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Herein, a series of alumina supports were prepared by rehydration-dehydration of the traditional γ-Al2O3 under different hydrothermal temperatures. After loading CoMo species, it was found the selectivity factor of corresponding CoMo/Al2O3 catalysts was improved greatly from 1.21 to 2.51 with the increased hydrothermal temperature of alumina supports in the hydrodesulfurization (HDS) of a model fluid catalytic cracking (FCC) naphtha. The improved HDS selectivity is attributed to the weakened metal-support interaction and lowered dispersion of MoS2 particles, resulting in catalysts with larger edge-to-corner ratios of CoMoS slabs ((fe/fc)CoMo). Besides, the recombination mercaptans formed by reaction of produced H2S and olefins were found as a big challenge to reach a high HDS conversion (S

Solar thermochemical CO2/H2O splitting cycles based on redox oxides have emerged as a potential strategy to store dilute and intermittent solar energy. It is desirable to explore other materials that can convert solar energy into chemical energy with high efficiency. Herein, a thermochemical water splitting (TCWS) cycle based on Sr- and Co-doped LaGaO3−δ (La1−xSrxGa1−yCoyO3−δ) was successfully developed. Compared with inert LaGaO3−δ, the oxygen vacancy concentration (δ) is gradually increased as the contents of Sr- and/or Co-dopants increased. The δ value of LaGa0.4Co0.6O3−δ (LGC60) reaches 0.16 after reduction for 40 min at 1350 °C, which is 5 and 4 times that of Ce0.85Zr0.15O2−δ and LSMA6464, respectively. The H2 yield of LGC60 (478 μmol H2 g−1perovskite) is 15 times that of the current state-of-the-art material, CeO2−δ (32 μmol H2 g−1material), when reduced at 1350 °C and re-oxidized at optimized 800 or 1000 °C. 1.0 atom% IrOx as a catalyst doped into the structure of LGC50, named LGC50-Ir(1.0), can increase the H2 release rate by 1.3-fold. XPS results reveal that the H2O splitting reaction is driven by the Co2+/Co3+ redox pair. DFT calculations predict that the oxygen vacancy formation energies (EV) of La1−xSrxGa1−yCoyO3 span from nearly 0.7 to about 5.3 eV under vacuum conditions at 1623 K, depending on the contents of Sr- and Co-dopants. Thus, doping Co at the B-site is responsible for the introduction of redox activity, and adjusting Sr- and Co-contents is effective in tuning the δ and EV values of La1−xSrxGa1−yCoyO3−δ. It should be pointed out that, at present, the steam to hydrogen conversion ratios for LaGa1−yCoyO3−δ under the used evaluation conditions are still very low (

Traditionally prepared CoMo/Al2O3 hydrotreating catalysts, although efficient for deep desulfurization, are not suitable for fluid catalytic cracking (FCC) gasoline hydrodesulfurization (HDS) due to their high olefin hydrogenation (HYD) activity especially when the HDS conversion is high. Herein, two alumina supports with tailored surface properties were prepared by calcination of hydrothermally treated pseudo-boehmite (PB) and hydrothermally treated γ-Al2O3 in order to design CoMo/Al2O3 catalysts with high HDS selectivity. It is found that compared with the traditional alumina prepared by direct calcination of PB, the two tailored alumina supports have notably decreased surface area, surface hydroxyl groups and Lewis acidity. The characterization results show that the catalysts obtained from CoMo supported on the two tailored supports have lowered Mo dispersion, weakened metal-support interaction, increased Mo sulfidation degree and longer MoS2 slabs than the traditional CoMo/Al2O3 catalyst. The catalytic results of three different CoMo/Al2O3 catalysts in the HDS of a full-range FCC gasoline show that the HDS selectivity is increased remarkably (selectivity factors increase from 5.5 to 11.0) with the decreased surface area, surface hydroxyl groups and Lewis acidity of the alumina supports. Especially, CoMo supported on the tailored alumina support prepared by calcination of hydrothermally treated γ-Al2O3 (denoted as CoMo/Al2O3-3) exhibits a 15% lower olefin HYD activity than traditional CoMo/Al2O3 catalyst even at the same and high HDS conversion (95%). The greatly improved HDS selectivity can be well explained by the increased slab length of supported MoS2 particles, resulting in notably decreased HYD activity catalyzed by the corner sites. Besides, CoMo/Al2O3-3 also shows superior HDS selectivity in the HDS of a real heavy FCC naphtha, where the sulfur content can be reduced from 309 ppm to 10 ppm with an accompanying RON loss of only 1.0 unit.

The morphology-performance relation is of great importance for designing a catalyst with high performance in the selective hydrodesulfurization (HDS) of fluid catalytic cracking (FCC) gasoline. Herein, we report a simple one-pot hydrothermal method to prepare the unsupported MoS2 catalysts with controlled morphology by adjusting the pH values and using different precursors. It is found that smaller MoS2 crystallites are produced when the pH value decreases in the synthetic process. With the increased MoS2 crystallite size, the HDS selectivity factor (SF) increases from 1.46 to 1.52 for non-promoted MoS2 catalysts, and from 13.96 to 19.69 for Co-promoted MoS2 catalysts. On the other hand, for MoS2 catalysts with similar stacking, the MoS2 with longer slab length exhibits improved HDS selectivity (SF from 2.90 to 2.99). These results confirm that the slab length instead of the stacking for MoS2 particles is more important to influence the HDS selectivity. Due to the fact that the corner sites could catalyze both HDS and HYD reactions while edge sites only catalyze the HDS reaction, thus increasing the edge/corner ratio by preparing (Co)MoS2 catalysts with longer MoS2 slab length is an efficient way to improve the selectivity in the selective HDS of FCC gasoline.

