Preparation of Highly Active Pt-K/γ-Al2O3 Catalyst for o-Phenylphenol Synthesis from o-Cyclohexenyl-cyclohexanone Dehydrogenation

0.5%Pt-K/γ-Al2O3 catalysts for the synthesis of o-phenylphenol（OPP） from o-cyclohexenyl-cyclohexanone （dimer） dehydrogenation were prepared by means of a two subsequent impregnation method. The effects of catalyst preparation parameters, such as K promoters, calcination, and reduction conditions, were investigated. The results showed that the addition of K2SO4 to Pt/γ-Al2O3 catalyst notably promoted the selectivity of OPP, and its optimum content was found to be 6% in mass fraction. The higher activity was obtained when Pt/γ-Al2O3 catalyst was calcined in nitrogen atmosphere at 400--500 ℃ and then reduced at the same temperature for 3 h in hydrogen atmosphere. The conversion of the dimer and the selectivity of OPP were always above 99% and 90%, respectively, over 0.5%Pt-6% K2SO4/γ-Al2O3 catalyst during the pilot scale test of 8000 h.     

Hydrogenation of phenylpyruvic acid to phenylalanine catalyzed by Ni-B/SiO2

Phenylalanine （Phe） is a significant amino acid that cannot be synthesized by human themselves but must be taken from environment. It was initially found that the nanosized amorphous Ni-B/SiO2 alloy prepared by the chemical reduction method was an effective catalyst for the preparation of Phe from phenylpyruvic acid （PPA） by amination and hydrogenation. It has been found that the amorphous Ni-B/SiO2 alloy catalyst exhibits superior activity and selectivity to the traditional catalysts Raney Ni and Urushibara nickel. The effects of reaction time, amounts of catalysts and ammonia solution, reaction temperature, and H2 pressure on the reaction have been investigated systematically. The results indicated that the yield of Phe was 97.9%, and the selectivity for Phe reached 98.9% when the reaction was carried out for 3 h at 333 K and 2.0 MPa of H2 with m（Cat.） ： m（PPA） = 0.6 ： 1.0 and n（NH3） ： n（PPA） = 3 ： 1. The catalysts were characterized by XRD, AAS, XPS, BET, and TEM, and the relationship between the catalyst structure and the catalytic activity was discussed in detail. It was found that the reason why Ni-B/SiO2 amorphous alloy catalyst was much more active for the preparation of Phe could be accounted for by the presence of electron-rich Ni due to electron donation from alloying B; the smaller size of Ni-B particles, the larger specific surface area of Ni-B/SiO2.     

溶剂化金属原子浸渍法制备Pd-Cu/γ-Al2O3低温CO氧化催化剂

Nano-particle Pd/γ-Al₂O₃ monometallic and Pd-Cu/γ-Al₂O₃ bimetallic catalysts were prepared by solvated metal atom impregnation (SMAI) method. The results of XRD measurement indicated that Pd- Cu alloy was formed in the bimetallic catalysts and the crystalline particle size of the alloy increased as Cu contents increased with av-erage diameters < 6.0nm for all the samples. XPS and Auger spectra showed that Pd was in zero- valent state, Cu existed mainly in zero- valent state and partially in monovalent state Cu⁺. The Pd/γ-Al₂O₃ and Pd-Cu/γ-Al₂O₃ catalysts exhibited higher activity for CO oxidation at low temperature. The activity of Pd-Cu/γ-Al₂O₃ bimetallic catalyst was higher than that of Pd/γ-Al₂O₃ monometallic catalyst. The Pd-Cu/γ-Al₂O₃ catalyst with Pd/Cu atomic ratio of 1∶1 showed the highest activity.     

