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RISS 인기검색어
- 검색키워드
- 저자 : Debao Li (검색결과 5 건)
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Ren, Jun,Song, Kai-he,Li, Zhenhuan,Wang, Qiang,Li, Jun,Wang, Yingxiong,Li, Debao,Kim, Chan Kyung Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.456 No.-
<P><B>Abstract</B></P> <P>The first principle calculations with on-site Coulomb repulsion U terms were carried out to investigate the 5-hydroxymethylfurfural (HMF) adsorption on the CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces, two widely used oxidation catalysts. The adsorption of HMF molecule is energetically favoured in both cases, and HMF is more inclined to bridge adsorption via hydroxyl and formyl groups binding with surface O and metal sites. Moreover, the adsorption energy relies on both the coordination type of surface lattice oxygen to which the H atom binds and the formation of H-bond involving hydroxyl and formyl groups on the adsorbed HMF. Also, the hydroxyl OH bond breaking is very easy and is likely to be the first step in HMF oxidation, and then the OH insertion reaction to produce 2,5-furandicarboxylic acid (FDCA). The corresponding experimental results also show that the CuO and Co<SUB>3</SUB>O<SUB>4</SUB> surfaces are promising candidate catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces catalyze the oxidation of 5-hydroxymethylfurfural (HMF). </LI> <LI> Initial binding was formed through bridged-adsorption with O atoms in HMF. </LI> <LI> Oxidation reaction proceeds through the OH bond breaking pathway. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic potential energy diagram for the formyl CH and hydroxyl OH bonds of HMF dissociation on CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces. Obviously, the hydroxyl OH bond breaking is easier than that of the formyl CH bond on the two surfaces, which indicates the first step of oxidation of HMF to FDCA should be hydroxyl OH bond breaking.</P> <P>[DISPLAY OMISSION]</P>
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Methanol selective oxidation to dimethoxymethane on H3PMo12O40/SBA-15 supported catalysts
Heqin Guo,Debao Li,Haicheng Xiao,Jianli Zhang,Wenhuai Li,Yuhan Sun 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
A series of SBA-15 supported H3PMo12O40 catalysts were prepared for the one-step oxidation of methanol to dimethoxymethane (DMM). The evaluation and characterization revealed that higher DMM selectivity obtained on the incipient wetness impregnation (IM) catalyst was related to the instability of H3PMo12O40 on it. Raman spectra showed that 12-molybdophosphoric acid was more stable on the direct synthesis (DS) catalyst than on the IM catalyst and the existence of SBA-15 support enhanced the stability of H3PMo12O40. Moreover, higher H3PMo12O40 loading resulted in more acid sites and low DMM selectivity, furthermore the thermal pretreatment on H3PMo12O40 influenced its structure and thus affected DMM selectivity.
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Chen Jiang,Qi Song,Debao Guo,Haolin Li 한국정밀공학회 2014 International Journal of Precision Engineering and Vol. No.
This work presents an investigation of the minimum dwell time during the precision cylindrical-plunge grinding process. Accordingto the model of acoustic emissions proposed in earlier work, two estimation algorithms of the dwell time, focused on the size errorand the surface roundness of the machined workpiece, are deduced from the models of the material removal and the surfaceroundness, respectively. Based on the proposed estimation algorithms, an on-line estimation method of the minimum dwell time isdeveloped using the measurement and analysis of the acoustic emission signal. A series of experiments of grinding C45 steel areconducted to confirm the validity of the proposed estimation algorithms and determine the model coefficient. The ability of theestimation algorithms to predict the minimum dwell time is deemed necessary for optimal control of the grinding process. In addition,the proposed model provides a new approach to estimate the machined qualities of a workpiece such as the surface roughness andsize error using the dwell time of the grinding process.
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Preparation and Characterization of Transitional Alumina Obtained through Ammonia Treatment
Yan Liu,Litao Jia,Bo Hou,Debao Li 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.12
In this study, different aluminas were obtained by precipitating Al(NO3)3·9H2O with different concentration of aqueous solution of ammonium carbonate. The obtained aluminas were treated by 50 (vol/vol) % ammonia via low temperature immersing and high temperature hydrothermal treatment, respectively, then, the treated aluminas were calcined again. The crystal types, morphology, textural properties, and pore distribution of the original alumina, ammonia-treated alumina, and the second calcined alumina were studied by characterizations of X-ray diffraction, thermogravimetric analyses, nuclear magnetic resonance, Brunauer-Emmett-Teller (BET), transmission electron microscopy, and so on. Several modified aluminas with specific morphology, desired pore structure, and pure crystal types were obtained, which can be used in some specific industrial application.
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Yuelun Wang,Bo Hou,Jiangang Chen,Litao Jia,Debao Li,Yuhan Sun 한국화학공학회 2009 Korean Journal of Chemical Engineering Vol.26 No.3
Co/SiO2 catalysts were prepared by sol-gel method with varied en (ethylenediamine)/Co molar ratios under the same pH. Their physical-chemical properties were compared with those prepared with similar en/Co molar ratios at natural pH or without adding ethylenediamine. Regardless of pH, the catalysts prepared using ethylenediamine possessed high microporosity, which led to a better selectivity to C5-18 hydrocarbons, versus the catalyst possessing higher mesoporosity which showed slightly higher C18+ selectivity. As enough positions in the coordination sphere were blocked by ethanediamine ligands, the formation of cobalt silicate disfavored for (en/Co=2) catalysts, which resulted in the higher activity in FT reaction. Whereas the catalysts prepared with lower or higher en/Co molar ratio both showed lower activity due to the formation of [(SiO)Co(en)(EtOH)3] species or the electronic adsorption of cobalt complexes in the negatively charged silica surface, respectively. However, for the catalyst without using ethylenediamine, the lowest activity and the highest CH4 selectivity obtained due to its much lower reducibility.
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