Synthesis and Characterization of pH-Responsive Organic–Inorganic Hybrid Material with Excellent Catalytic Activity

Poly(N-isopropylmethacrylamide-co-methacrylic acid) [p(NipAam-Mac)] microgels were synthesized and used as microreactors to fabricate silver nanoparticles. Pure and hybrid microgels were characterized using Ultraviolet–Visible (UV/Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and transmission electron microscopy (TEM). Catalytic activity of hybrid microgels and mechanism of catalysis by this system was explored using different reaction conditions. At the same temperature, apparent rate constant (k_app) was found to be varied from 0.0414 to 0.7852 min^?1 by increasing the concentration of NaBH₄ from 2.49 to 22.41 mM at constant concentration of substrate and catalyst. However upon extra increase in concentration of NaBH₄ from 22.41 to 37.35 mM reduced the value of k_app to 0.2178 min^?1. Likewise, the value of k_app was found to be increased from 0.1242 to 0.5495 min^?1 with increasing the concentration of 4-nitrophenol [Para-nitrophenol (p-Np)] from 0.063 to 0.079 mM keeping other parameters constant. Further increase in concentration of p-Np caused decline in the value of k_app. Kinetic data reveals that catalytic reduction of p-Np obeys Langmuir–Hinshelwood mechanism and p-Np is converted to p-Ap on the surface of the silver nanoparticles passing through various reaction intermediates.     

Co–Mg–Al Hydrotalcite Precursors for Catalytic Total Oxidation of Volatile Organic Compounds

Co–Mg–Al hydrotalcite type solids were synthesized as precursors of catalysts for the total oxidation of toluene. After calcination at 500 °C, different mesoporous mixed oxides were obtained with high specific surfaces. The comparison of the catalytic activities of the calcined hydrotalcites with those of calcined hydroxides evidenced the superiority of the first oxides explained meanly by higher specific surfaces and more easily reducible particles. DRIFT “operando” allowed to follow the oxidation reaction and the formation of light coke and carbonate species.     

Rapid Detection and Quantification by GC–MS of Camellia Seed Oil Adulterated with Soybean Oil

Camellia seed oil with high nutritional value is widely used in southern China and southeastern Asia for cooking. Due to the high price of camellia seed oil, fraudulent traders blended the oil with inexpensive oils to increase profits. In this paper, a new method was introduced to detect the adulteration of camellia seed oil with soybean oil by GC–MS with consideration of a parameter which was defined by the total content of oleic and linoleic acid, the oleic to linoleic acid ratio and the content of linolenic acid. Oils samples were prepared by blending pure camellia seed oil with pure soybean oil at levels from 1 to 50 %. Fatty acids esterified by TMSH and TBME in seconds were separated and identified by GC–MS. The detection limit of adulteration was as low as 5 %, and even much lower than 5 % for most kinds of camellia seed oil, which was lower than those measured by other methods. All the results indicated that this simple, accurate and rapid method can also be recommended for the authentication of olive oil with some modification.     

Catalytic Activity of MCM-41–TBD in the Selective Preparation of Carbamates and Unsymmetrical Alkyl Carbonates from Diethyl Carbonate

The synthesis of carbamates 3 and unsymmetrical alkyl carbonates 5 by reaction of diethyl carbonate with aliphatic amines or alcohols has been realized by using as heterogeneous catalyst a hybrid organic–inorganic material prepared by anchoring TBD to MCM-41 silica. Products are obtained in high yield and very good selectivity and the solid catalyst can be recovered simply by filtration and reused for different cycles without apparent lowering of activity. A supported N-carbethoxyguanidinium active intermediate is proposed, and some spectroscopic data are shown to support the mechanistic hypothesis.     

Preparation of Cobalt Nitride from Co–Al Hydrotalcite and its Application in Hydrazine Decomposition

Alumina supported cobalt nitride [Co₄N–Al₂O₃ (HT)] with high cobalt loading has been prepared for the first time from Co–Al hydrotalcite precursors. The formation of the Co₄N phase was confirmed by XRD, H₂-TPR, and XPS. Compared with Co₄N/Al₂O₃ (IMP) prepared by conventional impregnation and nitriding, the hydrotalcite derived catalyst exhibited a much better activity for hydrazine decomposition as consequence of higher dispersion of active species.     

Inclusion Complex of Sea Buckthorn Fruit Oil with β-Cyclodextrin: Preparation Characterization and Antioxidant Activity

This study aims to produce an inclusion complex between β-cyclodextrin (β-CD) and sea buckthorn fruit oil (SBFO) by using the saturated aqueous solution method and then to compare the resultant solution with the crude mixtures. In this study, the SBFO is extracted by Soxhlet extraction, which is optimized through the single-factor test. The main constituent of the SBFO is identified by gas chromatography-mass spectrometry (GC-MS), which confirms eight fatty acids. Fourier transform infrared spectroscopy, thermogravimetric analysis-differential scanning calorimetry, optical microscopy, scanning electron microscopy, and the result-characterized synthesized compounds confirm the formation of stable inclusion compounds by the SBFO with β-CD. The yield values of the inclusion complex and the SBFO loading content are 64.87 ± 2.26% and 9.2 ± 1.58%, respectively. Comparing the crude fruit oil, β-CD–SBFO, and saponified fruit oil reveals differences in their 2,2-diphenyl-1-pycrylhydrazyl and 2,2′-azinobis-(3-ethylbenzthiazoline-6-sulfonate) antioxidant activities. These findings suggest that the SBFO inclusion complex after β-cyclodextrin is stabilized and is a good antioxidant. This solution improves the inadequacy of the water solution and the instability of the SBFO. This study also implies that β-CD is a cost-effective and straightforward carrier for extending the applications of SBFO as a food or medicinal additive. Practical applications: In this experiment, the SBFO is converted from oil to powder to increase its efficacy as an additive to health and food products.     

