Presentation on theme: "Sterol Glucosides in Biodiesel"— Presentation transcript:
1Sterol Glucosides in Biodiesel Haiying Tang, Steven O. Salley, andK. Y. Simon NgNational Biofuels Energy LaboratoryNextEnergy/Wayne State UniversityDetroit, MI 48202
2OutlineChemical structure and physical properties of sterol glucosidesPrecipitates formation above cloud point in Soy-, Cottonseed-, and Poultry Fat-based Biodiesel Blends“Filter-Blocking Tendency ” test and cold soak filtrationAnalysis methodTypical processing technique for oil refiningPossible techniques to remove sterol glucosidesConclusion
4Sterol composition in seed oil (mg/kg) PalmSoybeanRapeseedCottonseedCorn oilSafflowerSunflowerβ-sitosterol1894190835493961772218092352campesterol35872015301702691452313stigmasterol20442702Δ5-avenasterol511081228546835156Δ7-stigmastenol25306-117696588other2636612173195Net % in oil0.26%0.36%0.61%0.43%1.18%0.35%0.39%Data From Gunston ed al, The lipid handbook, 1994
5Chemical Structure of Sterols Phytosterols mainly include campesterol, β-sitosterol, stigmasterol, Δ5-avenasterol, Δ7-stigmastenol, and brassicasterol.
6What 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
7Biodiesel Reaction- Base Transesterification 100 lbs of oil +10 lbs methanol lbs of biodiesel +10 lbs of glycerol
9Physical Properties of Free Sterol Glucosides Powdery solid, melting point °CLimited solubility in most organic solvents except pyridine, chloroform/methanol (2:1)Soluble in fresh biodiesel.
10Typical Concentration of SG in Biodiesel (ppm) FeedstockSG 1SG 2β-sitosterolTotal sterolSoy #1 Crude Grade2727819083600Soy #2 Degummed Grade54Soy #3 Refined Grade190Soy #4 (processed poorly)25Cottonseed oil #1221039614258Cottonseed oil #28Corn oil48045772211700Palm oil14111818942558Safflower Crude Grade1418093478Sunflower1823523917CanolaData 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.
11Precipitates Formation above Cloud Point in Soy-, Cottonseed-, and Poultry Fat-based Biodiesel Blends
12Cold Flow Properties: a current issue with biodiesel 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.
13ASTM Test MethodsCold–flow properties: traditional petroleum wax precipitationCloud 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 oxygenASTM D 2274 (Accelerated Method): Oxidation Stability of Distillate Fuel (95 ºC for 16 h).ASTM D 4625: Storage Stability of Middle Distillate, Petroleum (43 ºC for selected periods up to 24 weeks).
14Filtration system from ASTM D4625-04 ExperimentalSamples:SBO-, CSO-, and PF- based biodieselULSD, B2, B5, B10, B20, B50, B70, and B100300 mL volumeStorage Temperature and Time-15 ºC for 24 hr4 ºC for 24 hr23 ºC for 24 hr (Control)Allow to come to room temperaturewithout external heatingFilterVacuum pump: ~68 kpa0.7 mm glass fiber filterFiltration system from ASTM D
16Physical Appearance (at 4 ºC for 24 hours) SBO-based BiodieselULSDULSDULSDB2B10B5B20B50B70B100
17Physical Appearance (at -15ºC for 24 hours) B10ULSDB2B5B20B50B70B100
18Optical Images of Precipitates 50X200XTaken from B20 SBO-based biodiesel
19Time to Filter Vs. Temperature SBO-based biodiesel
20Insolubles 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.
21Insolubles 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.B100B20
22Insolubles 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.
23Cloud Point, Pour Point, and Cold Filter Plugging Point The CFPP may indicate relative extent of the insolubles formation at low temperature.
24Nature 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.
25Distilled and Oxidized Biodiesel 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;Distillated SBO-B20Oxidative Biodiesel Blends
26Nature of Insolubles: FTIR Spectra -CH2-CH2-OHC-O-CInsolubles from SBO-B100Insolubles from SBO-B20Insolubles fromCSO-B100Insolubles from CSO-B50Standard Sterol Glucosides
27Nature of Insolubles: GC-FID Chromatograms Insolubles from CSO-B100Insolubles from SBO-B100Internal StandardStandard Sterol GlucosidesThree kinds of Sterol Glucosides
28GC-FID Chromatogram (Continued) Precipitates from PF-B100Standard Glycerides
29Summary 1Storage 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 Tests300ml of fuel at 20ml/minFilterASTM D2068/IP3871.6 micronResult calculated based on pressure and volume measured during the test.
