First stage (2020): Physico-chemical properties and energy potential of softwood wastes

- collection (from the northeastern mountain region of Romania, specifically from Agapia production unit III, Valea Seacă/Tg. Neamt (47°08'55.1"N, 26°14'59.9"E)), processing (drying, particle size reduction, and sieving) and compositional characterization of forestry residues based on outer bark, cones and needles from silver fir, spruce and pine, of different ages: 40 and 100 years old.

Second stage (2021): Thermochemical conversion of forest biomass samples - torefaction, pyrolysis. Insight to potential applications

In the second stage of ForestChemiFuel project, torrefaction experiments were performed in order to obtain superior properties of forestry biomass residues for pyrolysis applications. 

The purpose of torefaction experiments was to optimize the operational conditions for obtaining higher yields of biochar with higher heating value (HHV), carbon content, and hydrogen/oxygen ratio and reduce moisture content.

The torefaction/pyrolysis experiments were conducted in a glass reactor by semi-batch operation under self-generated atmosphere. The effect of temperature (from 240 ºC to 310 ºC), on torrefaction at 60 min residence time, was evaluated in relation to its yield and higher heating value. It was found that the torrefied forestry biomass residues had a higher heating value than raw biomass, mainly due to the reduction of moisture content and the atomic oxygen/carbon and hydrogen/carbon ratios. The optimum conditions of torrefaction were found to be 250 ºC at 60 min of residence time. This reaction yielded approximatively 80% biochar, with 29 MJ/kg HHV. 

The pyrolysis products of forest biomass residues consisted in a solid residue (biochar), liquid pyrolysis product (an organic and a water fraction) and gaseous products (H2, CO, CO2, C1-C4 hydrocarbons).

Third stage (2022): Thermochemical conversion of forest biomass samples - catalytic pyrolysis. Insight to potential applications

In the third stage of ForestChemiFuel project, catalytic pyrolysis of biomass was performed in order to improve the quality of the bio-oils. Two types of mesoporous catalysts were used to convert pyrolysis oils into lighter compounds. 

Project results dissemination

Scientific papers:

1. Butnaru E, Stoleru E, Brebu M. Valorization of forestry residues by thermal methods. The effect of temperature on gradual degradation of structural components in bark from silver fir (Abies alba Mill.). Ind Crop. Prod. 187 (2022) 115376. https://doi.org/10.1016/j.indcrop.2022.115376.

2. Butnaru E, Brebu M. Torrefaction process of needles, cones and bark of spruce (Picea Abies (L.) Karst) and pine (Pinus Sylvestris L.) Rev. Chim. 73 (2022) 28-37. https://doi.org/10.37358/RC.22.3.8532. 

3. Butnaru E, Brebu M. The thermochemical conversion of forestry residues from silver fir (Abies alba Mill.) by torrefaction and pyrolysis. Energies 15 (2022) 3483. https://doi.org/10.3390/en15103483. 

4. Butnaru E, Pamfil D, Stoleru E, Brebu M. Characterization of bark, needles and cones from silver fir (Abies alba Mill.) towards valorization of biomass forestry residues. Biomass Bioenerg. 159 (2022) 106413. https://doi.org/10.1016/j.biombioe.2022.106413. 

Participations at international conferences:

1.    Butnaru E., Brebu M. Thermochemical conversion of forest biomass residues by torrefaction and pyrolysis. International conference Materials, Methods & Technologies, Burgas, Bulgaria, 19-22 August 2022 - oral communication.

2.    Butnaru E., Stoleru I.E., Brebu M. Valorization of forestry residues by thermal methods. 11th International Conference on Materials Science & Engineering. BraMat, Brasov, Romania, 9-12 Martie 2022 - oral communication.

3.    Butnaru E., Pamfil D., Stoleru E., Brebu M. Composition and antioxidant properties of extracts from silver fir residues. XXXIInd edition of the International Congress of “Apollonia” University of Iasi “By promoting excellence, we prepare the future”, Iasi, Romania. 28 Februarie-2 Martie 2022 - oral communication.

4.    Butnaru E., Serban A.M., Balmoj N., Spiridon I., Brebu M. Characterization of coniferous forestry residues for thermal valorization. International Conference Materials, Methods & Technologies, Burgas, Bulgaria, 19-22 August 2021 - oral communication.

5.    Pamfil D., Butnaru E., Vasile C., Brebu M. pH-sensitive controlled release of Ciprofloxacin from natural/synthetic polymeric hybrid systems. International Congress of the "Apollonia" University of Iași, "By promoting excellence, we prepare the future", the XXXI edition. Iasi, Romania. 01-03 Martie 2021 - oral communication.