Comparing the deactivation behaviour of Co/CNT and Co/γ-Al2O3 nano catalysts in Fischer-Tropsch synthesis

An extensive study of Fischer-Tropsch (FT) synthesis on cobalt nano particles supported on γ-alumina and carbon nanotubes (CNTs) catalysts is reported.20 wt% of cobalt is loaded on the supports by impregnation method.The deactivation of the two catalysts was studied at 220 C,2 MPa and 2.7 L/h feed flow rate using a fixed bed micro-reactor.The calcined fresh and used catalysts were characterized extensively and different sources of catalyst deactivation were identified.Formation of cobalt-support mixed oxides in the form of xCoO yAl2O3 and cobalt aluminates formation were the main sources of the Co/γ-Al2O3 catalyst deactivation.However sintering and cluster growth of cobalt nano particles are the main sources of the Co/CNTs catalyst deactivation.In the case of the Co/γ-Al2O3 catalyst,after 720 h on stream of continuous FT synthesis the average cobalt nano particles diameter increased from 15.9 to 18.4 nm,whereas,under the same reaction conditions the average cobalt nano particles diameter of the Co/CNTs increased from 11.2 to 17.8 nm.Although,the initial FT activity of the Co/CNTs was 26% higher than that of the Co/γ-Al2O3,the FT activity over the Co/CNTs after 720 h on stream decreased by 49% and that over the Co/γ-Al2O3 by 32%.For the Co/γ-Al2O3 catalyst 6.7% of total activity loss and for the Co/CNTs catalyst 11.6% of total activity loss cannot be recovered after regeneration of the catalyst at the same conditions of the first regeneration step.It is concluded that using CNTs as cobalt catalyst support is beneficial in carbon utilization as compared to γ-Al2O3 support,but the Co/CNTs catalyst is more susceptible for deactivation.     

Study of CO2 Hydrogenation to Methanol over Cu-V/γ-Al2O3 Catalyst

The effect of vanadium addition to CU/γ-Al2O3 catalyst used in the hydrogenation of CO2 to produce methanol was studied. It was found that the catalytic performance of the Cu-based catalyst improved after V addition. The influence of reaction temperature, space velocity and the molar ratio of H2 to CO2 on the performance of 12%Cu-6%V/γ-Al2O3 catalyst were also studied. The results indicated that the best conditions for reaction were as follows: 240℃, 3600 h-1 and a molar ratio of H2 to CO2 of 3:1. The results of XRD and TPR characterization demonstrated that the addition of V enhanced the dispersion of the supported CuO species, which resulted in the enhanced catalytic performance of CU-V/γ-Al2O3 binary catalyst.     

Hydrogen production through diesel steam reforming over rare-earth promoted Ni/γ-Al_2O_3 catalysts

Rare-earth (La, Ce, Yb) promoted Ni/γ-Al2O3 catalysts were prepared by impregnation method. Activity and carbon formation resistance of the prepared catalysts were evaluated under various reaction conditions. Catalyst characterizations with TG, TPR and H2 chemisorption were carried out to investigate the promoting mechanism. Experimental results show that rare-earth promoters, especially Yb promoter, obviously improve the activity and carbon formation resistance of Ni/γ-Al2O3 catalyst, and Yb-Ni catalyst shows even higher performance than several commercial catalysts. According to the characterization results, Yb promoter enhances the interaction between the active metal and support, thus increasing the active metal’s dispersion and improving its performance. Furthermore, the obvious difference in diesel conversion between Yb-Ni catalyst and others was shown in the temperature range of 450-550 °C, which would be the reason for its excellent carbon resistance.     

Vapor phase synthesis of N-butylaniline over copper-based catalysts

Cu-based catalysts, such as Cu/SiO2, Cu/γ-Al2O3 and Cu/SiO2-Al2O3, for the vapor phase synthesis of N-butylaniline from aniline and 1-butanol were investigated and the catalysts were characterized by BET, H2-TPR, XRD and NH3-TPD techniques. The results indicated that the dispersion of copper on support was greatly influenced by the interaction between Cu and the support. Copper-based catalyst with larger amounts of acidic sites did not favor the synthesis of N-butylaniline because more by-products were prod...     

