Journal articles: 'Langmuir-Hinshelwood equation'

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Słomkiewicz, Piotr M. "Determination of the Langmuir–Hinshelwood kinetic equation of synthesis of ethers." Applied Catalysis A: General 269, no. 1-2 (August 2004): 33–42. http://dx.doi.org/10.1016/j.apcata.2004.03.055.

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Net, S., L. Nieto-Gligorovski, S. Gligorovski, and H. Wortham. "Heterogeneous ozonation kinetics of 4-phenoxyphenol in presence of photosensitizer." Atmospheric Chemistry and Physics Discussions 9, no. 5 (October 15, 2009): 21647–68. http://dx.doi.org/10.5194/acpd-9-21647-2009.

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Abstract. In this work we have quantitatively measured the degradation of 4-phenoxyphenol adsorbed on silica particles following oxidative processing by gas-phase ozone. This was performed under dark conditions and in presence of 4-carboxybenzophenone under simulated sunlight irradiation of the particles surface. At mixing ratio of 60 ppb which corresponds to strongly ozone polluted areas, the first order decay of 4-phenoxyphenol is k1=9.95×10−6 s−1. At very high ozone mixing ratio of 6 ppm the first order rate constants for 4-phenoxyphenol degradation were the following: k1=2.86×10−5 s−1 under dark conditions and k1=5.58×10−5 s−1 in presence of photosensitizer (4-carboxybenzophenone) under light illumination of the particles surface. In both cases the experimental data do follow the modified Langmuir-Hinshelwood equation for surface reactions. Langmuir-Hinshelwood and Langmuir-Rideal mechanisms are also discussed along with the experimental results. Most importantly, the quantities of the oligomers such as 2-(4-Phenoxyphenoxy)-4-phenoxyphenol and 4-[4-(4-Phenoxyphenoxy)phenoxy]phenol formed during the heterogeneous ozonolysis of adsorbed 4-phenoxyphenol were much higher under solar light irradiation of the surface in comparison to the dark conditions.

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Net, S., L. Nieto-Gligorovski, S. Gligorovski, and H. Wortham. "Heterogeneous ozonation kinetics of 4-phenoxyphenol in the presence of photosensitizer." Atmospheric Chemistry and Physics 10, no. 4 (February 15, 2010): 1545–54. http://dx.doi.org/10.5194/acp-10-1545-2010.

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Abstract. In this work we have quantitatively measured the degradation of 4-phenoxyphenol adsorbed on silica particles following oxidative processing by gas-phase ozone. This was performed under dark conditions and in the presence of 4-carboxybenzophenone under simulated sunlight irradiation of the particles surface. At the mixing ratio of 60 ppb which corresponds to strongly polluted ozone areas, the first order of decay of 4-phenoxyphenol is k1=9.95×10−6 s−1. At a very high ozone mixing ratio of 6 ppm the first order rate constants for 4-phenoxyphenol degradation were the following: k1=2.86×10−5 s−1 under dark conditions and k1=5.58×10−5 s−1 in the presence of photosensitizer (4-carboxybenzophenone) under light illumination of the particles surface. In both cases, the experimental data follow the modified Langmuir-Hinshelwood equation for surface reactions. The Langmuir-Hinshelwood and Langmuir-Rideal mechanisms for bimolecular surface reactions are also discussed along with the experimental results. Most importantly, the quantities of the oligomers such as 2-(4-Phenoxyphenoxy)-4-phenoxyphenol and 4-[4-(4-Phenoxyphenoxy)phenoxy]phenol formed during the heterogeneous ozonolysis of adsorbed 4-phenoxyphenol were much higher under solar light irradiation of the surface in comparison to the dark conditions.

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Hejtmánková, Alena, Karel Jeřábek, and Karel Setínek. "Kinetics of methyl tert. butyl ether synthesis in gaseous phase." Collection of Czechoslovak Chemical Communications 55, no. 4 (1990): 1033–37. http://dx.doi.org/10.1135/cccc19901033.

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Kinetics of methyl tert.butyl ether synthesis from methanol and isobutene was measured in gaseous phase at 85 °C and atmospheric pressure on macroreticular ion exchanger catalyst containing strongly acidic functional groups SO3H and on the same catalyst partially neutralized by sodium and iron ions. The form of the best Langmuir-Hinshelwood type kinetic equation suggests absorption of the reactants in the polymer mass causing ìswellingî of it and influencing the accessibility of active sites by the reactants. Neutralization of the catalyst by metal ions suppresses this effect.

