能源化学(英文版)

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Mass production of LiFePO₄/C energy materials using Fe-P waste slag

Gen Li, Pengcheng Wu, Chunhui Luo, Qian Cui, Guixin Wang, Kangping Yan

2015, 21(4): 375-380.

摘要 ( 0 )

To effectively solve the agglomeration problems in the solid state reaction process, pre-adding glucose is adopted to the synthesis of LiFePO₄/C energy materials using Fe-P waste slag. The average particle & grain size of LiFePO₄/C decreases, and the impurities in LiFePO₄/C composites reduce to a great extent. It makes great sense to the mass industrial production. The optimum synthesis conditions determined in this work are based on the orthogonal experiments. The samples synthesized in a scale of 500 g exhibit high purity, excellent electrochemical performance, high reaction activity, good reversibility, and low polarization level. The discharge capacities are 145, 134, 117, and 102 mAh/g at the current densities of 0.1 C, 0.2 C, 0.5 C and 1 C, respectively. This work puts forward a practical suggestion for mass producing environmental benign and low cost LiFePO₄/C as cathode materials of lithium ion batteries.

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Mass production of LiFePO₄/C energy materials using Fe-P waste slag

Gen Li, Pengcheng Wu, Chunhui Luo, Qian Cui, Guixin Wang, Kangping Yan

2015, 24(4): 375-380. DOI: 10.1016/j.jechem.2015.07.007

摘要 ( 5339 )

To effectively solve the agglomeration problems in the solid state reaction process, pre-adding glucose is adopted to the synthesis of LiFePO₄/C energy materials using Fe-P waste slag. The average particle & grain size of LiFePO₄/C decreases, and the impurities in LiFePO₄/C composites reduce to a great extent. It makes great sense to the mass industrial production. The optimum synthesis conditions determined in this work are based on the orthogonal experiments. The samples synthesized in a scale of 500 g exhibit high purity, excellent electrochemical performance, high reaction activity, good reversibility, and low polarization level. The discharge capacities are 145, 134, 117, and 102 mAh/g at the current densities of 0.1 C, 0.2 C, 0.5 C and 1 C, respectively. This work puts forward a practical suggestion for mass producing environmental benign and low cost LiFePO₄/C as cathode materials of lithium ion batteries.

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Transformation of alkali and alkaline-earth metals during coal oxy-fuel combustion in the presence of SO₂ and H₂O

Liying Wang, Haixin Mao, Zengshuang Wang, Jian-Ying Lin, Meijun Wang, Liping Chang

2015, 21(4): 381-387.

摘要 ( 0 )

The occurrence modes of alkali and alkaline-earthmetals (AAEMs) in coal relate to their release behavior and ash formation during combustion. To better understand the transformation of AAEMs, the release behavior of water-soluble, HCl-soluble, HCl-insoluble AAEMs during Shenmu coal (SM coal) oxy-fuel combustion in the presence of SO₂ and H₂O in a drop-tube reactor was investigated through serial dissolution using H₂O and HCl solutions. The results show that the release rates of AAEMs increase with an increase in temperature under the three atmospheres studied. The high release rates of Mg and Ca from SM coal are dependent on the high content of soluble Mg and Ca in SM coal. SO₂ inhibits the release rates of AAEMs, while H₂O promotes them. The effects of SO₂ and H₂O on the Na and K species are more evident than those on Mg and Ca species. All three types of AAEMs in coal can volatilize in the gas phase during coal combustion. The W-type AAEMs release excessively, whereas the release rates of I-type AAEMs are relatively lower. Different types of AAEMmay interconvert through different pathways under certain conditions. Both SO₂ and H₂O promote the transformation reactions. The effect of SO₂ was related to sulfate formation and the promotion by H₂O occurs because of a decrease in the melting point of the solid as well as the reaction of H₂O.

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Transformation of alkali and alkaline-earth metals during coal oxy-fuel combustion in the presence of SO₂ and H₂O

Liying Wang, Haixin Mao, Zengshuang Wang, Jian-Ying Lin, Meijun Wang, Liping Chang

2015, 24(4): 381-387. DOI: 10.1016/j.jechem.2015.07.006

摘要 ( 8898 )

The occurrence modes of alkali and alkaline-earthmetals (AAEMs) in coal relate to their release behavior and ash formation during combustion. To better understand the transformation of AAEMs, the release behavior of water-soluble, HCl-soluble, HCl-insoluble AAEMs during Shenmu coal (SM coal) oxy-fuel combustion in the presence of SO₂ and H₂O in a drop-tube reactor was investigated through serial dissolution using H₂O and HCl solutions. The results show that the release rates of AAEMs increase with an increase in temperature under the three atmospheres studied. The high release rates of Mg and Ca from SM coal are dependent on the high content of soluble Mg and Ca in SM coal. SO₂ inhibits the release rates of AAEMs, while H₂O promotes them. The effects of SO₂ and H₂O on the Na and K species are more evident than those on Mg and Ca species. All three types of AAEMs in coal can volatilize in the gas phase during coal combustion. The W-type AAEMs release excessively, whereas the release rates of I-type AAEMs are relatively lower. Different types of AAEMmay interconvert through different pathways under certain conditions. Both SO₂ and H₂O promote the transformation reactions. The effect of SO₂ was related to sulfate formation and the promotion by H₂O occurs because of a decrease in the melting point of the solid as well as the reaction of H₂O.

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Preparation of nano-PANI@MnO₂ by surface initiated polymerization method using as a nano-tubular electrode material: The amount effect of aniline on the microstructure and electrochemical performance

Fen Ran, Yunlong Yang, Lei Zhao, Xiaoqin Niu, Dingjun Zhang, Lingbin Kong, Yongchun Luo, Long Kang

2015, 21(4): 388-393.

摘要 ( 1 )

In this study, nano-polyanline and manganese oxide nanometer tubular composites (nano-PANI@MnO₂) were prepared by a surface initiated polymerization method and used as electrochemical capacitor electrode materials; and the effect of aniline amount on the microstructure and electrochemical performance was investigated. The microstructures and surface morphologies of nano-PANI@MnO₂ were characterized by X-ray diffraction, scanning electron microscopy and fourier transformation infrared spectroscope. The electrochemical performance of these composite materials was performed with cyclic voltammetry, charge-discharge test and electrochemical impedance spectroscopy, respectively. The results demonstrate that the feed ratio of aniline to MnO₂ played a very important role in constructing the hierarchically nano-structure, which would, hence, determine the electrochemical performance of the materials. Using the templateassisted strategy and controlling the feed ratio of aniline to MnO₂, the nanometer tubular structure of nano-PANI@MnO₂ was obtained. A maximum specific capacitance of 386 F/g was achieved in aqueous 1 mol/L NaNO₃ electrolyte with the potential range from 0 to 0.6 V (vs. SCE).