Methane Coupling Using Hydrogen Plasma and Pt／γ—Al2O3 Catalyst

In this paper,methane coupling at ambient temperature, under atmospheric pressure and in the presence of hydrogen was firstly investigated by using pulse corona plasma and Pt/γ-Al2O3 catalyst. Experimental results showed that Pt/γ-Al2O3 catalyst has catalytic activity for methane couplin to C2H4. Over sixty percent o outcomes of C2 hydrocarbons were detected to be ethylene.     

用固体碱催化Michael加成反应的研究

Different Michael addition reactions catalyzed by solid base K2O/γ-Al2O3 and KF/γ-Al2O3, MgO/γ-Al2O3 prepared by microwave irradiation method were reported in this paper. For the K2O/γ-Al2O3, not only good yield was attained but also made the reaction of Acetonitrile that usually is regarded as inactive carbonion and α, β-unsatumted compound to carry out. The yield of Michael reaction of Ethyl acetoacetate and Crotonaldehyde catalyzed by KF/γ-Al2O3, MgO/γ-Al2O3, MgO/NaY all could reach to 80% and the latter could reach to 90%. At the same time, the catalysts of different content(the ratio of load) of MgO were also applied in this reaction, and it was found that the best content of MgO was 20% ～ 25%。     

Preparation of Nano-Sized γ-Al2O3 Supported Iron Catalyst for Fischer-Tropsch Synthesis by Solvated Metal Atom Impregnation Methods

Two types of small iron clusters supported onγ-Al2O3-RT(dehydroxylated at room temperature) andγ-Al2O3-800 (dehydroxylated at 800℃) were prepared by solvated metal atom impregnation (SMAI) techniques. The iron atom precursor complex, bis(toluene)iron(0) formed in the metal atom reactor, was impregnated intoγ-Al2O3 having different concentrations of surface hydroxyl groups to study the effect of surface hydroxylation on the crucial stage of iron cluster formation. Catalysts prepared in this way were characterized by TEM, Mossbauer, and chemisorption measurements, and the results show that higher concentration of surface hydroxyl groups ofγ-Al2O3-RT favors the formation of more positively charged supported iron cluster Fen/γ-Al2O3-RT, and the lower concentration of surface hydroxyl groups ofγ-Al2O3-800 favors the formation of basically neutral supported iron cluster Fen/γ-Al2O3-800. The measured results also indicate that the higher concentration of surface hydroxyl groups causes the rapid decomposition of precursor complex, bis(toluene)iron(0), and favors the formation of relatively large iron cluster. Consequently, these two types of catalysts show different catalytic properties in Fischer-Tropsch reaction. The catalytic pattern of Fen/γ-Al2O3-RT in F-T reaction is similar to that of the unreducedα-Fe2O3 and that of Fen/γ-Al2O3-800 is similar to that of the reducedα-Fe2O3.     

Efficient oxidative degradation of 2-chlorophenol and 4-chlorophenol over supported CuO-based catalysts

A series of metal oxide catalysts for catalytic oxidative degradation of 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP) were prepared, and the supported CuO catalysts were studied particularly. The supported CuO catalysts were characterized by XRD and NH3-TPD techniques, in which CuO/γ-Al2O3 exhibited high degradation activity. The addition of Na2O or K2O into CuO/γ-Al2O3 improved the oxidative degradation of CPs remarkably, in which Na2O was more efficient than K2O. Over CuO/γ-Al2O3-Na2O, CPs were completely converted and the liberation of the inorganic chloride from 2-CP or 4-CP reached 97% or 100% respectively at 30 ?C for 2 h. The supported CuO catalysts with good dispersion of CuO particles and less acid sites were favorable for the efficient oxidative degradation of CPs. In addition, the initial pH of the reaction solution was found to be an important factor which influenced the catalytic oxidative degradation of CPs and the initial pH of 11.2 and 9.8 was preferred for the oxidative degradation of 2-CP and 4-CP respectively over CuO/γ-Al2O3 catalyst.     

