Direct Synthesis,Characterization and Catalytic Performance of Iron-Containing SBA-15 for Phenol Degradation

An iron-containing SBA-15（Fe-SBA-15） has been synthesized via one-pot hydrothermal method under weak acidic conditions. A series of characterizations show nanocomposite materials of iron particles supported over mesostructured materials. The catalytic activity of these iron-containing SBA-15 materials has been tested for the heterogeneous Fenton degradation of phenolic aqueous solutions. The catalytic performance has beta monitored in terms of phenol conversion, whereas the catalytic stability was evaluated by catalyst recycle. The influence of concentration of hydrogen peroxide, catalyst loading, catalyst prepared with different Fe/Si molar ratios in the gel and pH values of the solution on phenol conversion has been studied. Achieving a good catalytic performance accompanied with a noteworthy stability, Fe-SBA-15 materials prepared by this method are shown as the successful catalyst for degradation of phenolic aqueous solutions by Fenton process.

Catalytic methanation of syngas over Ni-based catalysts with different supports

Co-precipitation method was selected for the preparation of Ni/Al_2O_3, Ni/ZrO_2 and Ni/CeO_2 catalysts, and their performances in methanation were investigated in this study. The structure and surface properties of these catalysts were characterized by BET, XRD, H_2-TPD, TEM and H_2-TPR. The results showed that the catalytic activity at low temperature followed the order: Ni/Al_2O_3>Ni/ZrO_2>Ni/CeO_2. Ni/Al_2O_3 catalyst presented the best catalytic performance with the highest CH_4 selectivity of 94.5%. The characterization results indicated that the dispersion of the active component Ni was the main factor affecting the catalytic activity and the one with higher dispersion gave better performance.

Boosting CO_(2) hydrogenation to high-value olefins with highly stable performance over Ba and Na co-modified Fe catalyst

CO_(2)hydrogenation has been considered to be a highly promising route for the production of high-value olefins(HVOs)while also mitigating CO_(2)emissions.However,it is challenging to achieve high selectivity and maintain stable performance for HVOs(ethylene,propylene,and linear a-olefins)over a prolonged reaction time due to the difficulty in precise control of carbon coupling and rapid catalyst deactivation.Herein,we present a selective Ba and Na co-modified Fe catalyst enriched with Fe_(5)C_(2)and Fe_(3)C active sites that can boost HVO synthesis with up to 66.1%selectivity at an average CO_(2)conversion of 38%for over 500 h.Compared to traditional NaFe catalyst,the combined effect of Ba and Na additives in the NaBaFe-0.5 catalyst suppressed excess oxidation of FeCxsites by H_(2)O.The absence of Fe3O4phase in the spent NaBaFe-0.5 catalyst reflects the stabilization effect of the co-modifiers on the FeCxsites.This study provides a strategy to design Fe-based catalysts that can be scaled up for the stable synthesis of HVOs from CO_(2)hydrogenation.

Gold stabilized on various oxide supports catalyzing formaldehyde oxidation at room temperature

Gold stabilized on reducible oxide （CeO2 and FeOx） and irreducible oxide （γ‐Al2O3, SiO2, and HZSM‐5） were prepared by deposition precipitation method and tested for catalytic oxidation of formaldehyde （HCHO） at room temperature under high GHSV of 600000 ml/（g＆#183;s）. Au/γ‐Al2O3 cata‐lyst showed distinctive catalytic performance, presenting the highest initial HCHO conversion and stability. Correlating the reaction rate with Au particle size, there is a linear relationship, suggesting that the smaller Au particle size with higher dispersion possesses high reactivity for HCHO oxida‐tion. All the catalysts deactivated at high GHSV （600000 ml/（g＆#183;s））, but in a quite different rate. Re‐ducible oxide （CeO2 and FeOx） could stabilize gold through O linkage and therefore exhibits a better stability for HCHO oxidation reaction. However, the aggregation of gold particles occurred over Au/SiO2 and Au/HZSM‐5 catalysts, which result in the fast deactivation. Therefore, our results sug‐gest that the reducibility of the supports for Au catalysis has no direct influence on the activity, but affects the catalytic stability.