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Bandyopadhyay, Debajyoti, and Ahindra Ghosh. "Validity of rate equation based on Langmuir-Hinshelwood mechanism for gasification of carbon - a reappraisal." Steel Research 67, no. 3 (March 1996): 79–86. http://dx.doi.org/10.1002/srin.199605462.

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Urmès, Caroline, Jean-Marc Schweitzer, Amandine Cabiac, and Yves Schuurman. "Kinetic Study of the Selective Hydrogenation of Acetylene over Supported Palladium under Tail-End Conditions." Catalysts 9, no. 2 (February 14, 2019): 180. http://dx.doi.org/10.3390/catal9020180.

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The kinetics of the selective hydrogenation of acetylene in the presence of an excess of ethylene has been studied over a 0.05 wt. % Pd/α-Al2O3 catalyst. The experimental reaction conditions were chosen to operate under intrinsic kinetic conditions, free from heat and mass transfer limitations. The data could be described adequately by a Langmuir–Hinshelwood rate-equation based on a series of sequential hydrogen additions according to the Horiuti–Polanyi mechanism. The mechanism involves a single active site on which both the conversion of acetylene and ethylene take place.

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Xu, Huan Yan, Xue Li, Yan Li, Ping Li, and Wei Chao Liu. "Photocatalytic Degradation of Methyl Orange by TiO₂/Schorl Photocatalyst: Kinetics and Thermodynamics." Applied Mechanics and Materials 713-715 (January 2015): 2789–92. http://dx.doi.org/10.4028/www.scientific.net/amm.713-715.2789.

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An active dye, Methyl Orange (MO) was employed as the target pollutant to evaluate the photocatalytic activity of TiO2/schorl composite and the kinetics and thermodynamics of this process was emphasized in this work. Langmuir–Hinshelwood kinetic model was employed for the kinetic studies and the results revealed that the process of MO photocatalytic discoloration by TiO2/schorl composite followed one order reaction kinetic equation under different conditions. The reaction rate constant (k) increased with initial MO concentration decreasing. When the catalyst dosage or solution pH increased,kvalues increased and then decreased. The possible reasons for these phenomena were discussed. Finally, the thermodynamic parameters ΔG, ΔH, ΔSwere obtained by the classical Van't Hoff equation.

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Frontistis, Z., M. Papadaki, and D. Mantzavinos. "Modelling of sonochemical processes in water treatment." Water Science and Technology 55, no. 12 (June 1, 2007): 47–52. http://dx.doi.org/10.2166/wst.2007.376.

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The mechanisms and kinetics of the sonochemical degradation of organic molecules in water are relatively complex since several parameters such as physicochemical properties, substrate concentration, water matrix, reactor geometry, ultrasound properties (frequency, power, emission system) all typically affect the process. In this work, simple kinetic models were used to predict the degradation of 2-chlorophenol and sodium dodecylbenzene sulphonate in aqueous solutions and verified against experimental data taken from previous studies. A pseudo-first order kinetic expression can adequately describe the degradation of the phenolic substrate, while a heterogeneous model based on the Langmuir-Hinshelwood equation is suitable for the surfactant degradation.

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Du, Qingyang, Huijun Xu, Zhihao Yu, Baoliang Liu, Qian Peng, Dongsheng Li, Tao Ben, and Huaqin Yu. "Study on the Preparation of Zn-Doped NaA Molecular Sieve and Its Photocatalytic Performance." Journal of Physics: Conference Series 2168, no. 1 (January 1, 2022): 012026. http://dx.doi.org/10.1088/1742-6596/2168/1/012026.

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Abstract Zn-doped NaA molecular sieves were prepared by hydrothermal method using zinc nitrate, sodium metaaluminate, silica sol, etc. as raw materials. The samples were characterized by XRD, SEM, FT-IR, etc., using 300W xenon lamp as the light source. Rhodamine B (RhB) was used as the target degradant for photocatalytic experiments for its photocatalytic activity. The results showed that zinc ion doping increased the number of active sites on the NaA molecular sieve, effectively reduced the photoelectron-hole recombination probability in the molecular sieve, and improved the photocatalytic activity. The degradation rate of rhodamine B was 50.8% after 2 hours of light exposure, and its photocatalytic process complied with the Langmuir-Hinshelwood first-order kinetic equation.

