Patent Publication Number: US-2011071327-A1

Title: Process for co-producing jet fuel and lpg from renewable sources

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. application Ser. No. 12/062,970, filed Apr. 4, 2008, which claims benefit under 35 U.S.C. 119(e) of U.S. Provisional Application Ser. No. 60/910,573, filed Apr. 6, 2007, both of which are hereby expressly incorporated herein by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention generally relates to a method for producing from a renewable feedstock an isoparaffinic product useful in producing jet fuel and/or jet fuel blendstock (hereinafter referred to as “jet fuel”) or an LPG product. The present invention also relates to the resultant jet fuel, whereby the jet fuel has improved cold flow properties. 
     BACKGROUND OF THE INVENTION 
     Due to concerns with limited resources of petroleum-based fuels, the demand for using renewable feedstock, such as vegetable oils and animal fats, to produce hydrocarbon fuels has increased. There are a number of well-known methods for making diesel fuels or diesel fuel additives from renewable feedstock. Such methods, however, have limitations, including producing fuels that are not always acceptable for commercial use. 
     Additives for diesel fuels whereby the additives have high cetane numbers and serve as fuel ignition improvers are known to have been made. One method for making such additives includes subjecting a biomass feedstock, such as tall oil, wood oil, animal fats, or blends of tall oil with plant or vegetable oil, to a hydroprocessing method to produce a product mixture. The product mixture is then separated and fractionated to obtain a hydrocarbon product that has a diesel fuel boiling range commensurate with known diesel fuel products. This method results in an additive product that is characterized as performing poorly at low temperatures. In particular, the additive has a high cloud point at 25° C. 
     Another method of making a hydrocarbon suitable for use as diesel fuel includes subjecting a renewable feedstock, comprising C8-C24 fatty acids, derivatives of C8-C24 fatty acids, or combinations thereof, to a decarboxylation/decarbonylation reaction followed by an isomerization reaction. The product of the isomerization reaction is a hydrocarbon suitable for use as a diesel fuel additive. This process also produces a product having a high cetane value but poor low temperature properties, such as a high cloud point at around 25° C. As such, both mentioned resultant products are useful as diesel fuel additives but not usable as diesel or jet fuel replacements. Note that jet fuel requires significantly better low temperature properties than diesel. The cloud point is the temperature at which a fuel becomes hazy or cloudy because of the appearance of crystals within the liquid fuel. 
     A separate process produces a middle distillate fuel useful as diesel fuel having a cloud point of −12° C. from vegetable oil. The process includes hydrogenating the fatty acids or triglycerides of the vegetable oil to produce n-paraffins and then isomerizing the n-paraffins to obtain branched-chain paraffins. This process still suffers from a cloud point at a temperature that is comparatively too high. 
     To date, there appear to be no processes that produce a fuel having lower cold flow requirements, i.e., a cloud point lower than −12° C. In particular, there are no known processes to produce a stand-alone jet fuel from a renewable feedstock. To this end, it is to such a process and jet fuel composition that the present invention is directed. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a method for producing from a renewable feedstock an isoparaffinic product useful for producing a jet fuel. The renewable feedstock includes animal fats, vegetable oils, plant fats and oils, rendered fats, restaurant grease, waste industrial frying oils, fish oils, and combinations thereof. 