31Filter-blocking tendency (FBT) Effect of SG on FBTSG content (ppm)Filter-blocking tendency (FBT)22 (Control)1.05 (pass)321.47 (fail)522.90 (fail)7215.03(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.
32Biodiesel Cold Soak Filtration Storage temperature and time4 ºC (refrigerator)16 hoursAllow sample to come to the room temperature (23 ºC to 24 ºC )FilterVacuum pump: 22.5 inches Hg (~76.2 Kpa)Whatman 47 mm GF/F, 0.7 mm.
35Different Feedstocks of Biodiesel 1234567FeedstockCanolaSoyAnimal FatImprSoyDist SoyPalm
36Analysis of Sterol Glucosides The presence of sterol glucosides in biodiesel residues has been confirmed using FTIR and GC-FIDQualification will be evaluated by GC- FID, HPLC, and FTIR with purchased known standards
37Preliminary results :GC-FID Chromatograms sitosterol glucosidestigmasterol glucosidecampesterol glucosidePrecipitates from REGPrecipitates from NextdieselStandard sterol glucosides
38Process of Crude Soybean Oil to Food-grade Oil Chemical refiningWater degummingChemical neutralizationBleachingDeodorizationPhysical refiningAcid degummingRefiningWater degummingCaustic refiningBleachingDeodorization
39Conventional RBD Process Phospholipids and gums Phosphoric acidNaOHBleaching claysSteam vacuumCRUDE OILCHEMICAL NEUTRALIZATIONBLEACHINGDEODORIZATION(Distillation)WATER DEGUMMINGREFINED OILPhospholipids and gumsFree fatty acidsPigmentsTrace componentReduce portion of free sterolsReduce portion of free sterolsRemove portion of SG
40Average Composition for Crude and Refined Soybean oil Data from Van Gerpen, J.; Biodiesel production technology, 2004
41Process techniques to remove SG Filtering: removal of particulate from media with a steel screen, cartridge or filter paperEffect of filter pore sizesEffect of filter typesCold filtering: holding the biodiesel at a lower temperature for desired time before the filtering process. Effects of cold filter temperatureEffect of storage timeParticle
42Preliminary Results: Effect of temperature on removing particles with filtration ppm23 ºC4 ºC-15 ºCULSD0.91.43B21.231.672.57B53.94.23B106.67B201.577.774.57B502.231422.33B703.3319.2320.77B1005.7184.108.40.2062.574.236.674.5722.3320.7732.23Cold filtration is better to remove particles than room temperature filtration
43Preliminary Results: Effect of storage time on removing particles with cold filtration (4 ºC ) ppmB100B205.671.671 hr-32 hr3.334.834 hr5.838 hr57.3320 hr13.677.1724 hr11.678.53 days309.331 weeks4014.332 weeks4325.17Longer storage time in cold soak test could more effective to remove particles in biodiesel.1.6734.835.836.837.3220.127.116.1114.3325.17
44Process techniques to remove SG (Con.) Adsorbent treatment:Removal of particulate with a porous pad or a “cake” of filter-aid-type materialsDiatomaceous earth (DE)MagnesolCarbonMagnesium silicateAct as deep filtrationEffect of concentrationEffect of incubation timeEffect of temperatureMix TankFilterFinished product tankUntreated BiodieselAdsorbent
45SG content of biodiesel after incubation and filtering through DE Incubation temperature (ºC)Incubation timeSG content (ppm)(FBT)5415.03 (fail)46 hr221.2 (pass)12 hr25-1027211 day192 days16.293 days17.29Data from Lee et al. Processes of producing biodiesel and biodiesel produced therefrom; Patent application publication, 2007.
46Process techniques to remove SG (Con.) Water degumming: a basic process to wash biodiesel product to remove contaminantsEffect of water ratioEffect of mixing temperatureVacuum distillation: an energy intensive technique for biodiesel processingEffect of temperatureEffect of pressure
47Preliminary Result: GC-FID Chromatography Sterol glucosidesSBO-biodieselGlycerolPrecipitates from SBO-biodieselDistillated SBO-biodiesel
49Future WorkEvaluate and develop processing strategies to reduce sterol glucosides content in biodiesel;Develop a robust analytical method to determine the sterol glucosides content in biodiesel.In the next steps, we will