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Lozano-Morales, S., Graciela Morales, Miguel López Zavala, Augusto Arce-Sarria, and Fiderman Machuca-Martínez. "Photocatalytic Treatment of Paracetamol Using TiO2 Nanotubes: Effect of pH." Processes 7, no. 6 (May 29, 2019): 319. http://dx.doi.org/10.3390/pr7060319.

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Pharmaceuticals are considered among the group of emerging contaminants. Paracetamol is a moderate painkiller, which has been detected in ground and surface water. Photodegradation of paracetamol at a wavelength of radiation of 254 nm with TiO2 nanotubes was studied by UV-spectroscopy, HPLC and measurement of the potential zeta in dependence of the solution pH. The efficiency of the photodegradation of paracetamol (20 mg L−1) was 99% after 100 min exposure. Application of the Langmuir-Hinshelwood equation allowed the evaluation of the rate constant. Non-organic by-products were detected under the conditions of the chromatographic analysis. The photoreaction was faster at pH 6.5, a value at which adsorption was favored, leading to higher efficiency.

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Orudzhev, Farid F., F. G. Gasanova, A. B. Isaev, and N. S. Shabanov. "Influence of Oxygen Pressure to Photocatalytic Oxidation of Phenol on CuO/TiO₂." Materials Science Forum 855 (May 2016): 139–46. http://dx.doi.org/10.4028/www.scientific.net/msf.855.139.

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The photocatalytic oxidation of phenol on the composite copper oxide (II) modified titania photocatalyst (CuO/TiO2) with sunlight irradiation at high oxygen pressure are studied. The photocatalyst characterized by Scanning electron microscopy (SEM), UV-Visible Diffuse Reflectance spectroscopy (UV-DRS), Surface area analysis, and X-ray diffractometry (XRD). The composite photocatalyst based on the anatase includes 3% copper oxide (II). The CuO/TiO2 photocatalytic activity was investigated of phenol oxidation with sunlight irradiation at high oxygen pressure. The photocatalytic oxidation of phenol described Langmuir-Hinshelwood equation and calculated its parameters. With the increasing, the oxygen pressure the rate of phenol photocatalytic oxidation also increases. The quantum yield of the photocatalytic phenol oxidation at high oxygen pressure on the CuO/TiO2 composite photocatalyst are obtained.

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Sheidaei, Behnaz, and Mohammad A. Behnajady. "Mathematical Kinetic Modelling and Representing Design Equation for a Packed Photoreactor with Immobilised TiO2-P25 Nanoparticles on Glass Beads in the Removal of C.I. Acid Orange 7." Chemical and Process Engineering 36, no. 2 (June 1, 2015): 125–33. http://dx.doi.org/10.1515/cpe-2015-0010.

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In this work, a design equation was presented for a batch-recirculated photoreactor composed of a packed bed reactor (PBR) with immobilised TiO2-P25 nanoparticle thin films on glass beads, and a continuous-flow stirred tank (CFST). The photoreactor was studied in order to remove C.I. Acid Orange 7 (AO7), a monoazo anionic dye from textile industry, by means of UV/TiO2 process. The effect of different operational parameters such as the initial concentration of contaminant, the volume of solution in CFST, the volumetric flow rate of liquid, and the power of light source in the removal efficiency were examined. A rate equation for the removal of AO7 is obtained by mathematical kinetic modelling. The results of reaction kinetic analysis indicate the conformity of removal kinetics with Langmuir-Hinshelwood model (kL-H = 0.74 mg L-1 min-1, Kads = 0.081 mg-1 L). The represented design equation obtained from mathematical kinetic modelling can properly predict the removal rate constant of the contaminant under different operational conditions (R2 = 0.963). Thus the calculated and experimental results are in good agreement with each other.

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Nuryono, Nuryono, V. V. H. Susanti, and Narsito Narsito. "KINETIC STUDY ON ADSORPTION OF CHROMIUM(lIl) TO DIATOMACEOUS EARTH PRE-TREATED WITH SULFURIC AND HYDROCHLORIC ACIDS." Indonesian Journal of Chemistry 3, no. 1 (June 7, 2010): 32–38. http://dx.doi.org/10.22146/ijc.21903.

