In this study, we reported on the effect of promoting Ni/ZrO₂ catalysts with Ce, Ca (two different loadings), and Y for the aqueous-phase reforming (APR) of methanol. We mainly focused on the effect of the redox properties of ceria and the basicity provided by calcium or yttrium on the activity and selectivity of Ni in this reaction. A systematic characterization of the catalysts was performed using complementary methods such as XRD, XPS, TPR, CO₂-TPD, H₂ chemisorption, HAADF-STEM, and EDS-STEM. Our results reveal that the improvement in reducibility derived from the incorporation of Ce did not have a positive impact on catalytic behaviour thus contrasting with the results reported in the literature for other Ce-based catalytic compositions. On the contrary, the available Ni-metallic surface and the presence of weak basic sites derived from Ca incorporation seem to play a major role on the catalytic performance for APR of methanol. The best performance was found for a Ce-free catalyst with a molar Ca content of 4%.

A series of NiO–CeO₂ mixed oxide catalysts have been synthesized by a modified coprecipitation method at three different pH values (pH = 8, 9, and 10). The NiO–CeO₂ mixed oxide samples were characterized by TGA, XRD, inductively coupled plasma atomic emission spectroscopy (ICP-AES), FTIR, Brunauer–Emmett–Teller (BET) surface area, H₂ temperature-programmed reduction (H₂-TPR), and electron microscopy (high-angle annular dark-field transmission electron microscopy/energy-dispersive X-ray spectroscopy (HAADF-TEM/EDS)). The catalytic activities of the samples for soot oxidation were investigated under loose and tight contact conditions. The catalysts exhibited a high BET surface area with average crystal sizes that varied with the pH values. Electron microscopy results showed the formation of small crystallites (~5 nm) of CeO₂ supported on large plate-shaped particles of NiO (~20 nm thick). XRD showed that a proportion of the Ni²⁺ was incorporated into the ceria network, and it appeared that the amount on Ni²⁺ that replaced Ce⁴⁺ was higher when the synthesis of the mixed oxides was carried out at a lower pH. Among the synthesized catalysts, Ni-Ce-8 (pH = 8) exhibited the best catalytic performance.

Redox properties on CeO₂/TiO₂ system are reversibly modified with SRMO and SRSO treatments. The single low temperature peak featuring on SRMO samples is coming from a highly dispersed ceria thin layer extended over the TiO₂ surface.

Upgrading biorefinery-derived waste such as glycerol to fuel-additives and high-value products is essential to further enhance the productivity, profitability, and circularity of the biorefinery concept to achieve a green and sustainable net-zero world. This study explores the catalytic conversion of glycerol into glycerol carbonate using calcium oxide–cerium oxide (CaO–CeO₂) dual-function catalytic materials. Herein, a clean and efficient approach was developed to synthesize CaO–CeO₂ materials using a green mechanochemical method and then utilize these as catalyst in sustainable and solvent-free synthesis of glycerol carbonate to enhance the circular economy of biorefineries while reducing their carbon footprint. The catalysts were comprehensively characterized using XRD, FTIR, ICP, N₂ sorption, CO₂-TPD, and SEM/EDS analyses and evaluated for their catalytic activity. Among the catalysts studied, 40 wt % CaO–CeO₂ exhibited the highest catalytic activity, achieving 95% glycerol conversion and 99% selectivity to glycerol carbonate under optimized conditions (10 wt % catalyst loading relative to glycerol, 90 °C, 60 min, and a glycerol/ DMC molar ratio of 1:3). This catalyst showed excellent reusability, maintaining high conversion over four cycles. The transesterification reaction followed irreversible second-order reaction kinetics with an activation energy of 46.9 kJ mol^–1. The synergistic interplay between the basic sites of the Ca²⁺–O^2– pair and the oxygen vacancies in the CeO₂ matrix at the CaO–CeO₂ interface work in tandem to enhance the catalytic activity for glycerol carbonate production. We have developed a highly efficient, cost-effective, and environment-friendly approach for the sustainable production of glycerol carbonate from glycerol.

This study introduces an innovative hybrid approach combining salting-out and adsorption for the highly efficient removal of crystal violet (CV) dye from aqueous solutions. The method leverages high-ionic-strength brine discharge from the Complex of El-Outaya (CEO, ENASEL, Biskra, Algeria) and micro-mesoporous biochar derived from calves’ horn cores (BHC-800). Results demonstrate that both undiluted and diluted brine significantly enhance CV removal, while BHC-800, with a surface area of 258 m² g⁻¹, exhibits a maximum Langmuir adsorption capacity of 106.1 mg g⁻¹ (at 20 °C ± 2). Thermodynamic analysis confirms a spontaneous (ΔG° < 0) and exothermic (ΔH° = −0.86 kJ mol⁻¹) process, with increased interfacial disorder (ΔS° = 93.53 J mol⁻¹ K⁻¹). The synergistic effect of salting-out and adsorption achieved ~99.8% removal of CV at an initial concentration of 1000 mg L⁻¹. Furthermore, BHC-800 exhibited excellent reusability, maintaining high adsorption efficiency over multiple cycles. Economic assessment revealed operational costs of 0.45–0.89 US$ m⁻³ for 60% brine discharge. Biochar production costs were 0.076–0.18 US$ kg⁻¹, translating to 7.5–17.2 (10⁻⁴ US$) per gram of CV removed. This dual strategy not only offers an eco-friendly and cost-effective solution for dye-laden water but also promotes the valorization of saline effluents and animal byproducts, addressing critical environmental challenges in industrial wastewater treatment.