Hydrogenation of Olefins Catalyzed by Highly Active Titanocene/NaH or n-BuLi Catalyst Systems

The effects of the substituents on the cyclopentadienyl ring and the reducing agents on the catalytic activity and the stability of titanocene/NaH or n BuLi systems for the hydrogenation of olefins were investigated. For the catalyst systems composed of titanocene/NaH or n BuLi, the nature and the number of the substituents on the cyclopentadienyl ring control the catalytic behavior of those two systems. The effect of the reducing agent on the catalytic activity is relatively small. In addition, the characters of the hydrogenation of various olefins catalyzed respectively by Cp 2TiCl 2/NaH or n BuLi systems were compared.

A New Catalyst for Hydrogen Transfer Hydrogenation of Acetophenone

A new C-2-symmetric diamine/diphosphine Ruthenium (II) complex, RuCl2P2N2H4, was used as an excellent catalyst to carry out the catalytic hydrogen transfer reduction of acetophenone. The conversion of acetophenone to 2-phenylethanol was up to 99% under the following reaction conditions: substrate:Ru:(CH3)(2)CHOK = 200:1:12; reaction temperature of 65 degrees C; reaction time of 2 h; normal pressure. A hydride transfer mechanism was also discussed.

CATALYTIC PERFORMANCE OF MIXED-BIMETALLIC RUTHENIUM CARBONYL CLUSTERDERIVED CATALYSTS IN CO HYDROGENATION

The bimetallic catalysts prepared from SiO_2-supported Ru-Co,Ru- Fe and Ru-Mo carbonyl clusters exhibited high yields and selectivities towards oxygenates such as C_1-C_5 from CO+H_2,in contrast to the catalysts prepared from homometallic and bimetallic Ru,Ru-Ni,Ru-Rh,Ru-Mn,and Ru- Cr carbonyl clusters.The FTIR investigation revealed that the 1584 cm^(-1) species plays an important role in the formation of oxygenates in CO hydrogenation,which is possibly assigned to surface formyl species.

Successful Application of Novel α-Methylstyrene Hydrogenation Catalyst at Yanshan Petrochemical Company

The SHP-A1 type catalyst for hydrogenation of α-methylstyrene(AMS)developed by the SINOPEC Shanghai Petrochemical Research Institute(SPRI)has been successfully applied in the No.1 phenol unit at the Third Chemical Plant of Yanshan Petrochemical Company at the first attempt of commissioning.The said catalyst is the first AMS hydrogenation catalyst developed

CARBONACEOUS PRODUCTS OF POLYMER-PALLADIUM COMPLEXES AS CATALYSTS FOR THE HYDROGENATION OF METHYL ACRYLATE

Many catalysts were pcrpared by carbonization of ion exchange resin-PdCl_2 complexes at high temperature in nitrogen, hydrogen atmosphere. The rates for the hydrogenation of methyl acrylate and the amounts of Pd elution of the carbonaceous products were measured and compared with those of commercial Pd/C catalyst. It indicates that the carbonaceous products are less active than Pd/C. However, the leaching of Pd from carbonaceous products is very small and much less than that from Pd/C.

EFFECT OF ELECTRON DONORS ON THE SELECTIVE HYDROGENATION OF DIENE TO MONOENE OVER HETEROGENIZED Pd CATALYST

In the selective hydrogenation of diene (or alkyne) using heterogenized homogeneous catalyst, the high selectivity of monoene formation only appears in a very short time interval. The addition of suitable electron donors can decrease or even cease the monoene hydrogenation and thereby keep the high monoene selectivity after reaching its maximum.

Hierarchical molybdenum disulfide nanosheet arrays stemmed from nickel-cobalt layered double hydroxide/carbon cloth for highly-efficient hydrogen evolution reaction

The hierarchical structure of molybdenum disulfide(MoS2)nanosheet arrays stemmed from nickelcobalt layered double hydroxide(NiCo-LDH)/carbon cloth was prepared by growing the MoS_(2) nanosheet arrays onto the NiCo-LDH template which was pre-deposited onto the carbon cloth substrate.In this electrode configuration,carbon cloth is the three dimensional and conductive skeleton;NiCo-LDH nanosheets,as the template,ensure the oriented growth of MoS2 nanosheet arrays.Therefore,more MoS_(2) active sites are exposed and the catalyst exhibits good hydrogen evolution reaction activity.

