Dra. Azócar-Ulloa, Laura

This study investigated pellets produced using shrub biomass blended with pine sawdust to improve their physical and combustion properties by incorporating additives. First, the properties of pellets produced at different temperatures were analyzed. Pellets produced using pine sawdust blended with Teline monspessulana and Ulex europaeus biomasses (80/20 %m/m) exhibited good properties when prepared at 50–60 ◦C, whereas pellets produced using Rubus ulmifolius exhibited better characteristics at lower temperatures. The results showed that further studies on the physical properties and operational conditions of biomass from Ulex europaeus and Rubus ulmifolius are required. Furthermore, pellets blended with Teline monspessulana were evaluated using starch and lignin as binders, which exhibited all the physical properties of ISO 17225–6 when 1 wt% lignin was added owing to the stronger bonding induced by the additive. Because the fuel indices indicated a high corrosion risk, the additive CaO was used to improve the combustion performance of pellets blended with Teline monspessulana biomass and binders. The content of particulate matter smaller than 2.5 and 10 μm decreased by approximately 50%, and the crystallinity of the bottom ash, which usually contains undesirable elements, was improved by adding 1 wt% CaO, which raised the melting temperature of the ash.

Nowadays, leaves, bark, and branches are generated from the tree-pruning process in urban places, where their management is a problem because of the necessity of disposal. These wastes are lignocellulosic biomasses with poor properties for use in biofuel production, but with interesting projections for building block products such as phenol compounds. Therefore, extensive biomass characterization of urban pruning from Liquidambar styraciflua L. was developed to evaluate its composition as a tool for phenol production through thermal processing, in which solvent extraction is a complementary tool for selectivity improvement. The results showed high lignin content in bark and leaves at 45 and 28 %, respectively, compared with that in branches (14 %). Additionally, high extractives in leaves (14 %) could be an additional source of phenols. The lignin units were analyzed by Raman dispersion, revealing p–hydroxyphenyl (H) units in the bark, guaiacyl (G) units in the bark and leaves, and syringyl (S) units only in the branches. Furthermore, the micropyrolysis coupled with gas chromatography/mass spectrometry assay realized at 600 ◦C showed high presence of phenolic compounds in the three biomass investigated, where a high phenol concentration was identified in leaves, probably due to the S unit degradation during pyrolysis. With these results, an assay for bio-oil production was performed in a low-temperature pyrolysis reactor using leaves as feedstock, reaching a low bio-oil yield with high water content favored for the high inorganic content of leaves (13 %). The produced bio-oil was used for liquid–liquid extraction evaluation, where 1-octanol and methyl isobutyl ketone were identified as interesting solvents for catechol and phenol extraction, respectively. This article presents the challenge of characterizing each part of urban trees, which could be a tool to promote the use of urban pruning by studying the thermal degradation mechanism to implement processes for high-value products, such as phenols produced from L. styraciflua L.