루테늄 촉매를 이용한 에탄의 수증기 개질 반응 Kinetics와 반응기 Sizing

신미 ( Mi Shin ),성민준 ( Min Jun Seong ),장지수 ( Ji Su Jang ),이경은 ( Kyung Eun Lee ),조정호 ( Jung Ho Cho ),이영철 ( Young Chul Lee ),박영권 ( Young Kwon Park ),전종기 ( Jong Ki Jeon ) 한국공업화학회 2012 공업화학 Vol.23 No.2

상업용 루테늄 촉매 상에서 에탄의 수증기 개질 반응에 대한 kinetics 데이터를 얻기 위하여 반응온도, 에탄의 분압, 수증기/에탄의 비 등을 변화시키면서 반응 실험을 수행하였다. Kinetics 데이터를 사용하여 Power rate law kinetic model과 Langmuir-Hinshelwood model의 parameter를 구하였다. 또한 kinetic model식을 적용하여 PRO/II를 이용한 공정 모사를 통해서 에탄의 수증기 개질 반응기 sizing을 수행하였다. 동일한 전환율을 얻기 위해서는 Power rate law model을 적용하였을 경우가 Langmuir-Hinshelwood model을 적용하였을 경우보다 개질 반응기의 부피가 더 큼을 알 수 있었다. Langmuir-Hinshelwood model에 의해 계산된 반응 속도가 반응 실험 결과에 의해 구해진 반응 속도와 더 잘 일치했기 때문에 Langmuir-Hinshelwood model을 적용하여 계산된 반응기의 크기가 실제 반응기 설계에 더 적절하다고 판단된다. In this study, kinetics data was obtained for steam reforming reaction of ethane over the commercial ruthenium catalyst. The variables of ethane steam reforming were the reaction temperature, partial pressure of ethane, and steam/ethane mole ratio. Parameters for the power rate law kinetic model and the Langmuir-Hinshelwood model were obtained from the kinetic data. Also, sizing of steam reforming reactor was performed by using PRO/II simulator. The reactor size calculated by the power rate law kinetic model was bigger than that of using the Langmuir-Hinshelwood model for the same conversion of ethane. Reactor size calculated by the Langmuir-Hinshelwood model seems to be more suitable for the reactor design because the Langmuir-Hinshelwood model was more consistent with the experimental results.

Flocculation Kinetics Using Fe (III) Coagulant in Advanced Water Treatment : The Effect of Sulfate Ion 황산이온의 영향

Kang, Lim Seok,Lee, Byung Hun 한국환경과학회 1995 한국환경과학회지 Vol.4 No.4

The study of flocculation kinetics is of fundamental interest in the field of water treatment, because rational study of the factors affecting the coagulation process should be based on the rate of particle growth. The effect of sulfate on flocculation kinetics were examined using ferric nitrate as a coagulant to coagulate kaolin clay in water under several experimental conditions. Both the particle size distribution data obtained from the AIA and the on-line measurement of turbidity fluctuation by the PDA were used to measure flocculation kinetics. Results show that sulfate ion added to the kaolin suspension played an important role in the flocculation process, not only improving flocculation kinetics at more acidic pH levels but also changing surface charge of particles. The kinetics of flocculation were improved mainly by the enhanced rate and extent of Fe(Ⅲ) precipitation attributed to the addition of sulfate, and thereby, better interparticle collision frequency, but little by the charge reductions resulting from the sulfate addition. The increase in sulfate concentration beyond 3×10 exp (-4)M (up to 2×10 exp (-3)M) did not induce further improvement in flocculation kinetics, although the higher concentrations of sulfate ion substantially increased the negative ZP value of particles.

Effect of biochar particle size on hydrophobic organic compound sorption kinetics: Applicability of using representative size

Kang, Seju,Jung, Jihyeun,Choe, Jong Kwon,Ok, Yong Sik,Choi, Yongju Elsevier 2018 Science of the Total Environment Vol.619 No.-

<P><B>Abstract</B></P> <P>Particle size of biochar may strongly affect the kinetics of hydrophobic organic compound (HOC) sorption. However, challenges exist in characterizing the effect of biochar particle size on the sorption kinetics because of the wide size range of biochar. The present study suggests a novel method to determine a representative value that can be used to show the dependence of HOC sorption kinetics to biochar particle size on the basis of an intra-particle diffusion model. Biochars derived from three different feedstocks are ground and sieved to obtain three daughter products each having different size distributions. Phenanthrene sorption kinetics to the biochars are well described by the intra-particle diffusion model with significantly greater sorption rates observed for finer grained biochars. The time to reach 95% of equilibrium for phenanthrene sorption to biochar is reduced from 4.6–17.9days for the original biochars to <1–4.6days for the powdered biochars with <125μm in size. A moderate linear correlation is found between the inverse square of the representative biochar particle radius obtained using particle size distribution analysis and the apparent phenanthrene sorption rates determined by the sorption kinetics experiments and normalized to account for the variation of the sorption rate-determining factors other than the biochar particle radius. The results suggest that the representative biochar particle radius reasonably describes the dependence of HOC sorption rates on biochar particle size.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Phenanthrene sorption rate strongly depends on biochar particle size. </LI> <LI> The sorption kinetics is well described by the intraparticle diffusion model. </LI> <LI> Harmonic intensity averaged radius (<I>R</I> <SUB> <I>z</I> </SUB>) is used as a representative biochar radius. </LI> <LI> <I>R</I> <SUB> <I>z</I> </SUB> describes the dependence of sorption kinetics on biochar particle size. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Determination of thermal decomposition kinetics of low grade coal employing thermogravimetric analysis

