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Jingyu Ran
Key Laboratory of Low-Grade Energy Utilization Technologies and Systems, Ministry of Education of PRC, Chongqing University, Chongqing, 400044, China

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Journal article
Published: 14 January 2021 in Molecular Catalysis
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The focus of this paper is to solve the carbon deposition on Ni catalyst during dry reforming of methane (DRM). Cu has shown a great carbon resistance in DRM. Different doping ratio of Cu on Ni(111) surface, Cu1Ni8 and Cu6Ni3, have been studied through density functional theory (DFT), and the same procedure has been proceeded on Ni(111) to compare with. It is found that introducing Cu into Ni(111) surface can weaken the interaction between the surface and the absorbates, thus decrease the energy barrier of CH dissociation. Furthermore, two good linear relationships between the electron transferring from the surface to reactants and the energy barrier of CH dissociation and C2 formation have been discovered. In addition, the adsorption energy and activation energy are obtained, from which the dominated reaction pathway can be deduced. On the three surfaces, the dominated reaction pathways are the same, which can be shown as CH* + O* → HCO* → CO* + H*. However, on the surface of Cu6Ni3, the activation energy of CH oxidation is 0.63 eV, which is almost half the activation energy on the other two surfaces (1.24 eV and 1.24 eV), indicating that the Cu6Ni3 surface has the extraordinary ability of carbon resistance. Nevertheless, when C is formed on the three surfaces, it would accumulate rather than be oxidized, especially on the Cu6Ni3 surface because it has the lowest energy barrier (0.28 eV). In general, Cu6Ni3 surface having the best carbon resistance for CH* is more easily to be consumed through oxidation than through direct dissociation, thus it can be regarded as one of the potential candidates as the catalyst for DRM.

ACS Style

Huayu Qiu; Jingyu Ran; Juntian Niu; Fan Guo; Zhiliang Ou. Effect of different doping ratios of Cu on the carbon formation and the elimination on Ni (111) surface: A DFT study. Molecular Catalysis 2021, 502, 111360 .

AMA Style

Huayu Qiu, Jingyu Ran, Juntian Niu, Fan Guo, Zhiliang Ou. Effect of different doping ratios of Cu on the carbon formation and the elimination on Ni (111) surface: A DFT study. Molecular Catalysis. 2021; 502 ():111360.

Chicago/Turabian Style

Huayu Qiu; Jingyu Ran; Juntian Niu; Fan Guo; Zhiliang Ou. 2021. "Effect of different doping ratios of Cu on the carbon formation and the elimination on Ni (111) surface: A DFT study." Molecular Catalysis 502, no. : 111360.

Journal article
Published: 26 November 2020 in Fuel
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Methanol-mixed fuels consisting of methanol, propane, and a small amount of auxiliary solvent are widely used as inexpensive industrial fuels, but the carbon deposition in the pyrolysis of this fuel seriously restrains its popularization. This paper studied the characteristics of gaseous products and carbon deposition in the pure propane and methanol-propane mixture pyrolysis experimentally, analyzed the effect of methanol addition on the reaction path of propane pyrolysis and production rate of key species by using detailed reaction mechanism. Results show that methanol addition can restrain C2H4 converting to C2H2 in the later stage of pyrolysis. The carbon deposition rate and particle diameter increase exponentially with the increase of reaction temperature in both pure propane and methanol-propane blend pyrolysis. Methanol addition can significantly reduce the carbon deposition rate and particle diameter. The reaction path analysis indicates that the main reaction paths forming benzene are C3H3 → A1 and C4H4 → I-C6H6 → A1, and C3H3 is a key specie to form benzene. The pyrolysis of methanol-propane mixture generates more H2 and H than that of pure propane pyrolysis, which makes most C3H6 convert to C2H4, reduces the amount of C3H3 and suppresses the conversion of C2H4 to C2H2. And then the amount of benzene is reduced significantly and the generation of subsequent PAHs and carbon deposition is inhibited. Lots of H2 also restrains the hydrogen abstraction from benzene resulting in the delay of the formation of PAHs and carbon deposition. This study is of great significance to research the soot formation in hydrocarbon combustion with alcohol fuel.

ACS Style

Jun Shi; Hui Yan; Qi Huang; Jingyu Ran. Inhibition effect of methanol addition on carbon deposition in propane pyrolysis. Fuel 2020, 288, 119717 .

AMA Style

Jun Shi, Hui Yan, Qi Huang, Jingyu Ran. Inhibition effect of methanol addition on carbon deposition in propane pyrolysis. Fuel. 2020; 288 ():119717.