     The method for producing an isoparaffinic product useful as jet fuel typically includes hydrotreating a renewable feedstock to produce a hydrotreated heavy fraction and a light fraction. This is followed by hydroisomerizing the hydrotreated heavy fraction to produce a hydroisomerized heavy fraction and a light fraction. The hydroisomerized heavy fraction is passed into a separator to remove the isoparaffin product with the remainder recycled back into the hydroisomerizing unit to produce an isoparaffinic product. 
     The method may also include fractionating the isoparaffinic product to produce a jet fuel, as well as naphtha and liquefied petroleum gas (LPG), which includes primarily propane, iso-butane, n-butane, as well as small quantities of methane and ethane. 
     The resultant jet fuel product has improved cold flow properties. In particular, the jet fuel product has a viscosity of less than 5 centistokes at about −20° C., a boiling range of about 150° C. to about 300° C. and a freezing point of less than about −47° C. 
     A blended jet fuel composition of the present invention includes 0.1 to 99% by volume of a renewable jet fuel and a balance of at least one non-renewable resource. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a method for co-producing an isoparaffinic product that may be fractionated into jet fuel, naphtha, and LPG from a renewable feedstock. 
         FIG. 2  is a gas chromatogram of hydrotreater effluent, showing absence of unconverted feed component and cracked products. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to a method for producing from a renewable feedstock an isoparaffinic product that can then be fractionated into a jet fuel or a liquefied petroleum gas (LPG) fraction. The process is illustrated by  FIG. 1 , with the method including hydrotreating the renewable feedstock to produce a hydrotreated heavy fraction that includes n-paraffins. Next, the hydrotreated heavy fraction, in particular the n-paraffins, is isomerized to produce among other products, isoparaffins. The method includes recycling a hydroisomerized heavy fraction back through the hydroisomerization unit to produce the isoparaffin product. The isoparaffin is then fractionated into a jet fuel and an LPG fraction. The LPG fraction includes primarily propane, iso-butane, n-butane, as well as small quantities of methane and ethane. A jet fuel is produced from a renewable feedstock whereby the jet fuel has improved cold flow properties. 
     The present method for co-producing an isoparaffinic product useful as a jet fuel and an LPG fraction includes three steps, a hydrotreating step, a hydroisomerization step, and a fractionation step having recycle of the heavy hydroisomerization products. As shown on  FIG. 1 , a renewable feedstock is initially fed to the processing system. The renewable feedstock can include animal fats, animal oils, vegetable fats, vegetable oils, plant fats, plant oils, rendered fats, restaurant grease, waste industrial frying oils, fish oil, and combinations thereof. It should be understood by one of ordinary skill in the art that other oils can be used so long as they are of a sufficient structure to be ultimately converted into the isoparaffinic product. In particular, the renewable feedstock includes triglycerides and free fatty acids. Triglycerides are esters of fatty acids and have a formula of CH 2  (OOCR 1 ) CH (OOCR 2 ) CH 2  (OOCR 3 ), where R 1 , R 2 , and R 3  are typically of a different chain length. Fatty acids have a formula of CH 3  (CH 2 ) x  COOH and contain 4 to 22 carbon atoms. 
