过刊目录

2011, Vol. 20, No. 4　Online: 2011-07-20

上一期    下一期

全全选选:

导出引用 EndNote Ris BibTeX

隐藏/显示图片

article

Select

Influences of reaction conditions on methane decomposition over non-supported Ni catalyst Wei Zhang, Qingjie Ge*, Hengyong Xu* 2011, 20(4): 339-344.  DOI: 10.1016/S1003-9953(10)60205-8 摘要 ( 10089 )   Effects of reaction temperature and methane gas hourly space velocity (GHSV) on methane decomposition over non-supported Ni catalyst have been investigated in this work. Methane molecules activation, Ni particles growth and nano-carbon diffusion were the main factors influencing methane decomposition stability of non-supported Ni. The results of methane decomposition activity test on the non-supported Ni catalyst showed that the prepared non-supported Ni could exhibit a good methane decomposition performance with 273 gC/gNi and 2667 molH2/molNi at 500 ℃ and 45000 mL/(gcat·h). Scanning electron microscope (SEM), X-ray powder diffraction (XRD) and temperature-programmed oxidation (TPO) have been carried out to characterize the used catalysts. The deposited carbon was carbon nanofibers, among which graphitic carbon formation increased with the reaction time of methane decomposition. Ni particle size was not the decisive factor during the carbon break growing stage.

Select

Double perovskite oxides Sr2Mg1-xFexMoO6-δ for catalytic oxidation of methane Chen Li, Wendong Wang*, Congying Xu, Yuanxu Liu, Bo He, Chusheng Chen 2011, 20(4): 345-349.  DOI: 10.1016/S1003-9953(10)60211-3 摘要 ( 11191 )   The double perovskite oxides Sr2Mg1-xFexMoO6-δ were investigated as catalysts for the methane oxidation. The structural properties of catalysts were characterized in detail by X-ray diffraction, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. The catalytic property was strongly influenced by the Fe substitution. The relation between catalytic performance and the degree of Fe substitution was examined with regard to the structure and surface characteristics of the mixed oxides. The Fe-containing catalysts exhibited higher activity attributable to the possible (Fe2+, Mo6+) and (Fe3+, Mo5+) valency pairs, and the highest activity was observed for Sr2Mg0.2Fe0.8MoO6-δ. The enhancement of the catalytic activity may be correlated with the Fe-relating surface lattice oxygen species and was discussed in view of the presence of oxygen vacancies.

Select

Effect of vacuum impregnation on the performance of Co/SiO2 Fischer-Tropsch catalyst Xiaofeng Zhou*, Qingling Chen, Yuewu Tao, Huixin Weng 2011, 20(4): 350-355.  DOI: 10.1016/S1003-9953(10)60200-9 摘要 ( 10784 )   Two silica-supported cobalt catalysts were prepared by incipient wetness impregnation under atmospheric and vacuum conditions. N2 physisorption, H2 chemisorption, XRD, SEM, TEM, XPS and H2-TPR were used to characterize the catalysts. The results showed that the impregnation methods had an effect on the size, dispersion and reducibility of cobalt particles. Under vacuum conditions, cobalt-containing steeping liquor could penetrate into the inner pores of silica support and more bivalent cobalt oxides were formed in the Co3O4 crystallites. Furthermore, cobalt precursors were rarely inclined to agglomerate and the smaller cobalt particles were uniform on the support, which led to the higher activity of the Co/SiO2 (B) catalyst than the normal one under the reaction conditions of 483-523 K, 1-2 MPa, gas hourly space velocity of 500--1000 h-1 and molar ratio of H2/CO = 0.5-2.0.

Select

CFD modeling of reaction and mass transfer through a single pellet: Catalytic oxidative coupling of methane Siavash Seyednejadian, Nakisa Yaghobi*, Ramin Maghrebi, Leila Vafajoo 2011, 20(4): 356-363.  DOI: 10.1016/S1003-9953(10)60206-X 摘要 ( 12164 )   In this study a mathematical model of a small scale single pellet for the oxidative coupling of methane (OCM) over titanite pervoskite is developed. The method is based on a computational fluid dynamics (CFD) code which known as Fluent may be adopted to model the reactions that take place inside the porous catalyst pellet. The steady state single pellet model is coupled with a kinetic model and the intra-pellet concentration profiles of species are provided. Subsequent to achieving this goal, a nonlinear reaction network consisting of nine catalytic reactions and one gas phase reaction as an external program is successfully implemented to CFD-code as a reaction term in solving the equations. This study is based on the experimental design which is conducted in a differential reactor with a Sn/BaTiO3 catalyst (7-8 mesh) at atmospheric pressure, GHSV of 12000 h-1, ratio of methane to oxygen of 2, and three different temperatures of 1023, 1048 and 1073 K. The modeling results such as selectivity and conversion at the pellet exit are in good agreement with the experimental data. Therefore, it is suggested that to achieve high yield in OCM process the modeling of the single pellet should be considered as the heart of catalytic fixed bed reactor.