Chicago/Turabian Style

Jun Shi; Hui Yan; Qi Huang; Jingyu Ran. 2020. "Inhibition effect of methanol addition on carbon deposition in propane pyrolysis." Fuel 288, no. : 119717.

Journal article
Published: 19 September 2020 in International Journal of Hydrogen Energy
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To uncover the effects and the underlying mechanisms of Co content on CH4 dehydrogenation over Ni–Co bimetal catalyst, the CH4 successive dehydrogenation process over Ni (111) and different Co doped Ni (111) surface has been systematically studied via DFT calculation. Active sites and electronic properties have been obtained. CH4 physically located at the top site of Ni or Co, while other CHx species preferably occupied the threefold site. Besides, the charge transferred from surface to absorbates and the p-band center of absorbates could well describe the adsorption strength of CHx and the activation barrier of CH dehydrogenation on different surfaces. More importantly, the addition of small Co could improve the resistance to carbon deposition by weakening the adsorption of C, suppressing the activity of CH4 dehydrogenation and promoting C hydrogenation process.

ACS Style

Zhiliang Ou; Jingyu Ran; Juntian Niu; Zhonghui Zhang; Tao Deng; Ziqiang He; Changlei Qin. Effect of active site and charge transfer on methane dehydrogenation over different Co doped Ni surfaces by density functional theory. International Journal of Hydrogen Energy 2020, 45, 31849 -31862.

AMA Style

Zhiliang Ou, Jingyu Ran, Juntian Niu, Zhonghui Zhang, Tao Deng, Ziqiang He, Changlei Qin. Effect of active site and charge transfer on methane dehydrogenation over different Co doped Ni surfaces by density functional theory. International Journal of Hydrogen Energy. 2020; 45 (56):31849-31862.

Chicago/Turabian Style

Zhiliang Ou; Jingyu Ran; Juntian Niu; Zhonghui Zhang; Tao Deng; Ziqiang He; Changlei Qin. 2020. "Effect of active site and charge transfer on methane dehydrogenation over different Co doped Ni surfaces by density functional theory." International Journal of Hydrogen Energy 45, no. 56: 31849-31862.

Review article
Published: 27 August 2020 in International Journal of Hydrogen Energy
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Dry reforming of methane (DRM) is a promising reaction, it could convert two greenhouse gases CO2 and CH4 into syngas (CO and H2) which could provide a mixed fuel for daily life or chemical feedstock for industrial application. Transition metals were widely applied in this process, however, single component of transition metal catalysts could not meet the stability, selectivity and activity demands simultaneously. And the coke formation on the catalysts is the major barrier to the commercialization of DRM. This review presents a systematic discussion and analysis of methane dry reforming to syngas in the catalytic process from both experimental study and density functional theory (DFT) calculation based on recent research. It includes catalytic performance test of activity, selectivity and stability in DRM on monometallic and bimetallic systems, and also gives the discussion of carbon formation in the former parts. The later parts focus on CH4 and CO2 activation over monometal and bimetal surface using DFT simulation. The rate determining step and reaction mechanisms involved in DRM are obtained based on thermodynamic analysis and microkinetic model. In the end, we give our outlook to the design and preparation of good performance catalysts as well as further theoretical simulation and analysis in DRM. This review could provide some useful information for going into methane dry reforming from both experimental application and atomic scale.

ACS Style

Juntian Niu; Fan Guo; Jingyu Ran; Wenjie Qi; Zhongqing Yang. Methane dry (CO2) reforming to syngas (H2/CO) in catalytic process: From experimental study and DFT calculations. International Journal of Hydrogen Energy 2020, 45, 30267 -30287.

AMA Style

Juntian Niu, Fan Guo, Jingyu Ran, Wenjie Qi, Zhongqing Yang. Methane dry (CO2) reforming to syngas (H2/CO) in catalytic process: From experimental study and DFT calculations. International Journal of Hydrogen Energy. 2020; 45 (55):30267-30287.

Chicago/Turabian Style

Juntian Niu; Fan Guo; Jingyu Ran; Wenjie Qi; Zhongqing Yang. 2020. "Methane dry (CO2) reforming to syngas (H2/CO) in catalytic process: From experimental study and DFT calculations." International Journal of Hydrogen Energy 45, no. 55: 30267-30287.

