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Abstract: The catalytic N2O decomposition was investigated over a series of Cu x Ce1−x O y mixed oxides with different Cu/Ce molar ratios. Effects of synergy over mixed oxides of CeO2 and CuO were observed significantly, the catalyst of Cu0.67Ce0.33O y exhibited the high activity among the Cu–Ce–O mixed oxides for N2O decomposition. Characterizations of XRD, N2-adsorption, XPS, and H2-TPR were applied to correlate their properties with the corresponding catalytic performance, and reveal the synergetic effect between CuO and CeO2 for N2O decomposition. In situ DRIFTS investigation confirmed the presence of CuI species that was closely related with the activity of Cu x Ce1−x O y catalyst. The synergy of Cu x Ce1−x O y promoted the stability and the ability to regenerate the active CuI site. [Copyright &y& Elsevier]

Abstract: Cerium-doped MCM-41 (Ce-MCM-41) was prepared by a hydrothermal method and its catalytic activity for ozonation of p-chlorobenzoic acid (p-CBA) in aqueous solution was studied. For comparison, cerium-loaded MCM-41 (Ce/MCM-41) was prepared by a dipping method. Ce-MCM-41 was characterized by the low and wide angle X-ray powder diffraction (XRD), nitrogen adsorption–desorption, transmission electron microscopy (TEM) and ultraviolet–visible diffuse reflection spectrum (UV–vis DRS). The results showed that the material retained the highly ordered mesopore structure of MCM-41 and had a surface area of 852m2 g−1. Cerium was incorporated into the framework of MCM-41, locating at tetrahedrally coordinated sites. The cerium doping content, initial pH of aqueous solution and reaction temperature played important roles in catalytic ozonation of p-CBA. Under the chosen conditions (1.39mgl−1 ozone dosage, 10mgl−1 p-CBA solution and 1gl−1 catalyst dosage), the high mineralization rate (86%) was achieved by Ce-MCM-41/O3 process at 60min reaction time, only 52% by O3 alone. The combination of Ce-MCM-41 and O3 exhibited a significant synergetic effect. Ce-MCM-41 showed the better activity and stability than cerium-loaded MCM-41(Ce/MCM-41) during catalytic ozonation of p-CBA, its cerium leaching was greatly reduced (only 0.085mgl−1) and below detection limit after being reused, compared with that of Ce/MCM-41 (0.44mgl−1) with the presence of the same theoretical cerium content. TOC removal rate slightly decreased from 86% to 81% and kept stable after Ce-MCM-41 being re-utilized two times, which illustrated that Ce-MCM-41 was a kind of promising catalyst for ozonation of p-CBA. The addition of Ce-MCM-41 significantly improved ozone decomposition into HOus solution and reduced ozone concentration in equilibrium. [Copyright &y& Elsevier]

Abstract: Silica-supported MoP catalysts were prepared by temperature-programmed reduction (H2-TPR) at 550, 600 and 700°C of the corresponding dried or calcined substrates. Two catalysts were prepared by using two different synthetic approaches. A MoP catalyst was prepared using the method described in the literature that uses ammonium phosphate (NH4H2PO4) and ammonium heptamolybdate ((NH4)6Mo7O24·4H2O) precursors, calcination and subsequent H2-TPR at high temperature. A new synthetic approach was carried out to prepare another MoP catalyst using ammonium molybdate ((NH4)2MoO4) and phosphorous acid (H2PO3H) as precursors and subsequent H2-TPR. The catalytic activity was evaluated in the individual and simultaneous hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) reactions performed in a flow reactor under a hydrogen pressure of 3.0MPa. The fresh reduced and spent catalysts were characterized by ICP, N2 adsorption–desorption isotherms at −196°C, XRD, HRTEM, NH3-TPD, XPS and elemental chemical CNHS analysis. The silica-supported MoP catalysts prepared by the new synthetic method were more active in the HDS of DBT than the catalyst prepared by reduction of calcined substrate. The catalyst characterization results showed that the lower reduction temperature required to form the MoP species is responsible for the enhancement in catalytic performance. The key factors influencing on the catalytic activity are: a large specific surface area, high acidity and good dispersion of MoP phase on the support substrate. Activity measurements in simultaneous HDN–HDS showed that quinoline conversion is enhanced in the presence of a small amount of DBT whereas the HDS of DBT reaction does not appear to be inhibited by a small amount of quinoline added to the feed. [Copyright &y& Elsevier]

