Javier Remón
University of York
Dr. Javier Remón is currently a Postdoctoral Research Associate in the Green Chemistry Centre of Excellence (GCCE), in the Chemistry Department at the University of York (UK). His research activity is focused on the valorisation of different biomass residues for the production of value-added chemicals and energy using different thermochemical processes.
1. Introduction
Renewable biomass sources are of considerable interest because they provide an interesting route for the production of chemicals and energy. Among the different feedstocks, glycerol is of particular interest because of its ample availability as a biodiesel by-product; thus converting this feedstock into a cheap resource for which new valorisation routes need to be developed. Hydrothermal decomposition is a promising technology for glycerol valorisation, while microwave heating represents a potentially faster, more efficient and selective technology than conventional heating. Therefore, the combination of hydrothermal conditions together with microwave heating offers an interesting new technology for the valorisation of glycerol.
2. Method
Given this scenario, a novel microwave-assisted hydrothermal process has been addressed for the valorisation of a 30 wt.% glycerol solution with a Ni-Co/Al-Mg catalyst, analysing the effects of the most important operating conditions on the process. These include the temperature (150-250 ºC), pressure (50-120 bar), reaction time (0-2h) and catalyst/glycerol mass (5-15 wt.%) The experiments were planned according to a full factorial design and analysed by means of an ANOVA test.
3. Results and discussion
The statistical analysis of the results revealed that the operating conditions had a significant influence on the process. The global glycerol conversion, and the carbon converted to gas and liquids varied by 5-54%, 1-21%, 3-42%, respectively. The liquid phase was made up of mixture of monohydric alcohols (MeOH, EtOH); polyhydric alcohols (1,2-Propanediol, 1,3-Propanediol and 1,2-Ethanediol); C3-ketones (hydroxyacetone and acetone); carboxylic acids (acetic and propionic acids); together with unreacted glycerol. The carbon converted to liquids (26%) and the proportion of C3-ketones (85 wt.%) in the liquid can be maximised by using a temperature of 210ºC, a pressure of 50 bar, employing a catalyst mass of 5 wt.% for 2 h. Around 40 % of the glycerol can be purely converted to a rich mixture of monohydric and polyhydric alcohols by employing a temperature of 250 ºC, a pressure of 83 bar and a catalyst mass of 10 wt.% for 2 h. This preliminary study with glycerol suggests that this process is a very promising route for the selective valorisation of crude glycerol.