To remove sulfur-containing molecules from gasoline via hydrodesulfurization (HDS) while minimizing olefin hydrogenation is quite difficult. In this work, we report that an unsupported Co-Mo catalyst can achieve high HDS activity with low activity in olefin hydrogenation. The HDS selectivity of the Co-Mo catalyst is fourfold that of CoMo/γ-Al 2 O 3 for both model gasoline and full-range FCC gasoline. For Co-Mo sulfide catalysts, we found that the MoS 2 slab morphologies such as curvature, stacking number and slab length were important factors influencing the catalytic performance. Co-Mo catalyst with longer slab length and higher stacking number of MoS 2 exhibited higher HDS selectivity. Nevertheless, it was found that the slab length showed much more influence on HDS selectivity than the stacking number. Furthermore, the curved MoS 2 could facilitate the olefin isomerization. Present work provides a new way to develop a highly selective HDS catalyst by controlling the MoS 2 morphology.

Ferrites have emerged as potential materials in thermochemical fuel production due to its appreciated thermodynamic driving force of H 2 O/CO 2 splitting and inexpensive. Herein, to enhance the utility of iron element and fuel release rate/production, dopants (such as Co, Mn, Sr, and Ce) and SiO 2 support are used to improve the reactivity of LaFeO 3 /SiO 2 derived two-step thermochemical water splitting (TCWS). It was found that the pure LaFeO 3 perovskite shown negligible TCWS reactivity; cobalt doped into the structure of LaFeO 3 could result in enhanced but limited utility of oxygen vacancy. Compared with unsupported LaFeO 3 , the actual redox phases of SiO 2 supported samples are doped iron silicon oxides, (M,Fe) 3-x Si x O 4 (M = dopants); the normalized molar iron based O 2 production (mL per mmol of Fe) is increased by 5-fold for LaFeO 3 (25 wt%)/SiO 2 and is further increased by 10 times for LaFe 0.8 Co 0.2 O 3 (25 wt%)/SiO 2 . It suggests that SiO 2 support is helpful to disperse iron silicon oxides and alleviate sintering at high temperatures. XPS results reveal that the LaFeO 3 /SiO 2 derived TCWS is driven by a repeated Fe 2+ /Fe 3+ redox cycle and the utility of iron element is enhanced via the addition of cobalt dopant and SiO 2 support. The cycle performance of LaFe 0.8 Co 0.2 O 3 (25 wt%)/SiO 2 demonstrated that ∼2.8 mL O 2 g −1 material and ∼4.2 mL H 2 g −1 material were stably released when the TCWS was operated between 1350 °C and 1100 °C. The total mass based O 2 and H 2 productions of LaFe 0.8 Co 0.2 O 3 (50 wt%)/SiO 2 can be further increased to ~4.5 and ~7.8 mL g −1 material , respectively.

Most of the solar-driven thermochemical CO2 dissociation reactions have been focused on two-step processes. In this study, a one step CO2 thermolysis process was considered. It was found that direct thermolysis of CO2 obviously occurred at temperatures as low as 1200 °C within a corundum tube. The reaction rate could be enhanced by several times in the presence of metal oxides, which may be attributed to the catalysis of oxygen vacancies in the metal oxides.

To improve the hydrodesulfurization activity while to minimize the hydrogen consumption from the hydrogenation of olefins is of importance for the deep desulfurization of gasoline. Herein, a series of Co/MoS 2 ± x catalysts were prepared by impregnating Co-promoter to MoS 2 ± x (x ≤ 0.06) with controllably varied S/Mo atomic ratio. The S/Mo atomic ratio of MoS 2 ± x in Co/MoS 2 ± x catalysts influences the catalytic performance of Co/MoS 2 ± x in simultaneously thiophene hydrodesulfurization (HDS) and cyclohexene hydrogenation (HYD) reactions. With decreasing the S/Mo atomic ratio in Co/MoS 2 ± x , the HDS selectivity factor (k HDS /k HYD ) increases to two times (from 37 to 89), although the catalytic activities of HDS and HYD decrease due to the low content of CoMoS phase. The higher selectivity of Co/MoS 2 ± x with lower S/Mo atomic ratio could be well explained by larger size of sulfide crystallites exposed lower corner sites. Therefore, a high HDS selectivity catalyst could be developed by properly controlling the crystal size of sulfide crystallites.

Thiophene is one of the main sulfur-containing compounds present in gasoline and difficult to be oxidized with the conventional oxidative processes. Photocatalytic oxidation is believed to be a promising way to remove the sulfur-containing compounds from gasoline. Here we studied the photocatalytic oxidation of thiophene on RuO2/SO42−-TiO2 photocatalyst. We found that high activity can be achieved on 0.045 wt.% RuO2/1 M SO42−-TiO2 using molecular oxygen as oxidant. The sulfur in thiophene is oxidized to SO3 finally. SEM and XRD measurements show that the crystallinity of TiO2 is greatly improved by sulfation process. IR spectra of pyridine adsorption measurements gives the evidence for that the surface acidity property of TiO2 is also greatly improved. We can conclude that the synergistic effect of RuO2 acting as an oxidation cocatalyst and SO42−-TiO2 acting as a Lewis acid which capture superoxide species/activate thiophene molecules is responsible for the activity enchancement of thiophene photocatalytic oxidation. The synergistic effect between oxidation catalysis and acid catalysis is crucial for developing highly active photocatalysts for environmental protection.

