RSC Advances
·
2019
·Vol. 9
·期 23
·13234-13242
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IF 3.049
Peidong Li,Qiao Han,Xiaomin Zhang,Yangyang Yuan,Yanfei Zhang,Li Xu,Hongchen Guo,Lei Xu
The effect of the introduced base sites in CsX with alkali oxide modification towards side-chain alkylation of toluene with methanol was systematically investigated in the present work. A series of alkali oxide modified CsX with a base properties (base strength and amount) gradient were prepared by impregnating CsX with alkali metal hydroxide. Here, CsX with different base strengths were selected as the parent zeolite, which is favorable to clarify the different types of base site in the modified CsX. The base properties of the samples were elucidated based on the CO2-TPD results as well as with characterization by XPS and FT-IR of adsorbed CO2. It was revealed that the base strength of the oxygen atoms with negative charge (Oδ−) in the zeolite framework can be strengthened by the electron donating function of the alkali oxides in the supercage of CsX. Detailed analysis of the correlation between the reaction behaviors of side-chain alkylation reaction and the base properties of the indicated catalysts was carried out. It was found that the dehydrogenation of methanol to formaldehyde step was promoted by the increasing base properties of Oδ− in the CsX framework and that was the main reason for the promotion of the whole side-chain alkylation reaction. However, it was also found that the stronger base properties of the alkali oxide modified CsX would enhance the formation of active hydrogen atoms, which aggravated the unwanted styrene conversion to ethylbenzene.
研究领域:
催化
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化学工程
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材料科学
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产品关联
DOI
PubMed
高影响因子
Molecular Catalysis
·
2024
·
IF 3.9
Jia Ding,Jinghui Qin,Shengyu Zhou,Yuanhao Wu,Chao Fan,Yulong Li,Jianguo Wang
LaBO 3 ( B = Fe, Co, Ni) perovskite catalysts were prepared by the sol-gel method. The physical properties and active sites were characterized by XRD, BET, SEM, TEM, XPS, EPR, and CO 2 -TPD. The results indicated that catalysts had fine perovskite structure and high crystallinity. The as-synthesized catalysts were used for the glycerol carbonylation with CO 2 to glycerol carbonate (GC). The LaCoO 3 exhibited high conversion and selectivity of 26.3 and 72.4 % at a reaction temperature of 150 °C for 12 h under CO 2 pressure of 3 MPa in the presence of 2-cyanopyridine with DMF as the solvent. It was found that surface oxygen defects favored the glycerol conversion, while the high concentration of total weak and medium basic sites promoted the GC selectivity. The LaCoO 3 also displayed excellent reusability performance, indicating its great potential in industrial applications.
研究领域:
化学
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催化
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材料科学
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绿色化学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2017
·
IF 3.582
Yinghui Sun,Guojie Zhang,Jiwei Liu,Peiyu Zhao,Peng Hou,Ying Xu,Riguang Zhang
CH 4 CO 2 reforming to syngas was investigated over three different activated carbon catalysts. To better understand the influence of the supports on the catalytic properties , catalysts were analyzed by some characterization methods, such as nitrogen adsorption–desorption isotherms, XRD , H 2 -TPR, NH 3 -TPD, CO 2 -TPD, FTIR, TEM and EDX . The results showed that the catalyst with AC 2 as the support provided the best catalytic activity . The CH 4 conversion and CO 2 conversion were 92% and 98% at 900 °C, respectively; best selectivity with the H 2 /CO ratio was close to 1 among the three supports used. It also showed a better stability at 900 °C. H 2 -TPR analysis showed that Co species in Co/AC 2 catalyst were strong interaction with the support. It was observed that active metals were well dispersed on the AC 2 support by the TEM. In addition, the ratio of CH 4 /CO 2 also had great influence on the CH 4 and CO 2 conversion.
研究领域:
催化
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化学工程
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材料科学
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产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2021
·
IF 5.816
Xiaodi Zhang,Guojie Zhang,Xiaowei Qin,Jun Liu,Guoqiang Li,Ying Xu,Yongkang Lv
A series of nitrogen doped biomass carbon catalysts were prepared through two different nitrogen doped methods by using soybean meal as the raw material, melamine as nitrogen source and KOH as the activators. The catalysts were characterized by BET, SEM , CO 2 -TPD, EA , FTIR , XPS and Raman. The catalytic performances of CH 4 –CO 2 reforming over different samples were also studied. The results show that the preparation method of the catalyst significantly affects the structural characteristics, N content and N species type of the catalyst. The characterization results also show the proportion of pyrrolic-N in the catalyst prepared by in-situ nitrogen doped method (Y-NC) is higher than that in prepared by the post-treatment method (H-NC). Pyrrole-N is more conducive to the adsorption and activation of CO 2 . So, the catalyst prepared by in-situ nitrogen doped method has good catalytic activity and stability. The conversion of CH 4 and CO 2 were respectively 40% and 65% at 900 °C after 50 h of CH 4 –CO 2 reforming reaction .