Select

Experimental determination and prediction of the compressibility factor of high CO2 content natural gas with and without water vapor Xiaoqiang Bian*, Zhimin Du, Yong Tang 2011, 20(4): 365-371.  DOI: 10.1016/S1003-9953(10)60210-1 摘要 ( 11576 )   In order to study the effect of different CO2 contents on gas compressibility factor (Z-factor), the JEFRI-PVT apparatus has been used to measure the Z-factor of dry natural gas with CO2 content range from 10.74 to 70.42 mol% at the temperature range from 301.2 to 407.3 K and pressure range from 7 to 44 MPa. The results show that Z-factor decreases with increasing CO2 content in natural gas at constant temperature and increases with increasing temperature for natural gas with the same CO2 content. In addition, the Z-factor of water-saturated natural gas with high CO2 content has been measured. A comparison of the Z-factor between natural gas with and without saturated water vapor indicates that the former shows a higher Z-factor than the latter. Furthermore, Peng-Robinson, Hall-Yarborough, and Soave-Benedict-Webb-Rubin equations of state (EoS) are used for the calculation of Z-factor of high CO2 content natural gas with and without water vapor. The optimal binary interaction parameters (BIP) for PR EoS are presented. The measured Z-factor is compared with the calculated Z-factor based on three models, which shows that PR EoS combined with van der Waals mixing rule for gas without water and Huron-Vidal mixing rule for water-saturated gas, are in good agreement with the experimental data.

Select

Production of single-walled carbon nanotubes from methane over Co-Mo/MgO nanocatalyst: A comparative study of fixed and fluidized bed reactors Alimorad Rashidi*, Roghayeh Lotfi, Ehsaneh Fakhrmosavi, Masoud Zare 2011, 20(4): 372-376.  DOI: 10.1016/S1003-9953(10)60208-3 摘要 ( 11205 )   In this study, the performances of fixed and fluidized bed reactors in the production of single-walled carbon nanotubes (SWNTs) have been investigated. In both reactors, single-walled carbon nanotubes were grown by catalytic chemical vapor decomposition (CCVD) of methane over Co-Mo/MgO nanocatalyst under two different operating conditions. The synthesized samples were characterized by TEM, TGA and Raman spectroscopy. It is found that the performance of a fluidized bed in the synthesis of carbon nanotubes is much better than that of a fixed bed. The quality of carbon nanotubes obtained from the fluidized bed was significantly higher than that from the fixed bed and the former one with the ID/IG ratio of 0.11 while the latter one with the ID/IG ratio of 0.71. Also, the yield of SWNTs in the fluidized bed was 92 wt%, while it was 78 wt% in the fixed bed. These advantages of fluidized bed reactors for the synthesis of carbon nanotubes can be attributed to more available space for the growth of carbon nanotubes and more uniform temperature and concentration profiles.

Select

Catalytic steam reforming of biomass over Ni-based catalysts: Conversion from poplar leaves to hydrogen-rich syngas Lingyan Cao, Zhigang Jia, Shengfu Ji*, Jinyong Hu 2011, 20(4): 377-383.  DOI: 10.1016/S1003-9953(10)60195-8 摘要 ( 11382 )   A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt% and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%–9.8 wt% have been prepared. The structure of the catalysts was characterized using X-ray diffraction (XRD), N2 adsorption-desorption, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The performance of catalytic steam reforming of the poplar leaves to the hydrogen-rich syngas was tested in a fixed-bed reactor. The results indicate that the 7.0wt%CaO-12.5wt%Ni/SBA-15 catalyst exhibits the best performance for the catalytic steam reforming of poplar leaves to hydrogen-rich syngas. The ratio of H2 : CO can reach ca 5 : 1 in the hydrogen-rich syngas. The yield of H2 can reach 273.30 mL/g (poplar leaves). In the CaO-Ni/SBA-15 catalyst, Ni active component mainly fills the role of catalytic steam reforming of the poplar leaves, and CaO active component mainly plays the role as water-gas shift and CO2 sorbent.