The multi-step thermochemical water splitting cycle based on MnFe2O4–Na2CO3 has emerged as an attractive process due to its relatively low reaction temperature. The main challenges are how to enhance its H2/O2 release rates and capacities. Herein, a series of MnFe2O4 with different microstructures synthesized by hydrothermal method were tested in H2O splitting reaction. It was found that MnFe2O4 samples with smaller particle size and fine crystallinity exhibited higher H2 production which was benefit from enhanced intimate contact between homogeneous particles and better ionic transport within fine crystals. In order to enhance the reaction kinetics of the O2 release reaction, a hydrolysis treatment was introduced to the multi-step cycle. As a result, the lamellar structure of Na+ extracted Na1−x(Mn1/3Fe2/3)O2 oxide became unstable and collapsed into cubic MnFe2O4 spinel structure more easily under heating, a structure characteristic suitable for O2 release reaction. Compared to direct O2 release reaction between layered Na(Mn1/3Fe2/3)O2 oxide and CO2, the hydrolysis treatment lead to much faster reaction rate.

To increase the dispersion of active species and full utilization of active metals are of great importance for hydrodenitrogenation (HDN) performance of unsupported hydrotreating catalysts. Herein, a series of unsupported Ni(Zr)MoS and Ni(Zr)WS catalysts were prepared from Ni(Zr) layered double hydroxide (LDH) precursors. The Zr species remarkably promote the dispersion and reducibility of NiMo and NiW composite species. Also, the total HDN rate constants are increased from 2.42 h−1 to 9.18 h−1 for Ni(Zr)MoS and from 5.68 h−1 to 23.0 h−1 for Ni(Zr)WS, and exhibit a maximum at a Zr/Ni atomic ratio of about 0.04. The HDN selectivities indicate that the Zr species increase the number of superficial active sites without affecting their structure. The present work shows that the crystallinity of LDH precursors is crucial to the structure of unsupported sulfide catalysts, and a suitable amount of Zr could be a dispersive promoter to increase the HDN activity.

Splitting CO2 into CO and O2 via a two-step thermochemical cycle by utilizing concentrated solar energy is a promising option for CO2 reduction. Herein, to enhance the solar to fuel energy conversion efficiency, IrOx as a catalyst is used to increase the fuel production rate of the LaFeO3-based two-step thermochemical CO2-splitting reaction. Compared with LaFeO3, 0.6 atom % IrOx as a catalyst that loaded on LaFeO3 can almost double the maximal CO release rate and increase the maximal O2 evolution rate 0.5 times; when a small amount of IrOx (2.5 atom %) is doped into the structure of LaFeO3 through a solution combustion method, the initial CO generation rate can be increased by 5-fold. This work demonstrates that the catalytic function is still necessary in the two-step thermochemical CO2-splitting reaction even at high temperatures.

Multi-metallic bulk HDS catalysts NixZnyAlzMoW with different Zn/Al molar ratio were prepared using a NiZnAl-layered hydroxide precursor by co-precipitation method. XRD, HRTEM, and SEM results show that the catalysts possess layered structure, and the layered precursor NixZnyAlz-LDH is a mixture of ZnAl-LDH and NiAl-LDH. Ni(Zn)-promoted Mo(W) active species Ni(Zn)–Mo(W)–S are detected by Raman spectroscopy and HRTEM. Hydrodesulfurization (HDS) result of 4,6-dimethyldibenzothiophene (4,6-DMDBT) shows that catalysts NixZnyAlzMoW exhibit excellent HDS performance and the sulfur content in the model diesel could be reduced from 517 ppm to less than 10 ppm (under mild reaction conditions of 3.0 MPa of H2 pressure, 300 °C, LHSV of 9 h−1, and H2/oil ratio of 800 Ncm3/cm3). Catalysts NixZnyAlzMoW show higher HDS activity than the commercial catalyst CoNiMoW/Al2O3 due to the high active metal content, the layered structure, and the positive promoter effect of Zn. Besides, Zn-doping also reduces the apparent activation energy of catalysts and results in larger pore volume and larger pore size for catalysts. Part of Zn (Ni) acts as a promoter but other part as a support. The promoter effect of Zn is partially responsible for the high HDS activity. It is found that the second promoter Zn decreases the interaction between alumina and active components Ni, Mo, W to form more Ni(Zn)–Mo(W)–S active species.

Silica-supported Zr-doped cobalt ferrite complex oxides, Co1-2xZrxFe2O4/SiO2 (0

A new vanadoperiodate [HIV9O28]3− has been synthesized by a simple, one-pot stoichiometric reaction of HIO4·2H2O with NaVO3 in aqueous solution and then isolated as [C8H17N(CH3)3]3HIV9O28 by cation exchange. We have found that [C8H17N(CH3)3]3HIV9O28 shows high catalytic activity in the oxidation of refractory sulfur-containing compounds to their corresponding sulfones using molecular oxygen as oxidant under mild reaction conditions.