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Preparation of nano-PANI@MnO₂ by surface initiated polymerization method using as a nano-tubular electrode material: The amount effect of aniline on the microstructure and electrochemical performance

Fen Ran, Yunlong Yang, Lei Zhao, Xiaoqin Niu, Dingjun Zhang, Lingbin Kong, Yongchun Luo, Long Kang

2015, 24(4): 388-393. DOI: 10.1016/j.jechem.2015.07.003

摘要 ( 5268 )

In this study, nano-polyanline and manganese oxide nanometer tubular composites (nano-PANI@MnO₂) were prepared by a surface initiated polymerization method and used as electrochemical capacitor electrode materials; and the effect of aniline amount on the microstructure and electrochemical performance was investigated. The microstructures and surface morphologies of nano-PANI@MnO₂ were characterized by X-ray diffraction, scanning electron microscopy and fourier transformation infrared spectroscope. The electrochemical performance of these composite materials was performed with cyclic voltammetry, charge-discharge test and electrochemical impedance spectroscopy, respectively. The results demonstrate that the feed ratio of aniline to MnO₂ played a very important role in constructing the hierarchically nano-structure, which would, hence, determine the electrochemical performance of the materials. Using the templateassisted strategy and controlling the feed ratio of aniline to MnO₂, the nanometer tubular structure of nano-PANI@MnO₂ was obtained. A maximum specific capacitance of 386 F/g was achieved in aqueous 1 mol/L NaNO₃ electrolyte with the potential range from 0 to 0.6 V (vs. SCE).

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Effect of CO₂ on the structural variation of Na₂WO₄/Mn/SiO₂ catalyst for oxidative coupling of methane to ethylene

Jia Shi, Lu Yao, Changwei Hu

2015, 21(4): 394-400.

摘要 ( 0 )

In this work, the influence of CO₂ on the structural variation and catalytic performance of Na₂WO₄/Mn/SiO₂ for oxidative coupling of methane to ethylene was investigated. The catalyst was prepared by impregnation method and characterized by XRD, Raman and XPS techniques. Appropriate amount of CO₂ in the reactant gases enhanced the formation of surface tetrahedral Na₂WO₄ species and promoted the migration of O in MO_x, Na,Wfrom the catalyst bulk to surface, which were favorable for oxidative coupling of methane. When the molar ratio of CH₄/O₂/CO₂ was 3/1/2, enriched surface tetrahedral Na₂WO₄ species and high surface concentration of O in MO_x, Na, W were detected, and then high CH₄ conversion of 33.1% and high C₂H₄ selectivity of 56.2% were obtained. With further increase of CO₂ in the reagent gases, the content of active surface tetrahedral Na₂WO₄ species and surface concentration of O in MO_x, Na, W decreased, while that of inactive species (MnWO₄ and Mn₂O₃) increased dramatically, leading to low CH₄ conversion and low C₂H₄ selectivity. It could be speculated that Na₂WO₄ crystal was transformed into MnWO₄ crystal with excessive CO₂ added under the reaction conditions. Pretreatment of Na₂WO₄/Mn/SiO₂ catalyst by moderate amount of CO₂ before OCM also promoted the formation of Na₂WO₄ species.

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Effect of CO₂ on the structural variation of Na₂WO₄/Mn/SiO₂ catalyst for oxidative coupling of methane to ethylene

Jia Shi, Lu Yao, Changwei Hu

2015, 24(4): 394-400. DOI: 10.1016/j.jechem.2015.06.007

摘要 ( 9033 )

In this work, the influence of CO₂ on the structural variation and catalytic performance of Na₂WO₄/Mn/SiO₂ for oxidative coupling of methane to ethylene was investigated. The catalyst was prepared by impregnation method and characterized by XRD, Raman and XPS techniques. Appropriate amount of CO₂ in the reactant gases enhanced the formation of surface tetrahedral Na₂WO₄ species and promoted the migration of O in MO_x, Na,Wfrom the catalyst bulk to surface, which were favorable for oxidative coupling of methane. When the molar ratio of CH₄/O₂/CO₂ was 3/1/2, enriched surface tetrahedral Na₂WO₄ species and high surface concentration of O in MO_x, Na, W were detected, and then high CH₄ conversion of 33.1% and high C₂H₄ selectivity of 56.2% were obtained. With further increase of CO₂ in the reagent gases, the content of active surface tetrahedral Na₂WO₄ species and surface concentration of O in MO_x, Na, W decreased, while that of inactive species (MnWO₄ and Mn₂O₃) increased dramatically, leading to low CH₄ conversion and low C₂H₄ selectivity. It could be speculated that Na₂WO₄ crystal was transformed into MnWO₄ crystal with excessive CO₂ added under the reaction conditions. Pretreatment of Na₂WO₄/Mn/SiO₂ catalyst by moderate amount of CO₂ before OCM also promoted the formation of Na₂WO₄ species.

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Synthesis of SAPO-34 using metakaolin in the presence of β-cyclodextrin

Chen Zhang, Xuchen Lu, Tizhuang Wang

2015, 21(4): 401-406.

摘要 ( 0 )

SAPO-34 molecular sieves were synthesized by the addition of β-cyclodextrin (β-CD) as crystal growth inhibitor using metakaolin as silicon and aluminum sources. Properties of the obtained samples were characterized by XRD, SEM, N₂ adsorption-desorption, FTIR, XRF, EDX, NH₃-TPD and ²⁹Si MAS NMR. When β-CD was added, crystal size of the SAPO-34 crystals decreased. Variation of Si content from the crystal center to surface decreased while total Si content hardly changed. ²⁹Si MAS NMR results showed that β-CD contributed to better Si dispersion and decreased the size of Si(4Si) patches. Moreover, the MTO (methanol-to-olefin) process was conducted to investigate the influence of β-CD on catalytic performance. The synthesized sample with molar ratio of β-CD/Al₂O₃ equaling 0.055 remained active for 610 min while the sample synthesized without β-CD for only 280 min, which indicates that the lifetime of catalyst synthesized with β-CD is greatly prolonged.

