能源化学(英文版)

Select

Metathesis of 1-butene and 2-butene to propene over Re₂O₇ supported on macro-mesoporous γ-alumina prepared via a dual template method

Lei Sang, Sheng-Li Chen*, Guimei Yuan, Min Zheng, Ju You, Aicheng Chen, Rui Li,

2012, 21(2): 105-108. DOI: 10.1016/S1003-9953(11)60340-X

摘要 ( 8423 )

PDF(70KB) ( 203 )

Macro-mesoporous γ-alumina support (MMA) was prepared by a sol-gel route in aqueous medium using pseudo-boehmite as aluminum source and polystyrene microspheres and Pluronic P123 as hard and soft dual templates, respectively. MMA had a BET specific surface area of about 259 m²·g^-¹, total pore volume of about 1.61 cm³·g^-¹, macropore diameter of about 102 nm, and mesopores of about 14 nm. Re₂O₇/MMA and conventional Re₂O₇/Al₂O₃ were prepared by a incipient-wetness impregnation method, and their catalytic performances in the metathesis of 1-butene and 2-butene were tested in a fixed-bed tubular reactor. The result showed that Re₂O₇/MMA possessed higher activity and far longer working life-span than conventional Re₂O₇/Al₂O₃.

Select

CF₄ decomposition over solid ternary mixture NaF-Si-MO (MO = La₂O₃, CeO₂, Pr₆O₁₁, Nd₂O₃, Y₂O₃)

Yanfei Pan, Xianjun Niu, Yanan Wang, Xiufeng Xu*

2012, 21(2): 109-112. DOI: 10.1016/S1003-9953(11)60341-1

摘要 ( 8373 )

PDF(57KB) ( 227 )

A solid ternary mixture consisting of NaF, silicon and one metal oxide such as La₂O₃, CeO₂, Pr₆O₁₁, Nd₂O₃, and Y₂O₃ was prepared and used as de-fluorinated reagent for CF₄ decomposition. The results show that 90% conversion of CF₄ can be reached initially over NaF-Si-La₂O₃, NaF-Si-CeO₂, NaF-Si-Nd₂O₃, and NaF-Si-Y₂O₃ at 850 ℃. The fresh and used reagents were characterized using XRD and XPS techniques. It was found that the active components of NaF and metal oxides in NaF-Si-CeO₂, NaF-Si-Pr₆O₁₁, NaF-Si-Nd₂O₃, and NaF-Si-Y₂O₃ were transformed into inert phases of mixed metal fluorides and silicates, respectively, resulting in an ineffective utilization of these de-fluorinated reagents, whereas no inert phases from NaF and La₂O₃ can be observed in the used NaF-Si-La₂O₃, indicating the NaF-Si-La₂O₃ reagent could be utilized more efficiently than the other reagents in CF₄ decomposition.

Select

Preparation of LaFe_0.95Pd_0.05O₃ perovskites and their catalytic performances in methane combustion

Xiaojing Zhang, Yong Li, Huaju Li, Wenjie Shen*

2012, 21(2): 113-118. DOI: 10.1016/S1003-9953(11)60342-3

摘要 ( 10137 )

PDF(70KB) ( 153 )

The physic-chemical properties of LaFe_0.95Pd_0.05O₃ perovskites were strongly dependent on the temperature of calcination. Most of the organic substances and inorganic impurities were readily removed at 723 K but single-phase and well crystallized perovskite structure was formed at 873 K. With further raising the calcination temperature, the crystallite size of LaFe_0.95Pd_0.05O₃ increased considerably. The LaFe_0.95Pd_0.05O₃ sample that calcined at 1073 K showed only comparable activity as the reference LaFeO₃ catalyst, in particular below 923 K, but pre-treatment with the reaction gas at 1223 K resulted in significantly enhanced activity due to the generation of active PdO species on the surface. The hysteresis feature upon heating-cooling cycle further confirmed the strong interaction between Pd and LaFeO₃ in the perovskite structure.

