Pyrolysis characteristics and kinetics of microalgal aurantiochytrium sp. Krs101

( Vo The Ky ),( Hoang Vu Ly ),김진수,김승수,이은열 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.0

The pyrolysis characteristics and kinetics of Aurantiochytrium sp. KRS101 were investigated by means of a thermogravimetric analyzer and micro - tubing reactor, respectively. The apparent activation energy determined using Kissinger - Akahira - Sunose method was 118.54kJ/mol on average. The kinetic parameters of Aurantiochytrium sp. KRS101 pyrolysis in micro - tubing reactor were identified by applying nonlinear least-squares regression for the experimental data with reaction temperature ranging from 360 to 380°C. The results showed that the proposed lumped kinetic model is good in agreement with the experimental data. Activation energy for bio - oil formation from biomass was 71.16 kJ/mol, for gas formation from biomass and bio - oil were 157.08 and 164.68 kJ/mol, respectively. Simultaneously, the kinetic rate constants also indicated that the predominant reaction pathway was from B (biomass) to O (bio-oil), rather than from B (biomass) to G (gas).

Facile synthesis of Mo/Al₂O₃–TiO₂ catalysts using spray pyrolysis and their catalytic activity for hydrodeoxygenation

Vo, The Ky,Kim, Woo-Sik,Kim, Seung-Soo,Yoo, Kye Sang,Kim, Jinsoo Elsevier 2018 Energy conversion and management Vol.158 No.-

<P><B>Abstract</B></P> <P>In this study, spherical mixed oxides of Al<SUB>2</SUB>O<SUB>3</SUB> and TiO<SUB>2</SUB> supported molybdenum (Mo) catalysts, Mo/Al<SUB>2</SUB>O<SUB>3</SUB>−TiO<SUB>2</SUB>, were successfully prepared using a novel approach combining sol-gel and spray pyrolysis (SP) methods. First, both boehmite sol and titania sol were prepared by a sol-gel process, and then molybdate salt was dispersed in the sol mixture with the assistance of citric acid, followed by spray pyrolysis of the mixed precursor solution. Structural analyses of prepared catalysts showed that the dispersion of active sites was affected by the TiO<SUB>2</SUB> concentration in the Al<SUB>2</SUB>O<SUB>3</SUB>−TiO<SUB>2</SUB> mixed oxide support. The catalytic activities of reduced catalysts were investigated for hydrodeoxygenation (HDO) of palmitic acid, which is the main component of microalgae–derived biocrude. The results show that the Mo/Al<SUB>2</SUB>O<SUB>3</SUB>–TiO<SUB>2</SUB> catalysts exhibited excellent catalytic performance for the HDO of palmitic acid.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile synthesis of Mo/Al<SUB>2</SUB>O<SUB>3</SUB>−TiO<SUB>2</SUB> catalysts by combining sol-gel and spray pyrolysis methods. </LI> <LI> Spherical micron-sized catalysts with well–dispersed Mo species on the Al<SUB>2</SUB>O<SUB>3</SUB>−TiO<SUB>2</SUB> support. </LI> <LI> Effect of TiO<SUB>2</SUB> concentration in the mixed oxide support on the catalytic activity and selectivity of HDO. </LI> <LI> HDO conversion of 100% and hexadecane selectivity of 93.18% over Mo/(80Al−20Ti) catalyst. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Highly CO selective Cu(I)-doped MIL-100(Fe) adsorbent with high CO/CO₂ selectivity due to π complexation: Effects of Cu(I) loading and activation temperature

Vo, The Ky,Bae, Youn-Sang,Chang, Bong-Jun,Moon, Su-Young,Kim, Jeong-Hoon,Kim, Jinsoo Elsevier 2019 Microporous and mesoporous materials Vol.274 No.-