Journal article
Published: 13 April 2020 in Journal of Hazardous Materials
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The reaction mechanisms of Hg oxidation on CeO2(111) and (110) surface are clarified by a group of designed experiments and density functional theory (DFT) calculations. CeO2 nanorods and nanoparticles with exposure (110) and (111) faces were prepared by hydrothermal methods, and their morphological properties were investigated using XRD, XPS and HRTEM. Combined experimental and DFT results, the nanorods show better activity than nanoparticles. The total oxidation of Hg can be partially prohibited by the high barriers for the incorporated chlorine activation at reduced surfaces, due to the strong electronic repulsion of heavily accumulated charges. The energy barrier profiles suggest Hg oxidation is much more favorable on CeO2(110) surface than that on CeO2(111) surface. In the Hg oxidation via HCl and O2, the role of O2 is not only replenishment of lattice oxygen, but also could generate surface oxygen as active center for HCl active. The complete catalytic cycle can be identified as four parts: (i) HCl activated by lattice oxygen, (ii) Hg oxidation on defect surface, (iii) HCl activated by adsorbed oxygen and (iv) Hg oxidation on stoichiometric surface. The results of this study provide deep insights into the effects of CeO2 nanocatalyst morphology on the Hg oxidation.

ACS Style

Wei He; Jingyu Ran; Juntian Niu; Guangpeng Yang; Zhiliang Ou; Zhi He. Insight into the effect of facet-dependent surface and oxygen vacancies of CeO2 for Hg removal: From theoretical and experimental studies. Journal of Hazardous Materials 2020, 397, 122646 .

AMA Style

Wei He, Jingyu Ran, Juntian Niu, Guangpeng Yang, Zhiliang Ou, Zhi He. Insight into the effect of facet-dependent surface and oxygen vacancies of CeO2 for Hg removal: From theoretical and experimental studies. Journal of Hazardous Materials. 2020; 397 ():122646.

Chicago/Turabian Style

Wei He; Jingyu Ran; Juntian Niu; Guangpeng Yang; Zhiliang Ou; Zhi He. 2020. "Insight into the effect of facet-dependent surface and oxygen vacancies of CeO2 for Hg removal: From theoretical and experimental studies." Journal of Hazardous Materials 397, no. : 122646.

Journal article
Published: 31 December 2019 in Journal of Hazardous Materials
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SCR activity of Cu-SAPO-34 catalyst was reduced by alkali metal ions. The alkali metals ions (Li+, Na+ and K+) have shown irregular influences on Cu-SAPO-34. The order of poisoning strengths under 400 °C was found to be: Na+ > K+ > Li+, which is not consistent with the basicities of their corresponding metals. Experimental results and calculations showed that the alkali metal ions readily replace H+ and Cu2+/Cu+ ions. These exchanges result in the loss of Brønsted acid sites and migration of isolated Cu2+ ions in Cu-SAPO-34, which decrease the NH3-SCR activity. Both the basicity and ion diameter will affect the exchanging behavior of an alkali ion. Na+ and Li+ ions will influence both H+ and Cu2+/Cu+ ions but K+ ions only preferably replace the H+. We hypothesize that K+ cannot enter into a small ring (6-membered ring) to replace a Cu2+/Cu+ ion because of its large ion diameter. The displaced Cu2+/Cu+ ions will transfer to adjacent unbonded Al site to form a CuAlO2 species.

ACS Style

Guangpeng Yang; Xuesen Du; Jingyu Ran; Xiangmin Wang; Yanrong Chen; Li Zhang; Vladislav Rac; Vesna Rakic; John Crittenden. Irregular influence of alkali metals on Cu-SAPO-34 catalyst for selective catalytic reduction of NOx with ammonia. Journal of Hazardous Materials 2019, 387, 122007 .

AMA Style

Guangpeng Yang, Xuesen Du, Jingyu Ran, Xiangmin Wang, Yanrong Chen, Li Zhang, Vladislav Rac, Vesna Rakic, John Crittenden. Irregular influence of alkali metals on Cu-SAPO-34 catalyst for selective catalytic reduction of NOx with ammonia. Journal of Hazardous Materials. 2019; 387 ():122007.

Chicago/Turabian Style

Guangpeng Yang; Xuesen Du; Jingyu Ran; Xiangmin Wang; Yanrong Chen; Li Zhang; Vladislav Rac; Vesna Rakic; John Crittenden. 2019. "Irregular influence of alkali metals on Cu-SAPO-34 catalyst for selective catalytic reduction of NOx with ammonia." Journal of Hazardous Materials 387, no. : 122007.