Study of Dibenzothiophene Adsorption Over Carbon Nanotube Supported CoMo HDS Catalysts

Adsorption properties of dibenzothiophene (DBT) on a CNT (carbon nanotube) support as well as on CoMoS/CNT and CoMoO/CNT catalysts have been studied. Consecutive desorption of adsorbates was measured by TGA. The commonly used carriers AC (activated carbon), γ-Al2O3, and their supported catalysts (CoMoO/AC, CoMoS/AC, CoMoO/γ-Al2O3, CoMoS/γ-Al2O3) were also subjected to analysis for comparison. The acidic properties of the samples were characterized using the NH3-TPD technique.Correlation between the adsorption of DBT and the acidic properties of the catalysts has been established.It was found that the Co-Mo catalysts in the sulfide state adsorbed much more DBT molecules than the corresponding Co-Mo catalysts in the oxide state. The CoMoS/CNT catalyst exhibited very high HDS activity and selectivity, as compared with the CoMoS/γ-Al2O3 catalysts. Based on the BET data and the high hydrogenolysis/hydrogenation selectivity of the CoMoS/CNT, it was deduced that more than 90% of the DBT molecules adsorbed on the CoMoS/CNT with an end-on mode, and the surface of the CoMoS/CNT catalyst was almost fully covered with DBT molecules. Although the AC support had very high surface area and high loading ability, the AC supported CoMoS catalyst showed lower HDS activity,as compared with the CoMoS/γ-Al2O3 catalyst.     

Autothermal reforming of methane over Ni catalysts supported over ZrO2-CeO2-Al2O3

Ni catalysts supported on Al2O3, ZrO2-Al2O3, CeO2-Al2O3 and ZrO2-CeO2-Al2O3 were prepared by coprecipitation method, and their catalytic performances for autothermal reforming of methane to hydrogen were investigated. The Ni-supported catalysts were characterized by XRD, TPR and XPS. The relationship between the structures and catalytic activities of the catalysts was discussed. The results showed that the catalytic activity and stability of the Ni/ZrO2-CeO2-Al2O3 catalyst was better than those of other catalysts with the highest CH4 conversion, H2/CO and H2/COx ratio at 750 ℃. The catalyst showed a little deactivation along the reaction time during its 72 h on stream with the mean deactivation rate of 0.08%/h. The catalytic performance of the Ni/ZrO2-CeO2-Al2O3 catalyst was also affected by reaction temperature, no2 ： nCH4 molar ratio and nH2O ： nCH4 molar ratio. TPR, XRD and XPS measurements indicated that the formation of ZrO2-CeO2 solid solution could improve the dispersion of NiO, and inhibit the formation of NiAl2O3, and thus significantly promoted the catalytic activity of the Ni/ZrO2-CeO2-Al2O3 catalyst.     

Additive effects of alkaline-earth metals and nickel on the performance of Co/γ-Al_2O_3 in methane catalytic partial oxidation

Nano-sized γ-alumina (γ-Al2O3) was first prepared by a precipitation method. Then, active component of cobalt and a series of alkaline- earth metal promoters or nickel (Ni) with different contents were loaded on the γ-Al2O3 support. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD) and thermogravimetry analysis (TGA). The activity and selectivity of the catalysts in catalytic partial oxidation (CPO) of methane have been compared with Co/γ-Al2O3, and it is found that the catalytic activity, selectivity, and stability are enhanced by the addition of alkaline-earth metals and nickel. The optimal loadings of strontium (Sr) and Ni were 6 and 4 wt%, respectively. This finding will be helpful in designing the trimetallic Co-Ni-Sr/γ-Al2O3 catalysts with high performance in CPO of methane.     

