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A canola fatty acid methyl esters (FAME) mixture was synthesized through transesterification and modified by rhodium homogeneous tandem hydroformylation-amine condensation, with primary amines, yielding imine products. The obtained imines were reduced by maceration with sodium borohydride and alumina, yielding secondary amine products. The synthesized fatty imines and amines were evaluated as additives for commercial diesel and biodiesel on concentrations of 0.5 and 1.0 %, while tested for oxidative stability fallowing the EN14112 standard method. The tested amino products exhibited higher oxidative stability, which justifies its application as antioxidant additives, while the diesel blends did not show expressive physicochemical modifications. The modified amino-FAME antioxidant performance, justifies a renewable biorefinery application, extend the biodiesel shelf-life prior to diesel blending, complies with UN’s Sustainable Development Goals (SDGs) and if prepared from residues, enhance the circular economy appeal.

This paper evaluated steam and CO2-enhanced gasification of spent coffee ground (SCG) biomass, including energy and exergy aspects focusing on hydrogen production. The waste-to-hydrogen (WTH) conversion was performed via gasification (1000 °C) with a drop-tube-reactor investigating six different steam to biomass (SBR of 0.5, 0.8 and 1.2) and CO2 to biomass (CO2BR 0.09, 0.18 and 0.27) ratios. The syngas production indicated clear improvement against O2/N2 with an H2 yield increase up to 69.21% and 18.32% for steam and CO2 mediums. The energy and exergy analysis points out the 0.8 SBR as the optimum condition with 210% CGE and 48.05% exergy efficiency for H2 production. As a strategy for carbon capture and usage, the medium with 0.27 CO2BR provided a 28.52% exergy efficiency for H2 production and reduced soot formation, showing a potential gasification medium for SCG. Results encourage waste-to-hydrogen prospection within circular economy principles, boosting circular economy principles in urban districts.

The disposal of spent coffee grounds (SCG) and brewers' spent grains (BSG) has become an environmental issue. Thus, the waste-to-energy valorization of these two low-cost feedstocks was performed via gasification and pyrolysis to assess their potential as syngas and biochar fuels. The processes’ optimum conditions were investigated by a multiple-criteria decision support method. Firstly, both raw materials were gasified at 1000 °C with O2/N2, O2/CO2/N2 and O2/H2O/N2 atmospheres. The characteristics and energy performance of the producer gas were evaluated. In addition, the exergy analysis of green-H2 production was assessed. The pyrolysis experiments were conducted at 300, 500 and 700 °C, followed by a comprehensive characterization of the biochar properties and its combustion behavior. The syngas production based on CO2/Steam-enhanced gasification has indicated clear energetic and exergetic improvements against O2/N2 with a promising increase of 32.97% LHVsyngas for BSG. Obtained biochar possesses favorable fuel characteristics promoting an HHV enhancement up to 19.42% (SCG) and 83.11% (BSG). Furthermore, the combustion index indicated a great potential of using SCG and BSG as solid biofuel for straightforward application to heat generation in small-scale systems. Therefore, syngas and biochar characteristics encourage feasible biofuels from low-cost feedstocks for energy generation.

This work evaluated the sludge potential of the Wastewater Treatment Plant (ETA) in the city of Brasília to be used as a fuel by gasification. It is known that ETA sludge is a significant environmental liability, since current legislation restricts its final disposal. For this, the chemical characterisation of ETA sludge was performed by immediate and elemental analysis. No traces of heavy metals were observed, and the moisture (ω) and ash contents were 31.17 and 51.77%, respectively, different from those already reported in the literature because the composition depends on the water treatment technology employed. The gasification process was numerically simulated; once dry, it constitutes a residue with an energy content (HHV) of 22.4498 MJ kg−1, comparable with other types of biomass currently used for large-scale energy generation by thermochemical processes (e.g. agricultural residues, wood and sugar cane bagasse). For the numerical simulation with an equivalence ratio (Φ) near 3, higher concentrations of CO and H2 can only be achieved with ω lower than 15%. The results showed that gasification can be an attractive option for the disposal and use of a renewable waste resource, such as ETA sludge, in an environmentally safe way, and it is allowed by local legislation.

Soybean oil transesterification with ethanol was carried out in a batch reactor using USY zeolites modified with barium and strontium (15 wt.%) as catalysts. A series of three catalytic cycles were performed for each zeolite without any loss of activity. The biodiesel product was analyzed by HPLC and FT-Raman, and the catalysts by pyridine and CO2 adsorption. Ba/USY provided higher conversions (> 97%) than Sr/USY (< 75%). The increased catalytic activity of Ba/USY was attributed to two different effects: a larger number of basic sites; and a lower interaction between barium species and HUSY BrØnsted sites.