研究领域:
催化
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材料科学
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环境科学
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化学工程
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产品关联
DOI
高影响因子
RESEARCH ON CHEMICAL INTERMEDIATES
·
2022
·Vol. 48
·期 6
·2557-2573
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IF 3.134
Liu Yueyu,Yin Zhili,Wang Ziqing,Mou Ronglin,Wei Zhong
High surface area ZrO 2 –KOH sample was prepared and used the catalyst for the synthesis of glycerol carbonate (GC) from dimethyl carbonate (DMC) and glycerol. The structure properties of ZrO 2 –KOH were characterized by XRD, BET, CO 2 -TPD, XPS, and ICP-OES. It was found that the strong basicity of ZrO 2 –KOH might be attributed to the oxygen vacancies as well as the big surface area. Experiments were developed to evaluate the effects of catalysis loading, proportion of reactants, temperature and reaction time on the conversion of glycerol to GC. The consequences showed that ZrO 2 –KOH was a highly efficient basic catalyst for synthesis of GC from glycerol. The catalytic performance of ZrO 2 –KOH is much better than that of ZrO 2 –KOH–CP, ZrO 2 –NH 4 OH, and some reported heterogeneous catalysts. And the higher performance of ZrO 2 –KOH was ascribed to the strong basicity. 99.43% conversion was obtained in a particular situation of catalyst/glycerol weight ratio of 3 wt%, DMC/glycerol molar ratio of 3:1, reaction temperature of 80 °C, and reaction time of 2 h. The plausible reaction mechanism for the transesterification on the strong basic active sites was discussed.
研究领域:
催化
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化学工程
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材料科学
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DOI
高影响因子
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
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2019
·
IF 3.47
Zhi Zheng,Jun Wang,Yi Wei,Xuejun Liu,Fengwen Yu,Jianbing Ji
La-Fe modified Si-MCM-41 (La-Fe/Si-MCM-41) catalysts were prepared by the wet impregnation method and used in catalytic cracking of soybean oil (CCS) for biofuel production. The catalysts were characterized by BET, XRD, XPS, Py-FTIR and CO 2 -TPD. The results showed that the aromatics content increased with the increase in B/L value, while the content of oxygenated compounds decreased, indicating that Brönsted acid sites were the major active sites for deoxygenation and aromatization reactions. Compared with Si-MCM-41, the Brönsted acidity of LFM-6 sharply decreased from 22.49 to 5.86 μmol g −1 . Accordingly, the aromatics content was reduced from 37.51 wt.% to 14.52 wt.% which was lower than the limitation (15 wt.%) according to the global environmental legislation. However, for the LFM-6 catalyst, the excessive loss of Brönsted acid sites and sharp decrease in BET surface area and pore volume led to the decrease in deoxygenation. As a result, the fatty acids content increased from 2.71 wt.% to 16.67 wt.% and the acid value reached 35.20 mgKOH g −1 . When the La-Fe loading increased to 15 wt.%, part of fatty acids were converted into ketones by the active sites on Fe 2 O 3 /La 2 O 3 and strong Lewis acid sites on catalysts. Besides, the new weak Lewis acid and basic sites on Fe 2 O 3 /La 2 O 3 exhibited the synergistic effect on promoting the generation of alkenes. The CaO/LFM-6 composite catalysts prepared by the mechanical mixing of LFM-6 and CaO were used in CCS to reduce the acid value of biofuel. LFM-6-C-3 was proved to be an effective catalyst for CCS to produce biofuel with low aromatics (12.31 wt.%) and fatty acids (2.76 wt.%) content.
研究领域:
催化
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生物燃料
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化学工程
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环境科学
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产品关联
DOI
高影响因子
Journal of Inorganic and Organometallic Polymers and Materials
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2019
·Vol. 29
·期 6
·2003-2011
·
IF 1.637
Hua Rui,Li He,Liu Xiao-Qin,Liu Ding-Hua
With an increasing demand for green chemistry and sustainable development, it is needed to design a solid base with high catalytic activity, excellent stability and reusability. In this work, a new kind of magnetic solid basic catalyst KF/CaO–CoFe 2 O 4 was prepared by the method including co-precipitation and isochoric impregnation, and it was successfully applied in the preparation of polycarbonate diol (PCDL) from the transesterification of 1,4-butanediol with dimethyl carbonate. The characteristics and properties of the catalyst were examined and analyzed by XRD, TEM, CO 2 -TPD and VSM. The effects of various parameters such as shell-core mole ratio, KF loading, calcination temperature, catalyst dosage, and the mole ratio of the raw materials on the yield of PCDL were investigated and the yield of PCDL can reach to 71.2% under the optimal reaction conditions. In addition, the catalyst can be easily separated by an external magnet after reaction, and the catalytic activity of the catalyst can well be maintained for 4 cycles.
研究领域:
化学工程
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材料科学
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催化
·
绿色化学
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产品关联
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 4
·2040-2046
·
IF 3.361
Yang Liu,Xin Liang,Jie Zhang,Jimmy Yun,Zuobo Yang
In this study, monodispersed NiRu nanocrystals with a diameter of 3 nm were synthesized at 90 °C via a tuning hot-inject method to lower the temperature of the organic phase synthesis of monodispersed nanomaterials. The key factor for the nanocrystalline formation of NiRu alloy nanocrystals was summarized in detail. Simultaneously, the synergistic effect of Ni and Ru in CO2 methanation was explored. Doping trace Ru can significantly improve the conversion rate of CO2 methanation and CH4 selectivity. The underlying mechanism was studied in detail via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed hydrogen reduction (H2-TPR) and desorption (H2-TPD) tests, and temperature-programmed desorption of CO2 (CO2-TPD). This study gives out a new way for the general synthesis of monodisperse nickel-based nanocrystals and provides a reference for the development and application of monodispersed nanoparticles for CO2 methanation.
研究领域:
材料科学
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催化
·
纳米技术
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化学工程
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产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）