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Synthesis of SAPO-34 using metakaolin in the presence of β-cyclodextrin

Chen Zhang, Xuchen Lu, Tizhuang Wang

2015, 24(4): 401-406. DOI: 10.1016/j.jechem.2015.06.008

摘要 ( 7197 )

SAPO-34 molecular sieves were synthesized by the addition of β-cyclodextrin (β-CD) as crystal growth inhibitor using metakaolin as silicon and aluminum sources. Properties of the obtained samples were characterized by XRD, SEM, N₂ adsorption-desorption, FTIR, XRF, EDX, NH₃-TPD and ²⁹Si MAS NMR. When β-CD was added, crystal size of the SAPO-34 crystals decreased. Variation of Si content from the crystal center to surface decreased while total Si content hardly changed. ²⁹Si MAS NMR results showed that β-CD contributed to better Si dispersion and decreased the size of Si(4Si) patches. Moreover, the MTO (methanol-to-olefin) process was conducted to investigate the influence of β-CD on catalytic performance. The synthesized sample with molar ratio of β-CD/Al₂O₃ equaling 0.055 remained active for 610 min while the sample synthesized without β-CD for only 280 min, which indicates that the lifetime of catalyst synthesized with β-CD is greatly prolonged.

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A reevaluation of the correlation between the synthesis parameters and structure and properties of nitrogen-doped carbon nanotubes

Kunpeng Xie, Fengkai Yang, Petra Ebbinghaus, Andreas Erbe, Martin Muhler, Wei Xia

2015, 21(4): 407-415.

摘要 ( 0 )

Nitrogen-doped carbon nanotubes (NCNTs) were synthesized by chemical vapor deposition using cobaltbased oxides as catalyst and ethylenediamine (EDA) as carbon/nitrogen precursor. The influence of growth time, EDA concentration and growth temperature on the morphology, yield, composition, graphitization and oxidation resistance of the NCNTs was systematically investigated by using Raman spectroscopy, temperature-programmed oxidation and other techniques. The NCNT growth from ethylenediamine with a high N/C ratio involves several processes including mainly (1) catalytic growth of NCNTs, (2) homogeneous gas-phase decomposition of EDA, (3) non-catalytic deposition of pyrolytic carbon/nitrogen species and (4) surface etching of amorphous carbon or carbon at defect sites through gasification. At a later growth stage the etching process appears to be dominating, leading to the thinning of nanotubes and the decrease of yield. Moreover, the surface etching through carbon gasification strongly influences the structure and degree of graphitization of NCNTs.

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A reevaluation of the correlation between the synthesis parameters and structure and properties of nitrogen-doped carbon nanotubes

Kunpeng Xie, Fengkai Yang, Petra Ebbinghaus, Andreas Erbe, Martin Muhler, Wei Xia

2015, 24(4): 407-415. DOI: 10.1016/j.jechem.2015.06.016

摘要 ( 6141 )

Nitrogen-doped carbon nanotubes (NCNTs) were synthesized by chemical vapor deposition using cobaltbased oxides as catalyst and ethylenediamine (EDA) as carbon/nitrogen precursor. The influence of growth time, EDA concentration and growth temperature on the morphology, yield, composition, graphitization and oxidation resistance of the NCNTs was systematically investigated by using Raman spectroscopy, temperature-programmed oxidation and other techniques. The NCNT growth from ethylenediamine with a high N/C ratio involves several processes including mainly (1) catalytic growth of NCNTs, (2) homogeneous gas-phase decomposition of EDA, (3) non-catalytic deposition of pyrolytic carbon/nitrogen species and (4) surface etching of amorphous carbon or carbon at defect sites through gasification. At a later growth stage the etching process appears to be dominating, leading to the thinning of nanotubes and the decrease of yield. Moreover, the surface etching through carbon gasification strongly influences the structure and degree of graphitization of NCNTs.

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Methane dry reforming on Ni/La₂Zr₂O₇ treated by plasma in different atmospheres

Honggen Peng, Youhe Ma, Wenming Liu, Xianglan Xu, Xiuzhong Fang, Jie Lian, Xiang Wang, Changqing Li, Wufeng Zhou, Ping Yuan

2015, 21(4): 416-424.

摘要 ( 0 )

A series of Ni/La₂Zr₂O₇ pyrochlore catalysts prepared by impregnation method and treated by dielectric barrier discharge (DBD) plasma in different atmospheres and varied sequences were prepared and applied for dry reforming of methane (DRM). It is found that all of the plasma treated catalysts show evidently improved activity and coke resistance in comparison with the non-plasma treated one. The best performance is achieved on Ni/La₂Zr₂O₇-H₂P-C, a catalyst treated in H₂ plasma before calcination. TGA-DSC and SEM demonstrate that carbon deposition is significantly suppressed on all of the plasma treated samples. Moreover, XRD and TEM results testify that both NiO and Ni sizes on the calcined and reduced samples treated by plasma are also decreased, which results in higher Nimetal dispersion on the reduced and used catalysts and enhances the interactions between Ni sites and the support. It is believed that these are the inherent reasons accounting for the promotional effects of plasma treatment on the reaction performance of the Ni/La₂Zr₂O₇ pyrochlore catalysts.

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Methane dry reforming on Ni/La₂Zr₂O₇ treated by plasma in different atmospheres

Honggen Peng, Youhe Ma, Wenming Liu, Xianglan Xu, Xiuzhong Fang, Jie Lian, Xiang Wang, Changqing Li, Wufeng Zhou, Ping Yuan

2015, 24(4): 416-424. DOI: 10.1016/j.jechem.2015.06.015

摘要 ( 5580 )

A series of Ni/La₂Zr₂O₇ pyrochlore catalysts prepared by impregnation method and treated by dielectric barrier discharge (DBD) plasma in different atmospheres and varied sequences were prepared and applied for dry reforming of methane (DRM). It is found that all of the plasma treated catalysts show evidently improved activity and coke resistance in comparison with the non-plasma treated one. The best performance is achieved on Ni/La₂Zr₂O₇-H₂P-C, a catalyst treated in H₂ plasma before calcination. TGA-DSC and SEM demonstrate that carbon deposition is significantly suppressed on all of the plasma treated samples. Moreover, XRD and TEM results testify that both NiO and Ni sizes on the calcined and reduced samples treated by plasma are also decreased, which results in higher Nimetal dispersion on the reduced and used catalysts and enhances the interactions between Ni sites and the support. It is believed that these are the inherent reasons accounting for the promotional effects of plasma treatment on the reaction performance of the Ni/La₂Zr₂O₇ pyrochlore catalysts.

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Catalytic conversion of guaiacol to alcohols for bio-oil upgrading

Minghao Zhou, Yuan Wang, Yanbin Wang, Guomin Xiao

2015, 21(4): 425-431.

