Controlled synthesis of bimetallic catalysts has attracted much attention in heterogeneous catalysis because their catalytic activity depends on the size of nanoparticles and hence the methods of synthesis. In this work, one convenient method was proposed, with an aim to control the size and dispersion of bimetallic nanoparticles. In this method, Cu2+ (or Ni2+) configurational ion of hydrotalcites was used as directing reagent, which directed the position and dispersion of the final bimetallic nanoparticles by employing the metal interaction between Cu and Au as the driving force. The size, structure and composition of bimetallic nanoparticles were characterized using techniques of X-ray diffraction (XRD), nitrogen physisorption, X-ray photoelectron spectra (XPS) and scanning transmission electron microscopy (STEM). The mean size of bimetallic AuCu nanoparticles was 2.5 nm, which was 1/4 (Step-impregnation) or 1/10 (Co-impregnation) of that prepared by traditional methods. Even if the loading of Au was increased to 10 wt%, the obtained AuCu nanoparticles were still well dispersed. The catalytic activity of AuCu and AuNi nanoparticles in aerobic oxidation of benzyl alcohol was far higher than those prepared by traditional methods. The mechanism of forming bimetallic nanoparticles was investigated. It was found that the dispersion of Cu2+ (or Ni2+) and the interaction between Cu0 (or Ni0) and Au0 are two key factors affecting the dispersion of AuCu (or AuNi) nanoparticles.

CuMgAl-hydrotalcite-supported Au catalysts were prepared and tested in the selective conversion of glycerol to dihydroxyacetone. The electron density of Au was decreased by Cu embedded in the supports, arising from the electron transfer from Au to Cu sites. The valence state (+ 1) of Cu ions was detected. Both Cu+ and basic sites (Mg–O) affected the catalytic activity of Au catalysts. The Cu+ sites promoted the selective oxidation of glycerol to dihydroxyacetone, while basic sites boosted the selectivity oxidation of glycerol to glyceric acid. The synergy of Cu+ sites and basic sites could effectively promote the activity and selectivity of Au catalysts in the selectively conversion of glycerol to dihydroxyacetone. A 53% conversion of glycerol and 72% of dihydroxyacetone selectivity were obtained under optimum reaction conditions.

Gold nanoparticles are attractive in catalytic field due to their high activity and selectivity. However, dispersion and sintering resistance have been two of the biggest issues in catalysis for preparation of gold nanoparticles. In this paper, a controlled impregnation method was employed to prepare highly dispersed and thermally stable Au-based catalysts for aerobic oxidation of benzyl alcohol. The size of hydrotalcites (HTs)-supported Au nanoparticles was 2.8 nm at 300 °C of calcination temperature, which was 3.2 nm when calcination temperature was increased to 600 °C. The mechanism of forming metal nanoparticles was proposed. The high dispersion of Au was ascribed to the directing role of Cu and the interaction between Au (and Pt) and Cu. It was proposed that the thermal stability of Au nanoparticles was due to the simultaneous employment of multiple additional effects. The activity of Au nanoparticles was far higher than those prepared by traditional methods. Furthermore, the PtCu elements in Au nanoparticles were homogeneously distributed. In contrast, they were randomly distributed in Au nanoparticles prepared by the traditional method.

Transesterification of β-keto esters and alcohols are traditionally catalyzed by acid or basic catalysts. However, these traditional catalysts do not always meet the requirements of modern synthetic chemistry which need to be highly efficient, selective, and environmentally friendly. In this work, Ag–Cu metal sites were first introduced as transesterification catalysts. The effect of the support, Ag:Cu molar ratio, and reaction conditions were investigated. The Ag–Cu metal sites were proved to be active in the β-ketoester transesterification with various alcohols, having yields comparable to the conventional acid- or base-catalysts.