<P><B>Abstract</B></P> <P>Cu(I) doping of octahedral MIL-100(Fe) was successfully performed by means of impregnation and consequent reduction under vacuum conditions. Although MIL-100(Fe) adsorbed CO<SUB>2</SUB> better than CO, Cu(I)@MIL-100(Fe) showed selective CO adsorption compared to CO<SUB>2</SUB> owing to π complexation between CO and Cu(I). Effects of Cu(I) loading concentration, activation temperature, and adsorption temperature upon CO/CO<SUB>2</SUB> adsorption properties were systematically investigated. The adsorption behaviors of CO and CO<SUB>2</SUB> on MIL-100(Fe) and Cu(I)@MIL-100(Fe) were well described by the dual-site Langmuir–Freundlich (DSLF) model. Ideal adsorbed solution theory (IAST) was used to predict adsorption isotherms of equimolar CO and CO<SUB>2</SUB> mixtures and to predict CO/CO<SUB>2</SUB> selectivities as a function of bulk pressure. The obtained results showed that 45 wt% Cu(I)-doped MIL-100(Fe) had CO adsorption capacity of 3.10 mmol g<SUP>−1</SUP> and CO/CO<SUB>2</SUB> selectivity of 420 at 298 K and 1 bar. In addition, a large CO working capacity of 1.39 mmol g<SUP>−1</SUP> was observed for 45 wt% Cu(I)-doped MIL-100(Fe) in the pressure range of 10–100 kPa. Cu(I)-doped MIL-100(Fe) thus appears promising as an adsorbent material for effective CO/CO<SUB>2</SUB> separation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cu(I) was doped onto MIL-100(Fe) for highly selective adsorption of CO compared to CO<SUB>2</SUB>. </LI> <LI> The effects of metal loading, activation temperature, and adsorption temperature were investigated. </LI> <LI> Cu(I)@MIL-100(Fe) exhibited the high CO adsorption capacity of 3.10 mmol g<SUP>−1</SUP>. </LI> <LI> The IAST prediction of CO/CO<SUB>2</SUB> selectivity was 420 at 298 K and 1 bar. </LI> <LI> The CO working capacity of 1.39 mmol g<SUP>−1</SUP> was obtained for 45Cu(I)@MIL-100(Fe). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A general reaction network and kinetic model of the hydrothermal liquefaction of microalgae <i>Tetraselmis</i> sp.

Vo, The Ky,Kim, Seung-Soo,Ly, Hoang Vu,Lee, Eun Yeol,Lee, Choul-Gyun,Kim, Jinsoo Elsevier Applied Science 2017 Bioresource technology Vol.241 No.-

<P><B>Abstract</B></P> <P>In this work, the hydrothermal liquefaction (HTL) of microalgal <I>Tetraselmis</I> sp. was conducted at various reaction temperatures (250–350°C) and reaction times (10–60min). A general reaction network and a quantitative kinetic model were proposed for the HTL of microalgae. In this reaction network, the primary decomposition of lipids, proteins, and carbohydrates generated heavy oil (HO), light oil (LO), and aqueous-phase (AP) products. Then, reversible interconversions and further decomposition of these product fractions to produce gas product were followed. The model accurately captures the trends observed in the experimental data. Analyses of the kinetic parameters (reaction rate constants and activation energies) suggested the dominant reaction pathways as well as the contribution of the biochemical compositions to the bio-oil yield. Finally, the kinetic parameters calculated from the model were utilized to explore the parameter space in order to predict the liquefaction product yields depending on the reaction time and temperature.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Systematic study of HTL conditions using microalga <I>Tetraselmis</I> sp. </LI> <LI> A general reaction network and a quantitative kinetic model was applied for the HTL. </LI> <LI> Kinetic parameters and activation energies were determined for each reaction pathway. </LI> <LI> Model prediction of HTL product yields according to reaction time and temperature. </LI> </UL> </P>

Facile synthesis and characterization of γ-AlOOH/PVA composite granules for Cr(VI) adsorption

Vo, The Ky,Park, Hyung-Kyu,Nam, Chul-Woo,Kim, Sung-Don,Kim, Jinsoo Elsevier 2018 Journal of industrial and engineering chemistry Vol.60 No.-