The catalytic properties of Co-supported activated carbon (AC) catalysts for ethyl acetate catalytic elimination in air were investigated. Results showed that air atmosphere promoted the generation of high-valence state cobalt oxides, and promote the production of reactive oxygen species (ROS) in the Co 3 O 4 /AC catalyst. ROS crucially functioned in improving the catalytic activity of Co 3 O 4 /AC catalysts. Therefore, CoACA catalyst prepared in air exhibited higher catalytic activity than CoACN catalyst prepared in nitrogen, and CoACA catalyst led to high ethyl acetate conversion (>93%) and stability at a low reaction temperature (210 °C).

The conversion of solar energy into chemical fuels from H2O and CO2 is a promising option to produce long-term storable and transportable energy in the future and it is also an ideal way for CO2 reduction. Solar-driven thermochemical approaches to CO2 and H2O dissociation inherently operate at high temperatures and use the entire solar spectrum; as such, they could provide the path to solar fuel production at high rates and efficiencies. This article briefly reviews the recent advances in solar thermal H2O and CO2 splitting reaction especially summarizes the recent progress in this group. The prospects for the development of highly efficient redox oxides for CO and H2 production are also discussed.

A bicapped Keggin structure vanadophosphate showed high catalytic activity in the oxidation of dibenzothiophene (DBT) to sulfone using molecular oxygen as oxidant under mild reaction conditions. This is a promising approach to the ultra-deep desulfurization of fuels (e.g. diesel) as sulfones can be removed from the fuel by extraction or selective adsorption.

An efficient redox material for two-step thermochemical CO2 splitting reaction requires high chemical yield at relatively low reduction temperature. Herein, the oxides with perovskite structure of formula La(x)A(1-x)Fe(y)B(1-y)O(3) (A = Sr, Ce, B = Co, Mn; 0

Layered multi–metallic bulk catalysts Ni x Zn y MoW with different Ni/Zn molar ratios were prepared based on the NiZn–layered hydroxide precursor by co–precipitation method and well characterized by various technologies including XRD, SEM, HRTEM and Raman spectroscopy. HRTEM images illustrated that both the slab sizes and stacking layers of sulfided catalysts were changed with different Zn contents. These catalysts were tested for hydrodesulfurization (HDS) of 4,6–dimethyldibenzothiophene (4,6–DMDBT) from model diesel. Hydrodesulfurization (HDS) reaction of 4,6–dimethyldibenzothiophene showed that all the catalysts Ni x Zn y MoW with layered structure exhibited high HDS activity and the sulfur content in the model diesel can be reduced from 517 ppm to less than 10 ppm under mild reaction conditions of 3.0 MPa of H 2 pressure, 300 °C, a LHSV of 9 h −1 , and H 2 /oil ratio of 800 N cm 3 /cm 3 . The catalysts Ni x Zn y MoW have shown much higher specific HDS activity than that of the commercial catalyst CoNiMoW/Al 2 O 3 . However, ZnMoW without Ni has shown relatively low activity. The higher HDS activity of Ni x Zn y MoW could be ascribed to high contents of active metals and the layered structure. Meanwhile, the synergism between Ni/Zn and Mo/W plays an important role in achieving the excellent HDS performance of catalysts Ni x Zn y MoW.

This study deals with doping of CeO 2 with different cations M (M = Ti 4+ , Sn 4+ , Hf 4+ , Zr 4+ , La 3+ , Y 3+ and Sm 3+ ) to improve the reaction activity in two step thermochemical CO 2 splitting reaction. The results show that the addition of tetravalent cations M (M = Ti 4+ , Sn 4+ , Hf 4+ and Zr 4+ ) into CeO 2 significantly enhances the O 2 evolution activity. The O 2 production at 1400 °C increases as follows: CeO 2 (2.5 ml/g) 0.75 Zr 0.25 O 2 (6.5 ml/g) 0.75 Hf 0.25 O 2 (7.2 ml/g) 0.8 Sn 0.2 O 2 (11.2 ml/g) 0.8 Ti 0.2 O 2 (13.2 ml/g). The corresponding CO production is increased from 4.5 ml/g for CeO 2 up to 10.6 ml/g for Ce 0.75 Zr 0.25 O 2 synthesized by solution combustion method. For Ce 0.75 Hf 0.25 O 2 and Ce 0.75 Zr 0.25 O 2 synthesized by hydrothermal method, steady-state CO and O 2 production with a ratio of near 2 occurs simultaneously when the temperature exceeds 1100 °C and we define the phenomena as “one step thermochemical CO 2 splitting reaction”. Further investigations for one step thermochemical CO 2 splitting with both CeO 2 and Ce 0.75 Zr 0.25 O 2 as catalysts and blank reaction tube as reference from 1200 °C to 1400 °C are also performed. 16.8 ml/h of CO was produced for 0.5 g of Ce 0.75 Zr 0.25 O 2 at 1400 °C which indicates that one step reaction may be a promising way for CO 2 reduction. For Ce 0.8 Ti 0.2 O 2 and Ce 0.8 Sn 0.2 O 2 , although the O 2 production is increased several times as compared to CeO 2 , the CO generation activity is still low due to the formation of Ce 2 Ti 2 O 7 and Ce 2 Sn 2 O 7 after the high temperature reduction reaction. The doping of trivalent cations M (M = La 3+ , Y 3+ and Sm 3+ ) into ceria has negative effect both on the O 2 evolution activity and the CO production. The estimated activation energy for the reduction step of Ce 0.75 Zr 0.25 O 2 is much lower than that of CeO 2 and Ce 0.85 La 0.15 O 2− δ . The CO generation reaction of CeO 2 , Ce 0.85 La 0.15 O 2− δ and Ce 0.75 Zr 0.25 O 2 –C (synthesized by solid solution combustion method) is a surface limited reaction.

