Production of fuel additives by direct conversion of softwood bark using a cheap metal salt

Abstract

Levulinates could be used as oxygenated fuel additives or as blending components in biodiesel. In this work, a metallic salt was used for the direct conversion of biomass, ie. (softwood bark), to produce methyl levulinate (ML) and levulinic acid (LA). The experimental data were analyzed through using a response surface methodology (RSM) as well as a central composite design (CCD). Three dependent responses (ML yield, LA yield, and residue production) were studied to determine the optimum combination of the four factors. The total yield of levulinates was 62% at the optimum process parameters, including catalyst concentration (0.067 mol/L), reaction time (5.67 h), and softwood bark concentration (2.5 wt%) at 200 °C. Finally, the results showed that Al2(SO4)3 allowed the production of levulinates probably in light of its good BrØnsted/Lewis acidity while also allowing t to decrease the corrosion inside the reactor (as compared to homogeneous acids such as H2SO4). This shows that the use of these metal salts for this specific application could positively affect the production costs of levulinates (either CAPEX or OPEX) at larger scale.

Keywords

• Softwood Bark
• Methyl levulinate
• Levulinic acid
• Metal salt
• Fuel additive