Our applications labs have developed a nice collection of biofuels application notes that include methods for ethanol, methanol, sugars in fermentation broths, and fatty acids in biodiesel. (More on these applications in later blog posts!)
Here we present two recent applications of using ion chromatography (IC) for the analysis ofbiobutanol, a second-generation biofuel. (Other second-generation biofuels include cellulosic ethanol and mixed alcohols.)
These second-generation biofuels are becoming increasingly popular because the production of first-generation biofuels–bioethanol and biodiesel–is placing a much greater demand on food and feed commodity markets, i.e., grain, sugar, natural oils, fats, and processing byproducts. The other drawbacks include the fact that ethanol has higher vapor pressure, an affinity for water, and a lower energy content than gasoline, which increases the complexity for blending, transport, and use. Also, the high blending ratios of ethanol with gasoline require modified engines, and the lower energy content of blended fuels reduces vehicle gas mileage.
Biobutanol overcomes many of the drawbacks associated with ethanol and is believed to have the most potential for significant growth. It can be produced from annual cereal crops (e.g., corn, rice, and barley) and from cellulosic biomass. Butanol has a higher molecular weight than ethanol and therefore has reduced vapor pressure, lower water solubility, and higher energy density. In addition, biobutanol can be blended at any point in the supply chain, requiring less adjustment in gasoline blendstocks, and increases vehicle gas mileage.
Currently there are no accepted regulations for butanol, but the biofuels industry is seeking to use standards and methods already in place for fuel ethanol, and, hence, these two application notes apply two existing ASTM IC methods for ethanol to the analysis of butanol.
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Application Note 296, Assay of Fuel-Grade Butanol for Total and Potential Sulfate and Total Chloride Per ASTM D7328-07, (downloadable PDF) describes a simple IC method, consistent with the procedure described inASTM D7328-07, to measure the potential sulfate and total chloride in butanol used as a gasoline additive. As mentioned earlier, ASTM D7328-07 is intended for the analysis of ethanol samples containing 0.55–20.0 mg/L total sulfate, 4.0–20 mg/L potential sulfate, and 0.75–50.0 mg/L chloride, but can also be applied to butanol samples.
Application Note 297, Determination of Total and Potential Sulfate and Total Chloride in Fuel-Grade Butanol Per ASTM D7319-09(downloadable PDF) describes a direct injection IC approach to determine total and potential sulfate and total chloride in butanol intended as a gasoline additive. This IC method allows for the analysis of butanol samples according to ASTM D7319-09, and has the sensitivity to meet the specifications described in ASTM D4806-11A. The sample is directly injecting onto a anion-exchange column (Thermo Scientific Dionex IonPac AS22 Carbonate Eluent Anion-Exchange column) and the analytes are detected using suppressed conductivity detection.
Have you checked our an earlier blog post that focused on the characterization of biofuels using gas chromatography?
Don’t forget to let us know of any specific applications for biofuels that we have not listed in the comments box below. Our applications lab would be pleased to consider your request!