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Fast pyrolysis of pitch pine biomass in a bubbling fluidized-bed reactor for bio-oil production
Quoc Khanh Tran,Manh Linh Le,Hoang Vu Ly,우희철,김진수,김승수 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-
The kinetic parameters for the pyrolysis of biomass of the pitch pine (Rigida pine P. Mill) were examinedby thermogravimetric analysis in the temperature range 25 C to 700 C, in which the maindecomposition was occurred from 250 C to 400 C. Pyrolysis of pitch pine has been investigated in abubblingfluidized bed reactor. In this system, silica sand and nitrogen were used as thefluidizing bedmaterial andfluidizing medium, respectively. The experimental was systemically performed on differenttemperature,fluidized velocity, and particle size of biomass. The optimum temperature condition atwhich the bio-oil yields reached the highest value (65.5%) was 500 C. In addition, the higher heatingvalues of bio-oils from pitch pine biomass were reached in the range 22 MJ/kg to 24 MJ/kg. Moreover, thisbio-oil had high content of useful chemicals including such as levoglucosan, furfural, and guaiacol. Thelarge amount of C5–C11 (gasoline fraction) produced make the pyrolyzed oil originating from pitch pinetrees a promising biofuel candidate.
Quoc Khanh Tran,Sangjin Han,Hoang Vu Ly,Seung-Soo Kim,Jinsoo Kim 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-
In this study, spherical g-Al2O3-SiO2 catalysts with various Al/Si ratios were prepared by combining thesol-gel and spray pyrolysis (SP) methods. The effectiveness of the product catalysts was then tested viathe hydrodeoxygenation (HDO) of guaiacol, a model compound of bio-oil obtained from the pyrolysis oflignocellulosic biomass. Our results showed that the g-Al2O3-SiO2 catalyst with a 50:50 Al/Si ratio aftercalcination at 450 C exhibited the highest guaiacol conversion (81.79%) at a reaction temperature of300 C, atmospheric pressure, and a weight hourly space velocity (WHSV) of 6.5 h 1. During guaiacolHDO, the carbon–oxygen cleavage and methyl group transfer reactions occurred on the g-Al2O3-SiO2catalyst, which converted the guaiacol into the respective deoxygenated products, including 2,6-xylenol,2,3,5,6-tetramethyl phenol, pentamethyl benzene, and hexamethyl benzene. The reaction pathways forthe conversion of guaiacol HDO were also proposed in this study.
Bio-oil production from fast pyrolysis of furniture processing residue
Hoang Vu Ly,Quoc Khanh Tran,천병희,오창호,김진수,김승수 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.2
The pyrolysis characteristic of furniture processing residue (FPR), which was analyzed by thermogravimetric analysis (TGA) under nitrogen atmosphere, mainly decomposed between 230 oC and 500 oC. The FPR was submitted to fast pyrolysis in a bubbling fluidized-bed reactor (BFR) for converting into bio-oil, bio-char. The product distribution and characteristics of bio-oil depend on the operating conditions (temperature, fluidizing flow rate, particle size of sample). The bio-oil yield showed the highest value (50.68 wt%) at the pyrolysis temperature of 450 oC with a biomass particle size of 1.0mm and a fluidization velocity of 2.0×Umf. The bio-oil had high selectivity for dioctyl phthalate, levoglucosan, and phenolic derivatives. The carbon number proportions in bio-oils of FPR were 32.74wt% for C5- C11 fraction, 47.60 wt% for C12-C18 fraction and 19.38 wt% of C25-C38 fraction, respectively. The gas product included CO, CO2, H2, and hydrocarbons (C1-C4), and the selectivity of CO2 was the highest. The high heating value (HHV) of gas products was between 4.60 and 12.90 MJ/m3. The bio-char shows high HHV (23.87 MJ/kg) and high C content (62.47wt%) that can be applied as a solid fuel.
TRAN, Thinh Quoc,LY, Anh Hoang,NGUYEN, Dung Khanh Ngoc Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.9
Earnings management behavior is the use of accounting procedures, through accounting policies, to intentionally purposeful control in the provision of information to users. The purpose of this paper is to examine the relationship between ownership structure factors and earnings management behavior of 30 Vietnamese commercial banks. The paper uses the ordinary least square method to examine this relationship and employs time series data of 15 years from 2005 to 2019. The study also uses agency theory an asymmetric information theory. The authors examined six independent variables related to the ownership structure and these variables are typical of Vietnamese commercial banks. The results of the study show that the foreign ownership ratio is an opposite effect, while the ownership concentration variable has a positive effect on earnings management behavior of Vietnamese commercial banks. Based on that, the article proposes a number of policy suggestions for the State bank of Vietnam and Board of directors of commercial banks as well as investors to identify and to limit the earnings management behaviors of Vietnamese commercial banks. This contributes to ensuring information transparency as well as improving the quality of accounting information of Vietnamese commercial banks in the coming years.
Nguyen Doan Quoc Anh,Tran Hoang Quang Minh,Nguyen Huu,Khanh Nhan 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.5
Recently, high-power light-emitting diodes (LEDs) have attracted great attention on the study and made remarkable progress. In this paper, method for enhancing uniform white light of a multi-chip white light LED by adding silicon dioxides in the phosphor layer is presented. Firstly, theory of study by using Mie theory and Monte Carlo ray-tracing is proposed. And then simulation and experimental results by using package LightTools software are performed. The experimental results and theory have the same direction: 1) the angular color temperature in narrow angles is much higher than that in wider angles for the non-SiO2 case and 2) in significantly reducing CCT deviation of a multi-chip white light LED by adding silicon dioxides in the phosphor layer.
