Binod Raj Giri

Glycerol carbonate as a fuel additive for a sustainable future

Policy-makers and researchers have been considering a shift from conventional fossil fuels to renewable sources due to the growing concerns over global warming and diminishing oil reserves. Biodiesel, a renewable bio-driven fuel, can be derived from vegetable oils and animal fats, and is considered to be bio-degradable, non-toxic and environmentally friendly. The cetane number and calorific power of biodiesel are quite similar to those of conventional diesel. Crude glycerol of about 10–20% by volume appears as a byproduct in biodiesel production. The increasing demand for biodiesel has led to a substantial increase of glycerol supply in the global market and a dramatic fall in the price of glycerol which has warranted alternative uses of glycerol. One potential way to deal with the crude glycerol overflow is to convert it to glycerol carbonate (GC) and use GC as a fuel or fuel additive. Prior studies have indicated that carbonate esters can significantly reduce particulate emissions during engine combustion. In this work, we have explored possible reaction pathways in the initial stage of glycerol carbonate pyrolysis. Ab initio/RRKM-master equation methods are employed to differentiate various reaction pathways and to obtain the pressure- and temperature-dependence of the major channels. We have found that glycerol carbonate decomposes almost exclusively to produce CO2 and 3-hydroxypropanal over 800–2000 K and radical forming channels are unimportant. As 3-hydroxypropanal is one of the main products of GC decomposition, and aldehydes are known to have a very high impact on soot reduction, we conclude that GC has great potential for cleaner combustion as a fuel additive.

Shock tube measurements of the branching ratios of propene + OH -> products

Absolute rate coefficients for the reaction of OH radical with propene (C3H6) and five deutrated isotopes, propene-1-d1 (CDHCHCH3), propene-1,1-d2 (CD2CHCH3), propene-2d1 (CH2CDCH3), propene-3,3,3-d3 (CH2CHCD3), and propene-d6 (C3D6), were measured in a shock tube behind reflected shock conditions over the temperature range of 812 K – 1460 K and pressures near 1 atm. The reaction progress was followed by monitoring OH radical near 306.7 nm using UV laser absorption. The first experimental measurements for the branching ratio of the title reaction are reported and compared with theoretical calculations. The allylic H atom abstraction of propene by OH radicals was found to be the most dominant reaction pathway followed by propen-1-yl and propen-2-yl channels over the entire temperature range of this study which is in line with theoretical predictions. Arrhenius parameters for various site-specific rate coefficients are provided for kinetic modeling.