Select

Methane hydrate stability in the presence of water-soluble hydroxyalkyl cellulose

M. Mohammad-Taheri, A. Zarringhalam Moghaddam*, K. Nazari, N. Gholipour Zanjani

2012, 21(2): 119-125. DOI: 10.1016/S1003-9953(11)60343-5

摘要 ( 8753 )

PDF(61KB) ( 173 )

The effect of low-dosage water-soluble hydroxyethyl cellulose (approximate M_W~90, 000 and 250, 000) as a member of hydroxyalkyl cellulosic polymer group on methane hydrate stability was investigated by monitoring hydrate dissociation at pressures greater than atmospheric pressure in a closed vessel. In particular, the influence of molecular weight and mass concentration of hydroxyethyl cellulose (HEC) was studied with respect to hydrate formation and dissociation. Methane hydrate formation was performed at 2 ℃ and at a pressure greater than 100 bar. Afterwards, hydrate dissociation was initiated by step heating from -10 ℃ at a mild pressure of 13 bar to -3 ℃, 0 ℃ and 2 ℃. With respect to the results obtained for methane hydrate formation/dissociation and the amount of gas uptake, we concluded that HEC 90, 000 at 5000 ppm is suitable for long-term gas storage and transportation under a mild pressure of 13 bar and at temperatures below the freezing point.

Select

Kinetic hydrate inhibitor performance of new copolymer poly(N-vinyl-2-pyrrolidone-co-2-vinyl pyridine)s with TBAB

Jun Hu, Sijia Li, Yanhong Wang, Xuemei Lang, Qingping Li, Shuanshi Fan*

2012, 21(2): 126-131. DOI: 10.1016/S1003-9953(11)60344-7

摘要 ( 8594 )

PDF(66KB) ( 193 )

In oil and gas field, the application of kinetic hydrate inhibitors (KHIs) independently has remained problematic in high subcooling and high water-cut situation. One feasible method to resolve this problem is the combined use of KHIs and some synergists, which would enhance KHIs' inhibitory effect on both hydrate nucleation and hydrate crystal growth. In this study, a novel kind of KHI copolymer poly(N-vinyl-2-pyrrolidone-co-2-vinyl pyridine)s (HGs) is used in conjunction with TBAB to show its high performance on hydrate inhibition. The performance of HGs with different monomer ratios in structure II tetrahydrofuran (THF) hydrate is investigated using kinetic hydrate inhibitor evaluation apparatus by step-cooling method and isothermal cooling method. With the combined gas hydrate inhibitor at the concentration of 1.0 wt%, the induction time of 19 wt% THF solution could be prolonged to 8.5 h at a high subcooling of 6 ℃ . Finally, the mechanism of HGs inhibiting the formation of gas hydrate is proposed.

Select

Decomposition of methylamine on Mo(100) surface: A DFT study

Jianhong Liu, Cunqin Lü*, Dongli Du, Yong Guo*

2012, 21(2): 132-137. DOI: 10.1016/S1003-9953(11)60345-9

摘要 ( 8392 )

PDF(54KB) ( 113 )

The initial decomposition of methylamine on Mo(100) surface has been investigated by self-consistent (GGA-PW91) density functional theory combined with periodic slab model. The adsorption energies of possible species and the activation energies for possible elementary reactions involved are obtained in the present work. Our results indicate that the barriers decreased with the order of C-N>N-H>C-H. In addition, metastable adsorption of the abstracted hydrogen atom on the hollow site in the final state is also considered for the N-H and C-H bond breaking. For the C-H bond cleavage, the reaction barrier that the abstracted hydrogen located on the hollow site in the final state is lower than that on the bridge site. However, for the N-H bond breaking, the barriers are alike for the abstracted hydrogen on both hollow and bridge sites in the final state.

Select

Effects of Zr/Ti molar ratio in SO^2-₄/ZrO₂-TiO₂ calcined at different temperatures on its surface properties and glucose reactivity in near-critical methanol

Lincai Peng, Junping Zhuang*, Lu Lin*

2012, 21(2): 138-147. DOI: 10.1016/S1003-9953(11)60346-0

摘要 ( 8879 )

PDF(55KB) ( 118 )

