FUEL
·
2020
·
IF 5.578
Huimin Chen,Fengjiao Yi,Caiping Ma,Xiang Gao,Suyao Liu,Zhichao Tao,Baoshan Wu,Hongwei Xiang,Yong Yang,Yong-wang Li
The bifunctional catalysts capable of regulating the metal dispersion and location through encapsulating palladium (Pd) nanoparticles inside Beta and mordenite (MOR) zeolites were used for n-heptane hydroisomerization. Several characterizations such as X-ray powder diffraction (XRD), scanning electron microscope (SEM), N 2 -adsorption and so on suggested that the difference in the phase, textural property, morphology, and acidity of zeolites between the catalysts with encapsulation structure and prepared by impregnation method was negligible whether Beta- or MOR-series catalysts. Nevertheless, the higher Pd dispersion, smaller Pd particle size, and higher aggregation resistance can be achieved on the encapsulation catalysts as determined by H 2 -pulse and transmission electron microscopy (TEM). Compared to the palladium-loading catalyst prepared by conventional impregnation method, the encapsulation structure guaranteed the higher selectivity and yield in n-heptane isomerization due to the significantly improved balance and intimacy. Furthermore, the catalyst with the complete encapsulation structure for the Beta-series catalysts and the catalyst with partial encapsulation structure for the MOR-series catalysts respectively exhibited the highest isomer selectivity and yield. All results may be resulted from that the zeolite topology and crystal size acted a significant role in determining the intimacy of the bifunctional catalysts with encapsulation structure, due to the different diffusion hurdles of the channels structure.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CRYSTENGCOMM
·
2021
·Vol. 23
·期 25
·4549-4559
·
IF 3.545
Zongjian Liu,Zhicong Sun,Lin Zhang,Lifei Xu,Xinyue Lu,Qun Cui,Haiyan Wang
Hierarchical nanocrystal UiO-66 was synthesized by a template-free double solvent-modulated crystallization method. The influences of the ammonium hydroxide (NH4OH)/Zr and acetic acid (HAC)/Zr ratios and pH of reaction solution on the morphological and the porous properties of UiO-66 were investigated. The results show that the nanoscale grains of UiO-66 with the size of ∼20 nm and interparticle mesopores of ∼30 nm are obtained with the NH4OH/Zr of 0.96–3.84, HAC/Zr of 50 and the pH from 1.68 to 2.70. The introduction of NH4OH is favorable to the formation of Zr4+ oxo/hydroxo clusters and deprotonation of the ligands for accelerating the nucleation and crystallization, while HAC can effectively control the hydrolysis of zirconium chloride to avoid the formation of particles with low crystallinity. The equilibrium adsorption capacities of nHEP and MCH on UiO-66(2.88, 50) are higher than that on UiO-66-AS at 323–373 K, respectively. The effective diffusion coefficients of n-heptane/methyl cyclohexane on the hierarchical UiO-66 nanocrystals are about 5 and 18 times higher than that on microporous UiO-66 at 373 K and 0.05–6 kPa, respectively. The introduction of mesopores increases the adsorption performance of the adsorbent for alkanes and enhances mass transfer.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Xiaoyan Li,Yuan Zhuang,Yejian Qian,Xinyan Wang,Rui Zhai
Methanol is widely recognized as a carbon-neutral fuel. This work used synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) to study the oxidation process of water/methanol/n-heptane mixes in a jet-stirred reactor (JSR) at a pressure of 1 atm, equivalence ratios (ϕ) of 1 and a temperature range of 500–1100 K. The results of the experiment indicate that the inhibition of n-heptane's oxidation at low temperatures (500–740K) is the primary manifestation of the action of methanol/water mixtures on n-heptane oxidation. The strong interactions among the components of water/methanol/n-heptane mixtures at low temperatures are primarily between methanol and n-heptane. The higher the methanol content, the greater the strength of inhibition of n-heptane oxidation. This inhibitory effect primarily results from the competition of methanol with ˙OH radicals. It is noteworthy that the chemical kinetic interactions between methanol-water mixtures and n-heptane not only manifest changes in the ˙OH radical pools but are also associated with the intermolecular chemical kinetic interactions between peroxyalkyl radicals (ROO˙) and CH 3 OH.
研究领域:
化学工程
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燃烧科学
·
反应动力学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2019
·
IF 5.128
Li Gao,Zhiyuan Shi,Ubong Jerome Etim,Pingping Wu,Wei Xing,Yi Zhang,Peng Bai,Zifeng Yan
A composite material Beta-SBA-15 (BS) comprising zeolite Beta units and SBA-15-like mesoporous structure was hydrothermally synthesized and served as catalyst support for the hydroisomerization of n-heptane. Materials were characterized by a variety of techniques. Characterization results revealed that Beta-SBA-15 composite has a two-dimensional hexagonal mesoporous channel with a pore size of 6.4 nm and a high concentration of moderate-strength acid sites. Evaluation results showed that Pt/HBS exhibited a relatively high n-heptane conversion (75.57%) with a good selectivity to isoheptanes (90.04%), resulting in the highest isoheptanes yield (68.04%) among all samples. The micro-mesoporous composite structure with moderate surface acidity enhanced diffusion of large isomerized intermediates as well as inhibiting the occurrence of cracking side reactions, achieving a high isoheptanes yield. Experimental data demonstrates that the indexed isomerization factor (IIF) as a performance descriptor can accurately predict the isomerization performance of catalysts.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF RARE EARTHS
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2024
·
IF 5.2
Hao Qin,Hui Wan,Guofeng Guan
Hydroisomerization of n-alkanes plays an important role in fuel and lubricants processing. Bifunctional catalysts with ultralow platinum loading have recently been reported successively for hydroisomerisation. Herein, the catalysts were prepared successfully with different methods to improve the catalytic performance. The conversion of 0.01%Pt1@CeOx/SAPO-11 prepared by co-calcination method (0.01%Pt1@CS-c) is 71.4%, 25% higher than the other prepared by precipitation method. The turnover frequency per active surface platinum site (TOFPt) of 0.01%Pt1@CS-c is as high as 13115 h –1 . Revealed by the X-ray photoelectron spectroscopy (XPS) results, the quality of phase boundary/intersurface between ceria and zeolite is found significantly different. The conjunction quality of phase boundary directly affects the spillover rate of intermediate species, which further leads to an apparent activity difference. In addition, the possible role of ceria in the reaction is discussed, rather than just as a carrier for the active metal atoms.