Synthesis of Ni2P promoted trimetallic NiMoW/γ-Al2O3 catalysts for diesel oil hydrotreatment

The Ni2P promoted and γ-Al2O3 supported NiMoW sulfide catalyst consisting of 4 wt% Mo, 22 wt% W, 2 wt% Ni and 2.5 wt% Ni2P was synthesized by a co-impregnation method. The catalysts were characterized by N2 adsorption-desorption, X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, NH3 temperature-programmed desorption (NH3-TPD) and transmission electron microscopy (TEM). The results showed that Ni2P, Ni, Mo and W species were highly dispersed over γ-Al2O3. The hydrodesulfurization (HDS) of dibenzothiophene (DBT) showed that the presence of Ni2P brought a strong promotional effect on the HDS activity, which was further confirmed by the HDS and hydrodenitrogenation (HDN) of diesel oil under industrial conditions. The enhancement in HDN activity and stability by Ni2P addition could be attributed more to the effect of new active sites of Ni2P than that of acidity modification. The as-prepared Ni2P-NiMoW/γ-Al2O3 catalyst showed better hydrotreating performance than NiMoW/γ-Al2O3 and commercial catalysts.     

Preparation of Nano-Sized γ-Al2O3 Supported Iron Catalyst for Fischer-Tropsch Synthesis by Solvated Metal Atom Impregnation Methods

Two types of small iron clusters supported on γ-Al2O3-RT(dehydroxylated at room temperature) and γ-Al2O3-800 (dehydroxylated at 800 ℃) were prepared by solvated metal atom impregnation (SMAI) techniques. The iron atom precursor complex, bis(toluene)iron(0) formed in the metal atom reactor, was impregnated into γ-Al2O3 having different concentrations of surface hydroxyl groups to study the effect of surface hydroxylation on the crucial stage of iron cluster formation. Catalysts prepared in this way were characterized by TEM, M(o)ssbauer, and chemisorption measurements, and the results show that higher concentration of surface hydroxyl groups of γ-Al2O3-RT favors the formation of more positively charged supported iron cluster Fen/γ-Al2O3-RT, and the lower concentration of surface hydroxyl groups of γ-Al2O3-800 favors the formation of basically neutral supported iron cluster Fen/γ-Al2O3-800. The measured results also indicate that the higher concentration of surface hydroxyl groups causes the rapid decomposition of precursor complex, bis(toluene)iron(0), and favors the formation of relatively large iron cluster. Consequently, these two types of catalysts show different catalytic properties in Fischer-Tropsch reaction. The catalytic pattern of Fen/γ-Al2O3-RT in F-T reaction is similar to that of the unreduced α-Fe2O3 and that of Fen/γ-Al2O3-800 is similar to that of the reduced α-Fe2O3.     

Enhanced catalytic performance for direct synthesis of dimethyl ether from syngas over a La2O3 modified Cu-ZrO2/γ-Al2O3 hybrid catalyst

A series of hybrid catalysts were made by physically mixing Cu-ZrO 2 and γ-Al 2 O 3,for former it was modified with different loadings of La 2 O 3 prepared by co-precipitation method.The catalysts were characterized by BET,XRD,N 2 O-adsorption,EXAFS,H 2-TPR,NH 3-TPD techniques and evaluated in the synthesis of dimethyl ether from syngas.The results show that La 2 O 3 promoted catalysts displayed a significantly better catalytic performance compared with Cu-ZrO 2 /γ-Al 2 O 3 catalyst in CO conversion and DME selectivity,and the optimum catalytic activity was obtained when the content of La 2 O 3 was 12 wt%.The characterizations reveal that high copper dispersion,facile reducibility of copper particles and appropriate amount of acidic sites are responsible for the superior catalytic performance.     