Application of in-plasma catalysis and post-plasma catalysis for methane partial oxidation to methanol over a Fe_2O_3-CuO/γ-Al_2O_3 catalyst

Methane partial oxidation to methanol （MPOM） using dielectric barrier discharge over a Fe2O3-CuO/γ-Al2O3 catalyst was performed.The multicomponent catalyst was combined with plasma in two different configurations,i.e.,in-plasma catalysis （IPC） and post-plasma catalysis （PPC）.It was found that the catalytic performance of the catalysts for MPOM was strongly dependent on the hybrid configuration.A better synergistic performance of plasma and catalysis was achieved in the IPC configuration,but the catalysts packed in the discharge zone showed lower stability than those connected to the discharge zone in sequence.Active species,such as ozone,atomic oxygen and methyl radicals,were produced from the plasma-catalysis process,and made a major contribution to methanol synthesis.These active species were identified by the means of in situ optical emission spectra,ozone measurement and FT-IR spectra.It was confirmed that the amount of active species in the IPC system was greater than that in the PPC system.The results of TG,XRD,and N2 adsorption-desorption revealed that carbon deposition on the spent catalyst surface was responsible for the catalyst deactivation in the IPC configuration.

Investigation of High Catalyteal Durability for Porous Pt Films Deposited via Magnetron Sputtering

Porous Pt thin films were prepared on carbon papers by a single-step ultra-high dc magnetron sputtering method to obtain ideal electrodes for proton exchange membrane fuel cells.The platinum loading of the electrocatalyst layer is controlled at about 0.1 mg·cm^(-2).Structural characteristics and catalytic activities of the films were analyzed by scanning electron microscopy,atomic force microscopy,X-ray diffraction,cyclic voltammetry,and stress durability testing methods.The effect of treatment conditions of a substrate on the structural and performance characteristics of the catalytic films was shown as well.Films produced on acid-treated carbon papers at the argon pressure of 0.01 mbar possessed a homogeneous,highly developed surface along with a porous structure.Compared to Pt/TCPW(Toray carbon papers soaked in ultrapure water)electrodes,the film obtained on the acid-treated substrate had a larger electrochemical surface area(163.33 m^(2)·g^(-1))and exhibited better catalytic stability and durability due to a porous structure as a result of Pt particle accumulation.

Highly Active and Stable Ni_2P/SiO_2 Catalyst for Hydrogenation of C_9 Petroleum Resin

Catalytic hydrogenation is an appropriate method for the improvement of C9 petroleum resin（C9PR） quality. In this study, the Ni2P/SiO2（containing 10% of Ni） catalyst prepared by the temperature-programmed reduction（TPR） method was used for hydrogenation of C9 petroleum resins. The effect of reaction conditions on catalytic performance was studied, and the results showed that the optimum reaction temperature, pressure and liquid hourly space velocity（LHSV） was 250 ℃, 6.0 MPa, and 1.0 h-1, respectively. The bromine numbers of hydrogenated products were maintained at low values（250 mg Br/100g） within 300h, showing the high activity and stability of Ni2P/SiO2 catalyst. The fresh and spent catalysts were characterized by X-ray diffraction（XRD）, BET surface area（BET） analysis, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, Fourier transform infrared（FTIR） pyridine adsorption, and X-ray photoelectron spectroscopy（XPS）. Compared with the traditional sulfurated-Ni W catalysts, Ni2P possessed globe-like structure instead of layered structure like the active phase of Ni WS, thereof exposing more active sites, which were responsible for the high activity of Ni2P/SiO2 catalyst. The stability of Ni2P/SiO2 catalyst was probably attributed to its high sulfur tolerance, antisintering, anti-coking and carbon-resistance ability. These properties might be further ascribed to the special Ni-P-S surface phase, high thermal stability of Ni2P nanoparticles and weak surface acidity for the Ni2P/SiO2 catalyst.