     Referring now to the process embodiment of  FIG. 1 , renewable feedstock  101  is pressurized using pump  102  as stream  103  to a hydrotreater  109  operating pressure of about 1,000 to about 2,000 psig (with pressures as low as about 500 psig and as high as about 2,500 psig also within the embodiment operating range). The renewable feedstock liquid hourly space velocity through the hydrotreater  109  is preferably in the about 0.5 to about 5 h −1  range. The hydrotreater  109  catalyst is preferably a sulfided bimetallic catalyst such as NiW (nickel-tungsten), NiMo (nickel-molybdenum), and CoMo (cobalt-molybdenum) on alumina support. One suitable catalyst is sulfided NiMo on alumina. However, it should be understood that any catalyst may be used so long as the catalyst functions in accordance with the present invention as described herein. The catalyst may be in the oxide form and sulfided during startup, or pre-sulfided and active when loaded into the hydrotreater  109 . The liquid feedstock is then heated through a hydrotreater feed-effluent exchanger  104 . The heated feed  105  is combined with hot product  106  from hydroisomerizer reactor  148 . The diluted renewable feedstock  107  is then combined with hydrogen  108  before entering the hydrotreater  109 . Due to the high oxygen content and unsaturation level of the renewable feedstock, the exothermic hydrodeoxygenation and olefin hydrogenation reactions may result in a higher than desired adiabatic temperature rise. Quench hydrogen  110  may thus be used to maintain the hydrotreater temperature between about 500° F. to about 700° F. The gas to liquid ratio (renewable feed basis) for the hydrotreating reaction is in the about 2,000 to about 14,000 scf/bbl range. 
     The hydrotreater effluent  111  is subsequently cooled in exchanger  104 . A cooled stream  112  includes two phases. The vapor phase includes hydrogen, propane, carbon oxides, and water. The liquid phase is predominantly the middle distillate boiling range paraffin product. The vapor and liquid phases are separated in separator  113  as streams  114  and  128 , respectively. 
     The vapor phase  114  is cooled in air cooler  115  to condense the water. Wash water  114   a  may be introduced upstream to prevent scale formation in the cooler. A cooler outlet stream  116  includes liquid water, hydrogen/propane vapors, and condensed light hydrocarbons (mainly C3-C9 paraffins). These three phases are separated in drum  117 . Hydrogen-rich vapors  119  are recycled, a condensed hydrocarbon stream  129  is sent to the product recovery unit, and a water stream  118  is sent off-site for treatment prior to disposal or usage. 
     A liquid paraffin product  128  is combined with the condensed light hydrocarbon stream  129  to form a fractionation feed  130 . The fractionation feed  130  includes a debutanizer tower  133 , a naphtha stripper  138 , and a heavy paraffin recycle tower  141 . The fractionation feed  130  is preheated in exchanger  131 . The heated fractionation feed  132  is separated in the debutanizer tower  133  which is used to recover the LPG stream  136 . The effluent  137  from the debutanizer tower  133  is fed to the naptha stripper  138 . The naptha stripper  138  is used to separate naphtha as stream  139 . The high volatility, low flash point C5-C8 hydrocarbons are undesirable in jet fuel. The effluent  140  of the naptha stripper  138  is fed to the recycle tower  141 . The recycle tower  141  is used to separate the jet fuel  142  from the heavier paraffin stream  143 . In a preferred embodiment, the jet fuel  142  is mainly a C9-C15 isoparaffin composition, while the heavier stream  143  is a C16 +  n-paraffin composition. (For most renewable feedstocks wherein C16 and C18 fatty acids predominate, the heavy paraffin fraction is a C16-C18 composition; however, for renewable feedstocks with significant C20 and C22 fatty acids, such as peanut oil and rapeseed oil, respectively, the heavier paraffin stream may be a C16-C20 and a C16-C22 composition.) The distillation