Journal article
Published: 24 January 2019 in Processes
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The application of circulating fluidized bed technology in calcium looping (CaL) requires that CaO-based sorbents should be manufactured in the form of spherical pellets. However, the pelletization of powdered sorbents is always hampered by the problem that the mechanical strength of sorbents is improved at the cost of loss in CO2 sorption performance. To promote both the CO2 sorption and anti-attrition performance, in this work, four kinds of pore-forming materials were screened and utilized to prepare sorbent pellets via the extrusion-spheronization process. In addition, impacts of the additional content of pore-forming material and their particle sizes were also investigated comprehensively. It was found that the addition of 5 wt.% polyethylene possesses the highest CO2 capture capacity (0.155 g-CO2/g-sorbent in the 25th cycle) and mechanical performance of 4.0 N after high-temperature calcination, which were about 14% higher and 25% improved, compared to pure calcium hydrate pellets. The smaller particle size of pore-forming material was observed to lead to a better performance in CO2 sorption, while for mechanical performance, there was an optimal size for the pore-former used.

ACS Style

ZongHao Zhang; Shuai Pi; Donglin He; Changlei Qin; Jingyu Ran. Investigation of Pore-Formers to Modify Extrusion-Spheronized CaO-Based Pellets for CO2 Capture. Processes 2019, 7, 62 .

AMA Style

ZongHao Zhang, Shuai Pi, Donglin He, Changlei Qin, Jingyu Ran. Investigation of Pore-Formers to Modify Extrusion-Spheronized CaO-Based Pellets for CO2 Capture. Processes. 2019; 7 (2):62.

Chicago/Turabian Style

ZongHao Zhang; Shuai Pi; Donglin He; Changlei Qin; Jingyu Ran. 2019. "Investigation of Pore-Formers to Modify Extrusion-Spheronized CaO-Based Pellets for CO2 Capture." Processes 7, no. 2: 62.

Journal article
Published: 27 November 2018 in International Journal of Hydrogen Energy
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PtNi bimetallic catalysts show superior performance for CO2 catalytic conversion by hydrogen, but the underlying mechanism and the key elementary steps in controlling the activity and selectivity of CO2 hydrogenation remain unclear. In present work, the complete reaction network for CO2 hydrogenation has been investigated systematically over Pt/Ni (111) surface based on periodic density functional theory, and active sites and reaction mechanism have been determined. It is found that HCOOH is mainly produced by undergoing the HCOO pathways while synthesis of CH3OH and CH4 via RWGS+CO hydrogenation is the dominant reaction pathway, and their selectivity are determined by the competitive reaction between hydrogenation and CO bond scission of H2COH species. The dissociation of COOH is regarded as the rate-determining step as it has the highest barrier (2.07 eV) in RWGS+CO hydrogenation. Moreover, it is observed that the doping of Pt on Ni surface can promote the transformation of CO2 into chemisorbed CO2δ− and reduce the barrier in H2 dissociation, which further facilitate the activation and hydrogenation of CO2. More importantly, the doped Pt atom could promote HxCO hydrogenation to HxCOH, meanwhile, suppress HxCOH dissociation into CHx. Especially, the activation barrier and reaction energy for C formation is markedly enhanced, and the ability for C hydrogenation is promoted over Pt/Ni (111) surface, which could lower the possibility of coke formation. These results provide helpful information in understanding the process of CO2 hydrogenation at atomic scale, and could benefit for the synthesis of Ni-based bimetallic catalysts.

ACS Style

Zhiliang Ou; Changlei Qin; Juntian Niu; Lihui Zhang; Jingyu Ran. A comprehensive DFT study of CO2 catalytic conversion by H2 over Pt-doped Ni catalysts. International Journal of Hydrogen Energy 2018, 44, 819 -834.

AMA Style

Zhiliang Ou, Changlei Qin, Juntian Niu, Lihui Zhang, Jingyu Ran. A comprehensive DFT study of CO2 catalytic conversion by H2 over Pt-doped Ni catalysts. International Journal of Hydrogen Energy. 2018; 44 (2):819-834.

Chicago/Turabian Style

Zhiliang Ou; Changlei Qin; Juntian Niu; Lihui Zhang; Jingyu Ran. 2018. "A comprehensive DFT study of CO2 catalytic conversion by H2 over Pt-doped Ni catalysts." International Journal of Hydrogen Energy 44, no. 2: 819-834.