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In this research, the effect of Sangiran diatomaceous earth pre-treatment with sulfuric acid (H2SO4) and hydrochloric acid (HCl) on the kinetics of adsorption for Cr(III) in aqueous solution has been studied. The research has been carried out by mixing an amount of diatomeaeous earth with HCl or H2SO4 in various concentrations for two hours at temperature of 150 - 200°C. The mixture was washed with water until neutral, and the residue was dried at 70°C for four hours. The result then was used as adsorbent. Adsorption was carried out by mixing an amount of adsorbent with Cr(III) solution in various contact times. Ion adsorbed was determined by analyzing filtrate using atomic absorption spectrophotometry. The effect of pre-treatment on adsorption kinetics was evaluated based on kinetic parameters, i.e. constant of adsorption rate by using Langmuir-Hinshelwood kinetics and using two-process kinetics (fast and slow processes). Adsorption kinetics calculated using LH equation gave negative value for adsorption rate constant of zero order (k0). On the other words, the LH kinetics might not be applied for adsorption of Cr(III) to diatomaceous earth adsorbent. Results of kinetics study approached using two processes (fast and slow) showed that adsorption of Cr(III) occurred in two processes with rate constant of fast adsorption, kc, 0.041/min, rate constant of slow adsorption, kl, 0.0089/min, and of slow desorption, k'l, 0.089/menit. Pre-treatment with HCl up to 10 M decreased either kc, kl or k'l, while pre-treatment with H2SO4 1M increased kc to 0.061/min, decreased kl to 0.00424 and k'l to 0.0139/min. On pre-treatment with H2SO4 higher than 6 M significantly decreased three constants above. Based on the Gibbs energy change (4.31 - 6.79 kJ/mole) showed that adsorption involved physical interaction. Keywords: adsorption, chromium, diatomaceous earth, kinetics, Langmuir-Hinshelwood

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Jia, Ruo Kun, Yang Yu, Song Zhu Lin, and Na Bai. "Kinetics of TiO₂/Polyurethane Films for Degradation of Organic Pollutants in Water." Advanced Materials Research 610-613 (December 2012): 1560–64. http://dx.doi.org/10.4028/www.scientific.net/amr.610-613.1560.

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In this paper,TiO2was prepared by the sol-gel Method,which has high activity and oxidation abilities .The polyurethane is famous for its transmittance and film forming properties,we use polyurethane and titanium dioxide to produce TiO2/polyurethane films. In this paper, phenolic wastewater was considered as the research object,Discussed photocatalytic properties and photocatalytic reaction kinetics model of TiO2/polyurethane film at 253.7nm UV irradiation.The results show that degradation rate of phenolic wastewater approached to 14.6mg.L-1.h-1.m2-1 when Ti02dosage of 60 mg/L,reaction time of 240 min,Phenolic wastewater initial concentration of 10mg/L and pH5.0.The dosage of TiO2,wastewater initial concentration and pH have significant influence on apparent first-order rate constants of photocatalytic degradation,Reaction kinetics of photocatalytic degradation to phenolic wastewater accordances with the quasi-one grade equation of Langmuir-Hinshelwood.

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Li, Jian, Tuqiao Zhang, and Miaomiao Ye. "Heterogeneous oxidation of diclofenac in the presence of α-MnO2 nanorods: influence of operating factors and mechanism." Water Science and Technology 71, no. 9 (March 5, 2015): 1340–46. http://dx.doi.org/10.2166/wst.2015.068.

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Diclofenac (DCF), one of the pharmaceutical and personal care products that has been widely detected in water, was selected as a model pollutant to evaluate the oxidation activity of α-MnO2 nanorods. The results showed that the heterogeneous oxidation process is highly pH dependent, with higher degradation efficiency at lower pH values. The complete removal of DCF was obtained within 80 min at the solution pH value of 2.5. The oxidation kinetics of DCF can be modeled by Langmuir–Hinshelwood equation (R2 > 0.999). The effects of various operating parameters, including initial solution pH, α-MnO2 dosage, anions, and cations, on the oxidation efficiency were investigated in detail. A possible reaction pathway for DCF was proposed. In addition, it was demonstrated that the α-MnO2 nanorods can be recycled without decreasing their oxidation activity after 10 cycles.

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Jiaying, Zhang. "Kinetic study of carbon monoxide methanation over mesoporous Ni-Mo catalyst prepared by a hydrothermal method." Progress in Reaction Kinetics and Mechanism 44, no. 1 (February 2019): 3–17. http://dx.doi.org/10.1177/1468678319825692.

