Effect of niobium addition over Ni/MCM-41 catalysts for dry reforming of biogas.

This work aimed to evaluate the effect of niobium addition on nickel-based catalysts and their performance in dry reforming reactions to produce syngas (H2 and CO). Different quantities of Nb2O5 (5, 10, and 20% w/w) were used to prepare the catalysts, while a fixed content of Ni was applied (20%). The catalysts were supported on MCM-41. Physical, chemical, and morphological analyses were conducted to assess the characteristics of the materials. The produced Nb-Ni catalysts were applied in dry reforming reactions at 800 °C for 12 h. The dry reforming results indicated that the catalyst with 10% Nb-Ni demonstrated the best conversion of CH4 and CO2 (> 97%) and a significant H2 production (40%), with good stability during 12 h of reaction, while the catalyst with 5% Nb-Ni showed lower conversions and did not present good stability during the reaction. The catalyst with 5% Nb-Ni exhibited the highest production of H2 (44%), and the lowest of CO (50.87%), probably due to the presence of parallel reactions that increased H2 content and caused carbon (coke) formation. The characterization results of this material revealed the greatest formation of carbon on its surface. The presence of coke can prejudice the efficiency of the catalyst during a reaction and significantly reduce its lifetime. The catalyst with 10% Nb-Ni did not present coke formation, while the catalyst with 20% Nb-Ni showed carbon presence. The good dispersion of Ni on supports (Nb2O5 and SiO2/MCM-41) can explain the best behavior of 10% Nb-Ni for dry reforming reactions. X-ray diffractometry of the solids suggests the contribution of both metals (Ni and Nb) to the reforming process. From the obtained results, the catalyst with 10% Nb-Ni was indicated as the most favorable for dry reforming reactions among the studied materials, displaying good stability and conversion along with resistance to carbon formation.

Briquette production from a mixture of biomass: poultry slaughterhouse sludge and sawdust.

This study refers to the development of hybrid briquettes using centrifuged sludge from the wastewater treatment of poultry and sawdust from furniture industry. The aim was to evaluate the performance of briquettes as a source of thermal energy, mitigating the risks of the current elimination and reducing the operational costs of their destination. To know the oxidizing characteristics of the briquettes and their mechanical resistance, superior calorific power, ash content, volatile materials, fixed carbon, and resistance to axial compression were evaluated. Thermogravimetric and differential exploratory calorimetry analyses were performed. Statistical treatments were carried out to verify the most significant factors to produce briquettes, the best proportions of the raw materials, and to evaluate whether there is interference from moisture and glue flour used as a binder. The best condition of the sludge-sawdust mixture was 15% and 85%, respectively, with 6.0% moisture. The best-case treatment had 23.82-MPa mechanical resistance, a calorific value of 17.20 MJ kg-1, and a density of 1374.15 kg m-3.