摘要 ( 0 )

Guaiacol was chosen to represent O-containing chemicals with lower effective hydrogen carbon ratio (H/C_eff factor) in bio-oil, and the hydrodeoxygenation of guaiacol was investigated over non-precious and nonsulfided catalysts. Effects of metal composition, reaction temperature, and hydrogen pressure on conversion and selectivity were investigated systematically. Among various compositions of catalysts, NiCo/CNT exhibited best performance of guaiacol conversion with higher selectivity towards desired alcohols with higher H/C_eff factor. The reaction pathways of guaiacol in aqueous were proposed based on the product analyzed. Results show that metal composition and temperature have great effects on the conversion of guaiacol and the yields of desired products.

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Catalytic conversion of guaiacol to alcohols for bio-oil upgrading

Minghao Zhou, Yuan Wang, Yanbin Wang, Guomin Xiao

2015, 24(4): 425-431. DOI: 10.1016/j.jechem.2015.06.012

摘要 ( 9225 )

Guaiacol was chosen to represent O-containing chemicals with lower effective hydrogen carbon ratio (H/C_eff factor) in bio-oil, and the hydrodeoxygenation of guaiacol was investigated over non-precious and nonsulfided catalysts. Effects of metal composition, reaction temperature, and hydrogen pressure on conversion and selectivity were investigated systematically. Among various compositions of catalysts, NiCo/CNT exhibited best performance of guaiacol conversion with higher selectivity towards desired alcohols with higher H/C_eff factor. The reaction pathways of guaiacol in aqueous were proposed based on the product analyzed. Results show that metal composition and temperature have great effects on the conversion of guaiacol and the yields of desired products.

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The tuning of pore structures and acidity for Zn/Al layered double hydroxides: The application on selective hydrodesulfurization for FCC gasoline

Tinghai Wang, Jingfeng Li, Yi Su, Chenchen Wang, Yuan Gao, Lingjun Chou, Wenjun Yao

2015, 21(4): 432-440.

摘要 ( 0 )

Co-Mo catalysts applied on the hydrodesulfurization (HDS) for FCC gasoline were prepared with Zn-Al layered double hydroxides (LDHs) to improve their performances, and the effects of pore structures and acidity on HDS performances were studied in detail. A series of Zn-Al/LDHs samples with different pore structures and acidities are synthesized on the bases of co-precipitation of OH^-, CO^2-, Al³⁺, and Zn²⁺. The neutralization pH is a main factor to affect the pore structures and acidity of Zn-Al/LDHs, and a series of Zn-Al/LDHs with different pore structures and acidities are obtained. Based on the representative samples with different specific surface areas (S_BET) and acidities, three CoMo/LDHs catalysts were prepared, and their HDS performances were compared with traditional CoMo/Al₂O₃ catalysts. The results indicated that catalysts prepared with high S_BET possessed high HDS activity, and Brönsted acid sites could reduce the thiol content in the product to some extent. All the three catalysts prepared with LDHs displayed little lower HDS activity but higher selectivity than CoMo/Al₂O₃, and could restrain the reactions of re-combination between olefin and H₂S which could be due to the existence of Brönsted acid sites.

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The tuning of pore structures and acidity for Zn/Al layered double hydroxides: The application on selective hydrodesulfurization for FCC gasoline

Tinghai Wang, Jingfeng Li, Yi Su, Chenchen Wang, Yuan Gao, Lingjun Chou, Wenjun Yao

2015, 24(4): 432-440. DOI: 10.1016/j.jechem.2015.06.013

摘要 ( 5305 )

Co-Mo catalysts applied on the hydrodesulfurization (HDS) for FCC gasoline were prepared with Zn-Al layered double hydroxides (LDHs) to improve their performances, and the effects of pore structures and acidity on HDS performances were studied in detail. A series of Zn-Al/LDHs samples with different pore structures and acidities are synthesized on the bases of co-precipitation of OH^-, CO^2-, Al³⁺, and Zn²⁺. The neutralization pH is a main factor to affect the pore structures and acidity of Zn-Al/LDHs, and a series of Zn-Al/LDHs with different pore structures and acidities are obtained. Based on the representative samples with different specific surface areas (S_BET) and acidities, three CoMo/LDHs catalysts were prepared, and their HDS performances were compared with traditional CoMo/Al₂O₃ catalysts. The results indicated that catalysts prepared with high S_BET possessed high HDS activity, and Brönsted acid sites could reduce the thiol content in the product to some extent. All the three catalysts prepared with LDHs displayed little lower HDS activity but higher selectivity than CoMo/Al₂O₃, and could restrain the reactions of re-combination between olefin and H₂S which could be due to the existence of Brönsted acid sites.

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Effect of loading on the Ni₂P/Al₂O₃ catalysts for the hydrotreating reactions

Junen Wang, Shaozhong Li, Jun Xu, Hui Chen, Jiangyu Yuan, Jianyi Shen

2015, 24(4): 441-447. DOI: 10.1016/j.jechem.2015.06.014

摘要 ( 1 )

The 80%Ni₂P/Al₂O₃ catalysts were prepared by the phosphidation of corresponding 80%Ni/Al₂O₃ with triphenylphosphine in liquid phase and compared with the 60%Ni₂P/Al₂O₃ for hydrotreating reactions. Both the 60%Ni₂P/Al₂O₃ and 80%Ni₂P/Al₂O₃ in comparison exhibited the small and uniform Ni₂P particles (6.3 and 8.4 nm, respectively), high CO uptakes (305 and 345 μmol/g, respectively) and thus high activities for the hydrotreating reactions. After the hydrotreating reactions, the small and uniform Ni₂P particles were remained, although the CO uptakes on the used 60%Ni₂P/Al₂O₃ and 80%Ni₂P/Al₂O₃ were greatly decreased (to 68 and 95 μmol/g, respectively) due to the incorporation of S into the Ni₂P surfaces. The 80%Ni₂P/Al₂O₃ was found to be significantly more active than the 60%Ni₂P/Al₂O₃ due to that the 80%Ni₂P/Al₂O₃ possessed more, and more active Ni₂P sites than the 60%Ni₂P/Al₂O₃, probably due to the less S incorporated in the 80%Ni₂P/Al₂O₃ than in the 60%Ni₂P/Al₂O₃ during the hydrotreating reactions.

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Effect of loading on the Ni₂P/Al₂O₃ catalysts for the hydrotreating reactions

Junen Wang, Shaozhong Li, Jun Xu, Hui Chen, Jiangyu Yuan, Jianyi Shen

2015, 21(4): 441-447.

