Molybdenum carbide catalysts supported on carbon nanofibers (β-Mo 2 C/CNF) were synthetized employing different carburization parameters: five temperatures (550-750 ºC) and four heating rates (1-10 ºC/min) were tested. The carburization process of the Mo precursor in the catalysts was studied by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, N 2 physisorption, inductively coupled plasma optical emission spectrometry and transmission electron microscopy. The formation of the carbide phase was confirmed by the presence of the oxycarbide and carbide phases which were observed on the surface of all catalysts. Higher carburization temperatures resulted in an increase of the carbide phase content and crystal size at the expenses of the oxycarbide phase disappearance. High carburization temperatures and low heating rates were needed in order to obtain well-defined β-Mo 2 C crystals over the

No abstract

No abstract

In this work, a Mo 2 C catalyst that was supported on commercial carbon nanofibers (CNF) was synthetized and tested in the hydrodeoxygenation (HDO) of guaiacol. The effects of operating conditions (temperature and pressure) and reaction time (2 and 4 h) on the conversion of guaiacol and products selectivity were studied. The major reaction products were cresol and phenol, followed by xylenols and toluene. The use of more severe operating conditions during the HDO of guaiacol caused a diversification in the reaction pathways, and consequently in the selectivity to products. The formation of phenol may have occurred by demethylation of guaiacol, followed by dehydroxylation of catechol, together with other reaction pathways, including direct guaiacol demethoxylation, and demethylation of cresols. X-ray diffraction (XRD) analysis of spent catalysts did not reveal any significant changes as compared to the fresh catalyst.

Aiming to evaluate a possible loss of soil habitat function after amendment with organic wastes, a digested sewage sludge and derived composts produced with green residues, where biologically tested in the laboratory using soil animals (Eisenia andrei and Folsomia candida) and plants (Brassica rapa and Avena sativa). Each waste was tested mimicking a field application of 6ton/ha or 12ton/ha. Avoidance tests did not reveal any impact of sludge and composts to soil biota. Germination and growth tests showed that application of composts were beneficial for both plants. Composts did not affect earthworm's mass increase or reproduction, but the highest sludge amendment revealed negative effects on both parameters. Only the amendment of composts at the highest dose originated an impairment of springtails reproductive output. We suggest that bioassays using different test species may be an additional tool to evaluate effects of amendment of organic wastes in soil. Biological tests are sensitive to pollutants at low concentrations and to interactions undetected by routine chemical analysis.

No abstract

The concept of bioeconomy has been promoted worldwide in order to replace fossil-based resources and to find new strategies for waste management, by converting biomass into energy, chemicals, and value-added products, in a sustainable way. Despite the efforts that have been made in this area, there are still some unexplored raw materials globally, namely from agricultural and forestry industries. Therefore, the aim of this work was to characterize four abundant residues from the Portuguese agroforestry industry, including pruning residues (pine branches, PB) and stumps (PS), tomato waste (TW), and winery wastewater (WW), for analyzing their potential within the biorefinery context. Volatiles were analyzed by gas-chromatography, and compounds with repellent/attractant properties were found for PB and PS, while flavor-enhancers were particularly identified in agrowastes. Composition analysis revealed that both TW and WW had the potential for biogas generation (BMP ∼340 and ∼250 NL CH4/kg VS, respectively), whereas forestry residues (PS and PB) can be recovered for thermal energy (HHV ∼20 MJ/kg) and bioethanol production (∼0.3−0.4 L/kg). Among all the aqueous extracts that were obtained, PS showed both the highest antioxidant activity (IC 50 ∼6 μg/mL) and total phenolic content (∼400 mg GAE/g extract). All residues were demonstrated to be promising for the Portuguese biobased economy.

No abstract