In situ Fourier Transform Infrared Spectroscopy Diagnostic for Characterization and Performance Test of Catalysts

The present work establishes a systematic approach based on the application of in-situ Fourier transform infrared spectroscopy （FTIR） for the investigation of the crystal structure, thermal stability, redox behavior （temperature-programmed reduction/temperatureprogrammed re-oxidation） as well as the catalytic properties of Co3O4 thin films. The syntheses of Co3O4 were achieved by chemical vapor deposition in the temperature range of 400-500℃. The structure analysis of the as-prepared material revealed the presence of two prominent IR bands peaking at 544 cm-1 （υ1） and 650 cm-1 （υ2） respectively, which originate from the stretching vibrations of the Co-O bond, characteristic of the Co3O4 spinel. The lattice stability limit of Co3O4 was estimated to be above 650℃. The redox properties of the spinel structure were determined by integrating the area under the emission bands υ1 and υ2 as a function of the temperature. Moreover, Co3O4 has been successfully tested as a catalyst towards complete oxidation of dimethyl ether below 340 ℃. The exhaust gas analysis during the catalytic process by in situ absorption FTIR revealed that only CO2 and H2O were detected as the final products in the catalytic reaction. The redox behavior suggests that the oxidation of dimethyl ether over Co3O4 follows a Mars-van Krevelen type mechanism. The comprehensive application of in situ FTIR provides a novel diagnostic tool in characterization and performance test of catalysts.

Oxygen reduction on polycobaltprotoporphyrin film Ⅰ.Catalytic activity and stability of polycobaltprotoporphyrin film toward oxygen reduction

The catalytic activity of polycobaltprotoporphyrin(PCoPP)was compared with adsorbed cobaltprotoporphyrin monolayer.The results have shown that PCoPP film shows higher catalytic activity and stability than monolayer on glass carbon electrode in both alkaline and acid solution. Catalytic activity of PCoPP goes through a maximum with increase of film thickness.A model was proposed to explain such dependence.The effect of film thickness and solution pH on the stability of PCoPP film was studied.

Surface Ligand Evolution:Sulfur-Directed Covalent Bonding of PPh_(3) on Pd_(4)S with Improved Semi-hydrogenation of Terminal Alkynes

Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity,although offten at the expense of catalytic activity.In this study,we demonstrate a compelling approach by surface modifying Pd2S nanocrystals with PPhz ligands,resulting in a catalyst with excellent catalytic activity and durable selectivity for the semi-hydrogenation of terminal alkynes.Experimental and theoretical investigations reveal that the presence of S sites on the Pd surface directs PPh_(3) ligands to preferentially form covalent bonds with S,creating distinctive surface S=PPh_(3) motifs.This configuration induces a partial positive charge on Pd,facilitating hydrogen transfer and thus promoting catalytic activity.Furthermore,the covalent bond between the ligand and catalyst surface forms a robust network,ensuring ligand stability and increasing the hydrogenation energy barrier of olefins.Consequently,the Pd_(4)S@PPhz catalyst exhibits an improved catalytic selectivity with durability in terminal alkyne semi-hydrogenation.This study introduces an effective strategy for designing selective hydrogenation catalysts with an enhanced performance.

Synthesis and stability evaluation of hierarchical silicoaluminophosphates with different structural frameworks in the methanol to olefins process

Silicoaluminophosphates （SAPOs） with different pore structures were synthesized through the implementation of polyethylene glycol （PEG） as a mesopores impregnation agent. Using PEGs with different molecular weights （MWs） and concentrations in the synthesis precursor, several samples were synthesized and characterized. Applying a PEG capping agent to the precursors led to the formation of tuned mesopores within the microporous matrix of the SAPO. The effects of the PEG molecular weight and PEG/Al molar ratio were investigated to maximize the efficiency of the catalyst in the methanol-to-olefin （MTO） process. Using PEG with a MW of 6000 resulted in the formation of both Zeolite Rho and chabazite structural frameworks （i.e., DNL-6 and SAPO-34）. Pure SAPO-34 samples were successfully prepared using PEG with a MW of 4000. Our results showed that the PEG concentrations affect the porosity and acidity of the synthesized materials. Furthermore, the SAPO-34 sample synthesized with PEG （MW of 4000） and a PEG/Al molar ratio of 0.0125 showed a superior catalytic stability in the MTO reaction owing to the tuned bi-modal porosity and tailored acidity pattern. Finally, through reactivation experiments, it was found that the catalyst is stable even after several regeneration cycles.

