at a temperature of from 330° C. to 400° C.
8. The method of claim 6 wherein catalytic hydrotreating is conducted at a temperature of from 350° C. to 390° C.
9. The method of claim 1 wherein catalytic hydrotreating is conducted using a commercial hydrotreating catalyst.
10. The method of claim 9 wherein the commercial hydrotreating catalyst is nickel-molybdenum, cobalt-molybdenum or nickel-tungsten on a catalyst support.
11. The method of claim 1 , further comprising filtering the triglyceride feedstock to remove macroscopic contaminant particles before thermal cracking.
12. The method of claim 1 , further comprising conducting separation after catalytic hydrotreating to produce a gas stream, a water stream and a liquid organic product stream.
13. The method of claim 12 , further comprising distilling the liquid organic product stream to further separate diesel fuels from paraffinic residues.
14. The method of claim 12 , further comprising the step of recycling the gas stream as hydrogen recycle during catalytic hydrotreating.
15. A biomass-derived diesel fuel having a cetane-value of at least 70, a cloud point below 0° C. and a pour point of less than −4° C., produced by the process of claim 1 .
16. A blended diesel fuel comprising 5 to 20 vol. % biomass-derived diesel fuel as described in claim 15 and 80 to 95 vol. % petroleum diesel, based on a total volume of the blended diesel fuel.
17. A blended diesel fuel comprising 10 vol. % biomass-derived diesel fuel as described in claim 15 and 90 vol. % petroleum diesel, based on a total volume of the blended diesel fuel.
18. The diesel fuel of claim 15 , having a sulphur content of below 10 ppm.