Abstract
The present work deals with the kinetic analysis and modelling of glycerol (GLY) oxidation in the liquid phase over a supported gold catalyst. A Langmuir-Hinshelwood model was proposed, after considering the effect of the reaction temperature, the NaOH/GLY ratio and the initial concentrations of GLY and GLY-Product mixtures. The proposed model effectively predicted the experimental results, and both the global model and the individual parameters were statistically significant. The results revealed that the C–C cleavage to form glycolic and formic acids was the most important reaction without a catalyst. On the other hand, the supported Au catalyst promoted the GLY oxidation to glyceric acid and its further conversion to tartronic and oxalic acids. Regarding the adsorption terms, glyceric acid showed the highest constant value at 60 °C, whereas those of GLY and OH− were also significant. Indeed, this adsorption role of OH− seems to be the reason why the higher NaOH/GLY ratio did not lead to higher GLY conversion in the Au-catalysed reaction.
Highlights
During the past decade, the use of biofuels as an alternative energy source to fossil fuels has been established
To provide a sufficiently wide range of experimental data needed for kinetic modelling, four temperatures (40, 60, 80 and 100 ◦C) and four NaOH/GLY ratios (0, 1, 2 and 4 mol/mol in non-catalysed reactions and 0, 2, 4 and 6 mol/mol in Au-catalysed ones) were chosen
Regarding O2 partial pressure, it has been reported previously [19] that its effect on catalytic activity is negligible if the experiments are conducted in the kinetic regime, as they were in this work
Summary
The use of biofuels as an alternative energy source to fossil fuels has been established. In 2016, the total worldwide biofuels production reached 82 million tonnes of oil equivalent, this value being 2.6% higher than that of 2015. It has been reported that the trend for biofuels production will be upwards until 2035 [1,2]. The production of biodiesel, based on transesterification of vegetable oils from waste fats, leads to glycerol (GLY) as an inevitable by-product; over 100 kg of GLY is produced per tonne of biodiesel [3,4]. The valorisation of GLY could improve the competitiveness of the biodiesel value chain. Considering these facts, the consumption volume of GLY is expected to increase from 2000 kt in 2011 to 3070 kt in 2018 [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