Select

Catalytic combustion of soot particulates over La2-xKxNiMnO6 catalysts Wenjuan Shan*, Jiali Yang, Lihua Yang, Na Ma 2011, 20(4): 384-388.  DOI: 10.1016/S1003-9953(10)60202-2 摘要 ( 10028 )   Nanosized La2-xKxNiMnO6 catalysts with ABO3 type perovskite-like structure were prepared by auto-combustion method using citric acid as a ligand to control particle size and morphology. The structures and properties of these perovskite-like oxides were investigated by X-ray powder diffraction (XRD) and temperature-programmed reduction (TPR). The catalytic activities for soot combustion were evaluated by temperature-programmed oxidation (TPO) with pure O2 and O2/NOx as oxidant, respectively. In the La2-xKxNiMnO6 catalysts, the partial substitution of K at A-site leads to an increase of the concentrations of high valence cation and oxygen vacancy, which enhance the catalytic activity for soot combustion. The optimal substitution amount of K was equal to x = 0.4 among these samples. Tp (peak temperature) in O2-TPO profile was 420 ℃ and Tp in O2/NOx-TPO profile was 370 ℃ over La1.6K0.4NiMnO6 catalyst for soot particulates combustion under loose contact conditions between catalyst and soot.

Select

Product distributions of Fischer-Tropsch synthesis over Co/AC catalyst Weixin Qian, Haitao Zhang, Weiyong Ying*, Dingye Fang 2011, 20(4): 389-396.  DOI: 10.1016/S1003-9953(10)60203-4 摘要 ( 11796 )   The product distributions of Fischer-Tropsch synthesis over Co/AC catalyst are investigated under different reaction conditions in an integral fixed bed reactor. It is found that the product distributions deviate from the ASF distribution. The deviation from ASF distribution is analyzed by taking the readsorption of alkenes and the following secondary reaction into consideration. It is noted that the contents of alcohol, alkene and alkane decline with the increasing carbon number, showing a slighter declining tendency of alkanes than those of alkenes and alcohols. It is also found that high temperature, space velocity, H2/CO in feed gas and low pressure are preferential for light hydrocarbons and alcohols while against the chain propagation. The effect of space velocity on the product distributions especially on the light products is not obvious. It is noticed that low temperature, space velocity, H2/CO and high pressure lead to high contents of alcohols; high temperature, H2/CO and low space velocity lead to high contents of alkanes. The effect of pressure on the amounts of alkanes is not significant; high space velocity and low temperature, pressure, H2/CO are preferential for alkenes.

Select

Effect of activated carbon support on CS2 removal over coupling catalysts Li Wang, Yun Guo*, Guanzhong Lu 2011, 20(4): 397-402.  DOI: 10.1016/S1003-9953(10)60197-1 摘要 ( 9602 )   Supported coupling catalysts for CS2 removal were prepared with different activated carbons originated from wood, coconut shell and coal as supports, and their catalytic activities for CS2 removal were tested at ambient temperature. The textural and surface properties of the activated carbons were characterized by nitrogen adsorption, temperature-programmed desorption (TPD) and Boehm titration. The activated carbon support with meso- and macropores, and oxygen-functional groups performs higher CS2 removal ability at ambient temperature. The effects of flow rate, CS2 inlet concentration, temperature and relative humidity on CS2 removal were also investigated. High efficient removal is obtained at temperature of 50 ℃, space velocity of 2000 h-1, inlet CS2 concentration of 500 mgS/m3 and relative humidity of 20% with the breakthrough sulfur capacity up to 4.3 gS/gCat and working sulfur capacity up to 7 gS/gCat.

Select

Preparation of polythiophene/WO3 organic-inorganic hybrids and their gas sensing properties for NO2 detection at low temperature Jing Huang, Yanfei Kang, Taili Yang, Yao Wang, Shurong Wang* 2011, 20(4): 403-407.  DOI: 10.1016/S1003-9953(10)60196-X 摘要 ( 9474 )   Polythiophene/WO3 (PTP/WO3) organic-inorganic hybrids were synthesized by an in situ chemical oxidative polymerization method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermo-gravimetric analysis (TGA). The Polythiophene/WO3 hybrids have higher thermal stability than pure polythiophene, which is beneficial to potential application as chemical sensors. Gas sensing measurements demonstrate that the gas sensor based on the Polythiophene/WO3 hybrids has high response and good selectivity for detecting NO2 of ppm level at low temperature. Both the operating temperature and PTP contents have an influence on the response of PTP/WO3 hybrids to NO2. The 10 wt% PTP/WO3 hybrid showed the highest response at low operating temperature of 70 ℃. It is expected that the PTP/WO3 hybrids can be potentially used as gas sensor material for detecting the low concentration of NO2 at low temperature.