摘要 ( 0 )

The 80%Ni₂P/Al₂O₃ catalysts were prepared by the phosphidation of corresponding 80%Ni/Al₂O₃ with triphenylphosphine in liquid phase and compared with the 60%Ni₂P/Al₂O₃ for hydrotreating reactions. Both the 60%Ni₂P/Al₂O₃ and 80%Ni₂P/Al₂O₃ in comparison exhibited the small and uniform Ni₂P particles (6.3 and 8.4 nm, respectively), high CO uptakes (305 and 345 μmol/g, respectively) and thus high activities for the hydrotreating reactions. After the hydrotreating reactions, the small and uniform Ni₂P particles were remained, although the CO uptakes on the used 60%Ni₂P/Al₂O₃ and 80%Ni₂P/Al₂O₃ were greatly decreased (to 68 and 95 μmol/g, respectively) due to the incorporation of S into the Ni₂P surfaces. The 80%Ni₂P/Al₂O₃ was found to be significantly more active than the 60%Ni₂P/Al₂O₃ due to that the 80%Ni₂P/Al₂O₃ possessed more, and more active Ni₂P sites than the 60%Ni₂P/Al₂O₃, probably due to the less S incorporated in the 80%Ni₂P/Al₂O₃ than in the 60%Ni₂P/Al₂O₃ during the hydrotreating reactions.

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Core@shell sulfur@polypyrrole nanoparticles sandwiched in graphene sheets as cathode for lithium-sulfur batteries

Xiangyang Zhou, Feng Chen, Juan Yang

2015, 24(4): 448-455. DOI: 10.1016/j.jechem.2015.06.011

摘要 ( 6414 )

A nano sulfur-based composite cathode material featured by uniform core@shell-structured sulfur@ polypyrrole nanoparticles sandwiched in three-dimensional graphene sheets conductive network (S@PPy/GS) is fabricated via a facile solution-based method. The S@PPy nanoparticles are synthesized by in situ chemical oxidative polymerization of pyrrole on the surface of sulfur particles, and then graphene sheets are covered outside the S@PPy nanoparticles, forming a three-dimensional conductive network. When evaluating the electrochemical performance of S@PPy/GS in a lithium-sulfur battery, it delivers large discharge capacity, excellent cycle stability, and good rate capability. The initial discharge capacity is up to 1040 mAh/g at 0.1 C, the capacity can remain 537.8 mAh/g at 0.2 C after 200 cycles, even at a higher rate of 1 C, the specific capacity still reaches 566.5 mAh/g. The good electrochemical performance is attributed to the unique structure of S@PPy/GS, which can not only provide an excellent transport of lithium and electron ions within the electrodes, but also retard the shuttle effect of soluble lithium polysulfides effectively, thus plays a positive role in building better lithium-sulfur batteries.

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Kinetic and thermodynamic studies of the esterification of acidified oil catalyzed by sulfonated cation exchange resin

Lingling Ma, Ying Han, Kaian Sun, Jie Lu, Jincheng Ding

2015, 21(4): 456-462.

摘要 ( 0 )

This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins (SCER). The effects of the mass ratio of methanol to acidified oil, reaction temperature, and catalyst loading were studied to optimize the conditions for maximum conversion of free fatty acids (FFAs). The results showed that the optimal conversion rate of FFAs was 91.87% at the mass ratio of methanol to acidified oil of 2.5:1.0, reaction temperature of 65.0 ℃, catalyst loading of 5.0 g and reaction time of 8.0 h. The external and internal mass transfer resistances were negligible based on the experimental results and a pseudo-homogeneous kinetic model was proposed for the esterification. The activation energy and thermodynamic parameters including ΔG, ΔS and ΔH were determined. The conversion rates of FFAs obtained from the established model were in good agreement with the experimental data.

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Kinetic and thermodynamic studies of the esterification of acidified oil catalyzed by sulfonated cation exchange resin

Lingling Ma, Ying Han, Kaian Sun, Jie Lu, Jincheng Ding

2015, 24(4): 456-462. DOI: 10.1016/j.jechem.2015.07.001

摘要 ( 5203 )

This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins (SCER). The effects of the mass ratio of methanol to acidified oil, reaction temperature, and catalyst loading were studied to optimize the conditions for maximum conversion of free fatty acids (FFAs). The results showed that the optimal conversion rate of FFAs was 91.87% at the mass ratio of methanol to acidified oil of 2.5:1.0, reaction temperature of 65.0 ℃, catalyst loading of 5.0 g and reaction time of 8.0 h. The external and internal mass transfer resistances were negligible based on the experimental results and a pseudo-homogeneous kinetic model was proposed for the esterification. The activation energy and thermodynamic parameters including ΔG, ΔS and ΔH were determined. The conversion rates of FFAs obtained from the established model were in good agreement with the experimental data.

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Efficient production of biodiesel from both esterification and transesterification over supported SO₄^2--MoO₃-ZrO₂-Nd₂O₃/SiO₂ catalysts

Xiuqin Li, Dongmei Tong, Changwei Hu

2015, 21(4): 463-471.

摘要 ( 1 )

SO₄^2--MoO₃-ZrO₂-Nd₂O₃/SiO₂ (SMZN/SiO₂) catalysts for the production of biodiesel via both esterification and transesterification were prepared and characterized by N₂ adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry analysis (TGA), ammonia adsorption Fourier transform infrared spectra (NH₃-FTIR), and ammonia adsorption temperature programmed desorption (NH₃-TPD) to reveal the dependence of the stable catalytic activity on calcination time. The reason for catalyst deactivation was also studied. The calcination time remarkably affected the types of active centers on SMZN/SiO₂, and 4 h was found to be the optimal calcination time. SO₄^2- species bonded with small size ZrO₂ were found to be the stable active centers, where the leaching of SO₄^2- and the deposition of coke were inhibited. The deposition of coke was easier on large size ZrO₂ than on small size ones. Calcination in air flow could eliminate the deposited coke to recover the deactivated catalysts.

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Efficient production of biodiesel from both esterification and transesterification over supported SO₄^2--MoO₃-ZrO₂-Nd₂O₃/SiO₂ catalysts

Xiuqin Li, Dongmei Tong, Changwei Hu

2015, 24(4): 463-471. DOI: 10.1016/j.jechem.2015.06.010

摘要 ( 4527 )

SO₄^2--MoO₃-ZrO₂-Nd₂O₃/SiO₂ (SMZN/SiO₂) catalysts for the production of biodiesel via both esterification and transesterification were prepared and characterized by N₂ adsorption-desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry analysis (TGA), ammonia adsorption Fourier transform infrared spectra (NH₃-FTIR), and ammonia adsorption temperature programmed desorption (NH₃-TPD) to reveal the dependence of the stable catalytic activity on calcination time. The reason for catalyst deactivation was also studied. The calcination time remarkably affected the types of active centers on SMZN/SiO₂, and 4 h was found to be the optimal calcination time. SO₄^2- species bonded with small size ZrO₂ were found to be the stable active centers, where the leaching of SO₄^2- and the deposition of coke were inhibited. The deposition of coke was easier on large size ZrO₂ than on small size ones. Calcination in air flow could eliminate the deposited coke to recover the deactivated catalysts.