Five [BW12O40]5 − -containing metal-organic frameworks (MOFs), {K[Ln(H2O)4(pdc)]4}[BW12O40]·2H2O (Ln=La 1 and Ce 2, H2pdc = pyridine-2,6-dicarboxylate) and {K[Ln(H2O)3(pdc)]4}[BW12O40]·6H2O (Ln=Tb 3, Dy 4 and Er 5), are synthesized hydrothermally. Ln3+ and pdc2− are built into 3-D MOF segments containing large channels and cavities which are occupied by [BW12O40]5 − . Herein, we report MOF-containing polyoxometalates (POMs) as photocatalysts to oxidize thiophene with O2 as the oxidant. Photo-excited state species ([BW12O40]5−∗) are generated under UV irradiation and then H2O is oxidized into OH˙ radicals and O2 is reduced into O2 2−. The active oxygen species (O2 2−, OH˙) oxidize thiophene in the presence of photocatalysts and SO3, CO2, and H2O are obtained as photoproducts. ESR measurements provide evidence that OH˙ species are generated during photocatalysis.

Most of the solar-driven thermochemical CO

The effect of Mn doping on the adsorptive desulfurization performance of 5%Ni/ZnO adsorbents was investigated in model gasoline, with thiophene as a sulfur-containing compound, using a fixed-bed reactor. The 5%Ni/MnO-ZnO adsorbents with different levels of Mn doping were prepared using an incipient wetness impregnation method and characterized by powder X-ray diffraction (XRD). It was found that the adsorption performances of the 5%Ni/MnO-ZnO adsorbents were considerably improved after Mn doping compared with that of 5%Ni/ZnO. Moreover, the 5%NiO/MnO-ZnO adsorbents showed high desulfurization activities after regeneration. Sulfur removal by a 5%NiO/8%MnO-ZnO adsorbent after three reaction-regeneration cycles was 4% higher than that by a 5%NiO/ZnO adsorbent without Mn doping. The excellent performance of the 5%NiO/8%MnO-ZnO adsorbent in desulfurization, and its regenerability, were attributed to formation of a new compound, ZnMnO3, in the adsorbent; this compound was characterized using XRD.

Photocatalytic oxidation has been demonstrated to be an effective way for removing organic pollutants via a complete mineralization. The removal of sulfur-containing organic compounds in fuel oils and pollutants such as rhodamine B (RhB) and methyl orange (MO) present in the industrial wastewater is highly desired. Here we studied the photocatalytic oxidation of the pollutants on Pt-RuO2/TiO2 photocatalyst. We found that TiO2 co-loaded with noble metal Pt and metal oxide RuO2 shows the considerably synergistic effect between the two cocatalysts on photocatalytic oxidation activity. This effect has been demonstrated for photocatalytic oxidation of thiophene and successfully extended to photocatalytic oxidation of organic dyes. The high activity is achieved by co-loading less than 0.05 wt% Pt and 0.05 wt% RuO2 as cocatalysts on TiO2. ESR measurements give the evidence for that the active oxygen species ((OH)-O-center dot and O-2(center dot-)) generated by photocatalytic processes are involved in photocatalytic oxidation reactions. The reduction cocatalyst Pt and oxidation cocatalyst RuO2 play significant roles in the photocatalytic oxidation reaction and the co-existing of the dual function cocatalysts is crucial for developing highly active photocatalysts for environmental protection. (C) 2012 Elsevier B.V. All rights reserved.

The effect of zno particle size on the adsorptive desulfurization performance for ni/zno (5 wt% nio) adsorbent was investigated using thiophene as a sulfur containing compound in model gasoline with a fixed bed reactor. the ni/zno adsorbents with different zno particle sizes (8, 12, 20, 30 nm) were prepared by an impregnation method and characterized by powder x-ray diffraction (xrd), high resolution transmission electron microscopy (hrtem) and transmission electron microscopy (tem). it was found that the adsorption capacity of the ni/zno adsorbent for thiophene significantly increased with the decrease of the zno particle sizes. typically at a breakthrough sulfur level of 1 mg/l, sulfur capacity of ni/zno (8 nm) from model gasoline (500 mg/l) is much higher than that of ni/zno (30 nm) from 84 mg sulfur per gram adsorbent to nearly 0 mg sulfur per gram adsorbent. this higher desulfurization activity and sulfur capacity for ni/zno with smaller zno particle sizes could be derived from higher ni dispersion on zno and lower mass transfer limitations of sulfur to zno from ni in h-2. (c) 2012 elsevier bm. all rights reserved.