Magnetically recyclable Pd/γ-AlOOH@Fe_3O_4 catalysts and their catalytic performance for the Heck coupling reaction

Novel magnetically recyclable Pd/γ-AlOOH@Fe3O4 catalysts were prepared using γ-AlOOH@Fe3O4 as a magnetic supporter and nano-Pd particles as the active catalytic component.The structure of the catalysts was characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),N2 adsorption-desorption,and a vibration sample magnetometer(VSM).The catalytic activity and recyclability for the Heck coupling reaction were investigated.Results showed that the magnetic γ-AlOOH@Fe3O4 possessed a core-shell structure,as well as that the nano-Pd particles were 6–8 nm and had been well dispersed in the γ-AlOOH shell.In the Heck coupling reactions,the magnetic Pd/γ-AlOOH@Fe3O4 catalysts exhibited good catalytic activity and recyclability.For the(0.021 mol%)Pd/γ-AlOOH@Fe3O4 catalyst,the bromobenzene conversion and product yield reached about 100%and 96.3%,respectively,under a 120°C reaction temperature and 12 h reaction time.After being recycled 8 times,the conversion of bromobenzene and the recovery of the catalyst were about 90%and 93%,respectively.The nano-Pd particles were kept well dispersed in the used Pd/γ-AlOOH@Fe3O4 catalyst.     

States of Carbon Nanotube Supported Mo-Based HDS Catalysts

The dispersion of the active phase and loading capacity of the Mo species on carbon nanotube (CNT) was studied by the XRD technique. The reducibility properties of Co-Mo catalysts in the oxide state over CNTs were investigated by TPR, while the sulfided Co-Mo/CNT catalysts were characterized by means of the XRD and LRS techniques. The activity and selectivity with respect to the hydrodesulfurization (HDS) performances on carbon nanotube supported Co-Mo catalysts were evaluated. It was found that the main active molybdenum species in the oxide state MoO3/CNT catalysts were MoO2, but not MoO3, as generally expected. The maximum loading before the formation of the bulk phase was lower than 6% (percent by mass, based on MoO3). TPR studies revealed that the active species in the oxide state Co-Mo/CNT catalysts were reduced more easily at relatively lower temperatures in comparison to those of the Co-Mo/γ-Al2O3 catalysts, indicating that the CNT support promoted or favored the reduction of the active species. The active species of a Co-Mo-0.7/CNT catalyst were more easily reduced than those of the Co-Mo/CNT catalysts with Co/Mo atomic ratios of 0.2, 0.35, and 0.5, respectively, suggesting that the Co/Mo atomic ratio has a great effect on the reducibility of the active species. It was found that the incorporation of cobalt improved the dispersion of the molybdenum species on the support, and a phenomenon of mobilization and re-dispersion had occurred during the sulfurization process, resulting in low valence state Mo3S4 and Co-MoS2.17 active phases. HDS measurements showed that the Co-Mo/CNT catalysts were more active than the Co-Mo/γ-Al2O3 ones for the desulfurization of DBT, and the hydrogenolysis/hydrogenation selectivity of the Co-Mo/CNT catalysts was also much higher than those of the Co-Mo/γ-Al2O3. The Co-Mo/CNT catalyst with a Co/Mo atomic ratio of 0.7 showed the highest activity, whereas the catalyst with a Co/Mo atomic ratio of 0.35 had the highest selectivity.     

Methane Dry Reforming over Alumina Supported Co Catalysts

A series of Co/γ-Al2O3 catalysts were prepared with the impregnation .method and characterized by means of the BET specific surface area, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and Laser Raman spectroscopy. The Co/γ-Al2O3 catalysts were activated by using H2, 20%CH4/H2 or CH4, re-spectively. There was no obvious difference between the activities of the Co/γ-Al2O3 catalyst activated by us-ing the different activation methods for methane dry reforming. The catalytic properties of the Co/γ-Al2O3 catalysts with different Co loadings were also investigated. The optimized Co loading for the Co/γ-Al2O3 cata-lyst pretreated with 20% CH4/H2 is around 12% (mass fraction).