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The kinetics of carbon monoxide methanation over Ni-Mo-SiO2 catalyst were studied. The model was developed based on catalyst tests carried out in a fixed-bed reactor at a reaction temperature varied from 300 °C to 450 °C under a pressure from 0.1 to 1.5 MPa with a weight hourly space velocity of 60,000 mL h−1 g−1. An orthogonal design method was adopted to select test points with temperature, pressure, and feed compositions as factors. Based on the experimental observations, a Langmuir–Hinshelwood equation kinetic model was formulated and its parameters were estimated by fitting the experimental data implemented in MATLAB. The activation energy for the formation of CH4 was 45.4 kJ mol−1 and comparing the experimental and model-predicted data showed that the proposed model gives a reasonable fit with an average absolute relative deviation of ±9.8%.

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Behnajady, Mohammad A., Sadegh Amirmohammadi-Sorkhabi, Nasser Modirshahla, and Mohammad Shokri. "Investigation of the efficiency of a tubular continuous-flow photoreactor with supported titanium dioxide nanoparticles in the removal of 4-nitrophenol: operational parameters, kinetics analysis and mineralization studies." Water Science and Technology 64, no. 1 (July 1, 2011): 56–62. http://dx.doi.org/10.2166/wst.2011.666.

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In this study, to investigate the application of heterogeneous photocatalysis in the removal of organic contaminants from aqueous media a novel tubular continuous-flow photoreactor with supported TiO2-P25 on glass plates was designed and constructed. The photoreactor comprises six quartz tubes and a UV lamp which was placed in the center of the quartz tubes. 4-nitrophenol (4-NP) as a most refractory pollutant was chosen as a probe pollutant to examine the photoreactor efficiency for environmental cleaning applications. Results of experiments show that the removal efficiency of 4-NP in this photoreactor is a function of photoreactor length, gas and liquid flow rates and 4-NP initial concentration. Kinetics analysis indicates that degradation of 4-NP in continuous-mode can be modeled with the Langmuir–Hinshelwood (L–H) model (kL–H = 1.5 mg L−1 min−1, Kads = 0.11 mg−1 L). A design equation was obtained with a combination of L–H modified equation and tubular reactor design equation. This equation can be used for estimation of 4-NP concentration in different photoreactor lengths under various operational parameters. Mineralization study was followed through total organic carbon (TOC) analysis and measurement of nitrite and nitrate as final degradation products.

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Constantin, Mirela Alina, Florentina Laura Chiriac, Stefania Gheorghe, and Lucian Alexandru Constantin. "Degradation of Carbamazepine from Aqueous Solutions via TiO2-Assisted Photo Catalyze." Toxics 10, no. 4 (March 31, 2022): 168. http://dx.doi.org/10.3390/toxics10040168.

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Photocatalytic degradation of carbamazepine (CBZ) from spiked aqueous solutions, via a UV/TiO2 system, was investigated, and the optimum photocatalyst type (P25 Degussa) and dose (500 mg/L), as well as irradiation time (45 min), were established. The degradation process kinetics was studied, and a degradation rate constant of 3.14 × 10−5 M min−1 was calculated for CBZ, using the Langmuir–Hinshelwood equation. Experiments performed in the presence of scavengers showed that the main reactive species involved in the degradation process are holes and free hydroxyl radicals; superoxide radicals also play a role in CBZ degradation. Eight transformation products of CBZ were identified, and a possible degradation pathway, consisting of four routes, was proposed. Toxicity and genotoxicity tests were also performed for both untreated and treated CBZ solutions, proving that the use of a UV/TiO2 system represents a suitable treatment approach for aqueous systems with CBZ content.

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Zhong, Junbo, Hong Zhao, Di Ma, An Lian, Minjiao Li, Bin Xie, and Jianzhang Li. "RETRACTED ARTICLE: Kinetic and anion degradation products study on photocatalytic degradation of reactive orange 5 solution with phosphotungstic acid." Open Chemistry 6, no. 1 (March 1, 2008): 99–105. http://dx.doi.org/10.2478/s11532-007-0064-2.

