Presentation on theme: "1 Sterol Glucosides in Biodiesel Haiying Tang, Steven O. Salley, and K. Y. Simon Ng National Biofuels Energy Laboratory NextEnergy/Wayne State University."— Presentation transcript:
1 Sterol Glucosides in Biodiesel Haiying Tang, Steven O. Salley, and K. Y. Simon Ng National Biofuels Energy Laboratory NextEnergy/Wayne State University Detroit, MI 48202
2 Outline Chemical structure and physical properties of sterol glucosides Precipitates formation above cloud point in Soy-, Cottonseed-, and Poultry Fat-based Biodiesel Blends “Filter-Blocking Tendency ” test and cold soak filtration Analysis method Typical processing technique for oil refining Possible techniques to remove sterol glucosides Conclusion
4 Sterol composition in seed oil (mg/kg) CompositionPalmSoy bean RapeseedCottonseedCorn oil SafflowerSunflower β-sitosterol campesterol stigmasterol Δ5- avenasterol Δ7- stigmastenol other Net % in oil0.26 % 0.36 % 0.61%0.43%1.18%0.35%0.39% Data From Gunston ed al, The lipid handbook, 1994
5 Chemical Structure of Sterols Phytosterols mainly include campesterol, β-sitosterol, stigmasterol, Δ5-avenasterol, Δ7-stigmastenol, and brassicasterol.
6 What is Sterol Glucoside in Biodiesel? Sterol Glycosides occurs naturally in vegetable oils, mainly as soluble fatty acid esters ; Usually, the acyl sterol glycosides at concentrations are two to ten fold greater than those of the non-acylated forms; Hydrolyzed during transesterification process and become insoluble. β-sitosterol glucoside is the most typical sterol glucoside. β-sitosterol glucosides
7 Biodiesel Reaction- Base Transesterification 100 lbs of oil +10 lbs methanol 100 lbs of biodiesel +10 lbs of glycerol
9 Physical Properties of Free Sterol Glucosides Powdery solid, melting point °C Limited solubility in most organic solvents except pyridine, chloroform/methanol (2:1) Soluble in fresh biodiesel.
10 Typical Concentration of SG in Biodiesel (ppm) FeedstockSG 1 SG 2 β-sitosterolTotal sterol Soy #1 Crude Grade Soy #2 Degummed Grade54 Soy #3 Refined Grade190 Soy #4 (processed poorly)25 Cottonseed oil # Cottonseed oil #28 Corn oil Palm oil Safflower Crude Grade Sunflower Canola18 Data from 1 Ringwald SC. Biodiesel characterization in the QC environment; 2 Pfalzgraf et al, Identification of sterol glucosides in biodiesel and their effect on filterability.
11 Precipitates Formation above Cloud Point in Soy-, Cottonseed-, and Poultry Fat-based Biodiesel Blends
12 Precipitates formation in biodiesel blends may have serious implications. –Clogging of fuel filters. –Formation of deposits on engine parts such as injectors and other critical fuel system components. Cold Flow Properties: a current issue with biodiesel
13 Cold–flow properties: traditional petroleum wax precipitation –Cloud point (CP, ASTM 2500): at which crystallization begins. –Pour point (PP, ASTM 97): at which the fuel no longer will pour. –Cold filter plugging point (CFPP, ASTM 6371): at which fuel starts to plug a fuel filter. Total insoluble: high temperature in the presence of oxygen – ASTM D 2274 (Accelerated Method): Oxidation Stability of Distillate Fuel (95 º C for 16 h). –ASTM D 4625: Storage Stability of Middle Distillate, Petroleum (43 º C for selected periods up to 24 weeks). ASTM Test Methods
14 Experimental Samples: SBO-, CSO-, and PF- based biodiesel ULSD, B2, B5, B10, B20, B50, B70, and B100 300 mL volume Storage Temperature and Time -15 º C for 24 hr 4 º C for 24 hr 23 º C for 24 hr (Control) Allow to come to room temperature without external heating Filter Vacuum pump: ~68 kpa 0.7 m glass fiber filter Filtration system from ASTM D
15 Physical Appearance ( at 23 ºC for 24 hours ) SBO-based Biodiesel ULSDB5B10 B20B50B70 B100 B2
18 Optical Images of Precipitates 50X200X Taken from B20 SBO-based biodiesel
19 Time to Filter Vs. Temperature SBO-based biodiesel
20 Insolubles Mass Vs. Temperature No significant mass of “new” insolubles as result of blending at 23 ºC ; Significant effect at 4 ºC; Above the cloud point insolubles are very different in nature as compared to the normal wax-crystal like insolubles formed below cloud point.
21 Insolubles Mass Vs. Time Different mechanisms for the insolubles formation from B20 and B100; For B20, the relatively fast appearance of insolubles can be attributed to a solvency effect. B100 B20
22 Insolubles Mass Vs. Feedstock CSO- and PF- based biodiesel had lower insolubles levels than the SBO-based biodiesel; The difference may be attributed to the presence of naturally occurring levels of sterol glucosides in the feedstocks.
23 Cloud Point, Pour Point, and Cold Filter Plugging Point The CFPP may indicate relative extent of the insolubles formation at low temperature.
24 Nature of Insolubles Possibilities Sterol glucosides: Soluble within vegetable oil; however, hydrolyzed during transesterification process and become insoluble. Monoglycerides, diglycerides, triglycerides of total glycerin; Dimers, trimers, tetramers of oxidative products; Solvency effect when blended with ULSD.