Journal article
Published: 26 September 2018 in Applied Surface Science
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Periodic DFT computational studies are applied to investigate mercury adsorption and oxidation mechanism over RuO2 catalyst. The adsorption of mercury species (Hg0, HgCl, HgCl2) and HCl on RuO2(110) surface were obtained. The results indicate that all the mercury species have strong interaction with RuO2(110) surface and the unsaturated Ru sites have best ability for adsorption mechanism. HCl prefers to dissociate on the surface with adsorption energy of -238.00 kJ/mol, leading to a hydroxyl group and ruthenium-chlorine complex. After water desorption from the surface, different chlorinated surface has been formed at various oxygen coverage. The Hg oxidation reaction follows the Langmuir–Hinshelwood mechanisms in which both Hg and Cl are adsorbed before reacting with each other. Furthermore, reaction pathways of mercury oxidation on different chlorinated surfaces are examined and the activation barriers are 194.22 kJ/mol and 90.94 kJ/mol, respectively. These results revealed that precovered oxygen on the surface is more active than lattice oxygen, which can improve HCl dissociation and Hg oxidation. Our approach provides new insights into the role of O2 during Hg oxidation process.

ACS Style

Wei He; Jingyu Ran; Juntian Niu; Guangpeng Yang; Peng Zhang. Mechanism insights into elemental mercury oxidation on RuO2(1 1 0) surface: A density functional study. Applied Surface Science 2018, 466, 920 -927.

AMA Style

Wei He, Jingyu Ran, Juntian Niu, Guangpeng Yang, Peng Zhang. Mechanism insights into elemental mercury oxidation on RuO2(1 1 0) surface: A density functional study. Applied Surface Science. 2018; 466 ():920-927.

Chicago/Turabian Style

Wei He; Jingyu Ran; Juntian Niu; Guangpeng Yang; Peng Zhang. 2018. "Mechanism insights into elemental mercury oxidation on RuO2(1 1 0) surface: A density functional study." Applied Surface Science 466, no. : 920-927.

Journal article
Published: 23 August 2018 in Chemical Engineering Journal
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Here we provide new mechanistic and kinetic insights into the functions of oxides on Ni catalysts in methane dry reforming combining kinetic studies with density functional theory (DFT) calculations. Hydrotalcite derived Ni catalysts with a small amount of oxide additive (CeO2, ZrO2, ZnO) as promoters are synthesized and characterized by different techniques, X-ray diffraction (XRD), X-ray fluorescence (XRF), N2 physisorption, H2 chemisorption, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis combined with mass spectrometry (TGA-MS). Regarding H2/CO ratio, the CeO2-Ni shows the highest the values along all the temperatures. Moreover, the CeO2-Ni catalyst has the best stability among the four catalysts, while ZnO-Ni experiences the most severe deactivation. Kinetic studies in terms of reaction orders and activation energies are performed and compared to the DFT investigations, to assess the functions of oxide promoters. The CeO2-Ni catalyst shows the lowest apparent activation energy for CO2 activation, and it is also found that forward turnover rate is independent of CO2 partial pressure for all the samples. In DFT calculations, CO2 is more favorable to be activated on the support and the TOF obtained from G plot is in perfect agreement with our experiment value. In addition, it is also found that basicity of oxide additives and electronegativity of metal element can be well correlated to the activation of CO2 and catalyst’s deactivation. In general, both the increased basicity of oxide and the decreased electronegativity of metal element help to promote the CO2 activation and enhance the catalyst’s stability. We propose that the CeO2-Ni catalyst has best performance for CO2 activation, thus leading to a higher surface oxygen concentration to oxidize the carbon on the catalysts, which prolongs the catalyst’s life.

ACS Style

Juntian Niu; Shirley Elisabeth Liland; Jia Yang; Kumar R. Rout; Jingyu Ran; De Chen. Effect of oxide additives on the hydrotalcite derived Ni catalysts for CO2 reforming of methane. Chemical Engineering Journal 2018, 377, 119763 .

AMA Style

Juntian Niu, Shirley Elisabeth Liland, Jia Yang, Kumar R. Rout, Jingyu Ran, De Chen. Effect of oxide additives on the hydrotalcite derived Ni catalysts for CO2 reforming of methane. Chemical Engineering Journal. 2018; 377 ():119763.

Chicago/Turabian Style

Juntian Niu; Shirley Elisabeth Liland; Jia Yang; Kumar R. Rout; Jingyu Ran; De Chen. 2018. "Effect of oxide additives on the hydrotalcite derived Ni catalysts for CO2 reforming of methane." Chemical Engineering Journal 377, no. : 119763.

Journal article
Published: 22 November 2017 in Applied Surface Science
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Density functional theory combined with kinetic models were used to probe different kinetics consequences by which methane activation on different oxygen chemical potential surfaces as oxygen pressure increased. The metallic oxide → metal transformation temperature of Pd-Pt catalysts increased with the increase of the Pd content or/and O2 pressure. The methane conversion rate on Pt catalyst increased and then decreased to a constant value when increasing the O2 pressure, and Pd catalyst showed a poor activity performance in the case of low O2 pressure. Moreover, its activity increased as the oxygen chemical potential for O2 pressure increased in the range of 2.5–10 KPa. For metal clusters, the CH bond and OO bond activation steps occurred predominantly on *-* site pairs. The methane conversion rate was determined by O2 pressure because the adsorbed O atoms were rapidly consumed by other adsorbed species in this kinetic regime. As the O2 pressure increased, the metallic active sites for methane activation were decreased and there was no longer lack of adsorbed O atoms, resulting in the decrease of the methane conversion rate. Furthermore, when the metallic surfaces were completely covered by adsorbed oxygen atoms at higher oxygen chemical potentials, Pt catalyst showed a poor activity due to a high CH bond activation barrier on O*O*. In the case of high O2 pressure, Pd atoms preferred to segregate to the active surface of Pd-Pt catalysts, leading to the formation of PdO surfaces. The increase of Pd segregation promoted a subsequent increase in active sites and methane conversion rate. The PdO was much more active than metallic and O* saturated surfaces for methane activation, inferred from the theory and experimental study. Pd-rich bimetallic catalyst (75% molar Pd) showed a dual high methane combustion activity on O2-poor and O2-rich conditions.

ACS Style

Wenjie Qi; Jingyu Ran; Zhien Zhang; Juntian Niu; Peng Zhang; Lijuan Fu; Bo Hu; Qilai Li. Methane combustion reactivity during the metal→metallic oxide transformation of Pd-Pt catalysts: Effect of oxygen pressure. Applied Surface Science 2017, 435, 776 -785.

AMA Style

Wenjie Qi, Jingyu Ran, Zhien Zhang, Juntian Niu, Peng Zhang, Lijuan Fu, Bo Hu, Qilai Li. Methane combustion reactivity during the metal→metallic oxide transformation of Pd-Pt catalysts: Effect of oxygen pressure. Applied Surface Science. 2017; 435 ():776-785.

Chicago/Turabian Style

Wenjie Qi; Jingyu Ran; Zhien Zhang; Juntian Niu; Peng Zhang; Lijuan Fu; Bo Hu; Qilai Li. 2017. "Methane combustion reactivity during the metal→metallic oxide transformation of Pd-Pt catalysts: Effect of oxygen pressure." Applied Surface Science 435, no. : 776-785.

Journal article
Published: 30 May 2016 in Energies
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The combustion characteristics of methane/moist air in micro-tube reactors with different numbers and shapes of inner wall protuberances are investigated in this paper. The micro-reactor with one rectangular protuberance (six different sizes) was studied firstly, and it is shown that reactions near the protuberance are mainly controlled by diffusion, which has little effect on the outlet temperature and methane conversion rate. The formation of cavities and recirculation zones in the vicinity of protuberances leads to a significant increase of the Arrhenius reaction rate of CH4 and gas velocity. Next, among the six different simulated conditions (0–5 rectangular protuberances), the micro-tube reactor with five rectangular protuberances shows the highest methane conversion rate. Finally, the effect of protuberance shape on methane/moist air catalytic combustion is confirmed, and it is found that the protuberance shape has a greater influence on methane conversion rate than the number of protuberances. The methane conversion rate in the micro-tube decreases progressively in the following order: five triangular slight protuberances > five rectangular protuberances > five trapezoidal protuberances > smooth tube. In all tests of methane/moist air combustion conditions, the micro-tube with five triangular protuberances has the peak efficiency and is therefore recommended for high efficiency reactors.

ACS Style

Ruirui Wang; Jingyu Ran; Xuesen Du; Juntian Niu; Wenjie Qi. The Influence of Slight Protuberances in a Micro-Tube Reactor on Methane/Moist Air Catalytic Combustion. Energies 2016, 9, 421 .

AMA Style

Ruirui Wang, Jingyu Ran, Xuesen Du, Juntian Niu, Wenjie Qi. The Influence of Slight Protuberances in a Micro-Tube Reactor on Methane/Moist Air Catalytic Combustion. Energies. 2016; 9 (6):421.