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AbstractIncreasing environmental pollution caused by toxic dyes is a matter of great concern due to their hazardous nature. So it is crucial to develop processes which can destroy these dyes effectively. It has been generally agreed that reactive orange 5 (KGN) can be effectively degraded in aerated phosphotungstic acid (HPA) in a homogeneous reaction system using near-UV irradiation. In this paper, photocatalytic degradation of reactive orange 5 solutions with phosphotungstic acid was investigated, especially more attention was paid to the kinetic model and the anion degradation products. The results revealed that the photocatalytic degradation reaction of KGN with HPA in a homogenous solution can be described by Langmuir-Hinshelwood equation and Langmuir-Hinshewood kinetic model described it well. The reaction manifested the first order with lower concentration(⩽30 mg L−1) with the limiting rate constant and the adsorption constant in this case being 0.8098 mg L−1 min−1 and 4.359 10−2 L mg−1, respectively. The degradation mechanism of KGN with HPA is different from that with TiO2, the anion products of the two reaction systems are the same. The difference in degradation mechanism of KGN with HPA from that with TiO2 is caused by the nature of the photocatalyst.

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Chan, A. H. C., J. F. Porter, J. P. Barford, and C. K. Chan. "Photocatalytic thin film cascade reactor for treatment of organic compounds in wastewater." Water Science and Technology 44, no. 5 (September 1, 2001): 187–95. http://dx.doi.org/10.2166/wst.2001.0283.

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The photocatalytic oxidation of benzoic acid was investigated in a pilot scale-cascade photoreactor. The photoreactor consists of an array of UV lamps (40 W, 365 nm) illuminating a cascade of three inclined 316 stainless steel plates, on which titanium dioxide (TiO2) was immobilized by electrophoretic deposition. The percentage removal of total organic carbon (TOC) of liquid samples was determined. The photocatalytic process was affected by several operating parameters. Increasing the solution temperature was found to reduce the dissolved oxygen (DO) level and to decrease the rate of the degradation process. The Langmuir-Hinshelwood equation was found to be accurate for modeling the degradation of benzoic acid with initial concentrations of 50 ppm, 75 ppm and 100 ppm. The rate of removal of TOC was positively affected by UV light intensity, but appeared to be independent of solution flowrate in the range examined. Control experiments confirmed that the effects of adsorption of the solute onto the TiO2 catalysts and photolytic degradation were negligible.

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Alejandro-Martín, Serguei, Héctor Valdés, and Claudio A. Zaror. "Catalytic Ozonation of Toluene over Acidic Surface Transformed Natural Zeolite: A Dual-Site Reaction Mechanism and Kinetic Approach." Catalysts 11, no. 8 (August 10, 2021): 958. http://dx.doi.org/10.3390/catal11080958.

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Volatile organic compounds (VOCs) are responsible for damage to health due to their carcinogenic effects. Catalytic ozonation using zeolite appears as a valuable process to eliminate VOCs from industrial emissions at room temperature. For full-scale application of this new abatement technology, an intrinsic reaction rate equation is needed for an effective process design and scale-up. Results obtained here provide a mechanistic approach during the initial stage of catalytic ozonation of toluene using an acidic surface transformed natural zeolite. In particular, the contribution of Lewis and Brønsted acid sites on the surface reaction mechanism and overall kinetic rate are identified through experimental data. The least-squares non-linear regression method allows the rate-determining step to be established, following a Langmuir–Hinshelwood surface reaction approximation. Experimental evidence suggest that ozone is adsorbed and decomposed at Lewis acid sites, forming active atomic oxygen that leads to the oxidation of adsorbed toluene at Brønsted acid sites.

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Ryzha, Iryna. "Modeling of carbon monoxide oxidation on the catalytic surface in the two-dimensional case." Physico-mathematical modelling and informational technologies, no. 26 (December 30, 2017): 83–89. http://dx.doi.org/10.15407/fmmit2017.26.083.

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A two-dimensional model of carbon monoxide (CO) catalytic oxidation on a platinum (Pt) surface for the Langmuir-Hinshelwood mechanism is investigated. The adsorbate-driven (1×1)-(1×2) structural phase transition of Pt(110) and the formation of new crystal planes on the catalytic surface (faceting) as well as the effect of the substrate temperature are taken into account. It is shown that the stability region for CO oxidation reaction changes when two dimensions are taken into account. Similarly to the one-dimensional case, the reaction of CO oxidation on Pt-catalyst surface is periodic in the stability region. Mixed-mode oscillations (MMO) for CO and oxygen (O) surface coverages as well as the fraction of the surface in the non-reconstructed (1×1)-state were found. Such behavior cannot be predicted by one-dimensional models when the equation for the change of degree of faceting is not taken into account.

