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] reported that when Ni modified Co/γ-Al 2 O 3 catalyst was applied for the reaction, the ethanol conversion rate of 100% and the selectivity of acetonitrile up to 92.5% were obtained. However, the reaction temperature was as high as 420 °C. The reaction
over catalyst NiO supported on alumina (NiO/γ-Al 2 O 3 ). It is well known that alumina is a widely used support material for the dehydrogenation catalysts due to its superior capability in holding high dispersion of active phase [ 10 , 11
Abstract
The sorption of Cd(II) from aqueous solution on γ-Al2O3 was investigated under ambient conditions. Experiments were carried out as a function of contact time, solid content, pH, ionic strength, foreign ions, fulvic acid and temperature. The results indicated that the sorption of Cd(II) was strongly dependent on pH and ionic strength. At low pH, the sorption of Cd(II) was dominated by outer-sphere surface complexation and ion exchange with Na+/H+ on γ-Al2O3 surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The Langmuir, Freundlich and Dubinin–Radushkevich (D–R) models were used to simulate the sorption isotherms at three different temperatures. The thermodynamic data (ΔG 0, ΔS 0, ΔH 0) calculated from the temperature dependent sorption isotherms suggested that the sorption of Cd(II) on γ-Al2O3 was an spontaneous and endothermic process.
2 O 3 catalyst for the amination of morpholine with alcohols. This paper presents a systematic study on the amination of morpholine with different kinds of alcohols using the CuO–NiO/γ–Al 2 O 3 catalyst in a fixed-bed reactor. The purposes
and establish a new process for various saturated N-containing heterocycles over a catalyst. In this paper, the Cu-based catalysts were modified and Cu–Cr–La/ γ -Al 2 O 3 exhibited the best catalytic performance for the synthesis of the
Abstract
Polyaniline/γ-Al2O3 (PANI/γ-Al2O3) composites were synthesized by in-situ polymerization at the presence of HCl as dopant by adding γ-Al2O3 nanoparticles into aniline solution. The composites were characterized by FTIR and XRD. The thermogravimetry (TG) and modulated differential scanning calorimetry (MDSC) were used to study the thermal stability and glass transition temperature (T g) of the composites, respectively. The results of FTIR showed that γ-Al2O3 nanoparticles connected with the PANI chains and affected the absorption characteristics of the composite through the interaction between PANI and nano-sized γ-Al2O3. And the results of XRD indicated that the peaks intensity of the PANI/γ-Al2O3 composite were weaker than that of the pure PANI. From TG and derivative thermogravimetry (DTG) curves, it was found that the pure PANI and the PANI/γ-Al2O3 composites were all one step degradation. And the PANI/γ-Al2O3 composites were more thermal stable than the pure PANI. The MDSC curves showed that the nano-sized γ-Al2O3 heightened the glass transition temperature (T g) of PANI.
Abstract
Spinel (MgAl2O4) was synthesized mechanochemically (MC) by grinding MgO with γ-Al2O3 up to 10 hours. Examination of the MC product by neutron diffraction and infrared spectroscopy showed that it has a higher degree of inversion than its thermally produced counterpart—47% as against 10% respectively. X-ray studies showed that MgAl2O4 crystallites grow equidimensionally at a much higher rate than in the case of α-Al2O3. The higher degree of inversion and higher formation rate when γ-Al2O3 is used, is attributed to similarities in oxygen framework of MgO, Al2O3 and spinel and to the higher retention of the cations coordination number. The equidimensional growth is attributed to the presence of multiple soft modes, the {111} planes.
Abstract
Phase change nanocomposites were prepared by dispersing γ-Al2O3 nanoparticles into melting paraffin wax (PW). Intensive sonication was used to make well dispersed and homogeneous composites. Differential scanning calorimetric (DSC) and transient short-hot-wire (SHW) method were employed to measure the thermal properties of the composites. The composites decreased the latent heat thermal energy storage capacity, L s, and melting point, T m, compared with those of the PW. Interestingly, the composites with low mass fraction of the nanoparticles, have higher latent heat capacity than the calculated latent heat capacity value. The thermal conductivity of the nanocomposites was enhanced and increased with the mass fraction of Al2O3 in both liquid state and solid state.
Abstract
The fate and transport of toxic metal ions and radionuclides in the environment is generally controlled by sorption reactions. The extent of sorption of divalent metal cations is controlled by a number of factors including cosorbing or complexing. In this work, the effects of pH, humic acid HA/Co(II) addition orders, ionic strength, concentration of HA, and foreign cations on the Co(II) sorption on γ-Al2O3 in the presence of HA were investigated. The sorption isotherms of Co(II) on γ-Al2O3 in the absence and presence HA were also studied and described by using S-type sorption model. The experimental results showed that the Co(II) sorption is strongly dependent on the pH values, concentration of HA, but independent of HA/Co(II) addition orders, ionic strength, and foreign cations in the presence of HA under our experimental conditions. The results also indicated that HA enhanced the Co(II) sorption at low pH, but reduced the Co(II) sorption at high pH. It was hypothesized that the significantly positive influence of HA at low pH on the Co(II) sorption on γ-Al2O3 was attributed to strong surface binding of HA on γ-Al2O3 and subsequently the formation of ternary surface complexes such as ≡S-OOC-R-(COO−) x Co2−x . Chemi-complexation may be the main mechanism of the Co(II) sorption on γ-Al2O3 in the presence of HA.
Abstract
The catalytic synthesis of 2-amino-1-butanol from 1,2-butanediol and ammonia was studied in a continuous fixed-bed reactor. The catalysts prepared by doping Co–Ba/γ-Al2O3 with Sr, Ni, Ca, Zn, La, Fe, Mg, Zr, Mn, Cr were examined, among which the Co–Ba–Fe/γ-Al2O3 catalyst showed the best catalytic performance. These catalysts were characterized by XRD, XPS, and TPR. It was found that the addition of iron led to the formation of crystalline Co7Fe3, which modified the catalytic activity of Co species, inhibited the generation of CoAl2O4, improved the stability and enhanced the reduction of the Co–Ba–Fe/γ-Al2O3 catalyst. The conversion of 1,2-butanediol was 72.9% and the selectivity of 2-amino-1-butanol achieved 73.3% under the optimum reaction conditions.
