Reaction Kinetics Mechanisms and Catalysis
·
2023
·Vol. 136
·期 2
·771-786
·
IF 1.8
Su Haitang,Yang Zhixiu,Xiao Guomin,Gao Lijing,Wei Ruiping,Zhang Jin
A series of cost-effective (X) K 2 CO 3 /γAl 2 O 3 catalysts for efficient conversion of vinyltrimethoxysilane (VTMOS) to vinyltris(β-methoxyethoxy)silane (VTMOEOS) were synthesized. The microstructure and active site of the synthesized catalysts were analyzed by BET, XRD, FT-IR, SEM, and CO 2 -TPD. The results showed that the synthesized catalysts formed K–O–Al strong basic sites while maintaining the original structure, which greatly improved the basic strength of the catalysts. It was found that the 60%K 2 CO 3 /γAl 2 O 3 possessed the highest the catalytic activity under the activation temperature of 600 °C by optimizing the preparation conditions of K 2 CO 3 /γAl 2 O 3 . Moreover, the optimal reaction process conditions were also determined by optimizing the experimental reaction temperature, reaction time, catalyst dosage, and reactant molar ratio under (60%, 600 °C) K 2 CO 3 /γAl 2 O 3 catalysis. Under the optimal reaction conditions, the conversion of VTMOS was 92.5% and the yield of VTMOEOS was 65%. Meanwhile, the 60%K 2 CO 3 /γAl 2 O 3 catalyst was satisfactorily reusable and maintained a high catalytic activity after four cycles of catalytic reactions.
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高影响因子
ChemCatChem
·
2018
·Vol. 10
·期 24
·5637-5648
·
IF 4.674
Zhiquan Hou,Yuxi Liu,Jiguang Deng,Yue Lu,Shaohua Xie,Xiuzhong Fang,Hongxing Dai
Graphical Effective synergy : The Pd−GaO x /Al 2 O 3 catalysts are prepared via the oxidative transformation of intermetallic Pd 5 Ga 3 nanocrystals supported on Al 2 O 3 . A synergistic effect between palladium and gallium oxide via formation of a bi-functional active Pd−O−Ga phase is observed, resulting in a highly active and exceptionally stable catalyst that can markedly suppress the sintering of noble metals under harsh conditions. Surface oxygen vacancies and the surface Pd−O−Ga phase are the catalytically active sites. Catalytic combustion of methane is widely used in industrial and transportation activities. The commonly used Pd-based catalysts, however, are easily deactivated under hydrothermal conditions. In this work, we adopted a novel strategy to prepare a GaO x -doped Pd/Al 2 O 3 catalyst via the oxidative transformation of intermetallic Pd 5 Ga 3 nanocrystals supported on γ -Al 2 O 3 . We observed a synergistic effect between palladium and gallium oxide via formation of a bi-functional active Pd−O−Ga phase, resulting in a highly active and exceptionally stable catalyst that could markedly suppress the sintering of noble metals under harsh conditions (hydrothermal treatment at 750 °C). Moreover, the presence of a large amount of surface oxygen vacancies and the surface Pd−O−Ga phase could promote methane combustion over the catalysts. It is believed that such a novel dual-metal catalyst is promising in practical applications for methane combustion.
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高影响因子
GREEN CHEMISTRY
·
2019
·Vol. 21
·期 3
·606-613
·
IF 9.405
Zhenbing Xie,Bingfeng Chen,Haoran Wu,Mingyang Liu,Huizhen Liu,Jianling Zhang,Guanying Yang,Buxing Han
Transformation of biomass or biomass-based feedstocks into fuels or valuable chemicals is of great importance for the sustainable development of our society. Mesoporous Al2O3–ZrO2 with different Al : Zr molar ratios was prepared by the sol–gel method, and Cu–Ni/Al2O3–ZrO2 catalysts were fabricated by the impregnation method. The catalytic performances of the bifunctional catalysts were studied in the selective hydrogenation of levulinic acid (LA) into 2-methyltetrahydrofuran (MTHF). It was demonstrated that both Cu : Ni and Al : Zr ratios affected the selectivity to MTHF significantly. The bimetallic catalysts Cu–Ni/Al2O3–ZrO2 containing 10 wt% Ni and 10 wt% Cu gave 99.8% MTHF selectivity at full conversion of LA when the Al : Zr ratio was 9 : 1. The outstanding catalytic performance of the catalyst is related to the mesoporous structure, the acidic properties of the support and the synergistic effect between Cu and Ni. The catalyst could be reused five times without a considerable loss of catalytic activity and selectivity.
