Going Green: The Analysis of BioFuels

Transcription

1 Going Green: The Analysis of BioFuels Miles S Snow Sr. Product Specialist PerkinElmer LAS miles.snow@perkinelmer.com What is Biodiesel?? Biodiesel is a clean burning alternative fuel, produced from domestic, renewable resources. Soy bean, rapeseed, palm oil, Rendered animal byproducts, Reclaimed cooking oil Biodiesel contains no petroleum, but it can be blended at any level with petroleum diesel to create a biodiesel blend. (B20) Biodiesel is simple to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics. Biodiesel can be a direct replacement for petroleum-based diesel with little or no modification to diesel engines Up to B20 typically requires no modification B100 requires slight modification and has poor cold weather flow characteristics Page 2

2 Page 3 Sources of BioDiesel Bio-lipids: Rapeseed soybean, mustard, palm oils, algae Waste vegetable oils Animal fats, by-products from the production of Omega-3-fatty acids from fish oil Soybeans Rapeseeds Fruit of Palm Algae Biodiesel Specifications / Methods Characteristic Specification Standard Method Esters / Linolenic Acid Ester Sulfur 50 mg/kg D5453 Sulfated ash 0.020% mass D874 Carbon residue 0.050% mass D4530 Water and sediment 0.050% vol D2709 Phosphorus content 10 mg/kg D4951 Free Glycerin Glycerol total 0.020% mass 0.250% mass EN D6584 EN14105 Metals monovalent, di-valent 5 mg/kg EN14108 EN14109 EN14538 Alcohol 0.20% mass EN14110 = GC based test method = ICP/OES based method Page 4

3 Page 5 Biodiesel Production Catalyst Methanol Catalyst Mixing Purification Methanol Recovery Quality Control Methyl Ester Vegetable Oil, Cooking Oils, Animal Fats Transesterification Recycled Methanol Pharmaceutical Grade Glycerin Crude Biodiesel Glycerin Purification Neutralizing Acid Neutralization Phase Separation Reneutralization Methanol Recovery Crude Glycerin Transesterification Mechanism Transesterification: exchanging the alkoxy group of the ester by another alcohol. These reactions are often catalyzed by the addition of an acid or base O = R 1 COCH 2 CH 2 OH R 2 COCH + 3 CH 3 OH catalyst COCH 3 + HOCH methanol FAME CH 2 OH R 3 COCH 2 glycerol O = O = tri-glycerides O = Reaction proceeds in the presence of KOH or NaOH base Page 6

4 Page 7 Production basics. Stock + Methanol + catalyst = Biodiesel + glycerin + residual methanol Water wash 4-6 times to remove glycerin, methanol and catalyst Complete Reaction is a MUST!!! Complete wash is a MUST!!! Unreacted/ partially reacted oil and residual glycerin will cause injector coking and filter plugging Excess Catalyst Injector deposits and filter plugging Excess Alcohol Incompatibility with gaskets and polymers, cleans the fuel system, carrying deposits to the filter, corrosion Ethanol can be used to create ethyl ester, but methanol is most common The Importance of Quality. Acceptance of biodiesel into the market place is critical to success, the biggest hurdle to overcome is ensuring ONLY high quality biodiesel is available for sale Final product cannot be SOLD as fuel until it passes ASTM D6751. It can be used for private use. Two serious problems have been encountered with poor quality biodiesel- filter plugging and poor cold flow characteristic Testing final product before use is the only way to determine functionality in the market. Quality can only be determined through laboratory testing Manufacturers must make a commitment to QUALITY Page 8

5 Page 9 Biodiesel Specifications and Testing There are standards agencies involved in setting specifications- ASTM- American Society for Testing and Materials and CEN- European Committee for Standardization ASTM has published Specification- D Standard Specification for Biodiesel Fuel (B100) Blend Stock for Distillate Fuels Only biodiesel conforming to a standard should be considered acceptable for use ASTM D-6751 Property Flash Point Water & Sediment Kinematic Viscosity Sulfated Ash Sulfur Copper Strip Corrosion Cetane Cloud Point Carbon Residue 100% sample Acid Number Free Glycerin Total Glycerin Phosphorus Content Distillation Temp, Atmospheric Equivalent Temperature, 90% Recovered ASTM Method D93 D C/D445 D874 D5453 D130 D613 D2500 D4530** D664 D6584 D6584 D4951 D 1160 Limits 130 min. o C max. % vol mm 2 /sec max. % mass max. % mass (15 ppm) No. 3 max. 47 min. Report o C max.% mass 0.80max. mg KOH/gm max. % mass max. % mass max. % mass 360 max. o C Page 10

