Efficient catalytic gasification is essential for improving producer gas quality by enhancing tar destruction, and thus more sustainable biomass-to-energy pathways. Iron oxides and spinel ferrites (MFe2O4) have attracted attention as gasification catalysts due to their redox versatility and structural stability, with the divalent cation playing a crucial role in oxygen mobility and metal-oxygen bond strength. In this work, the effect of Co and Mn as divalent cations in spinel ferrites was investigated and compared with hematite during biomass gasification. Catalysts were synthesized via wet impregnation method combined with microwave-assisted calcination, and characterized by XRD, XRF, BET, SEM/EDS, TGA, and Raman. Their performance was evaluated following the improvement of gas quality during gasification of residual forest biomass in a bench-scale bubbling fluidized bed reactor. The gasification conditions were 850 °C, equivalence ratio of 0.25 and air as gasifying agent. The results show that catalytic activity for gas quality improvement followed the sequence CoFe2O4 > MnFe2O4 > Fe2O3, mainly due to differences in M − O bond strength and redox flexibility. The Co-based catalyst exhibited the highest performance, increasing the H2 production by 115% and the H2:CO molar ratio by 95%, while decreasing tar production by 66% relative to the reference condition. Process parameters such as CGE, CCE, gas yield and LHV were less affected by the catalyst than the producer gas composition. These results show the positive effect of divalent cations in spinel ferrites and contribute to the rational design of catalysts for efficient biomass to syngas conversion.
The transition toward low-carbon fuels demands efficient routes for converting renewable feedstocks into drop-in hydrocarbons. In this work, we report an alternative, metal-free photodecarboxylative protocol for the production of hydrocarbons within the Sustainable Aviation Fuel (SAF) range, starting from N-hydroxyphthalimide-derived redox-active esters obtained from C10-C18 fatty acids. The methodology relies on the in situ formation of an electron donor-acceptor (EDA) complex between the redox-active ester and the Hantzsch ester, which simultaneously acts as a hydrogen atom donor and photochemical activator, thereby eliminating the need for metal catalysts and molecular hydrogen. Under visible-light irradiation, at ambient temperature and atmospheric pressure, using isopropyl alcohol as solvent, saturated substrates achieved conversions exceeding 99% and afforded the corresponding n-alkanes (Cn-1) in yields of up to 83%. Chain-length variation influenced the overall efficiency, providing C9-C17 alkanes in yields ranging from 52 to 83%. Unsaturated C18 substrates furnished the corresponding olefins in moderate yields (up to 48%). The one-pot strategy maintained conversions above 90% and enabled the direct application of the protocol to a range of real lipidic biomasses, delivering overall yields between 31 and 79%. The protocol operates under mild conditions, tolerates open-air atmosphere, and can be driven by solar irradiation, representing a promising alternative to conventional SAF production pathways.
The growing demand for bio-based materials has stimulated the development of sustainable alternatives to conventional plastics, among which polyhydroxyalkanoates (PHAs) stand out due to their biodegradability and biocompatibility. In this context, the present study evaluated the production, recovery, and characterization of poly(3-hydroxybutyrate) [P(3HB)] synthesized by Bacillus megaterium ATCC 14581 using rice parboiling wastewater (RPW) and confectionery industry effluent (CIE) as agro-industrial substrates. P(3HB) production was carried out in a fed-batch bioreactor under controlled conditions employing two nitrogen-feeding strategies: continuous supplementation (Strategy I) and intermittent supplementation (Strategy II). The recovery of P(3HB) was investigated using ultrasound-assisted extraction, employing chloroform and 1,2-dichloroethane as solvents. The P(3HB) recovered under the selected conditions was characterized by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and biodegradability assays. Strategy II showed superior performance, reaching a maximum biomass concentration of 6.48 g/L at 27 h and a P(3HB) accumulation of 2.35 g/L, corresponding to 67.74% of cell dry mass, at 21 h of cultivation. Ultrasound-assisted extraction resulted in recovery yields of 6.16% for chloroform. Biodegradation tests demonstrated mass losses exceeding 80% after 84 days under controlled conditions, confirming the environmentally favorable behavior of the biopolymer. Overall, the results demonstrate that agro-industrial residues can be successfully valorized as low-cost substrates for P(3HB) production and that ultrasound-assisted technology represents a promising alternative for polymer recovery.
Sugar beet pulp (SBP) is an abundant polysaccharide-rich agro-industrial residue with distinctly low lignin and significant pectin content. Suitable pretreatment strategies tailored to SBP constituents are thus critical for its valorisation to diverse products. We developed two novel pretreatments, hydrogen peroxide-tween 80 (PS) and polypropylene glycol (PPG) and benchmarked them against dilute hydrochloric acid pretreatment (DAP). The process development includes response surface optimization, sequential pectinase-cellulase hydrolysis, and a techno-economic analysis (TEA). DAP achieved 75% theoretical arabinose yield (28.59 g/L) while solubilizing 80% of pectin, recovered via ethanol precipitation. A subsequent cellulase hydrolysis released 45.1 g/L glucose at 83% theoretical yield. PS removed 62-67% lignin through oxidative delignification with minimal sugar loss (less than 2 g/L), and PPG substantially improved enzyme accessibility through solvent-mediated surface disruption with negligible PPG loading. Sequential enzymatic hydrolysis produced 59.4 g/L and 55.3 g/L total sugars (ara + GalA dominant) from the pectinase stage, and 69.6 g/L and 81.7 g/L (glucose dominant) from the cellulase stage, for PS and PPG, respectively. TEA, using 100 MT SBP/day as plant capacity, showed that the production costs per kg of sugar mixtures were $0.41, $1.03, and $0.96 for DAP, PS, and PPG, respectively. However, DAP's apparent cost advantage is contingent on pectin co-product revenue. Without this credit, its production cost rises to $1.05/kg. This work validates PS and PPG as viable novel pretreatments and establishes a comparative framework linking process chemistry, enzymatic performance, and economics for pretreatment selection in SBP-based 2G biorefinery.