Effects of support property on the catalytic performance of CeO_2-ZrO_2-CrO_x for 1,2-dichloroethane oxidation

HZSM-5, Al_2O_3, TiO_2 and SiO_2 supported CeO_2-ZrO_2-CrO_x catalysts were prepared by deposition-precipitation method and tested for deep catalytic oxidation of 1,2-dichloroethane（DCE）, as one of the common chlorinated organic pollutants. All the catalysts were characterized by means of N_2 adsorption-desorption, X-ray photoelectron spectroscopy（XPS）, ammonia-temperatureprogrammed desorption（NH_3-TPD） and hydrogen temperature-programmed reduction（H2-TPR）. The characterization results revealed that there was strongly synergistic effect between the oxidizability of CZCr species and the acidity of supports, which obviously promoted the catalytic activity for DCE degradation. 20% CZCr/HZSM-5 showed the highest activity and good durability during the long-term continuous test. The catalytic activity decreased in the order： 20%CZCr/HZSM-5〉CZCr〉20%CZCr/TiO_2〉20%CZCr/Al_2O_3〉20%CZCr/SiO_2.

Lanthanum incorporated in MCM-41 and its application as a support for a stable Ni-based methanation catalyst

Herein, lanthanum was incorporated via hydrothermal synthesis into a MCM-41 framework structure with La/Si molar ratios from 0.01 to 0.1. Samples of NiO supported on LaMCM-41 were prepared using the impregnation method. The catalyst performance was evaluated using a fixed bed CO methanation reactor. A Ni/LaMCM-41 catalyst with La/Si = 0.1 shows the best catalytic performance with a CO conversion of almost 100% and a CH4 selectivity of 89.5% at 250 ℃ under a pressure of 1.5 MPa and at an airspeed of 36,000 mL/（g·h）. Compared with Ni-La/MCM-41（La/Si = 0.1） and Ni/MCM-41 prepared via the impregnation method, Ni/LaMCM-41（La/Si = 0.1） shows a higher CO conversion and CH4 selectivity.In a 100 h stability test, the Ni/LaMCM-41（La/Si = 0.1） catalyst shows excellent stability; furthermore, the CO conversion is always greater than 98.0%, which is significantly better than the results for Ni/MCM-41.We experimentally demonstrate that elemental La enters the framework of MCM-41. The Ni/LaMCM-41 catalyst performs well because the La reduces the average particle size of the NiO particles and enhances the interaction between NiO and MCM-41; moreover, the introduction of La significantly inhibits the sintering of the catalyst and the formation of carbon deposits.

A new class of rhodium complexes containing free donor atoms and their intramolecular substitution reaction

A new class of rhodium complexes with high catalytic activity as well as excellent stability, which was used as catalyst for carbonylation of methanol to acetic acid, is reported. It contains free donor (namely un-coordinated donor) atoms which enable to improve its stability by intramolecular substitution reaction. Its synthesis, characteristic and catalytic reaction were discussed here.

Studies on a New Material for Hydrogen Storage and Supply by Modified Fe and Fe2O3 Powder

Modified iron oxide, a new material for hydrogen storage and supply to polymer electrolyte fuel cell （PEFC）, was prepared by impregnating Fe or Fe2O3 powder with an aqueous solution containing metal cation additives （Al, Cr, Ni, Co, Zr and Mo）. Hydrogen storage properties of the samples were investigated. The results show that both Fe and Fe2O3 powder with additive Mo presented excellent catalytic activity and cyclic stability, and their hydrogen producing temperature could be surprisingly decreased. The temperature of forming hydrogen for the Fe2O3-Mo at the rate of 250 μmol·min^-1·Fe-g^-1 could be dramatically decreased from 527 ℃ before addition of Mo to 283 ℃ after addition of Mo in the fourth cycle. The cause for it was probably related to preventing the sinter of the sample particles. In addition, hydrogen storage capacity of the Fe2O3-Mo can reach w=4.5% （72 kg H2/m^3）, close to International Energy Agency （IEA） criterion. These show the value of practical application of the Fe2O3-Mo as the promising hydrogen storage material.