6 Page 11 Impact of Quality. Total and Free Glycerin Test and Oxidation Biodiesel over the specification(0.24%) will clog fuel filters Freeze point will be higher Effects oxidation stability Impact of Quality. Acid Number Direct relationship with oxidative stability Indicator of unreacted fatty acids Corrosion of metal parts High Acid Number Problems-pitting & varnish Page 12

7 Page 13 ASTM D6584- Free and Total Glycerin by Gas Chromatography ASTM D6584 is the main quantitative quality control method for B100 biodiesel. The method tests for glycerin, an unwanted by product of the reaction. Mono, Di, and Triglycerides, which are unreacted fatty acids remaining in the final product, also called Bound Glycerin Total Glycerin = Free glycerin + the Bound Glycerin ASTM D6751 specifies acceptable limits % mass Glycerin % mass Total Glycerin Recommended GC Configuration for ASTM D Clarus 500 GC with Liquid Autosampler and programmable pressure control (PPC) TotalChrom control and data handling software Programmable on Column inlet (POC) Flame Ionization Detector (FID) 5ul syringe with 0.47mm OD needle Digital flow meter Electronic leak detector D-6584 Standards & Reagents Inside the oven: Column- Elite 5 HT, 15 or 30 meter, 0.10 um film thickness, 0.32 mm ID High Temperature Guard Column, 0.53 mm diameter Low volume union or hourglass column connector Vu2 (Restek) Page 14

8 Page 15 Instrument conditions per ASTM D6584. Oven Ramp: Initial- 50 degrees, hold 1.0 minutes 15 deg/min to 180 degrees, hold 0.0 minutes 7 deg/min to 230 degrees, hold 0.0 minutes 30 deg/min to 380 degrees, hold 10.0 minutes Programmable On Column Inlet: Initial- 50 degrees Oven tracking mode to 380 degrees FID detector: 380 degrees, 45 ml/min Hydrogen and 450 ml/min Air Carrier Gas Flow: 3.0 ml/min Helium Sample Preparation, per ASTM D6584. Weigh 100 mg +/- 0.1 mg of biodiesel into a 10 ml septa vial Internal Standard Addition (ISTD) Add 100 ul of 1,4 Butantriol & Tricaprin by syringe, to the vial Add 100 ul of MSTFA (derivitizing solution) Shake solution and allow to react to for minutes Dilute with 8 ml of Heptane and shake to mix. This solution is now ready for analyses! Page 16

9 Page 17 Laboratory SOP Heptane Blank In 2ml autosampler vial Fill with heptane, inject into GC Calibration Standards This procedure is the five fold reduction in volume of the stock standards Only as needed, whenever recalibrating or with a new column In a 2ml autosampler vial 200ul standard solution 1 (use disposable tip pipette) 20ul ISTD1 (use 25ul syringe) 20ul ISTD2 20ul MSTFA cap, shake, stand 30 min 1.6ml heptane cap, shake, inject into GC Repeat for standard solutions 2-5 Biodiesel Samples In 10ml screw cap vial (or larger) tare balance with empty vial, shut doors on balance weigh approximately 100mg of biodiesel sample, record weight (will require just over 100ul) 100ul ISTD1 (use 100ul disposable tip pipette) 100ul ISTD2 100ul MSTFA cap, shake, stand 30min 8ml heptane cap, shake, transfer to 2ml autosampler vial, inject into GC Supelco U Kit for Biodiesel B-100 by ASTM D6584 Calibration Standard Repackaging According to Supelco part # U, 1ml of each standard is used to make each calibration level. This would consume the entire contents of the calibration standards supplied. In an effort to stretch the use of the expensive calibration standards, a five fold decrease of the amounts used will allow the calibration standards to be used for multiple calibrations. This is not a dilution but a reduction in the volumes of each solution measured out into the calibration solution. The ratios must remain the same for calibration to be valid. To assist in stretching the use of the calibration standards, the original vials are repackaged into screw cap storage vials, which are then stored refrigerated until the next use. Repackage each standard, Mix1 Mix5 into individual 2ml screw cap vials. Cap, label and store in refrigerator. Repackage each internal standard into individual 5-8ml screw cap vials. Cap, label and store in refrigerator. Option: Both internal standard solutions can be mixed together into one solution and then twice the volume can be pipetted at once. This reduces the pipetting. Page 18