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Synthesis of silica/metatitanic acid nanocomposite and evaluation of its catalytic performance for aquathermolysis reaction of extra-heavy crude oil

Xueliang Liu, Yiguang Li, Zhijun Zhang, Xiaohong Li, Mengyun Zhao, Changming Su

2015, 21(4): 472-476.

摘要 ( 2 )

A lipophilic silica/metatitantic acid (denoted as SiO₂/H₂TiO₃) nanocomposite was synthesized by hydrothermal reaction with surface-modified SiO₂ as the lipophilic carrier. As-synthesized SiO₂/H₂TiO₃ nanocomposite was used as a catalyst to promote the aquathermolysis reaction of extra-heavy crude oil thereby facilitating the recovering from the deep reservoirs at lowered temperature. The catalytic performance of the as-synthesized SiO₂/H₂TiO₃ catalyst for the aquathermolysis reaction of the heavy oil at a moderate temperature of 150 ℃ was evaluated in relation to the structural characterizations by TEM, FTIR, XRD and FESEM as well as the determination of the specific surface area by N₂ adsorption-desorption method. Findings indicate that as-synthesized SiO₂/H₂TiO₃ nanocomposite exhibits an average size of about 20 nm as well as good lipophilicity and dispersibility in various organic solvents; and it shows good catalytic performance for the aquathermolysis reaction of the extra-heavy oil extracted from Shengli Oilfield of China. Namely, the assynthesized SiO₂/H₂TiO₃ catalyst is capable of significantly reducing the viscosity of the tested heavy oil from 58,000 cP to 16,000 cP (referring to a viscosity reduction rate of 72.41%) at a mass fraction of 0.5%, a reaction temperature of 150 ℃ and a reaction time of 36 h, showing potential application in downhole upgrading heavy crude oils.

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Synthesis of silica/metatitanic acid nanocomposite and evaluation of its catalytic performance for aquathermolysis reaction of extra-heavy crude oil

Xueliang Liu, Yiguang Li, Zhijun Zhang, Xiaohong Li, Mengyun Zhao, Changming Su

2015, 24(4): 472-476. DOI: 10.1016/j.jechem.2015.06.005

摘要 ( 4665 )

A lipophilic silica/metatitantic acid (denoted as SiO₂/H₂TiO₃) nanocomposite was synthesized by hydrothermal reaction with surface-modified SiO₂ as the lipophilic carrier. As-synthesized SiO₂/H₂TiO₃ nanocomposite was used as a catalyst to promote the aquathermolysis reaction of extra-heavy crude oil thereby facilitating the recovering from the deep reservoirs at lowered temperature. The catalytic performance of the as-synthesized SiO₂/H₂TiO₃ catalyst for the aquathermolysis reaction of the heavy oil at a moderate temperature of 150 ℃ was evaluated in relation to the structural characterizations by TEM, FTIR, XRD and FESEM as well as the determination of the specific surface area by N₂ adsorption-desorption method. Findings indicate that as-synthesized SiO₂/H₂TiO₃ nanocomposite exhibits an average size of about 20 nm as well as good lipophilicity and dispersibility in various organic solvents; and it shows good catalytic performance for the aquathermolysis reaction of the extra-heavy oil extracted from Shengli Oilfield of China. Namely, the assynthesized SiO₂/H₂TiO₃ catalyst is capable of significantly reducing the viscosity of the tested heavy oil from 58,000 cP to 16,000 cP (referring to a viscosity reduction rate of 72.41%) at a mass fraction of 0.5%, a reaction temperature of 150 ℃ and a reaction time of 36 h, showing potential application in downhole upgrading heavy crude oils.

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Performance evaluation of LPG desulfurization by adsorption for hydrogen production

S. Al-Zuhair, A. Khalil, M. Hassan, A. Abdulrazak, K. Basel, A. Fardoun

2015, 21(4): 477-484.

摘要 ( 4 )

The adsorption of sulfur compounds, in commercially available LPG, has been studied using different adsorbents, namely Zeolite, ZnO and house made date pits activated carbon (DP-AC). It was found that the three adsorbents are capable of effectively removing sulfur compounds at different feed sulfur concentrations. The effects of height to diameter aspect ratio of the adsorption column, flow rate of LPG and input sulfur concentrations have been studied. A first order kinetics model has been used to describe the adsorption, and the kinetics constant was found to increase by increasing the flow rate of LPG and decrease by increasing the amount of adsorbent used. The developed model described the system fairly well, and can be used in designing and scaling-up of fixed-bed adsorption columns.

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Performance evaluation of LPG desulfurization by adsorption for hydrogen production

S. Al-Zuhair, A. Khalil, M. Hassan, A. Abdulrazak, K. Basel, A. Fardoun

2015, 24(4): 477-484. DOI: 10.1016/j.jechem.2015.06.001

摘要 ( 5 )

The adsorption of sulfur compounds, in commercially available LPG, has been studied using different adsorbents, namely Zeolite, ZnO and house made date pits activated carbon (DP-AC). It was found that the three adsorbents are capable of effectively removing sulfur compounds at different feed sulfur concentrations. The effects of height to diameter aspect ratio of the adsorption column, flow rate of LPG and input sulfur concentrations have been studied. A first order kinetics model has been used to describe the adsorption, and the kinetics constant was found to increase by increasing the flow rate of LPG and decrease by increasing the amount of adsorbent used. The developed model described the system fairly well, and can be used in designing and scaling-up of fixed-bed adsorption columns.

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Understanding of the activity difference between nanogold and bulk gold by relativistic effects

Keju Sun, Masanori Kohyama, Shingo Tanaka, Seiji Takeda

2015, 21(4): 485-489.