columns range in pressure from 200 psig (debutanizer tower  133 ) to atmospheric or even vacuum (heavy paraffin recycle tower  141 ). The corresponding operating temperatures are in the about 300° F. to about 650° F. range. All the distillation towers are equipped with condensers ( 134   a - c ) and reboilers ( 135   a - c ). The condensers may be water- or air-cooled. For the higher temperature tower  141 , super-heated steam injection may be used instead of a reboiler exchanger. It should also be noted that any two distillation columns with similar pressures may be combined and one of the products separated as a side-draw. Further, it should be understood that any such combination of columns may be utilized so long as the combination functions in accordance with the present invention described herein. 
     The heavy paraffins  143  are pumped using pump  144  as stream  145  to hydroisomerizer reactor pressure, preferably about 1,000 to about 2,000 psig, and combined with hydrogen  146 . The hydrogen containing heavier recycle stream  147  is then heated in heater  149  to the desired hydroisomerizer inlet temperature of about 580° F. to about 680° F. Suitable catalysts for the hydroisomerizer reactor  148  are bifunctional catalysts with hydrogenation and acidic functionalities. Such catalysts include Group VIII metals on amorphous (e.g., silica-alumina) or crystalline (e.g., zeolite) supports. One preferred hydroisomerization catalyst is platinum, palladium or combinations of same on an amorphous silica-alumina support. However, it should be understood that any catalyst may be used in accordance with the present invention so long as it functions as described herein. Preferred gas to liquid ratios are in the about 1,000 to about 10,000 scf/bbl range, and liquid hourly space velocity in the about 0.2 to about 5 h −1  range. The product of the mainly C15-C18 feed, stream  106 , is a C3-C18 isoparaffinic composition. This isoparaffinic product stream acts as a solvent/diluent for the hydrotreater feed. 
     Part of the hydrogen-rich vapor recycle stream  119  is purged as stream  120 . In some embodiments, the purge stream  120  is processed through a membrane separator to recover additional propane. The recycle hydrogen is processed through a purification unit  121  where ammonia, hydrogen sulfide, and carbon dioxide byproducts of hydrotreating are removed. Unit  121  may be a scrubber with an amine or caustic solvent. Clean hydrogen  122  is combined with makeup hydrogen  123  (pressurized through compressor  124 ) to form hydrogen stream  125 . Recycle compressor  126  supplies pressurized hydrogen  127  to both hydrotreater (stream  108 ) and hydroisomerizer (stream  146 ), including quench service ( 110  for hydrotreater and  146   b  for hydroisomerizer). 
     The resultant feedstock jet fuel meets aviation fuel cold flow properties. The jet fuel of the present invention, unlike its petroleum and synthetic jet fuel counterparts, such as Jet A-1, JP-8, and Fischer-Tropsch IPK Jet Fuel, has a lower viscosity, for example, a viscosity at about −20° C. of less than about 5 centistokes, with a higher isomer/normal mass ratio, as is detailed in Example 2. Table 1 summarizes the iso/normal ratio for each carbon group in the jet fuel composition of the present invention. The jet fuel composition of the present invention has an iso/normal ratio of about 3.0 to about 25.0. Typically, a higher isomer/normal mass ratio leads to a jet fuel product having a higher viscosity. That is not the case with the jet fuel of the present invention. It is believed that the lower viscosity of the jet fuel of the present invention is due to the distribution of the isomers in the isoparaffinic product as calculated by a nuclear magnetic resonance (NMR) apparatus. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Iso/Normal 
               