Select

Facile preparation of efficient oil-soluble MoS2 hydrogenation nanocatalysts Shutao Wang, Changhua An*, Jie He, Zongxian Wang 2011, 20(4): 408-412.  DOI: 10.1016/S1003-9953(10)60207-1 摘要 ( 11014 )   Oil-soluble MoS2 nanoparticles with narrow size distribution have been synthesized by a facile composite-surfactants-aided-solvothermal process. The as-prepared nanoparticles can be directly used as hydrogenation nanocatalysts or as precursors to achieve efficient supported nanocatalysts. The surfaces of these nanoparticles are proposed to be encapsulated within a layer of organic modifiers, which are responsible for the enhancement of their solubility in organic solvents. The activated-carbon supported MoS2 nanocatalysts exhibit higher activity than the unsupported ones towards hydrogenation reactions of naphthalene, owing to the synergistic effects between nanoparticles and supports. The advantages of the present nanocatalysts, such as removal of conventional presulfiding requirements and reduction of nanoparticle aggregations, make them become promising applications in related petroleum chemical industry.

Select

Photoreduction of CO2 to methanol over Bi2S3/CdS photocatalyst under visible light irradiation Xin Li*, Juntao Chen, Huiling Li, Jingtian Li, Yitao Xu, Yingju Liu, Jiarong Zho 2011, 20(4): 413-417.  DOI: 10.1016/S1003-9953(10)60212-5 摘要 ( 12531 )   The Bi2S3, CdS and Bi2S3/CdS photocatalysts were prepared by direct reactions between their corresponding salt and thiourea in a hydrothermal autoclave. The photocatalytic activities of these photocatalysts for reducing CO2 to CH3OH under visible light irradiation have been investigated. The results show that the photocatalytic activity and visible light response of Bi2S3 are higher than those of CdS. The Bi2S3 modification can enhance the photocatalytic activity and visible light response of CdS. The photocatalytic activity of Bi2S3/CdS hetero-junction photocatalyst was the highest and the highest yields of methanol was 613 μmol/g when the weight proportion of Bi2S3 to CdS was 15%, which was about three times as large as that of CdS or two times of that of Bi2S3.

Select

NF3 decomposition over Al2O3 reagents without water Xiufeng Xu*, Liang Sun, Yanan Wang 2011, 20(4): 418-422.  DOI: 10.1016/S1003-9953(10)60201-0 摘要 ( 12930 )   Several Al2O3 samples were prepared by a precipitation method coupled with ultrasonic treatment, and NF3 decomposition without water over Al2O3 reagents is carried out. The effect of preparation parameters of Al2O3 reagents, such as precipitating agents, structure directing agents, and calcining temperatures on their reactivity for NF3 decomposition has been investigated. The results show that NF3 can be decomposed completely at 400 ℃, and full conversion of NF3 maintains 580 min over the best Al2O3 reagent, calcined at 600 ℃ which was prepared using both PEG-2000 and Tween-60 as structure directing agents, ammonia as a precipitating agent.

Select

Fe-modified HZSM-5 catalysts for ethanol conversion into light olefins Jiangyin Lu*, Yancong Liu, Na Li 2011, 20(4): 423-427.  DOI: 10.1016/S1003-9953(10)60193-4 摘要 ( 11423 )   A series of Fe/HZSM-5 catalysts with different iron loadings were prepared by impregnation method. Characterization was performed by N2 adsorption-desorption, X-ray diffraction (XRD), NH3 temperature-programmed desorption (NH3-TPD), temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO) and thermogravimetry (TG) analysis. Iron content in the synthesized samples varied from 1.1 wt% to 20 wt%. The obtained samples have been used for ethanol conversion into light olefins. It was found that the amount of strong acidity at 300-550 ℃ on Fe-modified samples was decreased, going with another new acid site appearance at 550-600 ℃ and that Fe/HZSM-5 catalysts were highly selective towards light olefins, especially the 9FZ sample. In addition, Fe-modified catalysts suppressed the conversion of ethanol to aromatics and paraffins and enhanced their anti-carbon deposit ability.