Abstract: Na-montmorillonite (Na-mmt) and different pillared interlayered clays (Al-PILC, Zr-PILC, Ti-PILC and Al2O3/Ti-PILC) supported CrCe catalysts for the deep oxidation of nitrogen-containing VOCs (NVOCs) are synthesized and characterized by a combination of X-ray diffraction, N2 adsorption/desorption, high resolution transmission electron microscopy, temperature-programmed reduction, temperature-programmed desorption and adsorption capacity tests techniques. The results indicate that a porous structure named “house of cards” forms during the pillaring and calcination processes. Both porous structure and acidity play important roles in deep oxidation of NVOCs. The mesoporous structure and the proper acid sites improve the catalytic activity of supported CrCe catalysts. Among all these catalysts, CrCe/Ti-PILC and CrCe/Al2O3/Ti-PILC exhibit higher catalytic activity than other catalysts. N-butylamine and ethylenediamine with –NH2 groups are easier to be destructed may be involved in the stronger adsorption on the acid sites of the catalysts. Much too strong adsorption of ethylenediamine on the acid sites leads to a lower activity compared with n-butylamine. Acetonitrile with C≡N bond and little interaction with acid sites is the most difficult to be decomposed. All the catalysts show a good control quality of NO x , and the yield of NO x is limited within 2% during the whole experimental temperature range. [Copyright &y& Elsevier]

Abstract: A series of nanosized W,N-codoped and single-doped N- and W-anatase-TiO2 catalysts have been prepared by a microemulsion method and calcined at different temperatures. The activity in the sunlight selective photo-oxidation of toluene and styrene has been correlated with structural, electronic, and surface examinations of the catalysts done with the help of XRD-Rietveld, N2 physisorption, X-ray photoelectron, infrared, electron paramagnetic resonance (EPR) and UV–vis spectroscopies. Irrespective of the reaction, W,N-codoped nanocatalysts showed an enhanced photoactivity with respect to bare anatase and single-doped N-TiO2 and W-TiO2 materials. A strong W–N synergistic interaction appears to play a decisive role in driving the excellent photoactivity performance of W,N-codoped materials by affecting (i) electronic properties, particularly maximizing the anatase band gap decrease and enhancing the subsequent visible light photon absorption, and (ii) surface properties, in turn related to the formation of OH radicals upon light excitation. The maximum photoactivity is reached by calcination at 450°C and is concomitantly observed with a near complete selectivity to partial oxidation products. Higher calcination temperatures yielded solids with significantly inferior photocatalytic performance. The properties of the W–N interaction are discussed as a function of the calcination temperature. [Copyright &y& Elsevier]

Abstract: Birnessite and cryptomelane samples have been prepared and characterised by N2 adsorption at −196°C, XRD, XRF, XPS and H2-TPR. The activity of birnessite and cryptomelane for catalysed combustion of soot under NO x /O2 gas mixtures has been studied and compared with that of some other commercially available pure manganese oxides, namely MnO, MnO2, Mn2O3, Mn3O4, and natural MnO2. Birnessite and cryptomelane are more active for soot combustion than all the commercial oxides tested. Among the manganese oxides studied, birnessite shows the highest catalytic activity, lowering the soot combustion temperature by 150°C regarding the uncatalysed reaction, and cryptomelane lowers this temperature by 120°C. The NO x removal profiles suggest that birnessite chemisorbs NO x and forms potassium nitrate, which melts and reacts with soot. On the contrary, the main soot combustion pathway for cryptomelane and for the commercial manganese oxide tested is based on the catalytic oxidation of NO to NO2. Birnessite and cryptomelane only yield CO2 as carbon-containing soot combustion product. [Copyright &y& Elsevier]