A catalyst system composed of tungstate and Bronsted acidic ionic liquids (BAILs) was found to be highly active for the oxidative desulfurization (ODS) removal of thiophene, benzothiophene (BT), and their derivatives from model oil using 30 wt.% H2O2 as the oxidant. Five BAILs, [Hnmp]BF4, [Hmim]BF4, [Hnmp]HSO4, [Hmim]HSO4, and [Hnmp][CH3SO3] (nmp = N-methyl-pyrrolidonium, mim = N-methylimidazolium), and various commercial tungstate compounds were investigated. High activity was obtained for the combination of ammonium tungstate and BAILs [Hnmp]BF4. In this catalytic reaction, sulfur content of model oil containing BT could be decreased from 700 ng μL−1 to less than 1 ng μL−1. Turnover frequency (TOF) for BT oxidation is higher than 194 × 10−3 s−1 and that of in non-BAILs [Bmim]BF4 is less than 11 × 10−3 s−1. Noteworthily, the ODS of thiophene, which has been regarded as difficult task, can be also achieved up to 99% conversion with a TOF of 7 × 10−3 s−1. The FT-IR, 1H NMR and electrochemical measurements evidences indicate that the strong hydrogen bonding between the sulfur-containing compounds and [Hnmp]BF4 and the oxidative function of the tungstate synergistically activate the reactants and result in the excellent catalytic performance.

Thiophene is one of the main sulfur-containing compounds in gasoline and difficult to be oxidized with the conventional oxidative processes. Herein for the first time we report that thiophene can be oxidized to SO3 on BiVO4 co-loaded with Pt and RuO2 co-catalysts (denoted as Pt-RuO2/BiVO4) under visible light irradiation with molecular oxygen as oxidant. The high activity of the catalyst can be achieved by only loading as low as 0.03 wt% of Pt and 0.01 wt% of RuO2 as dual co-catalysts on BiVO4. ESR measurements give the evidence that the active oxygen species (˙OH and O2˙−) generated by photocatalytic processes are involved in the photocatalytic oxidation of thiophene. The considerable enhancement of photocatalytic activity can be attributed to the simultaneous presence of the reduction and oxidation co-catalysts which are beneficial for the efficient separation and transfer of the photo-generated electrons and holes.

Several attractive approaches toward oxidative desulfurization of fuel oils, such as using H 2 O 2 /organic acids, H 2 O 2 /heteropolyacid, H 2 O 2 /Ti-containing zeolites, and other non-hydrogen peroxide systems (e.g., t -butyl hydroperoxide etc.) are reviewed. A new alternative oxidative desulfurization process using emulsion catalysts was developed mainly by our group, is introduced in detail. Limitations because of interphase mass transfer are greatly reduced in the emulsion reaction medium. The amphiphilic emulsion catalysts can selectively oxidize the sulfur-containing molecules present in diesel to their corresponding sulfones when using H 2 O 2 as the oxidant under mild conditions. The sulfones in the oxidized fuel oils can be removed by a polar extractant. The sulfur level of a prehydrotreated diesel can be lowered from a few hundred μg/g to 0.1 μg/g after oxidation and subsequent extraction whereas the sulfur level of a straight-run diesel can be decreased from 6000 to 30 μg/g after oxidation and extraction.

A multi-metallic NiAlMoW catalyst with layered structure was prepared by surfactant-assisted co-precipitation method using NiAl-layered double hydroxide (NiAl-LDH) as the structure-directing template. By carefully tuning the composition of the layered structure and the synthesis conditions, we have prepared a series of Ni(m)Al(n)MoW catalysts. For the HDS of 4,6-DMDBT. NiAl(3)MoW-5 shows two times higher intrinsic catalytic activity (based on weight of active metals) compared to that of the commercial CoNiMoW/Al(2)O(3) catalyst. The sulfur content in the model compound could be reduced from 500 ppm to less than 20 ppm using this catalyst under the operation conditions of 3.0 MPa, 300 degrees C, a WHSV (weight hourly space velocity) of 9 h(-1), and H(2)/oil ratio of 800 Nm(3)/m(3). The synthesized catalysts were characterized by SEM. TEM, XRD, TG/DSC, nitrogen adsorption/desorption isotherms and XRF. This NiAlMoW catalyst has retained the unique layered structure of NiAl-LDH, which can facilitate uniform dispersion of the active species on both the surface and the edge of the layer. It was found that the layered structure has a great impact on the catalytic activity of the HDS reactions. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.

Ultra-deep Oxidative Desulfurization of Fuel Oil Catalyzed by Dawson-type Polyoxotungstate Emulsion Catalysts

A series of emulsion catalysts were successfully synthesized with quarternary ammonium cations and heteropolyanions, and they were characterized by TG/DTA, FTIR, (31)P MAS NMR and EPR. The emulsion catalyst with intact Keggin-structure, [C(18)H(37)N(CH(3))(3)]H(2)[PW(12)O(40)] (PW(12)), is inactive for benzothiophene (BT) oxidation with H(2)O(2) as oxidant under atmospheric pressure at 30 C. Moreover, the metal-substituted catalysts PW(11)M (M =Ti, Mn, Fe, Co, Ni and Cu) show rather low activity with the conversion less than 15% for BT oxidation. Whereas, the catalyst with mono-lacunary Keggin-structures, [C(18)H(37)N(CH(3))(3)](5)Na(2)[PW(11)O(39)] (PW(11)), could completely catalytic oxidize BT into the corresponding sulfone under the same conditions. After careful characterizations of the catalysts, it is found that only PW(11) catalyst could effectively transform into the active polyperoxometalates species in the presence of hydrogen peroxide in non-polar solvent. (C) 2010 Elsevier B.V. All rights reserved.