10 Page 19 Sample Preparation, per ASTM D6584. Weigh 100 mg +/- 0.1 mg of biodiesel into a 10 ml septa vial Internal Standard Addition (ISTD) Add 100 ul of 1,4 Butantriol & Tricaprin by syringe, to the vial Add 100 ul of MSTFA (derivitizing solution) Shake solution and allow to react to for minutes Dilute with 8 ml of Heptane and shake to mix. This solution is now ready for analyses! GC Testing ASTM D Page 20

11 Page 21 Typical Chromatogram of finished product.lower glycerin Free Glycerin. Page 22

12 Page 23 Calibration Table. Monoglycerides. Very important to chose the right peaks Run standard of all monoglycerides to determine actual retention times Page 24

13 Page 25 Monoglycerides. Must have the correct peaks to sum Note: this is a named group which sums all the monos Diglycerides. Diglycerides are a summed group from approximately minutes Page 26

14 Page 27 Diglycerides. Triglycerides. Triglycerides are also a summed group from minutes Page 28

15 Page 29 Reporting Results.. The Mono- Di- and Tri- glycerides have a portion of the molecule due to glycerin structure. This is the bound glycerin. Only the glycerin portion of the glycerides are to be included in the total glycerin in the biodiesel. This requires each of the calculated glycerides to be multiplied by a factor relating to the glycerin portion prior to summing all the results. Example, per the ASTM D6584: Glycerin * = Total Monoglycerides * = Total Diglycerides * = Total Triglycerides * = Total Glycerin = % mass Make sure your data handling package can do this without exporting to some other second party software Complete Reporting Functionality in TotalChrom.. Page 30

16 Page 31 Reported results.. Problem areas with D6584 Complex Chromatography Many peaks Union Connection Technique dependant/experience Multiple pipetting Labor intensive, prone to error Peak Identification Run ALL 5 monos to prove ID Calibration Software training Integration Verification Each chromatogram, time consuming Short column life Due to very high temperatures Shifting retention times Due to shortened column life Method updating Software training Page 32

17 Page 33 Tips and Tricks. Results are only valuable if they are reproducible and accurate A variety of things will affect this- weighing the sample, introduction of ISTD, water in the sample diminishes the effectiveness of MSTFA, not all MSTFA is suitable, sample carryover, column age and condition, improper integration parameters Test your GCs reproducibility- prepare a sample of in- spec biodiesel and inject this sample 3-5 times, the more the better, and calculate the relative standard deviation (RSD), expect your results to vary 1-2 %. Run individual monoglyceride standards to verify the retention times for summed monos. Very important. If you experience poor reproducibility, verify that there is no sample carryover from injection to injection by running solvent between samples. Ensure there are sufficient needle rinses and vials are clean If you have made a lot of injections replace the guard column Analytical columns typically last 250 to 500 injections Tips and Tricks. Prepare the same sample 3-5 times and inject each sample, again calculate the RSD, this should be 4% or less. This tests your sample prep and GC s reproducibility. Possible Problems: Weighing the biodiesel inaccurately Poor addition of ISTD MSTFA poor quality Suggestions: Try increasing the sample prep 10X, use 1.0 gram of biodiesel and 1.0 ml of ISTD and MSTFA Record the actual weight of the biodiesel and include this in the sequence table PRACTICE, sample preparation is technique sensitive Page 34

18 Page 35 Summary of Biodiesel Analyses by Gas Chromatography Free and Total Glycerin in B100 Residual Methanol (Ethanol) in Biodiesel B100 Methanol is more common: making the methyl esters Ethanol makes the ethyl esters of the fatty acids Analyzed by headspace Fatty Acid Methyl Ester (FAME) Ester content Dependant on source of feed stock Simulated Distillation In place of D1160 vacuum distillation Biodiesel Blend Determination Percent biodiesel blended into petroleum diesel Directly influences tax break & profit GC more accurate than IR, but slower Methanol Testing in Biodiesel