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Catalysis Science & Technology
·
2019
·Vol. 9
·期 9
·2282-2290
·
IF 5.726
Dawei Zhou,Peixue Wang,Yan Long,Yuqing Fei,Youquan Deng
The thermal cracking behavior of diethyl hexamethylenedicarbamate (EHDC) was investigated in this work. The polymers formed under different conditions were analyzed by IR and TG, indicating that the polymers were mixtures of EHDC, polyureas, imines and others. The polymers could be converted to EHDC by a simple alcoholysis reaction for the first time over Fe–Ni/Al2O3 catalysts. Under the optimized reaction conditions, the yield of EHDC could reach up to 52% with 99% selectivity over 8% Fe–3% Ni/Al2O3 catalysts. The catalysts were extensively characterized by BET, XPS, XRD, SEM, TEM, H2-TPR and NH3-TPD, showing that the interaction effect between Fe species and Ni species may be attributed to high catalytic performance of the catalyst. Meanwhile, the loss of active components resulted in decreased catalytic activity.
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高影响因子
Catalysis Science & Technology
·
2018
·Vol. 8
·期 6
·1621-1631
·
IF 5.365
Yuxi Gao,Xiaodong Wu,Robin Nord,Hanna Härelind,Duan Weng
The sulphur resistance and regeneration strategy of soot oxidation catalysts are critical to the application of catalytic diesel particulate filters (CDPFs). In the present work, Pt/MnOx–CeO2/Al2O3, Pt/Al2O3 and MnOx–CeO2/Al2O3 catalysts were sulphated and regenerated with ammonia. The soot oxidation activity of poisoned Pt/MnOx–CeO2/Al2O3 was recovered completely after 30 min reduction in 500 ppm NH3 at 550 °C. The amount, distribution and structure of sulphates were studied comprehensively for the sulphated and regenerated samples by thermogravimetric analysis (TGA), infrared (IR) spectroscopy, CO chemisorption and transmission electron microscopy (TEM). The NO oxidation of Pt catalysts was found to depend strongly on the particle size distribution, surface exposure and oxidation state of the precious metal. This, as well as the effect of the remaining surface sulphates, helped the regenerated catalysts achieve even higher catalytic activity for soot oxidation.
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高影响因子
FUEL
·
2018
·
IF 4.908
Haifeng Li,Sheng Su,Song Hu,Kai Xu,Long Jiang,Yi Wang,Jun Xu,Jun Xiang
A series of Mn x O y /Al 2 O 3 sorbents with different tissue and chemical structures were prepared by repeated incipient wet impregnation method with different calcination conditions, including calcination temperature from 500 °C to 900 °C and calcination time from 3 h to 9 h. The H 2 S absorption performances of the prepared sorbents were investigated by a model synthesis gas containing 2000 mg/m 3 H 2 S at 850 °C. The chemical and physical structures of the samples were characterized by Brunauer–Emmett–Teller, X-ray diffraction and scanning electron microscopy techniques to obtain fundamental information about the deactivation of Mn x O y /Al 2 O 3 sorbents during desulfurization–regeneration cycles. Results showed that the structural features of the sorbents at high reaction temperature played an important role in the stability of desulfurization performance. The analysis of the characteristics of the sorbents indicated that the sorbents obtained stabilized chemical and physical structures during desulfurization–regeneration cycles when the calcination temperature was 900 °C and the calcination time was above 6 h. The sorbent suffered serious deactivation during five successive desulfurization–regeneration cycles when the calcination temperature of sorbents was below 850 °C. The sulfur capacity decreasing of Mn x O y /Al 2 O 3 sorbents may probably be attributed to a part of Mn x O y covered by Al 2 O 3 , which can un-sulfide during adsorption process. The coverage of active phase Mn x O y may be caused by the shrinking and disappearing of some micropores, and phase transformation of Al 2 O 3 , as well as the transformation of MnAl 2 O 4 lead to a part of Mn x O y on the sorbents being covered by alumina.