Effects of Zr/Ti molar ratio in SO^2-₄/ZrO₂-TiO₂ solid acid catalyst calcined at different temperatures on its surface properties and catalytic activity were thoroughly investigated in this paper. The physicochemical characteristics of prepared samples were determined by N₂ adsorption-desorption, XRD, NH₃-TPD and XPS techniques, respectively. It was found that the crystallization temperature of the samples increased after the combination of ZrO₂ and TiO₂; and phase transformations from the anatase to the rutile of TiO₂ species and the tetragonal to the monoclinic of ZrO₂ species were effectively suppressed at higher temperature. The sample with a Zr/Ti molar ratio of 3/1 calcined at 450 ℃ showed the highest surface area and the most acid sites among all the tested samples. The acid site densities of samples were relatively closed to each other if they were calcined at the same temperature, however, decreased with the calcination temperature. The result indicates that the sulfur content in samples is a crucial factor to control the acid site density. Calcining the sample at 650 ℃ and higher temperatures resulted in a significant desorption of sulfate ion on the samples. The synthesized samples were evaluated as a potential catalyst for glucose conversion under the near-critical methanol conditions (200 ℃/4 MPa). The results suggested that the relatively weaker acid sites of the catalyst were more favorable for the accumulation of methyl glucosides, while the moderate acid sites were responsible for the formation of methyl levulinate. The catalytic activity for methyl levulinate production almost increases linearly with the catalyst acid site density. The catalyst deactivation is due to the loss of sulfate ion and the two catalysts with Zr/Ti molar ratios of 3/1 and 1/3 could effectively alleviate the deactivation caused by sulfate solution in the reaction medium and can be reused after calcination with the reuse rate of over 90% in terms of the methyl levulinate selectivity.

Select

Mathematical Modeling of a Slurry Reactor for DME Direct Synthesis from Syngas

Sadegh Papari, Mohammad Kazemeini*, Moslem Fattahi

2012, 21(2): 148-157. DOI: 10.1016/S1003-9953(11)60347-2

摘要 ( 8839 )

PDF(63KB) ( 200 )

In this paper, an axial dispersion mathematical model is developed to simulate a three-phase slurry bubble column reactor for direct synthesis of dimethyl ether (DME) from syngas. This large-scale reactor is modeled using mass and energy balances, catalyst sedimentation and single-bubble as well as two-bubbles class flow hydrodynamics. A comparison between the two hydrodynamic models through pilot plant experimental data from the literature shows that heterogeneous two-bubbles flow model is in better agreement with the experimental data than homogeneous single-bubble gas flow model. Also, by investigating the heterogeneous gas flow and axial dispersion model for small bubbles as well as the large bubbles and slurry (i.e. including paraffins and the catalyst) phase, the temperature profile along the reactor is obtained. A comparison between isothermal and non-isothermal reactors reveals no obvious performance difference between them. The optimum values of reactor diameter and height were obtained at 7 m and 50 m, respectively. The effects of operating variables on the axial catalyst distribution, DME productivity and CO conversion are also investigated in this research.

Select

Role of support nature (γ-Al₂O₃ and SiO₂-Al₂O₃) on the performances of rhenium oxide catalysts in the metathesis of ethylene and 2-pentene

Weena Phongsawat, Benjamas Netiworaruksa, Kongkiat Suriye, Siraprapha Dokjampa,

2012, 21(2): 158-164. DOI: 10.1016/S1003-9953(11)60348-4

摘要 ( 8320 )

PDF(54KB) ( 229 )

The metathesis of ethylene and 2-pentene was studied as an alternative route for propylene production over Re₂O₇/γ-Al₂O₃ and Re₂O₇/SiO₂-Al₂O₃ catalysts. Both NH₃-temperature-programmed desorption (NH₃-TPD) and H₂-temperature-programmed reduction (H₂-TPR) results showed that Re₂O₇/SiO₂-Al₂O₃ exhibited stronger acidity and weaker metal-support interaction than Re₂O₇/γ-Al₂O₃. At 35-60 ℃, isomerization-free metathesis was observed only over Re₂O₇/γ-Al₂O₃, suggesting that the formation of metal-carbene metathesis active sites required only weak acidity. Our results suggest that on the Re₂O₇/SiO₂-Al₂O₃, hydrido-rhenium species ([Re]-H) were formed in addition to the metathesis active sites, resulting in the isomerization of the initial 1-butene product into 2-butenes. A subsequent secondary metathesis reaction between these 2-butenes and the excess ethylene could explain the enhanced yields of propylene observed. The results demonstrate the potential for high yield of propylene from alternative feedstocks.

Select

Effect of Bi promoter on the performances of selective oxidation of isobutane to methacrolein over MoVO/AlPO₄ catalysts

Xitao Wang*, Mei Li, Fen Wang, Shunhe Zhong, Shi Jiang, Sihe Wang

2012, 21(2): 165-169. DOI: 10.1016/S1003-9953(11)60349-6

摘要 ( 7641 )

PDF(43KB) ( 184 )

The effects of Bi on the catalytic performance of selective oxidation of isobutane to methacrolein over MoVO/AlPO₄ catalyst were investigated by XRD, FT-Raman, XPS, UV-vis DRS techniques. The results show that the addition of Bi component into the MoVO/AlPO₄ catalyst obviously improves the catalytic performance, and the selectivity to methacrolein can increase from 14.2% to 45.1% with the increase of Bi/V molar ratio from 0 to 1. Combining the characterization results with the reaction evaluation, it is concluded that the catalytic activities of the MoV_0.3Bi_x/AlPO₄ catalysts are related to the crystalline phase composition and the dispersion of molybdenum and vanadium oxides species in general, and also to the V⁵⁺/V⁴⁺ molar ratio on the surface in particular.