Chicago/Turabian Style

Ruirui Wang; Jingyu Ran; Xuesen Du; Juntian Niu; Wenjie Qi. 2016. "The Influence of Slight Protuberances in a Micro-Tube Reactor on Methane/Moist Air Catalytic Combustion." Energies 9, no. 6: 421.

Journal article
Published: 18 October 2015 in Computational Materials Science
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Effects of hydrogen addition on methane catalytic combustion over Pt(1 1 1) surface were investigated with density functional theory (DFT) calculations and micro-kinetic modeling. Optimizations of initial and transition states were performed for elementary reactions that involve feasible steps of the overall reaction. The elementary reactions include the dissociation process of hydrogen–methane, oxidation of intermediates and desorption of products on Pt. Many feasible pathways were investigated and the calculated results showed that the main reaction pathways are CH4 → CH3∗ → CH2∗ → CH∗ → CHOH∗ → CHO∗ → CO∗ → COOH∗ → CO2∗ → CO2 and H2 → H∗ → OH∗ → H2O∗ → H2O. Chemical reaction kinetic theory was employed and showed that the rate determining step of methane oxidation is the elementary reaction CH4 + 2∗ → CH3∗ + H∗. This conclusion is in agreement with previous published results. In addition, the methane oxidation rate decreases with the increasing addition of hydrogen by analyzing a simple micro kinetic model. Meanwhile, the coverage density of the main species over Pt(1 1 1) surface were also studied. The results showed that hydrogen and methane keep a competitive relationship on dissociative adsorption over Pt(1 1 1). Even though H∗ is able to consume O∗ to release free site for methane adsorption, free sites are still rare for methane adsorption due to the addition of hydrogen. Therefore, even thought the heat release of hydrogen oxidation may accelerate the methane catalytic combustion, hydrogen addition will inhibit methane catalytic combustion in kinetically.

ACS Style

Wenjie Qi; Jingyu Ran; Ruirui Wang; Xuesen Du; Jun Shi; MingChu Ran. Kinetic mechanism of effects of hydrogen addition on methane catalytic combustion over Pt(1 1 1) surface: A DFT study with cluster modeling. Computational Materials Science 2015, 111, 430 -442.

AMA Style

Wenjie Qi, Jingyu Ran, Ruirui Wang, Xuesen Du, Jun Shi, MingChu Ran. Kinetic mechanism of effects of hydrogen addition on methane catalytic combustion over Pt(1 1 1) surface: A DFT study with cluster modeling. Computational Materials Science. 2015; 111 ():430-442.

Chicago/Turabian Style

Wenjie Qi; Jingyu Ran; Ruirui Wang; Xuesen Du; Jun Shi; MingChu Ran. 2015. "Kinetic mechanism of effects of hydrogen addition on methane catalytic combustion over Pt(1 1 1) surface: A DFT study with cluster modeling." Computational Materials Science 111, no. : 430-442.

Journal article
Published: 14 September 2015 in Fuel
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Numerous studies have focused on the utilisation of alcohol fuels because of the energy crisis. However, the combustion efficiency and stability of alcohol fuels are unacceptable. This study proposed an ejecting combustion method for utilising methanol-mixed fuels and numerically investigated the characteristics of adaptive air distribution in an ejector burner. The geometrical parameters of the ejector burner were optimised and validated by an experiment. Results show that the suction effect of negative pressure in the mixing chamber and the entrainment effect of fuel jet flow both play important roles for an ejector burner to draw air. The positions of ejector nozzle exit locating at the suction chamber axis and low operating pressure are beneficial for obtaining a stable air distribution. Molar entrainment ratio (MER) rapidly increases with an increase in parameter α, which is defined as the ratio of throat diameter to nozzle exit diameter, but declines with increasing ejector back pressure. In the experiment, the changing rate of MER is less than 6.4%, and combustion efficiency is higher than 99.2% in the load range of 20–120%, which is highly consistent with that of the simulation. The optimised burner could automatically distribute air supply and facilitate stable combustion.

ACS Style

Jun Shi; Jingyu Ran; Changlei Qin; MingChu Ran; Li Zhang. Adaptive air distribution in an ejector burner for the utilisation of methanol-mixed fuels. Fuel 2015, 162, 313 -322.

AMA Style

Jun Shi, Jingyu Ran, Changlei Qin, MingChu Ran, Li Zhang. Adaptive air distribution in an ejector burner for the utilisation of methanol-mixed fuels. Fuel. 2015; 162 ():313-322.

