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A series of calcium oxide-magnesium oxide (CaO-MgO) catalysts were prepared under the effects of different precipitating agents and using varied Mg/Ca ratios. The physiochemical characteristics of the prepared catalysts were analyzed using XRD, FE-SEM, BET, FTIR, and TG/DTA techniques. Quantification of basic active sites present on the surface of the CaO-MgO catalysts was carried out using the Hammett indicator method. The as-prepared mixed oxide samples were tested for propylene carbonate (PC) synthesis through the alcoholysis of urea with propylene glycol (PG). The effects of the catalyst composition, catalyst dose, reaction temperature, and contact time on the PC yield and selectivity were investigated. The maximum PC yield of 96%, with high PC selectivity of 99% and a urea conversion rate of 96%, was attained at 160 °C using CaO-MgO catalysts prepared using a Mg/Ca ratio of 1 and NaCO as a precipitating agent. The best-performing catalysts also exhibited good reusability without any significant loss in PC selectivity. It is expected that the present study will provide useful information on the suitability of different precipitating agents with respect to the catalytic properties of the oxides of Ca and Mg and their application in the synthesis of organic carbonates.
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http://dx.doi.org/10.3390/ma16020735 | DOI Listing |
ACS Omega
August 2025
Department of Pharmaceutical Chemistry, Telangana University, Nizamabad 503322, India.
A cost-effective and eco-compatible 1CaO-1.5MgO binary metal oxide (BMO-1) served as an efficient solid-base catalyst in the Knoevenagel condensation (KC) reaction of a range of aldehydes with active methylene reagents (i) malononitrile and (ii) ethyl cyanoacetate in water at room temperature (RT) to produce α,β-unsaturated compounds in purity with a good -factor. We also report the ketone-malononitrile KC reaction and salicylaldehyde-malononitrile tandem KC-Michael addition effectively catalyzed by BMO-1.
View Article and Find Full Text PDFACS Omega
July 2025
Laboratory of Carbon and Ceramic Materials, Department of Physics, Federal University of Espírito Santo, Vitória, Espírito Santo 29075-910, Brazil.
This work describes the optimization of the synthesis of carbon-supported heterogeneous catalysts containing CaO and MgO derived from ornamental stone waste (OSW) in view of their use for biodiesel production. The catalysts were prepared by mixing the OSW and coconut shell activated carbon (CSAC) powders with a NaOH solution under constant stirring; the mixture was then subjected to thermal treatments in an inert atmosphere. The variables of the synthesis process (thermal treatment temperature, residence time, and OSW/CSAC mass ratio) were analyzed using 2 full factorial designs; the response variable was the biodiesel conversion, monitored by solution H nuclear magnetic resonance (NMR) spectroscopy.
View Article and Find Full Text PDFRSC Adv
July 2024
Department of Chemistry, Faculty of Science and Data Analytics, Institut Teknologi Sepuluh Nopember Keputih, Sukolilo Surabaya 60111 Indonesia
High-purity CaO cubic crystallites extracted from limestone exhibited excellent activity as base catalysts for waste cooking oil (WCO) conversion into biodiesel. Saponin from extract acted as a surfactant in CaO extraction and transformation into well-defined cubic microcrystallites. The application of saponin from extract as a surfactant for CaO production results in a high level of CaO purity and particle size reduction compared to directly calcined limestone (CaO-MgO).
View Article and Find Full Text PDFJ Chem Theory Comput
November 2023
Department of Chemical and Biological Engineering, University of Colorado at Boulder, Boulder, Colorado 80309, United States.
The simulation of metals, oxides, and hydroxides can accelerate the design of therapeutics, alloys, catalysts, cement-based materials, ceramics, bioinspired composites, and glasses. Here we introduce the INTERFACE force field (IFF) and surface models for α-AlO, α-CrO, α-FeO, NiO, CaO, MgO, β-Ca(OH), β-Mg(OH), and β-Ni(OH). The force field parameters are nonbonded, including atomic charges for Coulomb interactions, Lennard-Jones (LJ) potentials for van der Waals interactions with 12-6 and 9-6 options, and harmonic bond stretching for hydroxide ions.
View Article and Find Full Text PDFJ Hazard Mater
January 2024
Department of Environmental Engineering, National Cheng Kung University, Tainan 70101, Taiwan; Hierarchical Green-Energy Materials (Hi-GEM) Research Center, National Cheng Kung University, Tainan 70101, Taiwan. Electronic address: