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Mechanism of K/Ni Etching for Biochar-H_(2)O Gasification

Journal of Harbin Institute of Technology(New Series) 2024年第3期31卷 1-18页

作者： Zhenyu Cheng Dongdong Feng Qi Shang Yijun Zhao Wenda Zhang Shaozeng Sun School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Biomass-H_(2)O gasification is a complex thermochemical reaction,including three processes of volatile removal:homogeneous/heterogeneous reforming,biochar gasification and etching.The rate-determining step is biochar-H_(2)O gasification and etching so the DFT is carried out to see the catalytic role of different metal elements(K/Ni)in the zigzag biochar model.The calculation results show that the gasification of biochar-H_(2)O needs to go through four processes:dissociative adsorption of water,hydrogen transfer(hydrogen desorption,hydrogen atom transfer),carbon dissolution and CO desorption.The energy barrier indicated that the most significant step in reducing the activation energy of K is reflected in the hydrogen transfer step,which is reduced from 374.14 kJ/mol to 152.41 kJ/mol;the catalytic effect of Ni is mainly reflected in the carbon dissolution step,which is reduced from 122.34 kJ/mol to 84.8 kJ/mol.The existence of K causes the edge to have a stronger attraction to H and does not destroy theπbonds of biochar molecules.The destruction ofπbonds is mainly due to the role of H free radicals,while the destruction ofπbonds will lead to easier C-C bond rupture.Ni shows a strong attraction to O in OH,which forms strong Ni-O chemical bonds.Ni can also destroy the aromatic structure directly,making the gasification easier to happen.This study explored the catalytic mechanism of K/Ni on the biochar-H_(2)O gasification at the molecular level and looked forward to the potential synergy of K/Ni,laying a foundation for experimental research and catalyst design.

关键词： Biochar Potassium-nickel catalysis H_(2)O gasification etching Quantum chemistry transition state theory

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Theoretical study on the reaction mechanism of ozone addition to the double bonds of keto-limonene

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Journal of Environmental Sciences 2012年第1期24卷 147-151页

作者： Lei Jiang Yisheng Xu Baohui Yin Zhipeng Bai College of Environmental Sciences and Engineering Peking UniversityBeijing 100871China state Key Laboratory of Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental SciencesBeijing 100012China

The reaction mechanism of ozone （O 3） addition to the double bonds of gas phase keto-limonene was investigated using ab initio methods.Two different possibilities for O 3 addition to the double bond were considered and two corresponding van der Waals complexes （Complex 1 and Complex 2） were found for 1-endo and 2-endo.The rate constants were calculated using the transition state theory at the CCSD（T）/6-31G（d）＋ CF//B3LYP/6-31G（d,p） level.The high-pressure limit of the total rate constant at 298 K was 3.51×10-16 cm 3/（molecule·sec）,which was in a good agreement with the experimental data.

关键词： keto-limonene O3 transition state theory

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A statistical model for predicting thermal chemical reaction rate

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Chinese Physics B 2014年第5期23卷 116-122页

作者：林正喆李王尧宁西京 Institute of Modern Physics Department of Nuclear Science and TechnologyFudan University Department of Physics Fudan University state Key Laboratory of Surface Physics Fudan University

A simple model based on the statistics of individual atoms [Europhys. Lett. 94 40002 （2011）] or molecules [Chin. Phys. Lett. 29 080504 （2012）] was used to predict chemical reaction rates without empirical parameters, and its physical basis was further investigated both theoretically and via MD simulations. The model was successfully applied to some reactions of extensive experimental data, showing that the model is significantly better than the conventional transition state theory. It is worth noting that the prediction of the model on ab initio level is much easier than the transition state theory or unimolecular RRKM theory.

关键词： chemical reaction rate transition state theory unimolecular reaction bimolecular reaction

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Simple statistical model for predicting thermal atom diffusion on crystal surfaces

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Chinese Physics B 2013年第11期22卷 458-462页

作者：于卫锋林正喆宁西京 Institute of Modern Physics Department of Nuclear Science and Technology Applied Ion Beam Physics Laboratory Fudan University

A simple model based on the statistics of single atoms is developed to predict the diffusion rate of thermal atoms in （or on） bulk materials without empirical parameters. Compared with vast classical molecular-dynamics simulations for predicting the self-diffusion rate of Pt, Cu, and Ar adatoms on crystal surfaces, the model is proved to be much more accurate than the Arrhenius law and the transition state theory. Applying this model, the theoretical predictions agree well with the experimental values in the presented paper about the self-diffusion of Pt （Cu） adatoms on the surfaces.

关键词： adatoms diffusion Arrhenius law transition state theory molecular dynamics simulations

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Unprecedented differences in the diamond nucleation density between carbon-and silicon-faces of 4H-silicon carbides

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Chinese Chemical Letters 2020年第7期31卷 2013-2018页

作者： Bo Wang Pitsiri Sukkaew Guichen Song Andreas Rosenkranz Yunxiang Lu Kazhihito Nishimura Jia Wang Jilei Lyu Yang Cao Jian Yi Lars Ojamae He Li Nanjiang Key Laboratory of Marine New Materials and Related Technology Zhejiang Key Laboratory of Marine Materials and Protection TechnologyNingbo Institute of Material Technology&EngineeringChinese Academy of SciencesNingbo 315201China Department of Physics Chemistryand BiologyLinkoping UniversitySE-58183 LinkopingSweden Department of Chemical Engineering Biotechnology and MaterialsUniversidad de ChileAvenida Beauchef 851SantiagoChile Mechanical Systems Engineering Kogakuin UniversityTokyo 192-0015Japan Department of Mechanical and Materials Engineering University of Nebraska-LincolnLincolnNE 68588United State

4H-silicon carbides deposited by diamond films have wide applications in many fields such as semiconductor heterojunction,heat sink and mechanical sealing.Nucleation plays a critical role in the deposition of the diamond film on 4H-silicon carbides.Nevertheless,as a typical polar material,the fundamental mechanism of diamond nucleation on different faces of 4H-silicon carbides has not been fully understood yet.In this contribution,nucleation of diamond was performed on the carbon-and silicon-faces of 4H-silicon carbides in a direct current chemical vapor deposition device.The nucleation density on the carbon-face is higher by 2-3 orders of magnitude compared to the silicon-face.Transmission electron microscopy verifies that there are high density diamond nuclei on the interface between the carbon-face and the diamond film,which is different from columnar diamond growth structure on the silicon-face.transition state theory calculation reveals that the unprecedented distinction of the nucleation density between the carbon-face and the silicon-face is attributed to different desorption rates of the absorbed hydrocarbon radicals.In addition,kinetic model simulations demonstrate that it is more difficult to form CH2(s)-CH2(s)dimers on silicon-faces than carbon-faces,resulting in much lower nucleation densities on silicon-faces.

关键词： 4H-silicon carbide Diamond nucleation mechanism Transmission electron microscopy transition state theory Kinetic model simulation

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