Thioetherification of isoprene and butanethiol on transition metal phosphides

Thioetherification between mercaptan and diolefin is an efficient process to remove mercaptans in FCC gasoline at mild condition, during which the selective hydrogenation of diolefin to monoolefin is also expected. Here, Si O2 supported transition metal（Fe, Co, Ni, Mo and W） phosphides were tested for the thioetherification of isoprene and butanethiol on a fixed-bed reactor at 120℃ and 1.5 MPa H2, and their structure before and after reaction was characterized by means of XRD, HRTEM, N2 sorption, CO chemisorption, NH3-TPD, XPS and TG. It was found that, among different metal phosphides, Mo P/Si O2 showed the best performance, and the optimal nominal Mo P loading was 25%. Apart from the nature of metal, the density of metal and acid sites determined the catalyst performance. Metal site was mainly responsible for hydrogenation of isoprene, while acid site dominantly contributed to the thioetherification and the polymerization of olefins. Moreover, a balance between metallic and acidic functions is required to arrive at a desired performance. Excessive metal sites or acid sites led to the over-hydrogenation of isoprene or the severe polymerization of olefins, respectively. 25%Mo P/Si O2 was tested for 37 h time on stream, and butanethiol conversion maintained at 100%; although isoprene conversion remarkably decreased, the selectivity to isopentenes exceeded 80% after reaction for 11 h. We suggest that the deactivation of Mo P/Si O2 is mainly ascribed to the butanethiol poisoning and the carbonaceous deposit, especially the former.

Simultaneous recovery of carbon and sulfur resources from reduction of CO_2 with H_2S using catalysts

An approach to the simultaneous reclamation of carbon and sulfur resources from CO2 and H2S has been proposed and effectively implemented with the aid of catalysts. A brief thermodynamic study reveals the potential of direct reduction of CO2 with H2S（15：15 mol% balanced with N2） for selective production of CO and elemental sulfur. The experiments carried out in a fixed-bed flow reactor over the temperature range of 400–800 °C give evidence of the importance of the employment of catalysts. Both the conversions of the reactants and the selectivities of the target products can be substantially promoted over most catalysts studied. Nevertheless, little difference appears among their catalytic performance. The results also prove that the presence of CO2 can remarkably enhance H2S conversion and the sulfur yield in comparison with H2S direct decomposition. A longtime reaction test on Mg O catalyst manifests its superior durability at high temperature（700 °C） and huge gas hourly space velocity（100,000 h-1）. Free radicals initiated by catalysts are supposed to dominate the reactions between CO2 and H2S.

RAMAN SPECTRA OF HYDROGEN ADSPECIES ON AMMONIA SYNTHESIS IRON CATALYST

Raman peaks at 1951 and 2165 cm^(-1) can be confirmed further by H_2/D_2 isotope exchange as H-adspecies on the doubly promoted iron catalyst for ammonia synthesis and are probably ascribed to two terminally adsorbed H-species.

Enrichment of Ni-Mo-V via pyrometallurgical reduction from spent hydrogenation catalysts and the multi-reaction mechanism

Spent hydrogenation catalysts are important secondary resources due to richness in the valuable metals of Ni,Mo and V.Recovery of valuable metals from spent catalysts has high economic value and environmental benefits since they are hazardous wastes as well.Traditional recycling processes including hydrometallurgical leaching and soda roasting-leaching have disadvantages such as generating large amounts of wastewater,long process,and low recovery efficiency of valuable metals.Thus,this paper proposed synergistic enrichment of Ni,Mo and V via pyrometallurgical reduction at 1400-1500℃.The melting temperature and viscosity of slag were reduced through slag designing by software FactSage 7.1.The phase diagram of Al_(2)O_(3)-Cap-SiO_(2)-Na_(2)O-B_(2)O_(3)was drawn,and low-temperature region(≤1300℃)was selected as target slag composition.Ni,Mo,and V can be collaborative captured and recovered through the mutual solubility at molten state.Increasing the melting temperature and the amount of CaO,Na_(2)O and C were conducive to improving the metals recovery rates.The kilogram-scale experiments were carried out,and the recovery efficiencies of Ni,Mo and V were 98.3%,95.3%and 97.9%under optimized conditions:at 1500℃,with the basicity of 1.0,13.1 wt%SiO_(2),7.0 wt%B_(2)O_(3),7.7 wt%Na_(2)O and 20.0wt%C.The distribution behavior of valuable metals was clarified by investigating the melting process of slag and the reduction in valuable metals.Ni was preferentially reduced and acted as a capturing agent,which captured other metals to form NiMoV alloys.

