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The main sulfur compounds in FCC gasoline and related hydrodesulfurization(HDS) technologies were reviewed.
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The effects of doping with different metal ions on the defects of nanometer TiO2 photocatalytic material and its mean electron density and photoactivity were investigated by means of positron annihilation technique. The results showed that the defects of nanometer TiO2 photocatalytic material were mostly oxygen vacancy, twin crystal boundary, dislocation and metal vacancy. The Doppler energy spectra for TiO2 positron annihilation indicated that doping of higher valence ion(Fe3+,W6+ and La3+) decreased the mean electron density of nanometer TiO2, and that of lower valence ions(Zn2+, Cu2+, Pb2+, Mn2+, Co2+, and Ag+) increased the mean electron density of nanometer TiO2 . Doping of Al3+、V5+、Ni2+、Cr3+ had no influence on the mean electron density of nanometer TiO2. The correlation between Doppler energy spectra for TiO2 positron annihilation and the photocatalytic activity indicated that formation of free volume defects by doping of Pb2+, La3+, Cr3+, Co2+ ions was disadvantageous to enhancement of the photocatalytic activity; formation of free volume defects by doping of Fe3+, W6+, La3+, Cu2+, Mn2+, Ag+, Al3+, V5+, Ni2+ ions was advantageous to enhancement of the photocatalytic activity.
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The effects of supports on catalytic activity of Ni-based catalysts for production of hydrogen peroxide via anthraquinone route were studied and the activity of the catalysts was compared with Raney nickel catalysts. The influence of Ni loadings on the catalytic activity was also investigated. The experimental results showed that catalytic activity of Ni-based catalyst supported on SiO2 was superior to that on γ-Al2O3. Maximal hydrogenation activity was obtained over Ni/SiO2 catalyst with Ni loadings of 28.57%-50%（mass fraction）. Ni/SiO2 catalyst was superior to Raney nickel catalyst in terms of hydrogen peroxide yield over unit mass of pure nickel. Hydrogenation activity of Ni/SiO2 catalyst declined when Ni loadings were over 50%. Hydrogenation of anthraquinone over Ni/SiO2 catalyst was structure-sensitive reaction. Optimal catalytic activity was obtained over Ni/SiO2 catalyst with Ni dispersion of about 18%
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Three ceramic honeycomb Pd catalysts with washcoat of γ-Al2O3, Ce0.67Zr0.33O2 solid solution and mixtures of the both were prepared for purification of exhaust gas from wire enameling machines. Activity for catalytic combustion of benzene, xylene and cresol were studied over the catalysts. The results showed that mixture washcoat of γ-Al2O3 and Ce0.67Zr0.33O2 exhibited superior catalytic activity. XRD and BET results indicated that mixture washcoat of γ-Al2O3 and Ce0.67Zr0.33O2 had better thermal stability, which favored maintenance of highly dispersion of the active components.
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Different FeAlPO-5 molecular sieves were synthesized by hydrothermal method by complete dissolution and partial dissolution of the aluminum sources. The catalysts were characterized by XRD, IR and SEM. The results indicated that solubility of the aluminum sources and iron loadings had influence on the structure and morphology of FeAlPO-5. Dense tridymite phase was likely to form over FeAlPO-5 when the aluminum sources were 100% dissolved followed by incorporation of other reagents. Excessive iron loadings favored partial transformation of FeAlPO-5 from AFI structure to dense tridymite phase.
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Pt/M/SiC CO oxidation catalysts were prepared by impregnation, using SiC as the support, platinum as the active constituent and transition metals(Fe, Co and Ni) as the promoters. Effects of different transition metals and their loadings, impregnation procedures, space velocity and calcination temperature on catalytic properties of the Pt/SiC catalysts were investigated. The results showed that addition of transition metals remarkably enhanced the catalytic activity by improving Pt dispersion and the interaction between Pt and transition metals. The catalyst promoted by Fe exhibited the highest activity. The catalyst prepared by co-impregnation was superior to those prepared by stepwise impregnation. Appropriate loadings of Fe apparently enhanced catalytic activity of Pt/SiC. The optimal calcination temperature for Pt-Fe/SiC catalyst was 500 ℃.
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Formed TiO2 support was prepared by extrusion using low cost metatitanic acid as starting material. The influence of calcination temperature on crush strength, surface area, pore volume, pore size distribution and crystal phase of the formed TiO2 supports were investigated, and the supports were characterized by XRD, BET, TG/DSC and SEM. Pd/TiO2 catalyst for hydrofining of raw terephthalic acid was prepared by impregnation. The results showed that higher calcination temperature favored higher crush strength but led to declining surface area and pore volume, and shift to macropores distribution. Crystal phase transformation of TiO2 supports from anatase to rutile occurred at calcination temperature of over 800 ℃. The formed TiO2 support calcined at 600 ℃ had crush strength of over 110 N·cm－1 and surface area of 60 m2·g－1. 0.5%Pd/TiO2 catalyst was prepared and used in hydrofining of raw terephthalic acid, with 4-CBA conversion of over 99%.
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Several tungsten phosphide catalysts using γ-Al2O3 as support and ammonium dibasic phosphate and ammonium metatungstate as raw material were prepared by impregnation method. The effects of impregnation sequence and loadings of W and P,calcination and reduction temperature on hydrogenation activity of the catalyst were investigated using HDS reaction of thiophene as the probe reaction. The results showed that thiophene HDS activity of suppoted WP-1 catalyst with WP loadings of 30% was superior to the others. Addition of P improved the hydrogenation activity.