19 Page 37 Residual Methanol Determination Methanol is used in the reaction process with a catalyst to create the fatty acid methyl ester, glycerin is formed as a by product Residual methanol and glycerin are removed by washing with water 4 to 6 times or more Methanol can be tested by: Flashpoint Quantification is Highly subjective and slow Infrared spectroscopy below 1% methanol is difficult to quantitate Gas Chromatography EN14110 Headspace GC ASTM methods yet to be created GC Testing EN MeOH by Headspace GC. Europe utilizes a HS GC technique for determination of residual MeOH, this is a simple technique. No ASTM method exists yet. Most users follow EN14110 or modify EN g of biodiesel is added to a 20 ml HS vial, with 5 µl of 2- propanol(istd),or ESTD procedure is also accepted The vial is heated and equilibrated, by the HS instrument, at 80 o C for 45 min Manual headspace injection is allowed but automated HS injection is recommended in the EN14110 method Any of several columns can be used, none are compatible in the same GC oven as the glycerin column due to the high temperature of the glycerin analysis, therefore a second GC is required. Page 38

20 Page 39 Modified Headspace Method 100ul sample instead of 5ml Heat for 10 minutes instead of 45 minutes Sample measured by positive displacement pipette instead of weight External standard Plenty of sensitivity Fine reproducibility 2 minute chromatography Higher throughput Quick, easy, precise and accurate The TurboMatrix Headspace Autosampler for GC 12-sample overlapping heating oven for high throughput Pressure balanced injection Very reliable and repeatable sampling Page 40

21 Page 41 Methanol in Biodiesel sample by HS/GC Calibration Curve for Methanol by EN % Page 42

22 Page 43 Methanol by Direct Injection with POC inlet.. Simplest and least expensive method, but not recommended Utilizes same GC and Column as glycerin analysis Biodiesel sample is diluted with heptane or injected neat Internal Standard can be used Not as accurate and slower than headspace Methanol is unretained and therefore co elutes with any very minor unretained artifacts (biggest reason for not recommended) Probably not acceptable once ASTM method is created Instrument Conditions POC inlet- 50 C initial, hold for 2 minutes, ramp to 380 C FID- 380 C Oven- 50 C initial, hold for 2 minutes, ramp to 380 C Method takes approximately 9 minutes Chromatogram on Direct Injection Page 44

23 Page 45 Other GC Testing Simulated Distillation- SimDis (ASTM D-2887) Biodiesel has a maximum boiling point specification of 360 o C. SimDis can be used to emulate a physical distillation and determine an equivalent boiling point distribution. Typically, Biodiesel contains carbon chains up to C24. Compounds are eluted based upon carbon number. This distribution and peak area are used in an algorithm to very accurately predict the boiling point. This is a very common test applied to crude oil. Methanol Purity Methanol that is fresh or recycled from production may be quality controlled for impurities. GC analysis for Ester content > 90% EN14103 Dilute enough to keep all methyl ester peaks on scale Page 46

24 Page 47 Biodiesel Blend Determination on C18:0 peak B10 fuel Summary of Biodiesel Analyses by Gas Chromatography Free and Total Glycerin in B100 Residual Methanol (Ethanol) in Biodiesel B100 Methanol is more common: making the methyl esters Ethanol makes the ethyl esters of the fatty acids Analyzed by headspace Fatty Acid Methyl Ester (FAME) Ester content Dependant on source of feed stock Simulated Distillation In place of D1160 vacuum distillation Biodiesel Blend Determination Percent biodiesel blended into petroleum diesel Directly influences tax break & profit GC more accurate than IR, but slower Page 48

25 Ethanol Biofuels Testing by Gas Chromatography Two Main Biofuels Ethanol Biodiesel billion gallon Jul 06 Jan 07 Jul 06 Jan 07 Current Capacity Under Construction Page 50

26 Page 51 Ethanol for Fuel - ASTM D5501 Clarus 500 GC with Liquid Autosampler and programmable pressure control (PPC) TotalChrom control and data handling software Capillary Injector Flame Ionization Detector (FID) Ethanol 93-97% Methanol % Higher boiling components 3-6% total Inside the oven: Column- Elite 1, meter, 0.5 um film thickness, 0.25 mm ID Any column allowed that can give separation Long columns = long analysis time Some people use 30m BAC1 type column for 10 min analysis Ethanol can be blended into gasoline E10 - E85 Pure ethanol at Indy 500 Page 52

27 Page 53 Ethanol fuel by GC/FID 100m x 250u x 0.5u RTx1-PONA Ethanol fuel contaminant compounds Page 54

28 Page 55 Summary PerkinElmer understands the needs of the market New, growing Need for complete solutions We can provide analytical solutions to help your company grow and generate profit Websites of Interest.. PerkinElmer NBB- National Biodiesel Board (USA) EBB- European Biodiesel Board Biodiesel Association of Australia ASTM- American Society for Testing and Materials Sigma-Aldrich Page 56

29 Thank You