Xabier Erdocia

Lignin oxidation and depolymerisation in ionic liquids

The depolymerisation of lignin directly in the black liquor was studied, comparing two ionic liquids as extracting solvents (butylimidazolium hydrogen sulphate and triethylammonium hydrogen sulphate), under oxidising conditions. H2O2 was chosen as the oxidant agent. It was observed that lignins derived from butylimidazolium hydrogen sulphate were more susceptible to degradation. The main degradation products found in the extracted oils were aromatic acids, such as vanillic acid, benzoic acid and 1,2-benzenedicarboxylic acid.

Effect of the photocatalytic activity of TiO2 on lignin depolymerization

Lignin is a good candidate for photocatalytic cracking due to the presence of hydroxyl groups. The photocatalytic cracking reaction involves TiO₂ as heterogeneous catalyst. In the present work lignin obtained by two different pulping methods is treated under photocatalytic conditions to be depolimerized. Different exposure times to UV radiation were carried out. The results of GS-MS revealed the degradation products of the hemicelluloses contained in the lignin samples. 1h of exposure to UV radiation shows the best yield in the obtaining of lignin degradation derived compounds; the main products obtained are syringaldehyde, pyrocatechol and raspberryketone, the concentration of syringaldehyde increases 20% and vanillin 30%.

Influence of Reaction Conditions on Lignin Hydrothermal Treatment

Organosolv lignin, obtained from olive tree pruning under optimised conditions, was subjected to a hydrothermal depolymerisation process catalysed by sodium hydroxide. The depolymerisation of lignin was carried out at 300 oC using different reaction times (20, 40, 60, 70, 80, 90 and 100 min) in order to study the influence of this parameter on lignin depolymerisation. The resulting products (oil and residual lignin) were measured and analysed by different techniques (GC/MS, HPSEC and pyrolysis-GC/MS) in order to determine their nature and composition. Coke was also formed, at a lower quantity, incompetitive repolymerisation reactions during the lignin hydrothermal treatment. The maximum oil yield and concentration of monomeric phenolic compounds was obtained after80 min of reaction time. The highest reaction time studied (100 min) had the worst results with the lowest oil yield and highest coke production.

Multistage treatment of almonds waste biomass: Characterization and assessment of the potential applications of raw material and products

Almond shells are waste biomass generated in agro-industrial activities, which represent a resource that can be further valorized upon treatment. The purpose of this work was to assess new value-added products obtained through a novel multi-stage delignification process of almond shells. A comprehensive chemical characterization of the raw materials and products involved in each stage of the process was carried out. Moreover, an extensive mass balance was developed, providing a full understanding of the extraction process. The pulps produced did not display a significant cellulose loss and hence they could be exploited as cellulose-rich materials. On the other hand, the obtained lignins presented high purity values (≈90%) and a high reactivity, and their structures became more condensed and homogeneous after each extraction cycle. These features would allow their utilization as feedstock of renewable materials such bio-sourced phenolic resins.

Catalytic Cascade Transformations of Biomass into Polyols

Among the many oxygen-rich chemicals that can be obtained from biomass, polyols, such as ethylene glycol and propylene glycol, are widely used in industry. Liquid polyols have been used in polyurethane foam preparation and as components of adhesives. Hydrolysis, coupled with hydrogenation and hydrogenolysis allows transformation of biomass or its constituents into polyols. Liquefaction is another approach which is efficient for converting biomass into liquid polyols that have high content of reactive hydroxyl groups.