研究领域:
催化化学
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能源材料科学
✓ 已验证
DOI
高影响因子
COMBUSTION AND FLAME
·
2012
·
IF 3.585
Olivier Herbinet,Benoit Husson,Zeynep Serinyel,Maximilien Cord,Valérie Warth,René Fournet,Pierre-Alexandre Glaude,Baptiste Sirjean,Frédérique Battin-Leclerc,Zhandong Wang,Mingfeng Xie,Zhanjun Cheng,Fei Qi
The low-temperature oxidation of n -heptane, one of the reference species for the octane rating of gasoline, was investigated using a jet-stirred reactor and two methods of analysis: gas chromatography and synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS) with direct sampling through a molecular jet. The second method allowed the identification of products, such as molecules with hydroperoxy functions, that are not stable enough to be detected using gas chromatography. Mole fractions of the reactants and reaction products were measured as a function of temperature (500–1100 K), at a residence time of 2 s, at a pressure of 800 Torr (1.06 bar) and under stoichiometric conditions. The fuel was diluted in an inert gas (fuel inlet mole fraction of 0.005). Attention was paid to the formation of reaction products involved in the low-temperature oxidation of n -heptane, such as olefins , cyclic ethers, aldehydes, ketones, species with two carbonyl groups (diones), and ketohydroperoxides. Diones and ketohydroperoxides are important intermediates in the low-temperature oxidation of n -alkanes, but their formation have rarely been reported. Significant amounts of organic acids (acetic and propanoic acids) were also observed at low temperatures. The comparison of experimental data and profiles computed using an automatically generated detailed kinetic model is satisfactory overall. A route for the formation of acetic and propanoic acids was proposed. Quantum calculations were performed to refine the consumption routes of ketohydroperoxides toward diones.
研究领域:
化学工程
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燃烧科学
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物理化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysts
·
2023
·Vol. 13
·期 10
·1383
·
IF 3.9
Zhen Jiang,Liduo Chen,Yanhong Cui,Huijie Gao,Yisi Zhou,Wei Zhang,Yanhua Suo,Yingjun Wang
n-Alkane hydroisomerization over bifunctional catalysts is an effective approach for clean fuel production. However, achieving metal–acid synergy and enhancing the catalytic performance by the preparation of bifunctional catalysts with suitable proximity between the metal sites and Brønsted acid sites are still challenging. In this work, a series of Pt/SAPO-11 catalysts with different Pt loading applied inn-heptane hydroisomerization was synthesized. SAPO-11 was synthesized by the Instant Exactness Synthesis (IES) method, which, with unique morphology and pore structure, was chosen as support for the hydroisomerization catalysts; Pt/SAPO-11 was synthesized with the impregnation method, Pt nanoclusters with trace loading were fabricated over the SAPO-11 support, and the as-synthesized catalysts with different Pt loading were labeled as xPt/SAPO-11 (x = 0.1, 0.3, 0.5, 0.8 and 1.0). Various characterizations, including XRD, nitrogen adsorption–desorption, SEM, TEM, NH3-TPD and XPS, were carried out on catalysts to obtain deep insights into the microstructure and valence states of xPt/SAPO-11. The catalytic performance of xPt/SAPO-11, including catalytic selectivity and conversion, was investigated in then-heptane hydroisomerization in detail. Pt loading affected the catalytic properties of xPt/SAPO-11 in the hydroisomerization ofn-heptane. The selectivity of 0.5Pt/SAPO-11 toward isomers was about 65% with a conversion of 77% at 310 °C, which was obviously higher than other xPt/SAPO-11 catalysts.
研究领域:
催化化学
·
能源化学
✓ 已验证
产品关联
DOI
高影响因子
Materials Today Chemistry
·
2023
·
IF 7.3
Pandong Ma,Yubing Li,Hexun Zhou,Mengheng Wang,Mengsi Zhu,Yaoyao Han,Xin Zhang,Kang Cheng,Abhishek Dutta Chowdhury
The unique physicochemical properties of “redox-acid” bifunctional zeolites make them an essential tool in the petrochemical industry, especially in the hydro-conversion of linear alkanes to deliver high-octane fuels. The current research activities in this domain are primarily tailored towards evaluating the “intimacy/proximity” criteria among two catalytically active sites and minimizing the loading of noble metals (e.g., Pd or Pt) in catalysis. However, the chemistry behind the communication mode (i.e., “through-space” or “through-bond” interaction between metallic and acid sites) has remained vastly underexplored during the hydro-conversion of n-alkanes over Pt or Pd/zeolites. To dig deeper into this uncharted territory, this work demonstrates that both “through-space” (cf. metals in extra-framework position in/on zeolite) and “through-bond” (cf. metals on the zeolite framework) bifunctionality favors the hydroisomerization step, while the later partially also promote the hydro-cracking. Their working protocol was probed by the diverse material characterization techniques that improved the understanding of the zeolite-catalyzed hydrocarbon conversion processes.
研究领域:
催化化学
·
石油化学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）