Preparation and Catalytic Activity of Gold–Copper Bimetallic Nanoparticles Stabilized by Poly (N-vinyl-2-pyrrolidone) and Immobilized onto Inorganic Supporters

This paper is devoted to preparation of gold–copper bimetallic nanoparticles deposited on inorganic supporters followed by their use in hydrogen peroxide decomposition and oxidation of ethylbenzene. The bimetallic nanoparticles of Au–Cu at molar ratio of 1:1 were synthesized by hydrothermal method in the presence of stabilizing agent—poly (N-vinyl-2-pyrrolidone) and reducing agent—glycine. The bimetallic nanoparticles were characterized by UV–Vis spectroscopy, DLS, and TEM techniques. The catalytic activity of Au–Cu bimetallic nanoparticles was evaluated with respect to decomposition of hydrogen peroxide and oxidation of ethylbenzene.     

Alumina Supported Co–K–Mo Based Catalytic Material for Diesel Soot Oxidation

Alumina supported Co–K–Mo based mixed metal oxide type catalytic materials have been prepared by co-impregnation. These catalysts show excellent activity for carbon as well as diesel soot oxidation, which could be due to the redox properties of Mo and Co as well as to a synergistic effect of molybdenum, cobalt, and K contents. The catalyst containing 5 wt% molybdenum shows a lowering of carbon oxidation by about 190 °C under loose contact conditions as compared to the non-catalyzed reaction, as well as to bare alumina. Characterization studies suggest a composite nature of these materials, while thermal stability investigations confirm the stable nature. The selected catalyst has been studied by XPS, however, it is difficult to conclude which are the important factors contributing to the catalytic activity. It appears to be a synergistic effect of Co, K, and Mo components as these catalysts show much improved activity as compared to the individual components in supported and unsupported forms.     

The Catalytic Baeyer–Villiger Oxidation of Cyclohexanone to ε-Caprolactone over Stibium-containing Hydrotalcite

A series of hydrotalcite-like compounds were prepared under microwave irradiation, which were used to catalyze the Baeyer–Villiger oxidation of cyclohexanone to ε-caprolactone with hydrogen peroxide as oxidant. The results show that stibium-containing hydrotalcite (Sb-HTL) has good catalytic properties in the reaction. In the Baeyer–Villiger oxidation of cyclohexanone to ε-caprolactone with H₂O₂ catalyzed by Sb-HTL, the effects of reaction time, reaction temperature, amount of catalyst and H₂O₂/cyclohexanone molar ratio are also investigated in details. It is shown the cyclohexanone conversion and ε-caprolactone selectivity can reach 79.15 and 93.84%, respectively, under the optimum reaction conditions. Furthermore, Sb-HTL can be reused for six times without obvious loss of activity and selectivity. Therefore, Sb-HTL is reusable and would be a promising catalyst for the Baeyer–Villiger oxidation using green and cheap oxidants like hydrogen peroxide instead of peroxycarboxylic acids.     

Measuring and Modeling Liquid–Liquid Equilibria for a Soybean Oil, Oleic Acid, Ethanol, and Water System

Vegetable oils can be deacidified by liquid–liquid extraction based on differences in polarity between triglycerides and fatty acids and differences in solubility. Information on the equilibrium between the phases of such systems is important for designing separation processes. The present paper reports experimental data for the extraction of fatty acid from soybean oil by (ethanol + water) as a mixed-solvent for system of soybean oil + oleic acid + ethanol + water at 30 °C at different water contents. The liquid–liquid equilibrium data of the systems were used to obtain interaction parameters in the universal quasi-chemical theory (UNIQUAC) activity coefficient model. These parameters can be used to predict equilibrium data of ternary and quaternary systems. The deviations between experimental and calculated compositions in both phases for each system using this model were calculated. The distribution coefficients and the selectivity factors of solvents for extraction of fatty acid from oil at 30 °C were calculated. Increasing of the water content as the co-solvent decreased the distribution coefficients and increased the selectivity factors of mixed-solvents, therefore considering the economical and practical aspects the optimum water content may be used for extracting oleic acid from soybean oil. We concluded that (ethanol + water) as a mixed-solvent can be used for extracting fatty acids from edible oils in a normal temperature.     

Urea and Thiourea-Functionalized Mesoporous Silica Nanoparticle Catalysts with Enhanced Catalytic Activity for Diels–Alder Reaction

A series of urea- and thiourea-functionalized mesoporous silica nanoparticles (MSN) was synthesized. These materials exhibited a superior catalytic reactivity for Diels–Alder reaction than their homogeneous analogues. The reactivity enhancement was attributed to the site isolation effect induced by the heterogenization of individual catalytic group. The surface hydrogen bonding between the organic catalysts and silanols also improved the catalytic reactivity.     

Transesterification of β-Keto Esters Catalysed by Basic Porous Material

-keto esters have been successfully transesterified with primary, secondary, tertiary, allylic and alkynic alcohols in good yields using TBD anchored on MCM support for the first time. The hybrid solid base catalyst can be recycled several times with consistent activity.