Nguyen Huu Khanh Nhan,Tran Hoang Quang Minh,Nguyen Doan Quoc Anh 보안공학연구지원센터 2016 International Journal of Database Theory and Appli Vol.9 No.4
In this paper, a novel solution and application of the red Y2O3:Eu3+ dopant phosphor for enhancing color rendering index to more 86 for multi-chip white LED lamps (MCW-LEDs), which have correlated color temperature (CCT) of 7700 K, 6600 K, 5600 K, are presented. Then the effect of the concentration of Y2O3:Eu3+ phosphor on the color rendering index (CRI) is simulated, analyzed and demonstrated. After that the lumen output of MCW-LEDs depended on concentration Y2O3:Eu3+ phosphor is discovered. The lumen output has a decrease tendency at large weight range due to the enhancement extinction coefficient, according to Mie-scattering theory. Simulation results provided important conclusions for selecting and developing the phosphor materials in MCW-LEDs manufacturing.
Hydrodeoxygenation of Spent Coffee Bio-oil from Fast Pyrolysis using HZSM-5 and Dolomite Catalysts
Park, Jeong Woo,Ly, Hoang Vu,Linh, Le Manh,Tran, Quoc Khanh,Kim, Seung-Soo,Kim, Jinsoo The Korean Society of Clean Technology 2019 청정기술 Vol.25 No.2
Spent coffee is one of biomass sources to be converted into bio-oil. However, the bio-oil should be further upgraded to achieve a higher quality bio-oil because of its high oxygen content. Deoxygenation under hydrotreating using different catalysts (catalytic hydrodeoxygenation; HDO) is considered as one of the promising methods for upgrading bio-oil from pyrolysis by removal of O-containing groups. In this study, the HDO of spent coffee bio-oil, which was collected from fast pyrolysis of spent coffee ($460^{\circ}C$, $2.0{\times}U_{mf}$), was carried out in an autoclave. The product yields were 72.16 ~ 96.76 wt% of bio-oil, 0 ~ 18.59 wt% of char, and 3.24 ~ 9.25 wt% of gas obtained in 30 min at temperatures between $250^{\circ}C$ and $350^{\circ}C$ and pressure in the range of 3 to 9 bar. The highest yield of bio-oil of 97.13% was achieved at $250^{\circ}C$ and 3 bar, with high selectivity of D-Allose. The carbon number distribution of the bio-oil was analyzed based on the concept of simulated distillation. The $C_{12}{\sim}C_{14}$ fraction increased from 22.98 wt% to 27.30 wt%, whereas the $C_{19}{\sim}C_{26}$ fraction decreased from 24.74 wt% to 17.18 wt% with increasing reaction time. Bio-oil yields were slightly decreased when the HZSM-5 catalyst and dolomite were used. The selectivity of CO was increased at the HZSM-5 catalyst and decreased at the dolomite.
Hydrodeoxygenation of Spent Coffee Bio-oil from Fast Pyrolysis using HZSM-5 and Dolomite Catalysts
Jeong Woo Park,Hoang Vu Ly,Le Manh Linh,Quoc Khanh Tran,Seung-Soo Kim,Jinsoo Kim 한국청정기술학회 2019 청정기술 Vol.25 No.2
Spent coffee is one of biomass sources to be converted into bio-oil. However, the bio-oil should be further upgraded to achieve a higher quality bio-oil because of its high oxygen content. Deoxygenation under hydrotreating using different catalysts (catalytic hydrodeoxygenation; HDO) is considered as one of the promising methods for upgrading bio-oil from pyrolysis by removal of O-containing groups. In this study, the HDO of spent coffee bio-oil, which was collected from fast pyrolysis of spent coffee (460 ℃, 2.0 × Umf), was carried out in an autoclave. The product yields were 72.16~96.76 wt% of bio-oil, 0~18.59 wt% of char, and 3.24~9.25 wt% of gas obtained in 30 min at temperatures between 250 ℃ and 350 ℃ and pressure in the range of 3 to 9 bar. The highest yield of bio-oil of 97.13% was achieved at 250 ℃ and 3 bar, with high selectivity of D-Allose. The carbon number distribution of the bio-oil was analyzed based on the concept of simulated distillation. The C12~C14 fraction increased from 22.98 wt% to 27.30 wt%, whereas the C19~C26 fraction decreased from 24,74 wt% to 17.18 wt% with increasing reaction time. Bio-oil yields were slightly decreased when the HZSM-5 catalyst and dolomite were used. The selectivity of CO was increased at the HZSM-5 catalyst and decreased at the dolomite.
Inverse MR and Dual-AMR Phenomena in Co/CoO/Ag/Co Sandwiches
Nguyen Anh Tuan,Luong Van Su,Hoang Quoc Khanh,Nguyen Anh Tue,Nguyen Thi Luyen 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.7
Band-form Co/CoO/Ag/Co sandwiches were prepared using radio-frequency magnetron sputtering. The sandwiches had rather thick Co (tCO = 63 nm) and Ag (tAg = 2 ÷ 65 nm) layers and a super-thin paramagnetic cobalt monoxide (CoO) layer (< 1 nm) inserted in the Co/Ag interface. The sandwiches exhibited anomalous magnetoresistance (MR) behavior depending on the tAg value. Inverse magnetoresistance (IMR) effect was observed only at thin tAg values of 2 nm and 6 nm, whereas the dual-anisotropic MR (dual-AMR) occurred at thicker tAg values of 12 nm, 25 nm and 65 nm. A superposition of the dual-AMR and the weak IMR effects was obtained at the thickest Ag layer of 65 nm. The origin of these anomalous MR behaviors was discussed to show the prominent role of the CoO layer and large thickness of the Co and Ag layers.