Pd/C modified with Sn catalyst for liquid-phase selective hydrogenation of maleic anhydride to gamma-butyrolactone

Pd catalysts suffered from poor selectivity and stability for liquid-phase hydrogenation of maleic anhydride（MA） to gamma-butyrolactone（GBL）.Thus,Pd/C catalysts modified with different Sn loadings were synthesized,and characterized by XRD,XPS,TEM and elemental mapping.The types of alloy phase and the amounts of the surface Pd-SnOx sites altered along with Sn/Pd mass ratios from 0-1.0synthesized in the process of preparation.The maximum reaction rate was 0.57 mol-GBL/（mol-Pd min）and selectivity was 95.94%when the Sn/Pd mass ratio was 0.6.It might be attributed to the formation of Pd2Sn alloy and less amounts of Pd-SnOx sites.

Hydrogenation of cinnamaldehyde over bimetallic Au-Cu/CeO_2 catalyst under a mild condition

Bimetallic Au_xCu_y/CeO_2（x/y = 3/1,1/1,and 1 /3） catalysts were prepared by direct anion exchange（DAE）,following impregnation（IMP） methods,and used for selective hydrogenation of cinnamaldehyde.The effects of pretreatments,such as calcination or reduction on the catalytic activities of these catalysts were investigated.XRD and HRTEM showed that for the reduced catalysts,there is the formation of an Au-Cu alloy.HAADF-STEM displayed that reduction pretreatment leads to a very homogenous distribution of Au and Cu on the external catalyst surface.Reaction parameters,such as CAL concentration,the stirring speed,nature of the solvent influence the catalytic activities.Pretreatments lead to a major effect on CAL conversion and HCAL selectivity.Catalysts Au_xCu_y/CeO_2 pretreated under reduction display higher CAL conversion and HCAL selectivity than that of under calcination mainly due to the synergistic effect resulting in a formation of Au-Cu alloy.

Immobilization of chiral Rh catalyst on glass and application to asymmetric transfer hydrogenation of aryl ketones in aqueous media

A chiral catalyst, Cp＊RhTsDPEN （Cp＊ = pentamethyl cyclopentadiene, TsDPEN = substitutive phenylsulfonyl-l,2-diphenylethylenediamine）, was synthesized and immobilized at the surface of glass. The immobilized catalyst exhibited good catalytic efficiency for asymmetric transfer hydrogenation of aromatic ketones in water with HCOONa as hydrogen source.

Pd/TiN nanocomposite catalysts for selective hydrogenation of phenol and its derivatives

Pd/TiN nanocomposite catalysts were fabricated for one-step selective hydrogenation of phenol to cyclohexanone successfully. High conversion of phenol （99%） and selectivity of cyclohexanone （98%） were obtained at 30 ℃ and 0.2 MPa H2 for 12 h in the mixed solvents of H20 and CH2C12. The Pd nanoparticles were stable in the reaction, and no aggregation was detected after four successive runs. The catalytic activity and selectivity depended on slightly the Pd particle sizes. The generality of the catalysts for this reaction was demonstrated by the selective hydrogenation of phenol derivatives, which showed that the catalyst was selective for the formation of cyclohexanone.

Mechanism of Hg^0 oxidation in the presence of HCl over a commercial V_2O_5–WO_3/TiO_2 SCR catalyst

Experiments were conducted in a fixed-bed reactor containing a commercial V2O5/WO3/TiO2 catalyst to investigate mercury oxidation in the presence of HCl and O2. Mercury oxidation was improved significantly in the presence of HCl and O2, and the Hg^0 oxidation efficiencies decreased slowly as the temperature increased from 200 to 400℃. Upon pretreatment with HCl and O2 at 350℃, the catalyst demonstrated higher catalytic activity for Hg^0 oxidation. Notably,the effect of pretreatment with HCl alone was not obvious. For the catalyst treated with HCl and O2, better performance was observed with lower reaction temperatures. The results showed that both HCl and Hg^0 were first adsorbed onto the catalyst and then reacted with O2 following its adsorption, which indicates that the oxidation of Hg^0 over the commercial catalyst followed the Langmuir–Hinshelwood mechanism. Several characterization techniques, including Hg^0temperature-programmed desorption（Hg-TPD） and X-ray photoelectron spectroscopy（XPS）, were employed in this work. Hg-TPD profiles showed that weakly adsorbed mercury species were converted to strongly bound species in the presence of HCl and O2. XPS patterns indicated that new chemisorbed oxygen species were formed by the adsorption of HCl, which consequently facilitated the oxidation of mercury.