               
                   
                 Group 
                 Ratio by Group 
               
               
                   
                   
               
             
            
               
                   
                 C6 
                 0.25-2.0  
               
               
                   
                 C7 
                 2.0-3.0 
               
               
                   
                 C8 
                 2.0-3.0 
               
               
                   
                 C9 
                 2.0-3.5 
               
               
                   
                 C10 
                 3.0-4.5 
               
               
                   
                 C11 
                 4.0-5.0 
               
               
                   
                 C12 
                 4.5-5.5 
               
               
                   
                 C13 
                 4.5-6.0 
               
               
                   
                 C14 
                 4.5-6.0 
               
               
                   
                 C15 
                 5.0-6.5 
               
               
                   
                 C16 
                 10.0-22     
               
               
                   
                 C17 
                 11.0-22     
               
               
                   
                   
               
            
           
         
       
     
     The feedstock jet fuel of the present invention also has a higher flash point than that required for JP-8 and Jet A-1, a lower viscosity and freezing point, and a higher smoke point. The jet fuel is almost sulfur-free and produces a higher heat of combustion than JP-8 and Jet A-1. In particular, the jet fuel of the present invention has a flash point of greater than about 38° C. and greater than about 45° C. One embodiment of the jet fuel of the present invention has a boiling point range between about 150° C. and about 300° C., and a viscosity at about −20° C. of less than about 5 centistokes. The jet fuel of the present invention also has a heat of combustion of greater than about 42 MJ/kg and a smoke point of greater than about 25 mm. The jet fuel has a freezing point of less than about −47° C., less than about −50° C., and less than about −55° C. The jet fuel also has a sulfur content of less than about 5 ppm, preferably less than about 2 ppm. 
     Jet fuel is exposed to very low temperatures, both at altitude—especially on polar routes in wintertime—and on the ground at locations subject to cold weather extremes. Consequently, the fuel must retain its fluidity at these low temperatures or fuel flow to the engines will be reduced or even stop. Viscosity is a measure of a liquid&#39;s resistance to flow under pressure, generated either by gravity or a mechanical source. 
     As such, jet fuel must be able to flow freely from fuel tanks in the wings to the engine through an aircraft&#39;s fuel system. Fluidity is a general term that deals with the ability of a substance to flow, but it is not a defined physical property. Viscosity and freezing point are the physical properties used to quantitatively characterize the fluidity of jet fuel. 
     Jet fuel at high pressure is injected into the combustion section of the turbine engine through nozzles. This system is designed to produce a fine spray of fuel droplets that evaporate quickly as they mix with air. The spray pattern and droplet size are influenced by fuel viscosity. If the viscosity is too high, an engine can be difficult to relight in flight. For this reason, jet fuel specifications place an upper limit on viscosity. 
     Despite conforming to jet fuel specifications, the renewable isoparaffinic jet fuel of the present invention may need to be blended with conventional petroleum jet fuel for use in existing aircraft. Due to absence of aromatic components, the isoparaffinic jet fuel does not swell the nitrile rubber closure gaskets of the fuel tank. Without swelling of the closure gasket, a tight seal is not achieved and fuel may leak out. Blending with petroleum fuel addresses this issue. In the present invention, the blended jet fuel composition is from about 0.01% to about 99% by volume and the balance being from at least one non-renewable source. 
     In order to further illustrate the present invention, the following examples are given. However, it is to be understood that the examples are for illustrative purposes only and are not to be construed as limiting the scope of the subject invention. 
     EXAMPLES 
     Example 1 
     Process of Making a Jet Fuel from Renewable Sources 
     The present example demonstrates how a jet fuel was made from a renewable feedstock. A 100 cc isothermal tubular reactor was filled with 80 cc of Criterion  424  Ni—Mo catalyst and +70-100 mesh glass beads. The catalyst was sulfided with dimethyl disulfide at two hold temperatures: 6 hours at 400° F. and 12 hrs at 650° F. Hydrogen sulfide break-through was confirmed before the temperature was raised from 400° F. to 650° F. at 50° F./hr. After sulfiding, the reactor was cooled to 400° F. 
     Next a triglyceride/fatty acid feed was introduced to the isothermal reactor. The reactor was slowly heated to 650° F. to achieve full conversion of the triglyceride/fatty acid feed to n-paraffins. The reactor temperature was further increased to 700° F. to maintain good catalyst activity at 80 cc/hr feed rate (1 LHSV). 
     The total liquid hydrocarbon (TLH) from the hydrotreater was then hydroisomerized to jet fuel using the conditions summarized in the last column of Table 2 to produce an isoparaffinic product useful as jet fuel. The hydrotreater performance with beef tallow as the triglyceride/fatty acid feed is also summarized in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Hydrotreater and Hydroisomerizer Operating 
               
               
                 Conditions and Conversion Performance 
               
            
           
           
               
               
               
            
               
                   
                 Hydrotreater 
                 Hydroisomerizer 
               
               
                   
                   
               
            
           
           
               
               
            
               
                 Catalyst 
                   
               
            
           
           
               
               
               
            
               
                 Active Metals 
                 Sulfided Ni/Mo 
                 Pt/Pd 
               
               
                 Support 
                 Alumina 
                 Alumina/silica 
               
            
           
           
               
               
            
               
                 Reactor Conditions 
                   
               
            
           
           
               
               
               
            
               
                 Feed 
                 Inedible tallow 
                 TLH from inedible tallow 
               
               
                   
                   
                 hydrotreating 
               
               
                 Temperature (F.) 
                 700 
                 685 
               
               
                 Pressure (psig) 
                 1,200 
                 1,000 
               
               
                 Gas/Oil Ratio (scf/bbl) 
                 14,000 
                 10,000 
               
               
                 LHSV 
                 1 
                 0.75 
               
            
           