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Alumina carrier for residue hydrogenation catalysts was prepared by supersolubilizing self-assembly micelles and structure of the carrier was characterized by SEM，BET and TG. The results indicated that nanoparticles alumina carrier had good stability, even distribution，large pore size, surface area and pore volume, high strength and lower bulk density, which conformed to characteristics of nanoparticles.
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ZSM-5 zeolites were synthesized by in-situ synthesis of supersolubility micelles. Influence of water and surfactant content, crystalization temperature and calcination temperature on the particle size, pore size, pore volume, surface area and crystal morphology was investigated by BET, XRD and TEM. The optimal synthesis condition for ZSM-5 zeolite was obtained as follows: water-to-silica molar ratio 90, mass percentage of surfactant=10%, crystallization temperature 180 ℃,calcination temperature 500 ℃. The product prepared had average particle size of (50-70) nm, spherical appearance and narrow particle size distribution, with single layer dispersion of the particles.
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TiO2-ZrO2 mixed supports were prepared by solgel method and used in preparation of MoP/TiO2ZrO2 catalysts by coimpregnation. Hydrodenitrogenation(HDN) activity of the catalysts was tested in a fixed bed reactor after insitu reduction. The results showed that titaniumtozirconium molar ratio and Mo loadings had remarkable influence on activity of the catalysts. Optimal HDN activity was attained over MoP/TiO2-ZrO2 catalysts under n(Ti)∶n(Zr) of 4∶1 and Mo loadings of 20%(mass fraction). HDN rate of the catalysts supported on TiO2-ZrO2 was 12.41% higher than that on TiO2-Al2O3.
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The preparation condition for Li-Fe/pillared layer clay catalyst was studied. Li-Fe supported pillared layer clay catalyst was prepared using as-synthesized pillared clay as support by co-impregnation method. Olefin polymerization was carried out over the as-prepared catalyst in a high pressure reactor. The results showed that the optimum reaction condition was as follows: reaction temperature 280 ℃, reaction time 4 h, and reaction pressure 3.5 MPa. Single pass life of the Li-Fe/pillared layer clay catalyst was over 100 h. The regeneration condition for the catalyst was calcination at 480 ℃ for 4 h.
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Polymerized metallocene catalysts were synthesized by copolymerization of styrene, 2-vinyl-benzene and allyl-substituted metallocene. Catalytic activity of the catalyst for ethylene polymerization was higher［1.95×107 g·(mol·h)－1］ with controllable polymer forms. The optimum condition for ethylene polymerization over the catalysts was as follows: reaction temperature 75 ℃，reaction pressure 1.4 MPa，n(Al)∶n(Zr)=400.
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Kinetics tests for ammonia synthesis over a Ba-Ru-K/AC catalyst were carried out under simulated industrial reaction condition［T=（350-450） ℃, p=10 MPa, V(H2)∶V(N2)=1.0, 1.5, 2.0, 2.5 and 3.0, GHSV=(60 000~180 000) h－1］ in a fixed-bed reactor. The experimental data was fitted with modified Temkin kinetic equation considering the suppressant effect of H2 and NH3 adsorption on N2 adsorption, and optimized kinetic model parameters of n,α, w1 and w2 were 1, 0.15, 0.5 and 1.4, respectively. The results indicated that a dependable kinetic model could be obtained by modifying the Temkin equation by considering the H2 and NH3 adsorption factors. Activation energy for the ammonia synthesis reaction was obtained as 90.2 kJ·mol－1 after linear fitting the kinetic and thermodynamic parameters k, KH2 and KNH3with the Arrhenius and Van't Hoff equation, which was much lower than that over iron-based catalyst, which indicated that the activation energy barrier of N2 dissociative adsorption on Ru was far lower than that on either the conventional magnetite-based catalyst or wustite-based catalyst; the hydrogen adsorption heat was 76.2 kJ·mol－1, indicating that the adsorption of hydrogen on the Ba-Ru-K/AC catalyst was so strong that it inhibitied the dissociative adsorption of nitrogen. The modified Temkin equation was applicable to the design and operation of ammonia synthesis reactor using Ru/C catalyst.
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Heterogeneous catalysts, i.e., metal phosphates and 12-tungstophosphoric acid (HPW), for synthesis of n-butyl lactate from lactic acid and n-butyl alcohol, were prepared and the effects of reaction condition investigated. The results showed that reaction temperature was an important influential factor, with optimal temperature of 120 ℃. Supported HPW was an appropriate catalyst for synthesis of n-butyl lactate and remarkably reduced the amount of HPW.
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A sulfuric acid supported on silica was prepared by sol-gel method and used as the catalyst for homogeneous-phase bisphenol A synthesis via condensation of phenol and acetone. The results showed that the as-prepared solid acid exhibited high conversion of acetone(94.0%) and selectivity to bisphenol A(91.0%). Effects of reaction temperature, reaction time, phenol/acetone ratio and water produced during the reaction were investigated.
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A new LaPW12O40 Keggin-structure catalyst was prepared and characterized by FT-IR. Cyclohexanone ethylene ketal was sythesized from cyclohexanone and ethylene over LaPW12O40 catalyst. The influence of feed ratio,catalyst dosage and reaction time on yield of the product was investigated. Cyclohexanone ethylene ketal yield of over 94.0% was obtained under the optimum condition as follows: cyclohexanone 0.1 mol, cyclohexanone to ethylene molar ratio 1∶1.5, catalyst dosage 0.5% of total mass of the feed, toluene 12 mL, and reflux reaction time 1.5 h.