Select

Kinetic study of oxidative coupling of methane over Mn and/or W promoted Na2SO4/SiO2 catalysts M. Ghiasi, A. Malekzadeh*, S. Hoseini, Y. Mortazavi, A. Khodadadi, A. Talebizade 2011, 20(4): 428-434.  DOI: 10.1016/S1003-9953(10)60199-5 摘要 ( 11832 )   A comprehensive kinetic model for oxidative coupling of methane (OCM) over Mn and/or W promoted Na2SO4/SiO2 catalysts was developed based on a micro-catalytic reactor data. The methane conversion and ethylene, ethane, carbon monoxide and carbon dioxide selectivities were obtained in a wide operating condition range of 750-825 ℃, CH4/O2 = 2.5-10 and contact time = 267-472 kg·s·m-3. Reaction networks of six models with different rate equation types were compared together. The kinetic rate parameters of each reaction network were estimated using linear regression or genetic algorithm optimization method (GA). A reaction network suggested by Stansch et al. for OCM was found to be the best one and was further used in this work. The suggested model could predict the experimental results of OCM reaction within a deviation range of ±20%.

Select

Methanation of syngas over coral reef-like Ni/Al2O3 catalysts Shengli Ma, Yisheng Tan, Yizhuo Han* 2011, 20(4): 435-440.  DOI: 10.1016/S1003-9953(10)60192-2 摘要 ( 14583 )   Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye. Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor. The structure and properties of the fresh and used catalysts were studied by SEM, N2 adsorption-desorption, XRD, H2-TPR, O2-TPO, TG and ICP-AES techniques. The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts. The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673>Ni/Al2O3-573>Ni/Al2O3-473>Ni/Al2O3-773. Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition, sintering, and Ni loss. Under the reaction conditions of CO/H2 (molar ratio) = 1 : 3, 593 K, atmospheric pressure and a GHSV of 2500 h-1, CH4 selectivity was 84.7%, and the CO conversion reached 98.2%.

Select

NiMo/Al2O3 catalyst containing nano-sized zeolite Y for deep hydrodesulfurization and hydrodenitrogenation of diesel Hailiang Yin*, Tongna Zhou, Yunqi Liu, Yongming Chai, Chenguang Liu* 2011, 20(4): 441-448.  DOI: 10.1016/S1003-9953(10)60204-6 摘要 ( 13891 )   Two mixed-matrix NiMo/Al2O3 catalysts containing nano- and micro-sized zeolite Y have been prepared to explore the size effect of zeolite Y particle on the hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities of fluid catalytic cracking (FCC) diesel. They were characterized by SEM, BET, XRD, H2-TPR, NH3-TPD and HRTEM. The results show that the catalyst containing nano-sized zeolite Y possesses larger average pore diameter, higher pore volume, weaker and lesser acid sites, more easily reducible metal phases, shorter MoS2 slabs and more slab layers than the catalyst containing micro-sized zeolite Y. The catalysts were also evaluated with a high-pressure fixed-bed reactor using real FCC diesel as feed. The results display that the catalyst containing nano-sized zeolite Y bears higher HDS and HDN activities and exhibits higher relative rate constant for the removal of total sulfur or nitrogen than the one containing micro-sized zeolite.

Select

Methane coupling in microwave plasma under atmospheric pressure Changsheng Shen*, Dekun Sun, Hongsheng Yang 2011, 20(4): 449-456.  DOI: 10.1016/S1003-9953(10)60209-5 摘要 ( 13448 )   Methane coupling in microwave plasma under atmospheric pressure has been investigated. The effects of molar ratio n(CH4)/n(H2), flow rate and microwave power on the reaction have been studied. (1) With the decrease of n(CH4)/n(H2) ratio, methane conversion, C2 hydrocarbon yield, energy yield and space-time yield of acetylene increased, but the yield of carbon deposit decreased. (2) With the increase of microwave power, energy yield of acetylene decreased, but space-time yield of acetylene increased. (3) With the increase of flow rate, energy yield and space-time yield of acetylene increased first and then decreased. Finally, under the reaction conditions of CH4 flow rate of 700 mL/min, n(CH4)/n(H2) ratio of 1/4 and microwave power of 400 W, the energy yield and space-time yield of acetylene could reach 0.337 mmol/kJ and 12.3 mol/(s·m3), respectively. The reaction mechanism of methane coupling in microwave plasma has been investigated based on the thermodynamics of chemical reaction. Interestingly, the acetylene yield of methane coupling in microwave plasma was much higher than the maximum thermodynamic yield of acetylene. This phenomenon was tentatively explained from non-expansion work in the microwave plasma system.