摘要 ( 2 )

It is a challenge to thoroughly understand the astonishing difference in catalytic activity between nanogold and bulk gold for some oxidation reactions. In this work, the Au-O interactions in various surroundings were investigated by DFT calculations and compared with the Ag-O interactions. We have found the three points. First, only Au-O bond can be significantly strengthened by the linear O-Au-O structure. Second, the Au-O bond is always stronger than the Ag-O bond when the bonds are embedded in common surroundings. Third, the Au-O bond becomes weaker than the Ag-O bond when the number of neighboring Au atoms becomes large, because the Au-O interactions are suppressed by the presence of neighboring gold atoms. The origin of these three points can be attributed to wider spatial extension of d orbitals of gold, induced by strong relativistic effects. The strong relativistic effects make nanogold with smaller coordinate numbers highly active due to the ease in forming strong Au-O bonds, especially for the O-Au-O bond, whereas gold atoms in bulk with larger coordination numbers chemically inert due to the strong suppression by neighboring gold atoms destabilizing the O-Au-O bond.

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Understanding of the activity difference between nanogold and bulk gold by relativistic effects

Keju Sun, Masanori Kohyama, Shingo Tanaka, Seiji Takeda

2015, 24(4): 485-489. DOI: 10.1016/j.jechem.2015.06.006

摘要 ( 5355 )

It is a challenge to thoroughly understand the astonishing difference in catalytic activity between nanogold and bulk gold for some oxidation reactions. In this work, the Au-O interactions in various surroundings were investigated by DFT calculations and compared with the Ag-O interactions. We have found the three points. First, only Au-O bond can be significantly strengthened by the linear O-Au-O structure. Second, the Au-O bond is always stronger than the Ag-O bond when the bonds are embedded in common surroundings. Third, the Au-O bond becomes weaker than the Ag-O bond when the number of neighboring Au atoms becomes large, because the Au-O interactions are suppressed by the presence of neighboring gold atoms. The origin of these three points can be attributed to wider spatial extension of d orbitals of gold, induced by strong relativistic effects. The strong relativistic effects make nanogold with smaller coordinate numbers highly active due to the ease in forming strong Au-O bonds, especially for the O-Au-O bond, whereas gold atoms in bulk with larger coordination numbers chemically inert due to the strong suppression by neighboring gold atoms destabilizing the O-Au-O bond.

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Production of gasoline range hydrocarbons from methanol on hierarchical ZSM-5 and Zn/ZSM-5 catalyst prepared with soft second template

Xiaodong Wang, Xiaoxia Gao, Mei Dong, Hongbin Zhao, Wei Huang

2015, 21(4): 490-496.

摘要 ( 1 )

Nano hierarchical mesoporous ZSM-5 catalystswere prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer (PDDA) as a soft second template. Using ZSM-5 catalyst as a matrix, Zn/ZSM-5 catalysts were also obtained by the wet impregnation method. The effect of the PDDA amount and Zn loadings on the properties of the catalysts, including crystallinity, morphology, textural properties, acid nature and catalytic activity in MTG reaction, was investigated by XRD, FESEM, TEM, Nitrogen adsorption-desorption isotherms and NH₃-TPD method, respectively. The MTG reaction was performed in a fixed bed reactor, and the result revealed that the nano hierarchical ZSM-5 catalyst prepared with a PDDA/Si molar ratio of 0.070 possesses longer stable phase of 70 h with a liquid hydrocarbon selectivity of 29.8%. Zn/ZSM-5 catalyst with a Zn/ZSM-5 ratio of 0.07 wt.% shows the highest liquid hydrocarbon selectivity, reaching 62.5%.

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Production of gasoline range hydrocarbons from methanol on hierarchical ZSM-5 and Zn/ZSM-5 catalyst prepared with soft second template

Xiaodong Wang, Xiaoxia Gao, Mei Dong, Hongbin Zhao, Wei Huang

2015, 24(4): 490-496. DOI: 10.1016/j.jechem.2015.06.009

摘要 ( 4807 )

Nano hierarchical mesoporous ZSM-5 catalystswere prepared with cationic dimethyldiallyl ammonium chloride acrylamide copolymer (PDDA) as a soft second template. Using ZSM-5 catalyst as a matrix, Zn/ZSM-5 catalysts were also obtained by the wet impregnation method. The effect of the PDDA amount and Zn loadings on the properties of the catalysts, including crystallinity, morphology, textural properties, acid nature and catalytic activity in MTG reaction, was investigated by XRD, FESEM, TEM, Nitrogen adsorption-desorption isotherms and NH₃-TPD method, respectively. The MTG reaction was performed in a fixed bed reactor, and the result revealed that the nano hierarchical ZSM-5 catalyst prepared with a PDDA/Si molar ratio of 0.070 possesses longer stable phase of 70 h with a liquid hydrocarbon selectivity of 29.8%. Zn/ZSM-5 catalyst with a Zn/ZSM-5 ratio of 0.07 wt.% shows the highest liquid hydrocarbon selectivity, reaching 62.5%.

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SnO₂/corncob-derived activated carbon nanohybrid as an anode material for lithium-ion batteries

Xiangyang Zhou, Zhen Geng, Cunman Zhang, Jue Wang, Dabin Wang

2015, 21(4): 529-533.

摘要 ( 1 )

A facile synthesis of SnO₂/corncob-derived activated carbon (CAC) composite was proposed, and the CAC used here has high specific surface area (over 3000 m₂/g) and ample oxygen-containing functional groups. The microstructures and morphology as well as electrochemical performance of the SnO₂/CAC composites were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and relevant electrochemical characterization. The results show that the mass ratios of SnO₂ to CAC have a significant effect on the structures and properties of the composites. The sample with 34% SnO₂ delivered a capacity of 879.8 mAh/g in the first reversible cycle and maintained at 634.0 mAh/g (72.1% retention of the initial reversible capacity) after 100 cycles at a current density of 200 mA/g. After 60 cycles at different specific currents from 200 to 2000 mA/g, the reversible specific capacity was still maintained at 632.8 mAh/g at a current density of 200 mA/g. These results indicate that SnO₂/CAC can be a desirable alternative anode material for lithium ion batteries.

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Plastic supported platinum modified nickel electrode and its high electrocatalytic activity for sodium borohydride electrooxidation

Bin Wang, Dongming Zhang, Ke Ye, Kui Cheng, Dianxue Cao, Guiling Wang, Xiaoli Cheng

2015, 24(4): 497-502. DOI: 10.1016/j.jechem.2015.06.002

摘要 ( 4878 )

A novel plastic/multi-walled carbon nanotube (MWNTs)-nickel (Ni)-platinum (Pt) electrode (PMNP) is prepared by chemical-reducing Pt onto the surface of Ni film covered plastic/MWNTs (PM) substrate. TheMWNTs are adhered by a piece of commercial double faced adhesive tape on the surface of plastic paper and the Ni film is prepared by a simple electrodeposition method. The morphology and phase structure of the PMNP electrode are characterized by scanning electron microscopy, transmission electron microscope and X-ray diffractometer. The catalytic activity of the PMNP electrode for NaBH₄ electrooxidation is investigated by means of cyclic voltammetry and chronoamperometry. The catalyst combines tightly with the plastic paper and exhibits a good stability. MWNTs serve as both conductive material and hydrogen storage material and the Ni film and Pt are employed as electrochemical catalysts. The PMNP electrode exhibits a high electrocatalytic performance and the oxidation current density reaches to 10.76 A/(mg cm^-2) in 0.1mol/dm³ NaBH₄ at 0 V,which is much higher than those in the previous reports. The using ofwaste plastic reduces the discarding of white pollution and consumption of metal resources.

