Production of high-cetane diesel fuel from low-quality biomass-derived feedstocks

Abstract

A method is taught for producing diesel fuels of high cetane value from a triglyceride feedstock, comprising pretreating the triglyceride feedstock by thermal cracking or rapid pyrolysis 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    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 of from 390° C. to 460° C.  
     
     
         5 . The method of  claim 1  wherein thermal cracking is conducted at a temperature 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.  
     
     
         16 . The diesel fuel of  claim 15 , having a sulphur content of below 10 ppm.  
     
     
         17 . The diesel fuel of  claim 15 , produced by the process of  claim 1 .  
     
     
         18 . 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.  
     
     
         19 . The blended diesel fuel of  claim 18  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.  
     
     
         20 . A method of producing diesel fuels of high cetane value from a triglyceride feedstock, comprising: 
 a. pretreating the triglyceride feedstock by rapid pyrolysis to partially convert the triglycerides and produce a middle distillates fraction; and    b. catalytically hydrotreating the middle distillate fraction to produce high cetane value diesel fuels.    
     
     
         21 . The method of  claim 20  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.  
     
     
         22 . The method of  claim 20  wherein the middle distillates have a boiling point in the range of from 160° C. to 345° C.  
     
     
         23 . The method of  claim 20  wherein rapid pyrolysis is conducted at a temperature of from 480° C. to 600° C.  
     
     
         24 . The method of  claim 20  wherein rapid pyrolysis is conducted at a temperature of from 550° C. to 600° C.  
     
     
         25 . The method of  claim 20  wherein rapid pyrolysis is conducted at a temperature of from 565° C. to 585° C.  
     
     
         26 . The method of  claim 20  wherein the triglyceride feedstock is fluidized with steam.  
     
     
         27 . The method of  claim 26  wherein the steam to triglyceride feedstock ratio ranges from 0.5 to 1.5.  
     
     
         28 . The method of  claim 27  wherein the steam to triglyceride feedstock ratio is 0.9.  
     
     
         29 . The method of  claim 20  wherein an inert gas is used to purge any oxidizing agents during rapid pyrolysis.  
     
     
         30 . The method of  claim 29  wherein the inert gas is nitrogen.  
     
     
         31 . The method of  claim 20  wherein a catalyst is used during rapid pyrolysis to enhance the cracking of triglycerides to largely free fatty acids.  
     
     
         32 . The method of  claim 31  wherein the catalyst is selected from the group consisting of acid washed activated carbon, calcined sewage sludge solids and silica sand.  
     
     
         33 . The method of  claim 20  wherein catalytic hydrotreating consumes less than 2.0 kg of hydrogen) per 100 kg of middle distillate fed to the hydrotreating step.  
     
     
         34 . The method of  claim 20  wherein catalytic hydrotreating is conducted at a temperature of from 330° C. to 400° C.  
     
     
         35 . The method of  claim 34  wherein catalytic hydrotreating is conducted at a temperature of from 350° C. to 390° C.  
     
     
         36 . The method of  claim 20  wherein catalytic hydrotreating is conducted using a commercial hydrotreating catalyst.  
     
     
         37 . The method of  claim 36  wherein the commercial hydrotreating catalyst is nickel-molybdenum, cobalt-molybdenum or nickel-tungsten on a catalyst support.  
     
     
         38 . The method of  claim 20 , further comprising filtering the triglyceride feedstock to remove macroscopic contaminant particles before rapid pyrolysis.  
     
     
         39 . The method of  claim 20 , further comprising conducting separation after catalytic hydrotreating to produce a gas stream, a water stream and a liquid organic product stream.  
     
     
         40 . The method of  claim 39 , further comprising distilling the liquid organic product stream to further separate diesel fuels from paraffinic residues.  
     
     
         41 . The method of  claim 39 , further comprising the step of recycling the gas stream as hydrogen recycle during catalytic hydrotreating.  
     
     
         42 . The diesel fuel of  claim 15 , produced by the process of  claim 20.