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Reaction Kinetics Mechanisms and Catalysis
·
2018
·Vol. 125
·期 1
·199-211
·
IF 1.515
Hao Fang,Yang Yongzhe,Xiong Wei,Liu Pingle,You Kuiyi,Luo He’an
Mesoporous SiO 2 –Al 2 O 3 supported Cr 2 O 3 catalysts were prepared by the sol–gel and impregnation methods. These catalysts were characterized and applied in cyclohexane nitrosation reaction. The effects of the preparation conditions and the catalyst deactivation were studied. The results show that 20% Cr 2 O 3 /SiO 2 –Al 2 O 3 catalyst calcined at 400 °C exhibits not only the larger surface area, smaller particle size, but also the larger amount of Cr 2+ and Brønsted acid sites. These catalysts show good catalytic performances in the cyclohexane nitrosation to ε-caprolactam and could be recycled for several times in this reaction system for the first time. The catalyst of Cr 2 O 3 /SiO 2 –Al 2 O 3 calcined at 400 °C gives 10.8% conversion with 79.9% selectivity to ε-caprolactam.
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高影响因子
RSC Advances
·
2018
·Vol. 8
·期 61
·35014-35022
·
IF 2.936
Menglu Song,Xiangui Yang,Gongying Wang
γ-Al2O3 loaded with potassium nitrate (KNO3/Al2O3) catalysts were prepared, characterized and employed as a type of heterogenous solid base catalyst in the synthesis of polycarbonate (1,4-butane carbonate)-diol (PBC–OH) via the transesterification of dimethyl carbonate (DMC) and 1,4-butanediol (BD). The relationship between physicochemical properties and catalytic performance for KNO3/Al2O3 in this transesterification reaction was investigated using various techniques. The results demonstrated that the performance of KNO3/Al2O3 catalysts was highly influenced by basic site amount and strength. The medium and strong basic sites were beneficial for this reaction. The catalyst with a KNO3 loading of 35% and a calcination temperature of 700 °C exhibited the best catalytic activity due to its highest basic site amount and appropriate base strength. The highest BD conversion and PBC–OH yield of 80.2% and 68.4% were obtained under optimal reaction conditions. Also, this solid base catalyst was successfully employed in the synthesis of copolycarbonate diols from DMC and two different diols. Different scanning calorimetry results indicated that the thermal properties of the copolycarbonate diols can be adjusted by regulating the average segment lengths, Mn and copolymer composition structure.
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PubMed
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2018
·Vol. 102
·期 3
·1362-1372
·
IF 2.956
Shunjie Deng,Chi Jiang,Tianwei Liu,Yin Hu,Jingjing Ding,Maobing Shuai
Al 2 O 3 -Y 2 O 3 -SiC composite coatings were prepared on depleted uranium by cathode plasma electrolytic deposition in Al(NO 3 ) 3 , Y(NO 3 ) 3 , SiC nanoparticles and anhydrous ethyl alcohol mixture. The resulting coating consisted of an inner barrier layer and an outer porous layer. The SiC nanoparticles were incorporated into the composite coating and decreased the coating porosity by filling the pores. The potentiodynamic polarization test and neutral salt spray test revealed that the corrosion resistance of depleted uranium was enhanced by the composite coating. Moreover, with increasing the content of SiC nanoparticles in the coating, the coating corrosion resistance was improved gradually.