The hydroisomerization of n-dodecane was investigated over Pt supported on unmodified ZSM-22 and on modified ZSM-22. The effect of ZSM-22 modification on Pt/ZSM-22 acidity and on catalytic performance is discussed in detail using MAS NMR and FT-IR results. The ZSM-22 was modified by NH4+ ion-exchange, HNO3 or (NH4)(2)SiF6 treatment, and by steam treatment in order to tune the acidity of the catalysts. The unmodified ZSM-22 catalyst shows very low activity in the hydroisomerization of n-dodecane due to the lowest acidity. The conversions of the catalysts for the reaction of n-dodecane are increased from 1.1% to 96.6% at 300 degrees C as the acidity of the ZSM-22 is increased from 0.043 mmol/g to 0.329 mmol/g, but the isomerization selectivity is reduced. The catalyst that was modified by the combination of NH4+ ion-exchange and (NH4)2SiF6 treatment possesses the Bronsted acid sites with medium strength and shows the high isododecane selectivity (88.0%) under high conversion (87.5%) at 300 degrees C. (C) 2007 Elsevier B.V. All rights reserved.

A series of molybdenum phosphide catalysts with initial Mo/P ratios varying in a narrow range of 0.90-1.10 was prepared by temperature-programmed reaction; characterized by X-ray diffraction, BET, elemental analysis, X-ray photoelectron spectroscopy, and CO chemisorption measurements; and tested for the hydrogenation of acetonitrile at different pressures (0.1-1.0 MPa) and temperatures (473-513 K). The catalysts exhibited attractive catalytic activity, especially at a H-2 pressure above 0.2 MPa. The surface composition of the MoP catalysts could be fine-tuned by the initial Mo/P ratio, which consequently led to different surface properties (e.g., CO uptakes) and catalytic behaviors. Catalysts with high initial Mo amount gave high selectivity to the primary amine, ethylamine, whereas those with high initial P amount created more condensed amines, diethylamine and triethylamine. (C) 2007 Elsevier Inc. All rights reserved.

A recyclable amphiphilic catalyst, which composed of peroxotungsten anion and quaternary ammonium cation assembled in the interface of the emulsion droplets, shows high selectivity and activity in the oxidation of sulfur-containing molecules to sulfones with hydrogen peroxide in diesel under mild reaction conditions. all the sulfur-containing molecules present in diesel can be completely oxidized into sulfones with -100% selectivity of sulfones in w/o (h2o2-in-diesel) emulsion system. the sulfones can be readily separated from the diesel, and the sulfur level of the desulfurized diesel can be lowered from about 500 ppm to below 1 ppm with about 98% yield of oil. in addition, the s-containing molecules in straight-run gas oil are also readily oxidized to their corresponding products in the oav emulsion reaction medium. the s-level of oil layer of the oxidized oil was reduced to below 1 ppm from 312 ppm in the original straight-run gas oil with above 99% yield of oil. the amphiphilic catalysts serve as not only a catalyst but also an emulsifying agent to stabilize the emulsion droplets. the emulsion droplets are not only in the highly dispersed form but also behave like homogenous catalyst with high activity. the limitations due to interphase mass transport are greatly reduced in emulsion reaction medium. moreover, the emulsion catalysts can be easily separated and recycled by demulsifying. (c) 2006 elsevier b.v. all rights reserved.

The oxidation of sulfur-containing compounds (benzothiophene, dibenzothiophene, and their derivatives) in diesel was conducted in emulsion oxidative system (water in oil [w/o]) composed of diesel. 30 wt% hydrogen peroxide, and ail amphiphilic catalyst [c18h37n(ch3)(3)](4)[h2napw10o36] under mild conditions. the amphiphilic catalyst in the w/o emulsion system exhibits very high catalytic activity such that all sulfur-containing compounds in either model or actual diesel can be selectively oxidized into their corresponding sulfones using hydrogen peroxide (o/s

Catalysts assembled in emulsions are found to be potentially recoverable and efficient for a number of catalytic reactions. The catalysts composed of polyoxometalate anions and quaternary ammonium cations have been designed and synthesized according to the catalytic reactions and by optimizing the structures of cations and anions. The catalysts act essentially as surfactants, which are uniformly distributed in the interface of the emulsion droplets, and accordingly behave like homogeneous catalysts. The catalysts show remarkable selectivity and activity in the oxidation of sulfur-containing molecules to sulfones in diesel and the selective oxidation of alcohols to ketones, using H2O2 as oxidant. For an example, the catalyst demonstrated over 96% efficiency of H2O2 and ˜100% selectivity to sulfones for the selective oxidation of sulfur-containing molecules in real diesel. Moreover, the catalysts can be separated and recycled by a simple demulsification and re-emulsification.

Silica-supported binary and ternary phosphides, mop/sio2, ni2p/sio2, and ni-mo-p/sio2 have been prepared and characterized by x-ray diffraction (xrd), bet surface area, co chemisorption, transmission electron microscopy (tem), and infrared spectroscopy (ir). the hydrodesulfurization (hds) activities of dibenzothiophene (dbt) were measured and compared at 593 k and 3.0 mpa for mop/sio2, ni2p/sio2, and ni-mo-p/sio2 catalysts with different mo and ni loadings. the activities of the phosphides follow the order ni2p/sio2 > ni-mo-p/sio2 > mop/sio2. the ni sites in the ni-mo-p/sio2 catalysts play a major role in the conversion of dbt, and the activity of the catalysts increases with increasing ni content. this is different from sulfides, nitrides, and carbides, as no synergetic effect is observed between the phosphided ni and the mo atoms. the surface of these phosphide catalysts is partially sulfided forming a surface phosphosulfide phase, while the bulk structure of the phosphides is maintained in the hds reactions. (c) 2004 elsevier inc. all rights reserved.