25 Distilled and Oxidized Biodiesel Oxidative Biodiesel Blends Distillated SBO-B20 After cold soak test, no insoluble was observed in distilled or oxidized B100, or even in B20; Insolubles formation is due to minor component; Insolubles formation is not due to oxidized product. The nature of “the above cloud point insolubles” formation is different from the oxidized insolubles observed in the high temperature stability test of biodiesel;
26 Nature of Insolubles: FTIR Spectra Insolubles from SBO-B100 Insolubles from SBO-B20 Insolubles fromCSO-B100 Insolubles from CSO-B50 Standard Sterol Glucosides -OH -CH 2 C-O-C
27 Nature of Insolubles: GC-FID Chromatograms Insolubles from CSO-B100 Insolubles from SBO-B100 Standard Sterol Glucosides Internal Standard Three kinds of Sterol Glucosides
28 GC-FID Chromatogram (Continued) Standard Glycerides Precipitates from PF-B100
29 Summary 1 Storage temperature, storage time, biodiesel blend level, and feedstock affect the mass of insolubles formed; Solvency of ULSD has a significant influence on insolubles formation; Insolubles from SBO- and CSO-based biodiesel are due to sterol glucosides. However, the insolubles from PF-based biodiesel can be attributed to glycerides.
30 “Filter-Blocking Tendency ”Test Tests –300ml of fuel at 20ml/min –Filter ASTM D2068/IP micron –Result calculated based on pressure and volume measured during the test.
31 Effect of SG on FBT SG content (ppm)Filter-blocking tendency (FBT) 22 (Control)1.05 (pass) (fail) (fail) (fail) Adding SG to biodiesel caused it to fail to the FBT test; SG presence at high enough levels could potentially cause filter problems. Data from Lee et al. The role of sterol glucoside on filter plugging, Biodiesel Magazine 2007.
32 Biodiesel Cold Soak Filtration Storage temperature and time –4 ºC (refrigerator) –16 hours Allow sample to come to the room temperature (23 ºC to 24 ºC ) Filter –Vacuum pump: 22.5 inches Hg (~76.2 Kpa) –Whatman 47 mm GF/F, 0.7 m.
34 Biodiesel Cold Soak Filtration
35 Different Feedstocks of Biodiesel Biodiesel FeedstockCanolaSoyAnimal Fat Impr Soy Dist Soy PalmSoy
36 Analysis of Sterol Glucosides The presence of sterol glucosides in biodiesel residues has been confirmed using FTIR and GC-FID Qualification will be evaluated by GC- FID, HPLC, and FTIR with purchased known standards
37 Precipitates from REG Standard sterol glucosides Precipitates from Nextdiesel campesterol glucoside stigmasterol glucoside sitosterol glucoside Preliminary results :GC-FID Chromatograms
38 Process of Crude Soybean Oil to Food-grade Oil Refining Water degumming Caustic refining Bleaching Deodorization Chemical refining –Water degumming –Chemical neutralization –Bleaching –Deodorization Physical refining –Acid degumming –Bleaching –Deodorization
39 CRUDE OIL WATER DEGUMMING CHEMICAL NEUTRALIZATION DEODORIZATION (Distillation ) BLEACHING Bleaching clays Steam vacuum Phospholi pids and gums Phosphoric acid Remove portion of SG NaOH Free fatty acids Reduce portion of free sterols Pigments Reduce portion of free sterols Trace component REFINED OIL Conventional RBD Process
40 Average Composition for Crude and Refined Soybean oil Data from Van Gerpen, J.; Biodiesel production technology, 2004
41 Process techniques to remove SG Filtering: removal of particulate from media with a steel screen, cartridge or filter paper Effect of filter pore sizes Effect of filter types Cold filtering: holding the biodiesel at a lower temperature for desired time before the filtering process. Effects of cold filter temperature Effect of storage time Particle
42 Preliminary Results: Effect of temperature on removing particles with filtration ppm 23 º C4 º C-15 º C ULSD B B B B B B B Cold filtration is better to remove particles than room temperature filtration
43 Preliminary Results: Effect of storage time on removing particles with cold filtration (4 º C ) ppmB100B hr-3 2 hr hr hr hr hr days weeks weeks Longer storage time in cold soak test could more effective to remove particles in biodiesel.
44 Process techniques to remove SG (Con.) Adsorbent treatment: Removal of particulate with a porous pad or a “cake” of filter-aid-type materials Diatomaceous earth (DE) Magnesol Carbon Magnesium silicate Act as deep filtration Effect of concentration Effect of incubation time Effect of temperature Mix Tank Filter Finished product tank Untreated Biodiesel Adsorbent
45 SG content of biodiesel after incubation and filtering through DE Incubation temperature ( º C) Incubation time SG content (ppm) (FBT) (fail) 46 hr221.2 (pass) 412 hr hr day days days Data from Lee et al. Processes of producing biodiesel and biodiesel produced therefrom; Patent application publication, 2007.
46 Process techniques to remove SG (Con.) Water degumming: a basic process to wash biodiesel product to remove contaminants Effect of water ratio Effect of mixing temperature Vacuum distillation: an energy intensive technique for biodiesel processing Effect of temperature Effect of pressure
49 Future Work Evaluate and develop processing strategies to reduce sterol glucosides content in biodiesel; Develop a robust analytical method to determine the sterol glucosides content in biodiesel.