Select

Ni/Al₂O₃ catalysts for syngas methanation: Effect of Mn promoter

Anmin Zhao, Weiyong Ying*, Haitao Zhang, Hongfang Ma, Dingye Fang

2012, 21(2): 170-177. DOI: 10.1016/S1003-9953(11)60350-2

摘要 ( 8627 )

PDF(67KB) ( 219 )

Ni/Al₂O₃ catalysts with different amounts of manganese ranging from 1 to 3 wt% as promoter were prepared by co-impregnation method. The catalysts were characterized by N₂ physisorption, XRD, TPR, SEM and TEM. Their catalytic activity towards syngas methanation reaction was also investigated using a fixed-bed integral reactor. It was demonstrated that the addition of manganese to Ni/Al₂O₃ catalysts can increase the catalyst surface area and average pore volume, but decrease NiO crystallite size, leading to higher activity and stability. The effects of reaction temperature, pressure and weight hourly space velocity (WHSV) on carbon oxides conversion and CH₄ formation rate were also studied. High carbon oxides conversion, CH₄ selectivity and formation rate were achieved at the reaction temperature range of 280-300 ℃.

Select

Dry reforming reaction over nickel catalysts supported on nanocrystalline calcium aluminates with different CaO/Al₂O₃ ratios

Atiyeh Ranjbar, Mehran Rezaei*

2012, 21(2): 178-183. DOI: 10.1016/S1003-9953(11)60351-4

摘要 ( 8373 )

PDF(51KB) ( 119 )

Nanocrystalline calcium aluminates with different CaO/Al₂O₃ ratios were prepared by a facile co-precipitation method using Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEG-PPG-PEG, MW: 5800) as a surfactant. They were employed as catalyst support for nickel catalysts in methane reforming with carbon dioxide. The prepared samples were characterized by X-ray diffraction (XRD), N₂ adsorption (BET), temperature-programmed reduction and oxidation (TPR-TPO), and scanning electron microscopy (SEM) techniques. Catalysts showed a relatively high catalytic activity and stability. TPR analysis revealed that the catalysts with higher CaO content are more difficult to be reduced. TPO analysis showed that the 5 wt%Ni/CA and 5 wt%Ni/C12A7 catalysts with higher CaO amount were effective against coke deposition.

Select

An accurate empirical correlation for predicting natural gas compressibility factors

Ehsan Sanjari, Ebrahim Nemati Lay*

2012, 21(2): 184-188. DOI: 10.1016/S1003-9953(11)60352-6

摘要 ( 9068 )

PDF(54KB) ( 203 )

The compressibility factor of natural gas is an important parameter in many gas and petroleum engineering calculations. This study presents a new empirical model for quick calculation of natural gas compressibility factors. The model was derived from 5844 experimental data of compressibility factors for a range of pseudo reduced pressures from 0.01 to 15 and pseudo reduced temperatures from 1 to 3. The accuracy of the new empirical correlation has been compared with commonly used existing methods. The comparison indicates the superiority of the new empirical model over the other methods used to calculate compressibility factor of natural gas with average absolute relative deviation percent (AARD%) of 0.6535.

Select

Comparative study between gas phase and liquid phase for the production of DMC from methanol and CO₂

Ahmed Aouissi*, Salem S. Al-Deyab

2012, 21(2): 189-193. DOI: 10.1016/S1003-9953(11)60353-8

摘要 ( 8616 )

PDF(39KB) ( 227 )

Direct synthesis of dimethyl carbonate (DMC) from methanol and carbon dioxide over Co_1.5PW₁₂O₄₀ in liquid and in gas phase is investigated. The synthesized catalyst has been characterized by means of FTIR and XRD. Liquid phase experiment results showed that high pressures are favorable for the synthesis of DMC. However, DMC formation is limited by the reaction with co-produced water. DMC selectivity is more strongly dependent on the temperature than on the pressure of CO₂. As for the reactions in gas phase, it has been found that both CH₃OH conversion and DMC selectivity decreased with increasing temperature, owing to the decomposition of DMC at high temperatures. High temperatures and more amount of Co_1.5PW₁₂O₄₀ catalyst favor the formation of dimethoxymethane (DMM) and methyl formate (MF).