Prakash Parthasarathy,최항석,황재규,박훈채 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.6

The decomposition kinetics of low grade coals was studied and compared with the kinetics of higher grade coals using thermogravimetric analysis. The effect of atmospheres (air, O2 and N2) on coal decomposition kinetics was also investigated. Experiments were carried out under non-isothermal conditions from room temperature to 950 oC at a heating rate of 10 oC/min. Three kinetic models--multiple linear regression equation, unreacted shrinking core and continuous reaction--were used to determine the kinetic parameters of coal decomposition. From the kinetic parameters determined through the multiple linear regression equation, coal type and the atmosphere had an effect on coal decomposition kinetics. Also, there was some variation in the kinetic parameters of coal decomposition determined by the chosen kinetic models. However, the model employing multiple linear regressions yielded consistent results with respect to theoretical background. Under air, the order of the secondary decomposition of coal samples was found to be 0.88, 1.33, 1.69 and 1.52 for samples A, B, C and D, respectively. The order of the secondary decomposition of coal samples when operated under O2 was 1.09, 1.45, 2.36 and 1.81 for samples A, B, C and D, respectively. Under N2, the order of the secondary decomposition of coal samples was 0.72, 0.79, 1.15 and 1.02 for samples A, B, C and D, respectively.

Sorption and desorption kinetics of PAHs in coastal sediment

신원식,오상화,Qiliang Wang,송동익 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.1

Sorption and desorption kinetics of PAHs (naphthalene, phenanthrene and pyrene) in coastal sediment were investigated. Several kinetic models were used to analyze the kinetics: one-site mass transfer model (OSMTM),pseudo-first-order kinetic model (PFOKM), pseudo-second-order kinetic model (PSOKM), two compartment firstorder kinetic model (TCFOKM) and modified two compartment first-order kinetic model (MTCFOKM). Among the models, the MTCFOKM was the best in fitting both sorption and desorption kinetic data, and therefore could predict the most accurately. In MTCFOKM, the fast sorption fraction (f'1, s) increased with the hydrophobicity (Kow) of the PAHs,whereas the fast desorption fraction (f '1, d) decreased. The fast sorption rate constant (k'1, s) was much greater than the slow sorption rate constant (k'2, s). Effect of aging on the desorption kinetics was also analyzed. The f '1, d in MTCFOKM decreased but the slow desorption fraction (f '2, d) increased with aging, indicating that slow desorption is directly related to aging.

Kinetics of Horseradish Peroxidase-Catalyzed Nitration of Phenol in a Biphasic System

( Mingming Kong ),( Yang Zhang ),( Qida Li Runan Dong ),( Haijun Gao ) 한국미생물 · 생명공학회 2017 Journal of microbiology and biotechnology Vol.27 No.2

The use of peroxidase in the nitration of phenols is gaining interest as compared with traditional chemical reactions. We investigated the kinetic characteristics of phenol nitration catalyzed by horseradish peroxidase (HRP) in an aqueous-organic biphasic system using n-butanol as the organic solvent and NO₂ - and H₂O₂ as substrates. The reaction rate was mainly controlled by the reaction kinetics in the aqueous phase when appropriate agitation was used to enhance mass transfer in the biphasic system. The initial velocity of the reaction increased with increasing HRP concentration. Additionally, an increase in the substrate concentrations of phenol (0-2 mM in organic phase) or H₂O₂ (0-0.1 mM in aqueous phase) enhanced the nitration efficiency catalyzed by HRP. In contrast, high concentrations of organic solvent decreased the kinetic parameter V_max/K_m. No inhibition of enzyme activity was observed when the concentrations of phenol and H₂O₂ were at or below 10 mM and 0.1 mM, respectively. On the basis of the peroxidase catalytic mechanism, a double-substrate ping-pong kinetic model was established. The kinetic parameters were K_m ^H2O2 = 1.09 mM, K_m ^PhOH = 9.45 mM, and V_max = 0.196 mM/min. The proposed model was well fit to the data obtained from additional independent experiments under the suggested optimal synthesis conditions. The kinetic model developed in this paper lays a foundation for further comprehensive study of enzymatic nitration kinetics.