           
               
               
            
               
                 Products (wt % feed basis) 
                   
               
            
           
           
               
               
               
            
               
                 C1 + C2 
                 1.5 
                 0.13 
               
               
                 LPG (C3 + C4) 
                 6.1 
                 8.6 
               
               
                 Water 
                 5.3 
                 0 
               
               
                 Total Liquid Hydrocarbons 
                 88.2 
                 91 
               
               
                 (TLH) 
               
               
                   
               
            
           
         
       
     
     Example 2 
     The hydrotreated effluent was analyzed using a gas chromatogram. In particular, the total liquid hydrocarbon (TLH) from the hydrotreater reaction of Example 1 was analyzed to confirm triglyceride conversion, and quantify cracking to light ends. 
     The gas chromatogram utilized the following materials: 
     Materials: 
     Analytical Balance, capability to 0.1 mg 
     Carbon Disulfide, High Purity 
     Custom Alkane Standard—Restek Cat #54521 
     Pasteur Pipette with bulb 
     HP 5860 Gas Chromatograph—FID 
     GC Column, Restek—Rtx—1 MS, Cat #11624 
     Helium Gas—Alpha Gas 
     Hydrogen Gas—Alpha Gas 
     Zero Air Gas—Alpha Gas 
     Sharpie 
     GC Vials and Caps 
     The gas chromatogram was operated under the following conditions: 
     Runtime 82 minutes 
     Injection Volume 1-pL 
     Inlet Temperature 320° C. 
     Detector Temperature 350° 
     Oven:
         Initial Temperature 35° C.   Rate (° C./min) 5.00   Equilibrate Time 0.20 min   Final Temperature 320° C.   Final Time (min) 25.0
 
As observed in the chromatogram of  FIG. 2 , virtually no triglycerides or cracked products were present in the TLH. Note the areas circled.
       

     Example 3 
     Jet Fuel from Renewable Sources 
     The resultant jet fuel and the isoparaffinic product from Example 1 was analyzed and compared to similar products. The feedstock jet fuel was found to have a cloud point of −53° C. 
     The composition of the isoparaffinic product was analyzed via Gas Chromatograph and is summarized in Table 3. A key property to observe is iso/normal ratio. The procedure employed to determine iso/normal ratio is shown below. As indicated by Table 3 data, the hydroisomerizer product may be fractionated to the desired jet fuel boiling range. Such separation was performed using standard lab distillation apparatus. The comparable properties of Fischer-Tropsch IPK jet fuel distillate are summarized in Table 5. As observed from Table 4, the renewable jet fuel of this invention met or exceeded all key specifications of commercial jet fuel. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Carbon Number Distribution and Iso/Normal 
               
               
                 Ratio of Hydroisomerizer Product 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Iso/Normal 
                 Normal 
               
               
                   
                   
                   
                 Isomer 
                 Normal 
                 Ratio by 
                 Mass % 
               
               
                 Group 
                 MW 
                 Mass % 
                 Mass % 
                 Mass % 
                 Group 
                 by Group 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 C6 
                 86.2 
                 0.8% 
                 0.0% 
                 0.8% 
                 0.00 
                 100.0 
               
               
                 C7 
                 100.2 
                 3.9% 
                 2.6% 
                 1.3% 
                 2.07 
                 32.6 
               
               
                 C8 
                 114.2 
                 6.6% 
                 4.9% 
                 1.7% 
                 2.87 
                 25.9 
               
               
                 C9 
                 128.3 
                 9.3% 
                 7.4% 
                 1.9% 
                 3.97 
                 20.1 
               
               
                 C10 
                 142.3 
                 11.5% 
                 9.7% 
                 1.7% 
                 5.57 
                 15.2 
               