The development of new and inexpensive heterogeneous catalysts for direct C–C cross-coupling of primary and secondary alcohols is a challenging goal and has great importance in academic and industrial sectors. In this work Cu–Ag/hydrotalcite (Cu–Ag/HT) catalysts were prepared and tested for their impact on this cross-coupling. The effect of supports, including MgO, γ-Al2O3 and HT with different Mg:Al molar ratios, was investigated. It was found that the acidic or basic properties of the supports affected product selectivity. The roles of Cu and Ag sites in the cross-coupling were also investigated with the prepared Cu–Ag/HT catalyst demonstrating high activity and selectivity for the reaction. The yield-to-target product of β-phenylpropiophenone reached 99% after 1 h under optimum reaction conditions. The stability in air and reusability studies show that Cu–Ag/HT can be stored for 6 days and can be used five times without apparent deactivation, respectively.

Introducing nanotechnology topics by demonstrating several colors of gold nanoparticles resulting from their size-dependent optical properties provides an easy, original, and appealing way to engage students in nanotechnology. In this classroom demonstration, solid gold nanoparticles were prepared by depositing gold nanoparticles on white solid supports, namely, TiO2, Mg(OH)2, CaCO3, Al2O3, and MgO. The color of the gold nanoparticles was changed by adjusting the type of supports or the concentrations of gold(III) solution. The gold nanoparticles exhibited many different colors, including purple, pink, gray, brown, dark red, and red. Typically, the preparations can be completed in less than 1 h, which makes this a feasible classroom demonstration.

Gold catalysts were loaded on supports of hydrotalcite (HT), MgO, or γ-Al2O3 using methods of sol-immobilisation, deposition–precipitation or impregnation. The aim of this work was to study the effect of basic properties of supports on catalytic activity and thermal stability of gold catalysts in the benzyl alcohol oxidation reaction. The structure and property of supports and catalysts were characterized using techniques of X-ray diffraction, scanning transmission electron microscopy, transmission electron microscopy, Hammett indicator, and N2 physisorption. Gold particles prepared using the sol-immobilisation method were the smallest, the most evenly dispersed, and had the best catalytic activity and lowest thermal stability. Nano-gold catalysts prepared with the other two methods had a lower catalytic activity and a good thermal stability. The thermal stability of gold catalysts varied with the support. The thermal stability of Au/HT and Au/MgO was better than that of Au/γ-Al2O3. It was found that the high thermal stability of Au/HT and Au/MgO was ascribed to the basic property of their supports. The finding is instructive in the design of Au catalysts of high activity.

A facile method was proposed for one-step preparation of Au/MgO. In this method, the Au/MgO kept both basic sites of MgO crystal and low size of gold nanoparticles. Compared with those of Au/MgO prepared by conventional methods, Au/MgO by this method had the highest activity.

Reconstructed hydrotalcite is a highly active heterogeneous base catalyst for a wide variety of reactions. Herein, we report a procedure to effectively prepare the reconstructed hydrotalcite. Mg–Al mixed oxide, which originates from hydrotalcite, is added directly to the aqueous-phase reaction system of the aldol condensation without the protection of an inert gas. Under the reaction conditions, the reconstructed hydrotalcite is in-situ generated, and is used as a catalyst for then aldol condensation as soon as it forms, resulting in the elimination of the deactivation of reconstructed hydrotalcite. The experimental results showed that the in-situ reconstructed hydrotalcite had higher catalytic activity and water tolerance. The work provides a simple and effective method for reconstructed hydrotalcite.

Biodiesel has gained attention in recent years as a renewable and environmentally friendly fuel source. A laboratory experiment designed for high school students is described to study biodiesel production. Under optimum conditions, the time of running the reaction of biodiesel synthesis was less than a half-hour. Moreover, based on the difference in density and solubility of reactants and products in the transesterification, one visualizing method of detection of biodiesel product was suggested. The results demonstrated that the visualizing method was simple, quick, and effective in determining whether biodiesel was produced. This proposed experiment is typically completed in less than two one-hour laboratory periods, which makes it suitable for a high school chemistry laboratory.Keywords: Biotechnology; Catalysis; Hands-On Learning/Manipulatives; High School/Introductory Chemistry; Inquiry-Based/Discovery Learning; Laboratory Instruction; Organic Chemistry; Student-Centered Learning; Synthesis;

Information on the catalytic mechanism is crucial for understanding heterogeneous catalysis of glycerol hydrogenolysis. In this work, we proposed a simple and effective method to study the catalytic mechanism of glycerol hydrogenolysis with Cu/Mg–Al mixed-oxide as catalyst. This method is based on the memory effect of the hydrotalcite-derived Mg–Al mixed-oxide and the tunable property of hydrotalcite interlayer distance. The experimental results showed that the basal spacing of hydrotalcite could work as an effective tool to reflect the relationship between desorption of products and reaction conditions. With this tool, the effect of H2 pressure on glycerol hydrogenolysis was elucidated. It was found that H2 pressure affected desorption and yield of products.