Reduction of CeO2 in composites with transition metal complex oxides under hydrogen containing atmosphere and its correlation with catalytic activity

Reduction behavior of pure and doped CeO2, the multi-phase La0.6Sr0.4CoO3.xCeO2, La0.sSr0.2MnO3 . xCeO2, and La0.95Ni0.6Fe0.4O3.xCeO2 composites, was studied under hydrogen containing atmosphere to address issues related to the improvement of electrochemical and catalytic performance of electrodes in fuel cells. The enhanced reduction of cerium oxide was observed initially at 800~C in all composites in spite of the presence of highly reducible transition metal cations that could lead to the increase in surface concentration of oxygen vacancies and generation of the electron enriched surface. Due to continuous reduction of cerium oxide in La0.6Sr0.4CoO3 ＂x- CeO2 and La0.sSr0.zMnO3 ＂xCeO2 （up to 10 h） composites the redox activity of the Ce4＋/Ce3＋ pair could be suppressed and additional measures are required for reversible spontaneous regeneration of Ce4＋. After 3 h exposure to H2-Ar at 800~C the reduction of cerium oxides and perovskite phases in La0.95Ni0.6Fe0.403 ＂xCeO2 com- posites was diminished. The extent of cerium oxide involvement in the reduction process varies with time, and depends on its initial deviation from oxygen stoichiometry （that results in the larger lattice parameter and the longer pathway for O2 transport through the fluorite lattice）, chemical origin of transition metal cations in the perovskite, and phase diversity in multi-phase composites.

Microfibrous entrapped ZnO-CaO/Al_2O_3 for high efficiency hydrogen production via methanol steam reforming

Sinter-locked microfibrous networks consisting of -3 vol.% of 8 p.m （dia.） nickel microfibers have been utilized to entrap -30vo1.% of 100-200 μm dia. porous AI203. ZnO and CaO were then highly dispersed onto the pore surface of entrapped A1203 by the incipient wetness impregnation method. Due to the unique combination of surface area, pore size/particle size, thermal conductivity, and void volume, the resulting microfibrous catalyst composites provided significant improvement of catalytic bed reactivity and utilization efficiency when used in methanol steam reforming. Roughly 260 mL/min of reformate, comprising 〉70% H2, 〈5% CO and trace CH4, with 〉97% methanol conversion, could be produced in a I cm3 bed volume of our novel microfihrous entrapped ZnO-CaO/Al2O3 catalyst composite at 470℃ with a high weight hourly space velocity （WHSV） of 15 h-1 using steam/methanol （1.3/1） mixture as feedstock. Compared to a packed bed of 100-200μm ZnO-CaO/Al2O3, our composite bed provided a doubling of the reactor throughput with a halving of catalyst usage.

Hydrogen generation from methanol reforming under unprecedented mild conditions

A homogeneous catalyst [Cp＊Rh（NH3）（H2O）2]-（3＋） has been found for the clean conversion of methanol and water to hydrogen and carbon dioxide. The simple and easily available reaction steps can circumvent the formation of CO, therefore, making it possible to avoid inactivating catalysts and contaminating the hydrogen fuel. Different from conventional reforming method for hydrogen production, no additional alkaline or organic substances are required in this method. Valuable hydrogen can be obtained under ambient pressure at 70 C, corresponding TOF is 83.2 h 1. This is an unprecedented success in reforming methanol to hydrogen. Effects of reaction conditions, such as reaction temperature, initial methanol concentration and the initial p H value of buffer solution on the hydrogen evolution are all systematically investigated. In a certain range, higher reaction temperature will accelerate reaction rate. The slightly acidic condition is conducive to rapid hydrogen production. These findings are of great significance to the present establishment of the carbon-neutral methanol economy.

Platinum single atom catalysts for hydrogen isotope separation during hydrogen evolution reaction

Electrolysis of water is widely used for hydrogen isotope separation and the development of hydrogen evolution reaction(HER)catalysts with high selectivity and activity is of key importance.Herein,we propose single atom catalysts(SACs)as promising catalysts for efficient hydrogen isotope separation.Pt SACs and Pt nanoparticles(NPs)have been fabricated on nanoarray-structured nitrogen-doped graphite foil(NGF)substrate by a polyol reduction method.The as prepared Pt1/NGF electrode exhibits high activity and selectivity toward HER with a low overpotential of 0.022 V at 10 mA·cm^(-2) and a high separation factor of 6.83 for hydrogen and deuterium separation,much better than Pt NPs counterpart.Density functional theory(DFT)calculations ascribe the high activity and selectivity to the constructed Pt-N_(2)C_(2) structure.This work develops a new opportunity for the design and application of high-efficiency and stable SACs toward hydrogen isotope separation by electrolysis of water.