               
                 C11 
                 156.3 
                 12.5% 
                 11.0% 
                 1.5% 
                 7.41 
                 11.9 
               
               
                 C12 
                 170.3 
                 12.1% 
                 10.9% 
                 1.3% 
                 8.71 
                 10.3 
               
               
                 C13 
                 184.4 
                 10.4% 
                 9.5% 
                 0.9% 
                 10.41 
                 8.8 
               
               
                 C14 
                 198.4 
                 8.5% 
                 7.6% 
                 0.9% 
                 8.86 
                 10.1 
               
               
                 C15 
                 212.4 
                 9.5% 
                 8.4% 
                 1.1% 
                 7.75 
                 11.4 
               
               
                 C16 
                 226.5 
                 8.5% 
                 7.7% 
                 0.7% 
                 10.50 
                 8.7 
               
               
                 C17 
                 240.5 
                 5.3% 
                 5.0% 
                 0.3% 
                 15.98 
                 5.9 
               
               
                 C18 
                 254.5 
                 1.1% 
                 1.1% 
                 0.0% 
                 23.91 
                 4.0 
               
            
           
           
               
               
               
               
               
               
            
               
                 TOTAL 
                 100.0% 
                 85.9% 
                 14.1% 
                 6.12 
                   
               
               
                 Narrow Jet 
                 73.8% 
                 64.6% 
                 9.2% 
                 7.01 
               
               
                 (C9-C15) 
               
               
                 Broad Jet 
                 88.9% 
                 77.2% 
                 11.7% 
                 6.62 
               
               
                 (C8-C16) 
               
               
                   
               
            
           
         
       
     
     The iso/normal ratio is derived by processing GC data. Data is first captured from the chromatogram, then it is compared to standard libraries. Next, the amount of normal paraffin present for each carbon number was calculated. Then, the amount of iso-paraffin present for each carbon number was calculated. Finally, the ratio for each carbon number was calculated. 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Jet Fuel Properties of Example Bio-jet Product Compared 
               
               
                 to Other Synthetic Jet Fuels and Industry Specifications 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                 ASTM D 1655 
                 MIL-3133E 
                 Fischer-Tropsch 
                 Example Bio- 
               
               
                 Property 
                 Units 
                 Jet A-1 
                 JP-8 
                 IPK Jet Fuel 
                 Jet Product 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Flash Point 
                 ° C. 
                 38 
                 min. 
                 38 
                 min. 
                 46 
                 47 
               
               
                 Distillation EP 
                 ° C. 
                 300 
                 max. 
                 300 
                 max. 
                 280 
                 275 
               
               
                 Viscosity 
                 cSt 
                 8.0 
                 max. 
                 8.0 
                 max. 
                 5.5 
                 4.58 
               
               
                 @ −20° C. 
               
               
                 Freezing Point 
                 ° C. 
                 −47 
                 max. 
                 −47 
                 max. 
                 −48 
                 −55 
               
            
           
           
               
               
               
               
               
               
            
               
                 Density 
                 g/ml 
                 0.775-0.840 
                 0.775-0.840 
                 0.76 
                 0.76 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Heat of 
                 MJ/kg 
                 42.8 
                 min. 
                 42.8 
                 min. 
                 43.8 
                 44.2 
               
               
                 Combustion 
               
               
                 Smoke Point 
                 Mm 
                 25 
                 min. 
                 25 
                 min. 
                 &gt;50 
                 33.4 
               
               
                 Sulfur 
                 ppm 
                 3,000 
                 max. 
                 3,000 
                 max. 
                 &lt;1 
                 1.2 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Hydrogen 
                 Mass % 
                 none 
                 13.4 
                 min. 
                 15.4 
                 15.3 
               
            
           
           
               
               
               
               
               
               
            
               
                 Color (Saybolt) 
                 — 
                 none 
                 report 
                 +30 
                 +30 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Carbon Number Distribution and Iso/Normal 
               