The surface properties, porosities, and adsorption capacities of activated carbons (AC) are modified by the oxidation treatment using concentrated H2SO4 at temperatures 150−270 °C. The modified AC was characterized by N2 adsorption, base titration, FTIR, and the adsorption of iodine, chlorophenol, methylene blue, and dibenzothiophene. The treatment of AC with concentrated H2SO4 at 250 °C greatly increases the mesoporous volume from 0.243 mL/g to 0.452 mL/g, specific surface areas from 393 m2/g to 745 m2/g, and acidic surface oxygen complexes from 0.071 meq/g to 1.986 meq/g as compared with the unmodified AC. The base titration results indicate that the amount of acidic surface oxygen groups on the modified AC increases with increasing the treatment temperatures and carboxyls and phenols are the most abundant carbon−oxygen functional groups. The carboxyl groups, COO- species, and hydroxyl groups are detected mainly for the sample treated at 250 °C. The mesoporous properties of the AC modified by concentrat...

A series of molybdenum phosphide catalysts were prepared from initial Mo/P molar ratios ranging from 0.6 to 2.6. The catalytic activity of the catalysts for the selective hydrogenation of acetonitrile was studied. The catalysts with initial Mo/P ratios > 1.0 have high selectivity for ethylamine (80%–90%), and for the catalysts with Mo/P ratios

An isopolyoxovanadate catalyst [C(8)H(17)N(CH(3))(3)](3)H(3)V(10)O(28) shows high catalytic activity in oxidation of dibenzothiophene (DBT) to its corresponding sulfone using molecular oxygen as oxidant under mild reaction conditions. This is potentially a promising approach to achieve ultradeep desulfurization of fuels (e.g. diesel) because the sulfones can be more conveniently removed from the fuels by either extraction or selective adsorption.

Drop it! A highly enantioselective catalytic cascade reaction of α-ketoacids and aldehydes is achieved using the title catalyst and water as the solvent. Fluorescence imaging shows that the catalyst is mainly distributed on the surface of emulsion droplets. Optically active isotetronic acids can be obtained with this method and the emulsion droplets are responsible for the high reactivity and enantioselectivity.

An amphiphilic fluorescent catalyst Q9[EuW10O36] (Q = [(C18H37)2N+ (CH3)2]), assembled in the interface of emulsion systems, was directly imaged by fluorescence microscopy; the catalyst shows high selectivity and activity in the oxidation of alcohols using H2O2 as oxidant and the catalyst can be easily separated and recycled by demulsifying.

Dibenzothiophene (DBT) is oxidized to the corresponding sulfoxide and sulfone in an emulsion system (W/O) composed of polyoxometalate anion [C(18)H(37)N(CH(3))3](5)[PV(2)Mo(10)O(40)] as both the surfactant and catalyst, using molecular oxygen as the oxidant and aldehyde as the sacrificial agent under mild conditions.

Zeolites NaY and LaNaY (ion-exchanged with aqueous lanthanum nitrate solution) were used as adsorbents for removing organic sulfur compounds from model gasoline solutions (without and with toluene) and fluid catalytic cracked gasoline in fixed-bed adsorption equipment at room temperature and atmosphere pressure. The adsorptive selectivity for organic sulfur compounds was significantly increased when Na(+) ions in zeolite NaY were exchanged with lanthanum ions. IR spectra of thiophene adsorption indicate that thiophene is adsorbed onto La(3+) ions via direct S-La(3+) interaction and Na(+) ions via pi-electronic interaction for La(3+)-exchanged zeolite NaY, but only via pi-electronic interaction with Na(+) ions for NaY. The amount of adsorbed thiophene on La(3+)-exchanged zeolite Y was slightly decreased by coadsorption of benzene, but greatly reduced on NaY. The adsorption of thiophene via interaction with La(3+) on La(3+)-exchanged zeolite Y is hardly replaced by benzene coadsorption. The direct S-La(3+) interaction might be the essential reason for the evidently improved adsorptive selectivity of LaNaY for removing organic sulfur compounds from solutions containing large amount of aromatics.

A [(C(18)H(37))(2)N(+)(CH(3))(2)](3)[PW(12)O(40)] catalyst, assembled in an emulsion in diesel, can selectively oxidize the sulfur-containing molecules present in diesel into their corresponding sulfones by using H(2)O(2) as the oxidant under mild conditions. The sulfones can be readily separated from the diesel using an extractant, and the sulfur level of the desulfurized diesel can be lowered from about 500 ppm to 0.1 ppm without changing the properties of the diesel. The catalyst demonstrates high performance (>/=96 % efficiency of H(2)O(2), is easily recycled, and approximately 100 % selectivity to sulfones). Metastable emulsion droplets (water in oil) act like a homogeneous catalyst and are formed when the catalyst (as the surfactant) and H(2)O(2) (30 %) are mixed in the diesel. However, the catalyst can be separated from the diesel after demulsification.