Abstract: Catalytic decomposition of N2O was studied on Na-MOR, H-MOR, and Na-MFI samples exchanged to various extents with cobalt or copper. Co-MOR samples were characterized by FTIR and volumetric measurements of NO adsorption. The most abundant species on Co-MOR was Co2+(NO)2. In agreement, the volumetric data yielded NO/Co=1.8±0.2. On Co-MOR, N2O conversion progressively increased as the cobalt content increased. All samples yielded similar apparent activation energy, E a =75±5kJmol−1. The reaction order was 0.9±0.1 for N2O, and 0.0±0.1 for O2. For samples having a Co-exchange percentage up to 61%, the turnover frequency per total Co atom was independent of the cobalt content and was significantly lower for more extensively exchanged samples. On all Co-MOR samples, the turnover frequency per isolated Co atom was nearly constant, indicating isolated Co2+ as the active site. On Cu-MOR and Cu-MFI samples, N2O conversion markedly increased with the copper content. Samples having a Cu-exchange percentage up to 62% yielded higher E a than more extensively exchanged samples (150±5kJmol−1 vs. 100±5kJmol−1). The reaction order was 0.5±0.1 for N2O, and 0.0±0.1 for O2. We conclude that in Co-MOR and Co-MFI catalysts the active site for N2O decomposition is isolated Co2+, whereas in Cu-MOR and Cu-MFI isolated Cu2+ is nearly inactive. In extensively exchanged Cu-MOR and Cu-MFI, the active site for N2O decomposition is most probably Cu1+. A similar reaction mechanism for N2O decomposition operates over Co-zeolites and extensively exchanged Cu-zeolites. [Copyright &y& Elsevier]

Abstract: This work investigates the use of calcined calcium zincate as solid base catalyst for the methanolysis of sunflower oil to FAME (biodiesel). The precursor and catalyst were characterized by XRD, XPS, SEM, EGA-MS, FTIR and N2 adsorption. The thermal treatment at temperatures as low as 400°C leads to a base catalyst which is very active and stable in biodiesel production from different vegetable oils (sunflower and soybean). The presence of carbonate on the calcium zincate, used as precursor, is negligible after remaining in contact with air for two weeks. The catalyst obtained at 400°C shows FAME yields higher than 90% after 45min of reaction, and the kinetic of the heterogeneous process (60°C, methanol:sunflower oil molar ratio of 12, 3wt.% of catalyst) is very close to that observed under homogeneous conditions (KOH dissolved in methanol). Under these experimental conditions, the catalyst is stable against lixiviation since it can be reutilized for three catalytic runs of 1h, reaching yields higher than 85%. Moreover, by increasing the acidity of the oil until 1.1° (typical value of fried oils), the catalytic performance is maintained. The presence of water has a negative influence on the catalytic activity, since the addition of a 0.2wt.% of water into the reaction medium decreases the FAME yield until 80% after 3h of reaction, although this yield is still higher than 60% after adding a 1wt.% of water. This catalyst is also very active in the transesterification of soybean oil. [Copyright &y& Elsevier]

Abstract: A series of Co–Mo–Mg/Al2O3, K–Co–Mo–Mg/Al2O3, and Co–Mo/silica catalysts were prepared and characterized by means of N2 adsorption, temperature-programmed desorption of ammonia (NH3-TPD), high-resolution transmission electron microscopy (HRTEM), and Fourier transformed infrared (FT-IR) spectra of adsorbed NO. The physicochemical properties of the catalysts were correlated with their hydrodesulfurization and olefin hydrogenation activities. The results showed that the dispersion and stacking of supported MoS2 were more important in influencing the selectivity of FCC gasoline hydrodesulfurization than the catalyst pore diameter and acidity. The compromise between the dispersion and the stacking of supported MoS2 slabs was crucial to form the sufficient and accessible Co–Mo–S phases for achieving optimal hydrodesulfurization selectivity. The present results form a fundamental basis for developing highly effective catalysts for the selective hydrodesulfurization of fluid catalytic cracking gasoline to meet the strict regulations for ultra-low sulfur gasoline. [Copyright &y& Elsevier]