<P><B>Abstract</B></P> <P>γ-AlOOH(boehmite)/PVA composite granules with high adsorption performance towards Cr(VI) were successfully synthesized by combining sol–gel and oil-drop methods. The γ-AlOOH/PVA sample with 35wt% PVA showed the highest Cr(IV) adsorption capacity of 35.91mg/g, which was much higher than that of the pure γ-AlOOH sample (17.08mg/g). The adsorption behaviors of Cr(VI) ions onto the γ-AlOOH and γ-AlOOH/PVA granules were well described by the pseudo-second-order kinetic model, and the adsorption mechanisms included electrostatic attraction, ligand exchange and redox reaction. The recovery of Cr(VI) under basic conditions was conducted to evaluate the practical utility of the synthesized composite granules.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Spherical γ-AlOOH/PVA composite granules were synthesized by sol–gel and oil-drop methods. </LI> <LI> The composite granules showed enhanced adsorption performance towards Cr(VI). </LI> <LI> A general adsorption mechanism of Cr(VI) onto the composite granules was proposed. </LI> <LI> Desorption experiment showed 79% recovery after 6h in a basic solution. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Pyrolysis characteristics and kinetics of microalgal <i>Aurantiochytrium</i> sp. KRS101

Vo, The Ky,Ly, Hoang Vu,Lee, Ok Kyung,Lee, Eun Yeol,Kim, Chul Ho,Seo, Jeong-Woo,Kim, Jinsoo,Kim, Seung-Soo Pergamon Press 2017 Energy Vol.118 No.-

<P><B>Abstract</B></P> <P>Microalgae have recently attracted tremendous attention as a possible feedstock for biofuel production. In this study, the pyrolysis characteristics and kinetics of <I>Aurantiochytrium</I> sp. KRS101, a kind of heterotrophic oleaginous microalgae, were investigated by means of thermogravimetric analysis and pyrolysis in a micro-tubing reactor. Most biochemical components of the microalgae (carbohydrates, proteins, and lipids) were decomposed between 150 and 600 °C at heating rates of 5–20 °C/min. Derivative thermogravimetry (DTG) curves were deconvoluted to more fully understand the separate decompositions of carbohydrates, proteins, and lipids. Experimental results of pyrolysis in the micro-tubing reactor were consistent with the predictions of the proposed lumped kinetic model, and the kinetic rate constants indicated that the predominant reaction pathway under the investigated pyrolysis conditions was from biomass to bio-oil rather than from biomass to gas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Systematic study and first attempt at pyrolysis of <I>Aurantiochytrium</I> sp. KRS101. </LI> <LI> Investigation of pyrolysis characteristics and kinetics by means of non-isothermal TGA and isothermal pyrolysis experiments. </LI> <LI> Study of the influence of pyrolysis conditions upon product yield distribution and composition. </LI> <LI> Application of a quantitative kinetic model and mechanism study for pyrolysis of microalgae. </LI> </UL> </P>

Genetically engineered hybrid poplars for the pyrolytic production of bio-oil: Pyrolysis characteristics and kinetics

Vo, The Ky,Cho, Jin-Seong,Kim, Seung-Soo,Ko, Jae-Heung,Kim, Jinsoo Pergamon 2017 Energy Conversion and Management Vol. No.

<P><B>Abstract</B></P> <P>In this study, hybrid poplars were genetically engineered to increase their biomass volume and change their biochemical composition to improve the pyrolytic production of bio-oil. Wild-type hybrid poplars (WT) and genetically engineered hybrid poplars (TP) were comparatively investigated with regard to their pyrolysis characteristics and kinetics via thermogravimetric analysis (TGA) and isothermal pyrolysis within a micro-tubing reactor. Model-free methods were used to determine the activation energy for the thermal decomposition of the WT and TP samples. The results showed that the activation energy of the WT sample was always greater than that of the TP sample at the same level of conversion. Isothermal pyrolysis experiments of the two biomass samples were performed at various temperatures (360–400°C) and durations (1–5min) using a micro−tubing reactor. The pyrolytic product distributions and chemical compositions were compared. The obtained results showed that the TP sample yielded a higher quantity of bio-oil compared to the WT sample under the same conditions with different chemical compositions. A reaction network and quantitative kinetic model were proposed for pyrolysis of the WT and TP samples. Kinetic parameters were obtained through an optimization function and used to explore the parameter space in order to predict product yields as a function of reaction time and temperature for both WT and TP feedstocks.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Genetic modification of hybrid poplars to improve the pyrolytic production of bio-oil. </LI> <LI> Pyrolysis characteristics and kinetics of wild-type and transgenic hybrid poplars. </LI> <LI> Lower activation energy and higher bio-oil yield after genetic modification. </LI> <LI> Application of a kinetic model to predict pyrolytic product yields. </LI> </UL> </P>

Pyrolysis characteristics and quantitative kinetic model of microalgae Tetralselmis sp.