Chicago/Turabian Style

Jun Shi; Jingyu Ran; Changlei Qin; MingChu Ran; Li Zhang. 2015. "Adaptive air distribution in an ejector burner for the utilisation of methanol-mixed fuels." Fuel 162, no. : 313-322.

Original articles
Published: 23 April 2015 in International Journal of Green Energy
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A plenty of studies on the utilization of biomass alcohol fuels have been conducted, but combustion efficiency and stability of this fuels still need to be improved. Based on biomass alcohol fuels (bio-methanol and bio-ethanol), this paper studied auto-adaptive air distribution characteristics and optimum structure parameters of an ejector burner by numerical simulation method. Also, an experiment was conducted to verify the numerical results. The results show that the mole air entrainment ratio (MAER) keeps almost constant when the ejector fuel nozzle exit locates at the segment between the ejector throat and the suction chamber entrance, but a bigger ratio α would lead to a higher MAER till the α is bigger than 8.5 for bio-methanol and 11.5 for bio-ethanol. The bio-ethanol fuel is more beneficial for air carrying role because of its big molecular weight. Operation pressure (Pw) has a little impact on MAER of the two fuels, but the rise of back pressure (Pb) would lead to rapid decrease of MAER for the two fuels. For the optimum structure burners, the MAER can be maintained at the value of theoretical complete combustion. Its changing rate is less than 2.3% for bio-methanol and 2.5% for bio-ethanol when the burner load changes from 30% to 120%, which is highly consistent with the experimental results. The optimum burner can distribute air supply automatically with the changing of burner load.

ACS Style

Jing-Yu Ran; Jun Shi; Lin Yang; Li Zhang. Auto-adaptive Air Distribution and Structure Optimization of Ejector Burner for Biomass Alcohol Fuels. International Journal of Green Energy 2015, 12, 1054 -1060.

AMA Style

Jing-Yu Ran, Jun Shi, Lin Yang, Li Zhang. Auto-adaptive Air Distribution and Structure Optimization of Ejector Burner for Biomass Alcohol Fuels. International Journal of Green Energy. 2015; 12 (10):1054-1060.

Chicago/Turabian Style

Jing-Yu Ran; Jun Shi; Lin Yang; Li Zhang. 2015. "Auto-adaptive Air Distribution and Structure Optimization of Ejector Burner for Biomass Alcohol Fuels." International Journal of Green Energy 12, no. 10: 1054-1060.

Journal article
Published: 07 November 2013 in Journal of Heat Transfer
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In this paper, a 2D model with detailed heterogeneous chemical mechanism has been employed to investigate the heat transfer phenomenon of premixed CH4/air catalytic combustion in a Pt coated microtube. Especially, the thermal processes such as coupled heat transfer between the internal surface of the microtube and the gas phase, thermal conduction along the solid structure, convection and radiation between the external surface and the environment are comprised in the simulation. The results show that the thermal conductivity of different solid wall materials dramatically affects the uniformity of temperature distribution of the catalytic surface. To maintain stable combustion in the microtube, the thermal conductivity should exceed 0.49 W/m/K at least and conductive walls (FeCr alloy and corundum ceramic) are more appropriate to manufacture microcombustors. The extremely small Biot number at the external surface indicates that convective heat transfer coefficient and emissivity to the environment are the key factors determining the heat loss of the microtube. The amount of heat loss influences the reaction rate and residence time of the mixtures in the microtube, which would affect the conversion of CH4. An increase of the wall thickness improves the heat transfer along the solid structure, also increases the total heat loss.

ACS Style

Jing-Yu Ran; Sheng Wu; Lin Yang; Li Zhang. The Wall Heat Transfer Phenomenon of Premixed CH4/Air Catalytic Combustion in a Pt Coated Microtube. Journal of Heat Transfer 2013, 136, 021201 .

AMA Style

Jing-Yu Ran, Sheng Wu, Lin Yang, Li Zhang. The Wall Heat Transfer Phenomenon of Premixed CH4/Air Catalytic Combustion in a Pt Coated Microtube. Journal of Heat Transfer. 2013; 136 (2):021201.

Chicago/Turabian Style

Jing-Yu Ran; Sheng Wu; Lin Yang; Li Zhang. 2013. "The Wall Heat Transfer Phenomenon of Premixed CH4/Air Catalytic Combustion in a Pt Coated Microtube." Journal of Heat Transfer 136, no. 2: 021201.