A number of KF-loaded heterogeneous base catalysts were prepared by doping KF on mixed oxide or single oxide supports containing Mg, Cu, Zn, Co, Al, Cr, Ni or Fe. The catalysts were characterized and tested for the transesterification of vegetable oil with methanol to produce biodiesel, in order to elucidate the active phase(s). The experimental results showed that KF doping increased activity irrespective of the nature of the support (i.e. whether it was mixed oxide or single oxide). For all catalysts KOH, formed during the treatment of each support with KF, was demonstrated to be the active phase. The activity of KF doped catalysts is promoted by the surface F-species. On this basis, it is possible to rationalize the general effect that KF has in promoting base catalyzed activity and select suitable supports in the design of highly active KF-loaded catalysts.

Information on the catalytic mechanism is crucial for understanding heterogeneous catalysis of glycerol hydrogenolysis. In this work, we proposed a simple and effective method to study the catalytic mechanism of glycerol hydrogenolysis with Cu/Mg–Al mixed-oxide as catalyst. This method is based on the memory effect of the hydrotalcite-derived Mg–Al mixed-oxide and the tunable property of hydrotalcite interlayer distance. The experimental results showed that the basal spacing of hydrotalcite could work as an effective tool to reflect the relationship between desorption of products and reaction conditions. With this tool, the effect of H2 pressure on glycerol hydrogenolysis was elucidated. It was found that H2 pressure affected desorption and yield of products.

Controlled synthesis of bimetallic catalysts has attracted much attention in heterogeneous catalysis because their catalytic activity often depends on their size and structure. Traditional modification methods have no control over the deposition of the first metal, but concentrate on using the dispersion of the first metal to control the deposition of the second metal, resulting in the deficiency in controlling the dispersion of final bimetallic catalysts. In this work, one new method was proposed to control the synthesis of supported bimetallic AuCu and AuNi catalysts by controlling the dispersion of both the first metal and second metal. The first metal (Cu or Ni) of bimetallic nanoparticles was well dispersed as a configurational ion of hydrotalcites (HTs), which interacted with the other metal (Au) of bimetallic nanoparticles by a spontaneous redox and alloying reaction. The good dispersion of the first metal controlled the good dispersion of the final bimetallic nanoparticles through the interaction between the two metals. The size, structure and composition of bimetallic nanoparticles were characterized using X-ray diffraction (XRD), nitrogen physisorption, X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM) techniques. The mean sizes of the bimetallic nanoparticles were 1.9 nm for AuCu and 2.8 nm for AuNi, which were much smaller than that prepared by traditional methods (>8.7 nm). The catalytic activity of AuCu and AuNi nanoparticles in the aerobic oxidation of benzyl alcohol was tested, which showed far higher activity than those prepared by traditional methods.

A number of KF-loaded heterogeneous base catalysts were prepared by doping KF on mixed oxide or single oxide supports containing Mg, Cu, Zn, Co, Al, Cr, Ni or Fe. The catalysts were characterized and tested for the transesterification of vegetable oil with methanol to produce biodiesel, in order to elucidate the active phase(s). The experimental results showed that KF doping increased activity irrespective of the nature of the support (i.e. whether it was mixed oxide or single oxide). For all catalysts KOH, formed during the treatment of each support with KF, was demonstrated to be the active phase. The activity of KF doped catalysts is promoted by the surface F-species. On this basis, it is possible to rationalize the general effect that KF has in promoting base catalyzed activity and select suitable supports in the design of highly active KF-loaded catalysts.