In recent years there has been a strong drive towards transitioning the transportation fuels market to a sustainable alternative. Biofuels has emerged as one of the solutions and is receiving a great deal of focus in research, industry, and politics. Ethanol is currently the most popular biofuel, but butanol has been acknowledged as a superior alternative in several regards. In this paper, the chemical and physical properties of butanol are compared to ethanol and gasoline. In addition, the feasibility of a butanol-based economy is assessed in terms of available supply, compatibility in spark ignition engines in terms of performance and emissions, and ability to easily transport, store, and dispense the fuel. Life cycle assessments of biobutanol are also reviewed, which ultimately suggest that butanol has the potential to be a sustainable alternative. However, the yield of biobutanol production via ABE fermentation, the primary process currently utilized to produce the fuel, is low. Ad... [more]

A nanocomposite polymer membrane based on quaternized poly(vinyl alcohol)/fumed silica (QPVA/FS) was prepared via a quaternization process and solution casting method. The physico-chemical properties of the QPVA/FS membrane were investigated. Its high ionic conductivity was found to depend greatly on the concentration of fumed silica in the QPVA matrix. A maximum conductivity of 3.50 × 10−2 S/cm was obtained for QPVA/5%FS at 60 °C when it was doped with 6 M KOH. The permeabilities of methanol and ethanol were reduced with increasing fumed silica content. Cell voltage and peak power density were analyzed as functions of fumed silica concentration, temperature, methanol and ethanol concentrations. A maximum power density of 96.8 mW/cm² was achieved with QPVA/5%FS electrolyte using 2 M methanol + 6 M KOH as fuel at 80 °C. A peak power density of 79 mW/cm² was obtained using the QPVA/5%FS electrolyte with 3 M ethanol + 5 M KOH as fuel. The resulting peak power densities are higher than the... [more]

Autoignition of an ethanol-based gel droplet was experimentally investigated by adding 10 wt % of methylcellulose as gellant to liquid ethanol. Experimental studies of the ignition behavior of the gel droplet were found to be quite rare. The initial droplet diameter was 1.17 ± 0.23 mm. The gel droplet was suspended on a K-type thermocouple and its evaporation, ignition and combustion characteristics were evaluated and compared with pure ethanol at an ambient temperature of 600, 700, and 800 °C under atmospheric pressure conditions. The gel droplet exhibited swelling and vapor jetting phenomena. Before ignition, a linear decrease in droplet diameter followed by a sudden increase was repeatedly observed, which was caused by evaporation and swelling processes, respectively. Major droplet swelling was detected just before the onset of ignition at all temperatures. But no further swelling was detected after ignition. For the gel droplet, the ignition delay accounted for 93% of the droplet l... [more]

Steam reforming of ethanol in the membrane reactor using the Pd77Ag23 membrane was evaluated in Ni/CeO₂ and Co/CeO₂ at atmospheric pressure. At 673 K, the H₂ yield in the Pd77Ag23 membrane reactor over Co/CeO₂ was found to be higher than that over Ni/CeO₂, although the H₂ yield over Ni/CeO₂ exceeded that over Co/CeO₂ at 773 K. This difference was owing to their reaction mechanism. At 773 K, the effect of H₂ removal could be understood as the equilibrium shift. In contrast, the H₂ removal kinetically inhibited the reverse methane steam reforming at low temperature. Thus, the low methane-forming reaction rate of Co/CeO₂ was favorable at 673 K. The addition of a trace amount of Ru increased the H₂ yield effectively in the membrane reactor, indicating that a reverse H₂ spill over mechanism of Ru would enhance the kinetical effect of H₂ separation. Finally, the effect of membrane performance on the reactor performance by using amorphous alloy membranes with different compositions was evalua... [more]

This work compares various chemicals for use as extractants in second-generation Acetone-Butanol-Ethanol fermentation on economic and environmental bases. Both non-toxic and toxic extractants are considered in this study. The combinative extractive-distillation separation process was modelled using a combination of Microsoft Excel 2013, MATLAB 2015 and Aspen Plus v8.8. Separation trains were designed and optimized for each extractant to best take advantage of extractant properties. Upstream units considered in this analysis include: biomass (switchgrass) solids processing, biomass pre-treatment and saccharification, and fermentation. Downstream processes considered include utility generation and wastewater treatment. The cost of CO2 equivalent emissions avoided (CCA) was used as the metric to compare the environmental impact of each process as compared to conventional petroleum-based gasoline. The economic and environmental best extractant is shown to be 2-ethyl-hexanol with a minimum... [more]

This work compares various chemicals for use as extractants in second-generation Acetone-Butanol-Ethanol fermentation on economic and environmental bases. Both non-toxic and toxic extractants are considered in this study. The combinative extractive-distillation separation process was modelled using a combination of Microsoft Excel 2013, MATLAB 2015 and Aspen Plus v8.8. Separation trains were designed and optimized for each extractant to best take advantage of extractant properties. Upstream units considered in this analysis include: biomass (switchgrass) solids processing, biomass pre-treatment and saccharification, and fermentation. Downstream processes considered include utility generation and wastewater treatment. The cost of CO2 equivalent emissions avoided (CCA) was used as the metric to compare the environmental impact of each process as compared to conventional petroleum-based gasoline. The economic and environmental best extractant is shown to be 2-ethyl-hexanol with a minimum... [more]