The activity and selectivity of several catalysts based on Ni(4,4′-bipyridine)Cl2 complex co-activated with AlCl(C2H5)2 and supported on different molecular sieves such as Y, L, mordenite, mesoporous MCM-41 and on amorphous silica–alumina utilised in the dimerization of ethylene at 298 K and initial pressure of the monomer 12 atm is presented. Chemo- and stereo-selectivity effects expressed as selectivity for dimers and oligomers, and respectively,

The paper presents a comparison between the catalytic performances of cobalt modified hydrotalcites obtained from different cobalt precursors in the epoxidation of cyclohexene using molecular oxygen, isobutyraldehyde as reductant, at 25 °C and 1 atmosphere pressure of oxygen in acetonitrile as solvent. Two different types of cobalt containing catalysts were prepared: (i) a hydrotalcite-like compound containing cobalt in the brucite type layer, CoMg/Al,

The epoxidation of cyclohexene by hydrogene peroxide and benzonitrile, in methanol as solvent on solid base catalysts, hydrotalcites (HT) and corresponding mixed oxides (C-HT) was investigated. The employed catalysts were as-synthesized Mg/Al; Mg,Zn/Al; Mg/Ga,Al hydrotalcites, their derived mixed oxides and the corresponding reconstructed hydrotalcite forms (R-HT) obtained via the “memory effect” upon a rehydration treatment of C-HT. The catalysts

NiMoO4 silica-supported samples (6.5% w/w) were prepared by coprecipitation technique. In order to study the influence of the surface area of the support material, silicas with different surface areas have been used: Durosil (60 m2/g) and Sipernat 22 (190 m2/g) from Degussa and silica prepared in the laboratory (590 m2/g). Nanosized grains of β-NiMoO4 phase were obtained for all the prepared samples. The crystallinity of the active phase (mixed

The goal of this paper was to study the synthesis of the cinamic acid, coumarin-3-carboxilic acid and their ethylesters by Knoevenagel condensation using the solid base catalysts obtained from calcined Mg–Al, Mg–Al + Ln (Ln = Dy, Gd) and Li–Al hydrotalcites, under solvent free conditions. Correlations between the basicity of the catalysts and the advancement degree in the pathway of the condensation reaction have also been investigated.

Several Mo-containing hydrotalcite-like compounds (HTlcs-Mo) were prepared by different ionic exchange procedures using as parent a synthetic hydrotalcite Mg3Al(OH)8(CO3)0.5·2H2O with a composition similar to the natural occurring mineral. Their physico-chemical properties determined by chemical and TG–DTA analyses, XRD, BET, FTIR, SEM-EDX, DR–UV–vis and Raman spectroscopy, were compared to those of two HTlcs-Mo prepared by direct synthesis

NiMoO4 catalysts supported on TiO2 (anatase) were prepared using two procedures: (i) wet impregnation of the support with an aqueous suspension of NiMoO4 and (ii) direct precipitation of NiMoO4 on the support surface using solutions of nickel nitrate and ammonia heptamolybdate. The catalysts and their precursors were characterised by XRD and TG/DTA and the catalytic behaviour of TiO2-supported NiMoO4 for the oxidative dehydrogenation of isobutane

The oxidative dehydrogenation of isobutane over SiO2-supported and unsupported NiMoO4 was studied under steady state conditions and the effect of active phase loading analysed. The SiO2-supported catalysts were prepared by direct precipitation of NiMoO4 on the support and characterised by BET, X-ray diffraction and temperature-programmed desorption of NH3. Used catalysts were characterised by thermal analysis. Results show that, in SiO2-supported

Catalysts containing Ni(2,2′-bipyridine)2Cl2 complex (K) encapsulated in Y zeolite cages (Ke/Y) or obtained by impregnation–complexation (Ki–c/Y), co-activated with AlCl(C2H5)2 show good activity and selectivity for ethylene dimerization at 333 K and W/F = 37 gcat h (moles C2H4)−1 molar contact time. Ke/Y co-activated with AlCl(C2H5)2 led to an ethylene conversion of 72.5% and 74.5% selectivity to C4H8, the prevailing isomer being 1-butylene.

This work presents results concerning the catalytic behaviour of silica-supported Zirconium (Zr)-doped NiMoO4 catalyst (NiMoZr1%Si) in the metathesis of 1-octene compared to that of the pure NiMoO4 (NiMo) and the un-doped supported catalyst (NiMoSi). The effect of doping on the physico-chemical properties of the catalysts is also investigated using X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman spectroscopy, Brunnauer-Emmet-Teller