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Reactive adsorption desulfurization coupling aromatization on Ni/ZnO-Zn₆Al₂O₉ prepared by Zn_xAl_y(OH)₂(CO₃)_z·xH₂O precursor for FCC gasoline

Tinghai Wang, Xueli Wang, Yuan Gao, Yi Su, Zhichao Miao, Chenchen Wang, Longgang Lu, Lingjun Chou, Xionghou Gao

2015, 24(4): 503-511. DOI: 10.1016/j.jechem.2015.07.002

摘要 ( 5035 )

Aiming to improve the reactive adsorption desulfurization (RADS) performances of Ni/ZnO adsorbents, Zn_xAl_y(OH)₂(CO₃)_z·xH₂O precursor is synthesized by coprecipitation of Zn²⁺, AlO₂^-, and CO₃^2-; the ZnOZn₆Al₂O₉ composite oxides are obtained by the calcination of Zn_xAl_y(OH)₂(CO₃)_z·xH₂O precursor, and the Ni/ZnO-Zn₆Al₂O₉ (6.0 wt% NiO) adsorbents are prepared by wetness impregnation method. The phase, acid strength, acid type and quantity, morphology, and thermal propertieswere characterized by X-ray diffraction, temperature-programmed desorption of ammonia, pyridine-adsorbed infrared spectrum, high-resolution transmission electron microscopy, and Thermo Gravimetry-Derivative Thermo Gravimetry (TG-DTG), respectively. The breakthrough sulfur capacities of six adsorbents are between 34.2 and 47.9 mg/g_cat. The kinetic studies indicated that the active energy of RADS (49.4 kJ/mol) could reach nano-sized ZnO, the particle size of is about 12.0 nm. All the excellent RADS performances can be due to the high S_BET. Also, there are some extents of aromatization reactions that occur, which can be contributed to the Bönsted acid rooted in Zn₆Al₂O₉ composite oxide, and the octane number of products can be preserved well.

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Nanoscale pore morphology and distribution of lacustrine shale reservoirs: Examples from the Upper Triassic Yanchang Formation, Ordos Basin

Yang Wang, Yanming Zhu, Hongyan Wang, Guangjun Feng

2015, 24(4): 512-519. DOI: 10.1016/j.jechem.2015.06.004

摘要 ( 5209 )

Pore structure plays an important role in the gas storage and flow capacity of shale gas reservoirs. Fieldemission environmental scanning electron microscopy (FE-SEM) in combination with low-pressure carbon dioxide gas adsorption (CO₂GA), nitrogen gas adsorption (N₂GA), and high-pressure mercury intrusion (HPMI) were used to study the nanostructure pore morphology and pore-size distributions (PSDs) of lacustrine shale from the Upper Triassic Yanchang Formation, Ordos Basin. Results show that the pores in the shale reservoirs are generally nanoscale and can be classified into four types: organic, interparticle, intraparticle, and microfracture. The interparticle pores between clay particles and organic-matter pores develop most often, l with pore sizes that vary from several to more than 100 nm. Mercury porosimetry analysis shows total porosities ranging between 1.93 and 7.68%, with a mean value of 5.27%. The BET surface areas as determined by N₂ adsorption in the nine samples range from 10 to 20 m₂/g and the CO₂ equivalent surface areas (< 2 nm) vary from 18 to 71 m₂/g. Together, the HPMI, N₂GA, and CO₂GA curves indicate that the pore volumes are mainly due to pores < 100 nm in size. In contrast, however, most of the specific surface areas are provided by the micropores. The total organic carbon (TOC) and clay minerals are the primary controls of the structures of nanoscale pores (especially micropores and mesopores). Micropores are predominantly determined by the content of the TOC, and mesopores are possibly related to the content of clay minerals, particularly the illite-montmorillonite mixed-layer content.

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Effect of support modification on the characterization and catalytic activity of Mo/Al₂O₃ catalysts

M. Riad, S. Mikhail

2015, 24(4): 520-528. DOI: 10.1016/j.jechem.2015.06.003

摘要 ( 4928 )

Molybdenum catalysts (15 wt% MoO₃ loading) supported on alumina, alumina-magnesia, and alumina-chromia were prepared via impregnation technique and studied for the reaction of methyl-cyclohexane dehydrogenation. The catalystswere evaluated bymeans of FT-IR, XRD, DSC, TPR, and N₂ adsorption-desorption isotherms. The results clarified that Mo/alumina-magnesia catalyst possesses small crystallite size and high surface area (240 m₂/g) and is selective toward the formation of dehydrogenated product (96.5%). The yield to ring-opening products is higher on Mo/alumina-chromia catalyst due to its higher acidity and larger metal crystals, which favor the ring-opening reaction and lowermetallic activitywith selectivity toward ringopening products (32%).

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SnO₂/corncob-derived activated carbon nanohybrid as an anode material for lithium-ion batteries

Xiangyang Zhou, Zhen Geng, Cunman Zhang, Jue Wang, Dabin Wang

2015, 24(4): 529-533. DOI: 10.1016/j.jechem.2015.07.008

摘要 ( 5000 )

A facile synthesis of SnO₂/corncob-derived activated carbon (CAC) composite was proposed, and the CAC used here has high specific surface area (over 3000 m₂/g) and ample oxygen-containing functional groups. The microstructures and morphology as well as electrochemical performance of the SnO₂/CAC composites were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and relevant electrochemical characterization. The results show that the mass ratios of SnO₂ to CAC have a significant effect on the structures and properties of the composites. The sample with 34% SnO₂ delivered a capacity of 879.8 mAh/g in the first reversible cycle and maintained at 634.0 mAh/g (72.1% retention of the initial reversible capacity) after 100 cycles at a current density of 200 mA/g. After 60 cycles at different specific currents from 200 to 2000 mA/g, the reversible specific capacity was still maintained at 632.8 mAh/g at a current density of 200 mA/g. These results indicate that SnO₂/CAC can be a desirable alternative anode material for lithium ion batteries.

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