The Ky Vo,김승수,김진수 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.6

Pyrolysis of microalgal biomass is a potential strategy for biofuel production. In this work, the pyrolysischaracteristics of microalgae, Tetraselmis sp., were systematically explored under isothermal and nonisothermal conditions. Analysis of nonisothermal decomposition of microalgae under nitrogen atmosphere at different heating rates (5,10, 15, and 20 oC min1) revealed that the conversion of microalgae was significantly affected by the heating rate andreached ~90% at approximately 500 oC. The mean activation energy for the pyrolysis of Tetraselmis sp. was calculatedusing model-free Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods. Microalgae pyrolysis in amicro-tubing reactor was performed at various temperatures (360-400 oC) and for different reaction times (0.5-3.0min). The results indicated that the maximum yield of biocrude (49.5 wt%) was attained during pyrolysis at 400 oCfor 2min. It was established that the chemical composition of the biocrude was significantly influenced by the pyrolysisconditions. A quantitative model was used to evaluate the composition of carbohydrates, proteins, and lipids in themicroalgae. This facilitated the determination of individual biochemical components in the pyrolytic products. Furthermore,the time- and temperature-dependent yields of the solid residue, biocrude, and gas were predicted, providingcritical information for microalgal pyrolysis design, control, and performance.

Facile synthesis of mesoporous Cr2O3 microspheres by spray pyrolysis and their photocatalytic activity: Effects of surfactant and pyrolysis temperature

The Ky Vo,김진수 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.3

Mesoporous Cr2O3 microspheres with improved pore structure were prepared by spray pyrolysis method. A precursor solution was nebulized into fine droplets containing chromium salt and cetyltrimethylammonium bromide (CTAB), which were then pyrolyzed to Cr2O3/Cx microspheres inside a tubular furnace, followed by post-heat treatment to eliminate the carbonaceous material. The produced Cr2O3 particles had a diameter of 0.5-1 m and their textural properties could be tuned by adjusting CTAB amount and pyrolysis temperature. The synthesized Cr2O3 microspheres had the highest surface area and pore volume of 52m2 g1 and 0.3 cm3 g1, respectively, which surpass those of Cr2O3 prepared using a conventional method such as thermal decomposition, hydrothermal reduction or wet chemical synthesis. The photocatalytic degradation of methyl orange dye (MO) was tested on the prepared Cr2O3 particles. It was determined that the spray pyrolysis-derived Cr2O3 exhibited greater photocatalytic activity than that of commercial TiO2 and Cr2O3 particles prepared by the thermal decomposition of chromium salt.

Facile synthesis of graphite oxide/MIL-101(Cr) hybrid composites for enhanced adsorption performance towards industrial toxic dyes

The Ky Vo,Tra Phuong Trinh,Van Cuong Nguyen,김진수 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.95 No.-

Graphite oxide (GrO), as a superb platform with highly dense arrays of atoms and abundantfunctionalities, can increase dispersive forces within metal–organic frameworks (MOFs), which providesa feasible strategy to control physicochemical properties of MOFs. In this study, a series of hybrid GrO/MIL-101(Cr) (GrO@MCr) nanocomposites were readily prepared via hydrothermal synthesis. Theprepared composites were applied to remove methyl orange (MO) and reactive blue 198 (RB198) asorganic pollutants from an aqueous solution. The surface area of GrO@MCr composite increased from2980 to 3540 m2 g 1 with increasing GrO loading amount from 0 to 6.0 wt.%. The highest adsorptioncapacities of MO (235 mg g 1) and RB198 (175 mg g 1) were obtained at 25 C and pH = 5.5 using 6 wt.%GrO loaded GrO@MCr composite; these values were 2.3 and 1.97 times higher than that of pristine MIL-101(Cr). The reusability and stability analyses showed that the sorption capacities of MO and RB198 ontothe fabricated GrO@MCr decreased to 89% and 86%, respectively, afterfive adsorption–desorption cycles. Moreover, the adsorption kinetics and adsorption isotherms were studied in detail to investigate theadsorption mechanism.