Kinetics of nitrification and acrylamide biodegradation by Enterobacter aerogenes and mixed culture bacteria in sequencing batch reactor wastewater treatment systems

Romsan Madmanang,Siriprapha Jangkorn,Jittima Charoenpanich,Tongchai Sriwiriyarat 대한환경공학회 2019 Environmental Engineering Research Vol.24 No.2

This study evaluated the kinetics of acrylamide (AM) biodegradation by mixed culture bacteria and Enterobacter aerogenes (E. aerogenes) in sequencing batch reactor (SBR) systems with AQUASIM and linear regression. The zero-order, first-order, and Monod kinetic models were used to evaluate the kinetic parameters of both autotrophic and heterotrophic nitrifications and both AM and chemical oxygen demand (COD) removals at different AM concentrations of 100, 200, 300, and 400 mg AM/L. The results revealed that both autotrophic and heterotrophic nitrifications and both AM and COD removals followed the Monod kinetics. High AM loadings resulted in the transformation of Monod kinetics to the first-order reaction for AM and COD removals as the results of the compositions of mixed substrates and the inhibition of the free ammonia nitrogen (FAN). The kinetic parameters indicated that E. aerogenes degraded AM and COD at higher rates than mixed culture bacteria. The FAN from the AM biodegradation increased both heterotrophic and autotrophic nitrification rates at the AM concentrations of 100-300 mg AM/L. At higher AM concentrations, the FAN accumulated in the SBR system inhibited the autotrophic nitrification of mixed culture bacteria. The accumulation of intracellular polyphosphate caused the heterotrophic nitrification of E. aerogenes to follow the first-order approximation.

Kinetic Data for Texture Changes of Foods During Thermal Processing

( Seung Hwan Lee ) 한국산업식품공학회 2017 산업 식품공학 Vol.21 No.4

To automate cooking processes, quantitative descriptions are needed on how quality parameters, such as texture change during heating. Understanding mechanical property changes in foods during thermal treatment due to changes in chemical composition or physical structure is important in the context of engineering models and in precise control of quality in general. Texture degradation of food materials has been studied widely and softening kinetic parameters have been reported in many studies. For a better understanding of kinetic parameters, applied kinetic models were investigated, then rate constants at 100°C and activation energy from previous kinetic studies were compared. The food materials are hardly classified into similar softening kinetics. The range of parameters is wide regardless of food types due to the complexity of food material, different testing methods, sample size, and geometry. Kinetic parameters are essential for optimal process design. For broad and reliable applications, kinetic parameters should be generated by a more consistent manner so that those of foods could be compared or grouped.

Dissolution Kinetics of Insoluble Chloride in MSWI Bottom Ash under Physical Condition with Submerged Particle via Accelerated Carbonation

( Namil Um ),( Jin-mo Yeon ),( Hee-sung Lee ),( Seong-kyeong Jeong ),( Min-young Choi ),( David Chung ),( Tae-wan Jeon ),( Sun-kyoung Shin ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-

This study investigated the dissolution kinetics of insoluble chloride in MSWI bottom ash under physical condition with submerged particle via accelerated carbonation. The water-to-solid ratio was controlled by the condition, 10 dm³/kg, and the CO₂ concentration was kept constant at 30%. The reaction temperature was varied from 20℃ to 40℃ for dissolution kinetics. The result of an XRD analysis indicated that insoluble chloride (Friedel’s Salt) in untreated bottom ash could combine with CO₂ to form mainly an amorphous Al-rich material and calcite. In addition, the theoretical model was fitted well to the kinetics data pertaining to the dissolved insoluble chloride as the carbonation process proceeded; in the theoretical model, the product-layer diffusion was predominant. The variation of the rate constant upon dissolution with the temperature obeyed the Arrhenius equation with activation energy of 24.61 kJ/mol.

Chemical kinetics of multi-component pyrotechnics and mechanistic deconvolution of variable activation energy

Ambekar, Anirudha,Yoh, Jack J. Elsevier 2019 Proceedings of the Combustion Institute Vol.37 No.3

<P>This study reports an experimental investigation into the chemical kinetics of several commercial pyrotechnic compositions. Differential Scanning Calorimetry (DSC) was utilized to elucidate the thermo-kinetic characteristics of four multicomponent pyrotechnic compositions. The combustion process of typical pyrotechnics is primarily driven by condensed phase reactions including processes such as phase change, decomposition, and oxidation. The multicomponent nature of practical pyrotechnics results in a particularly complex interaction between the components when heated. A thermo-kinetic study was performed to simulate the heating experienced by the pyrotechnics before the combustion zone. The physical processes occurring within these temperature limits provide important insight into the overall combustion rate. The non-isothermal DSC experimental technique combined with isoconversional methods, such as Friedman and Starink methods were utilized to evaluate the apparent chemical kinetics parameters for these propellants. The observations from the DSC study and isoconversional kinetic analysis provided an insight into the phenomenology of the combustion process of pyrotechnics. The problem of highly variable activation energy due to the presence of multiple reactions was addressed through a mechanistic deconvolution using nonlinear regression technique. The study confirmed the prominence of oxidizer decomposition on overall combustion reaction kinetics.</P>