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Gulková, Daniela, and Miloš Kraus. "Dehydrogenation of Substituted Alcohols to Aldehydes on Zinc Oxide-Chromium Oxide Catalysts." Collection of Czechoslovak Chemical Communications 57, no. 11 (1992): 2215–26. http://dx.doi.org/10.1135/cccc19922215.

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Sixteen primary alcohols of the structure RCH2OH (R = CH3, C2H5, (CH3)2CH, (CH3)3CCH2, HOCH2, CH3OCH2, C6H5, C6H5CH2, C6H5OCH2, ClCH2, BrCH2, F3C, CNCH2, (CH3)2NCH2, (C2H5)2NCH2 and tetrahydrofurfuryl) were explored for the possibility of obtaining the corresponding aldehydes by dehydrogenation on solid catalysts. Various catalysts were tested and two zinc oxide-chromium oxide catalysts were selected for further work because their activity and selectivity was satisfactory; moreover, the selectivity could be improved by addition of sodium into the catalysts and of water into the feed. The reaction was performed in the temperature range 250-450 °C and at atmospheric pressure. 2-Chloroethanol, 2-bromoethanol, ethylene glycol, 2-cyanoethanol and 2-(N,N-diethylamino)ethanol decomposed and deactivated the catalyst. The other alcohols were studied from the point of kinetics of dehydrogenation, which was described by a Langmuir-Hinshelwood type rate equation (3), and of substituent effects on rate, which were correlated by Taft equation (1) with the slope ρ = -1.46. The preparative value of catalytic dehydrogenation for obtaining substituted aldehydes was confirmed by prolonged runs and isolation of the aldehydic product by distillation using as the feeds 2-methoxyethanol and 2-(N,N-dimethylamino)ethanol, respectively.

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Ghosh, Malini, Pankaj Chowdhury, and Ajay K. Ray. "Photocatalytic Activity of Aeroxide TiO2 Sensitized by Natural Dye Extracted from Mangosteen Peel." Catalysts 10, no. 8 (August 10, 2020): 917. http://dx.doi.org/10.3390/catal10080917.

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Natural dye sensitizers are environment-friendly and inexpensive substances that could be used for photocatalytic decontamination of organic pollutants. In this study, a natural dye extracted from mangosteen peel, containing a significant amount of anthocyanin dye, has been successfully employed to sensitize aeroxide TiO2 to lower its bandgap, thereby making the process visible sunlight-driven. We have demonstrated the photocatalytic activity of mangosteen dye-sensitized-TiO2 (MS-TiO2) under visible solar light by studying the degradation of methylene blue (MB), a well-studied model compound. A multivariate parametric study was performed using factorial design methodology with three factors—pH, MS-TiO2 dosage, and visible light intensity. The study indicated that pH and MS-TiO2 dosage are the two most dominant factors for MB degradation under visible solar light. The kinetic rate constant and adsorption equilibrium constant were determined, and a Langmuir-Hinshelwood-type equation was proposed to describe MB degradation on MS-TiO2 under visible solar light. Apparent quantum yield was also reported for the MS-TiO2 photocatalyst at optimum experimental conditions.

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Sadr Manuchehri, Qazale, Navid Assi, Sanaz Pourmand, Maher Darwish, and Amir Pakzad. "Photocatalytic Activity of ZnO Nanoparticles Prepared by a Microwave Method in Ethylene Glycol and Polyethylene Glycol Media: A Comparative Study." Journal of Nano Research 42 (July 2016): 53–64. http://dx.doi.org/10.4028/www.scientific.net/jnanor.42.53.

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Zinc oxide nanoparticles have been synthesized by a sol-gel microwave assisted method using either ethylene glycol (ZnO-EG) or poly ethylene glycol ethanolic solution (ZnO-PEG) as dispersing media. The nanoparticles were characterized by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier transform infrared. X-ray analysis revealed a hexagonal phase structure of both zinc oxides. The average crystallite size calculated from Scherrer equation was 27 nm and 53 nm in good agreement with 24 nm and 55 nm microscopic results for ZnO-EG and ZnO-PEG, respectively. The catalytic activity of the as-prepared nanoparticles was compared by the photodegradation of 2-nitrophenol under UVC. The effect of various parameters such as pH, catalyst weight, and pollutant concentration on the percent degradation was investigated. Best optimization was pH=7, 0.06g of nanoparticles weight, and 10 mg.L-1 pollutant concentration. Furthermore, pseudo first order kinetic based on Langmuir–Hinshelwood (L–H) model was proposed for degradation reactions and experimental data were in good agreement with this model.