Select

Weakening internal diffusion effect in selective hydrodesulfurization of FCC gasoline by novel designed eggshell CoMoS/Al₂O₃ catalysts

Bin Liu, Yongming Chai*, Yajing Wang, Yunqi Liu, Chenguang Liu*

2012, 21(2): 194-199. DOI: 10.1016/S1003-9953(11)60354-X

摘要 ( 8429 )

PDF(65KB) ( 182 )

A simple method for preparation of presulfided eggshell CoMoS/γ-Al₂O₃ catalysts with sharp boundary is developed, through which the eggshell thicknesses of Co and Mo could be easily regulated by controlling the impregnation time. According to the results characterized by EDS, XRD, HRTEM and FT-IR of adsorbed CO, the active component structures, the nature and/or the amount of active sites on the eggshell catalyst are similar to these on the uniform catalyst. The evaluation results of the catalytic performance in selective hydrodesulfurization (HDS) of FCC gasoline show the presence of significant internal diffusion inhibition effect on HDS of S-compounds especially in the uniform catalyst. Compared with uniform catalyst, the eggshell catalyst could remarkably reduce such diffusion effect due to a shortened diffusion path of the reactants, thus showing higher HDS activity and selectivity.

Select

CO₂ reforming of methane over nickel catalysts supported on nanocrystalline MgAl₂O₄ with high surface area

Narges Hadian, Mehran Rezaei*, Zeinab Mosayebi, Fereshteh Meshkani

2012, 21(2): 200-206. DOI: 10.1016/S1003-9953(11)60355-1

摘要 ( 8556 )

PDF(64KB) ( 225 )

In this paper dry reforming of methane (DRM) was carried out over nanocrystalline MgAl₂O₄-supported Ni catalysts with various Ni loadings. Nanocrystalline MgAl₂O₄ spinel with high specific surface area was synthesized by a co-precipitation method with the addition of pluronic P123 triblock copolymer as surfactant, and employed as catalyst support. The prepared samples were characterized by X-ray diffraction (XRD), N₂ adsorption, H₂ chemisorption, temperature-programmed reduction (TPR), temperature-programmed oxidation (TPO), temperature-programmed desorption (TPD) and transmission and scanning electron microscopies (TEM, SEM) techniques. The obtained results showed that the catalyst support has a nanocrystalline structure (crystal size: about 5 nm) with a high specific surface area (175 m²·g^-¹) and a mesoporous structure. Increasing in nickel content decreased the specific surface area and nickel dispersion. The results showed that the prepared catalysts showed high catalytic activity and stability during the reaction. The nickel catalyst with 7 wt% of nickel showed the highest catalytic activity. SEM analysis revealed that whisker type carbon deposited over the spent catalysts. Increasing in nickel loading increased the amount of deposited carbon.

Select

Effect of aluminum modification on catalytic properties of PtSn-based catalysts supported on SBA-15 for propane dehydrogenation

Yongzheng Duan, Yuming Zhou*, Yiwei Zhang, Xiaoli Sheng, Shijian Zhou, Zewu Zhan

2012, 21(2): 207-214. DOI: 10.1016/S1003-9953(11)60356-3

摘要 ( 9333 )

PDF(54KB) ( 124 )

The catalytic properties of PtSn-based catalysts supported on siliceous SBA-15 and Al-modified SBA-15, such as Al-incorporated SBA-15 (AlSBA-15) and alumina-modified SBA-15 (Al₂O₃/SBA-15), for propane dehydrogenation were investigated. Al₂O₃/SBA-15 was prepared either by an impregnation method using aluminum nitrate aqueous solution, or by the treatment of SBA-15 with a Al(OC₃H₇)₃ solution in anhydrous toluene. N₂-physisorption, FT-IR spectroscopy, solid-state ²⁷Al MAS NMR spectroscopy, hydrogen chemisorption, XRF, NH₃ temperature-programmed desorption, X-ray photoelectron spectroscopy and TPO were used to characterize these samples. Among these catalysts, the PtSn-based catalyst supported on Al₂O₃/SBA-15, which was grafted with Al(OC₃H₇)₃, exhibited the best catalytic performance in terms of activity and stability The possible reason was due to the high Pt metal dispersion and/or the strong interactions among Pt, Sn, and the support.

过刊目录