               
                 Ratio of Fischer-Tropsch IPK Jet Fuel 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                   
                   
                   
                   
                 Iso/Normal 
                 Normal 
               
               
                   
                   
                   
                 Isomer 
                 Normal 
                 Ratio by 
                 Mass % 
               
               
                 Group 
                 MW 
                 Mass % 
                 Mass % 
                 Mass % 
                 Group 
                 by Group 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 C6 
                 86.2 
                 0.0% 
                 0.0% 
                 0.0% 
                 0.59 
                 62.9 
               
               
                 C7 
                 100.2 
                 0.6% 
                 0.4% 
                 0.2% 
                 2.16 
                 31.7 
               
               
                 C8 
                 114.2 
                 1.9% 
                 1.3% 
                 0.6% 
                 2.13 
                 32.0 
               
               
                 C9 
                 128.3 
                 7.2% 
                 4.8% 
                 2.4% 
                 2.02 
                 33.2 
               
               
                 C10 
                 142.3 
                 17.8% 
                 13.9% 
                 3.9% 
                 3.57 
                 21.9 
               
               
                 C11 
                 156.3 
                 20.2% 
                 16.4% 
                 3.9% 
                 4.25 
                 19.1 
               
               
                 C12 
                 170.3 
                 17.1% 
                 14.2% 
                 2.9% 
                 4.88 
                 17.0 
               
               
                 C13 
                 184.4 
                 15.2% 
                 12.8% 
                 2.4% 
                 5.46 
                 15.5 
               
               
                 C14 
                 198.4 
                 10.8% 
                 9.0% 
                 1.8% 
                 4.89 
                 17.0 
               
               
                 C15 
                 212.4 
                 6.3% 
                 5.3% 
                 1.0% 
                 5.41 
                 15.6 
               
               
                 C16 
                 226.5 
                 2.6% 
                 2.4% 
                 0.1% 
                 21.33 
                 4.5 
               
               
                 C17 
                 240.5 
                 0.4% 
                 0.4% 
                 0.0% 
                 11.77 
                 7.8 
               
               
                 C18 
                 254.5 
                 0.0% 
                 0.0% 
                 0.0% 
               
               
                   
               
            
           
         
       
     
     Thus, there has been shown and described a method for producing a jet fuel or LPG product from a renewable source and the resultant product that fulfills all objectives and advantages sought therefore. 
     The invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. Further review of the two jet fuels reveals that they are very similar in average carbon number (11.8 and 12.0 for the FT and renewable, respectively). Also, in the case of the FT jet fuel, the hydroisomerization conditions were 703° F. catalyst average temperature, LHSV of 0.83/hr (fresh feed basis) and G/O ratio of 3,000 SCF/BBL with overall system pressure of about 986 psig with the same catalyst (Pt/Pd on alumina/silica). It is surprising that the processing conditions of the present invention resulted in substantially different low temperature property performance; that is, that the renewable jet fuel would have had lower viscosity than the FT jet fuel product based upon the difference in processing conditions. 
     From the above description, it is clear that the present invention is well-adapted to carry out the objects and to attain the advantages mentioned herein, as well as those inherent in the invention. While presently preferred embodiments of the invention have been described for purposes of this disclosure, it will be understood that numerous changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the invention disclosed and claimed. 
     Those skilled in the art will appreciate that variations from the specific embodiments disclosed above are contemplated by the present invention. Specifically, the improvement in cold-flow performance of the renewable jet fuel was not anticipated based upon extensive experience with Fischer-Tropsch feedstocks. The typical Fischer-Tropsch feedstock to a hydroisomerization process is about 85-99 wt % normal paraffin. The feedstock to the renewable isomerization process is &gt;95 wt % normal paraffin. The distribution of isomers and the nature of the branching in those isomers (as indicated by NMR) is different for the renewable feedstock versus the Fischer-Tropsch feedstock. The invention should not be restricted to the above embodiments, but should be measured by the following claims.