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高影响因子
RSC Advances
·
2018
·Vol. 8
·期 32
·18059-18066
·
IF 2.936
Kaihong Xie,Yanxiong Fang,Baoyu Liu,Chengchao Li
Novel composites made from monodispersed porous Al-glycolate spheres (NiMo/Al-SP) were synthesized through alcoholysis or hydrolysis treatments. The obtained samples were characterized by a complementary combination of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2 physisorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), hydrogen temperature-programmed reduction (H2-TPR), and pyridine Fourier transform infrared spectroscopy (Py FT-IR). In addition, the catalytic performances of the resultant catalysts were evaluated in the simultaneous HDS of dibenzothiophene (DBT) and HYD of naphthalene (DBT and naphthalene represent the sulfur-containing compounds and polycyoalkanes, respectively). The experimental results showed that, 71.22% DBT and 88.28% naphthalene were converted by NiMo/Al-SP(H) under the conditions of 270 °C temperature, 5 MPa H2 (initial pressure at room temperature) and 10 h reaction time. The design and preparation of NiMo/Al-SP provide an effective and novel pathway for the development of high-performance catalysts and production processes.
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高影响因子
APPLIED ORGANOMETALLIC CHEMISTRY
·
2019
·Vol. 33
·期 11
·e5208
·
IF 3.259
Baowei Wang,Chengyu Wang,Wenxian Yu
Mo 2 C/Al 2 O 3 catalyst was prepared by the impregnation method with urotropine and ammonium paramolybdate. The catalytic effect of Mo 2 C as a typical transition-metal carbide in sulfur-resistant methanation was studied. The catalysts prepared were characterized by N 2 adsorption–desorption, X-ray diffraction, transmission electron microscopy, H 2 -temperature-programmed reduction, and Raman spectra, with the results confirming the formation of β-molybdenum carbide on the surface of the catalysts. Studies on catalysts with different loading doses indicate that the optimal loading of Mo 2 C/Al 2 O 3 is about 15 wt.%, which enables CO conversion rate of up to 47%, with methane selectivity of up to 53%. This work further explored the effect of different concentrations of H 2 S in the raw gas on the performance of the catalyst, with the results showing that high concentration of H 2 S (>1500 ppm) can lead to sulfuration of active species on the catalyst, while resulting in a decrease in the catalytic activity.
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NEW JOURNAL OF CHEMISTRY
·
2017
·Vol. 41
·期 21
·13036-13042
·
IF 3.269
Fenfen Lu,Yan Xu,Xia Jiang,Yang Liu,Jiale Huang,Daohua Sun
Low temperature 1,3-butadiene hydrogenation over biosynthesized Pd/γ-Al2O3 catalysts annealed under different atmospheres (H2 and air) was compared in a fixed bed reactor, and the catalysts were prepared using a facile sol-immobilization method. The structural properties of the Pd/γ-Al2O3 catalysts in relation to their activities in 1,3-butadiene hydrogenation were investigated by X-ray photoelectron spectroscopy, X-ray diffraction, hydrogen temperature-programmed reduction, thermogravimetry, transmission electron microscopy, CO chemisorption measurement techniques and Fourier transform infrared spectroscopy. The results of characterization revealed that the calcination atmosphere (H2 and air) exhibited a remarkable impact on the chemical state of Pd species and catalytic activity, and the coexistence of the metallic state and oxidation state of Pd was a key factor for higher catalytic activity and butene selectivity, while the catalyst with the existence of the metallic state only (H2–Pd/γ-Al2O3) showed lower butene selectivity, and the catalyst with the oxidation state alone (air–Pd/γ-Al2O3) hardly showed any activity in 1,3-butadiene hydrogenation. Therefore, the chemical state of Pd played an important role in the 1,3-butadiene hydrogenation reaction.
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