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Ling, Chin Mei, Abdul Rahman Mohamed, and Subhash Bhatia. "Photodegradation Kinetics of Phenol and Methylene Blue Dye Present in Water Stream Over Immobilized Film Ti02 Catalyst." ASEAN Journal of Chemical Engineering 5, no. 2 (December 1, 2005): 131. http://dx.doi.org/10.22146/ajche.50181.

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A photocatalytic reactor has been designed to study the kinetics of photocatalytic degradation of phenol and methylene blue dye present in water stream on immobilized Ti02 catalyst. The principal part of the reactor consisted of a cylindrical pyrex glass tube whose outer surface was coated with the synthetic Ti02 film catalyst prepared from sol-gel technique. An ultraviolet light lamp of 365 nm wavelength was set longitudinally in the center of the tube. The synthetic Ti02 film formulation with the molar ratio of 1 titanium isopropoxide : 8 isopropanol: 1.1 H20: 3 acetyl acetone: 0.05 acetic acid was used to develop the immobilized Ti02 film catalyst deposited over the glass support. The performance of the immobilized photocatalytic reactor was evaluated by studying the decomposition kinetics of phenol and methylene blue dye present in the aqueous stream. The kinetics of photocatalytic degradation of phenol and methylene blue obeyed first order heterogeneous equation. The kinetic parameters were evaluated from the kinetic data using the Langmuir"Hinshelwood-Hougen-Watson (LHHW) model. Keywords: Kinetics, methylene blue, phenol, photocatalytic reactor, and Ti02 film catalyst.

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Zhang, Jia Ying. "Intrinsic Kinetics Study of CO Methanation on Ni-Mo-SiO₂ Catalyst Prepared by Hydrothermal Method." Materials Science Forum 921 (May 2018): 40–47. http://dx.doi.org/10.4028/www.scientific.net/msf.921.40.

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A comprehensive kinetic model for methanation of syngas on Ni-Mo-SiO2catalyst was developed on a fixed bed reactor data. The CO and H2conversion, methane selectivity and yield were obtained in a wide range of operating conditions including 300 < T < 450°C, 1 < H2/CO <4 and 0.1 < P < 1.5 MPa with the total weight hourly space velocity (WHSV) of 60000 ml/h/g. A 6-step reaction scheme defined to the description of a reaction network that considers both catalytic and gas-phase as well as primary and consecutive reaction steps to predict the performance of the syngas methantion. Orthogonal design method was adopted to select test points with temperature, pressure and feed compositions as factors and the kinetic rates involved Langmuir – Hinshelwood equation kinetic model. The kinetic rate parameters were estimated using the Least Square Method by MATLAB. Comparing the experimental and model predicted data showed that presented model has a reasonable fit between the experimental data and the predicted values with average absolute relative deviation of ±9.8%.

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Zhang, Li Shan, Teng Fa Long, Chang Qi Yan, Xing Cun He, Meng Lin Cheng, and Shan Zhong. "Synthesis of AgCl/BiOCl Composite Photocatalyst and its Photocatalytic Activity under Visible-Light Irradiation." Advanced Materials Research 662 (February 2013): 372–78. http://dx.doi.org/10.4028/www.scientific.net/amr.662.372.

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A series of BiOCl photocatalysts with different AgCl contents have been synthesized by a simple hydrolysis method at room temperature using BiCl3 and Bi(NO3)3•5H2O as the main raw materials. The resulting products were characterized with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and UV‐vis diffuse reflectance spectra (DRS). The photocatalytic activities of these AgCl/BiOCl composites were evaluated by the degradation of rhodamine B (RhB) under UV and visible light. The results revealed that the BiOCl/AgCl with an initial 100:1 mole ratio of Bi to Ag have the highest photocatalytic activity. RhB (20 mg/L) was decolorized by 98.81% in 15 min under sun light, in contrast to 95.89% and 11.63% in 30 min under halogen lamp and UV light, respectively. The catalysts did not show any significant loss of activity after 19 recycles for the photodegradation of RhB, suggesting the photocatalyst is essential stable. Kinetic studies showed that the RhB photocatalytic degradation followed pseudo-first order kinetics reaction and fit the Langmuir-Hinshelwood kinetic equation. The rate controlling step was absorption reaction.

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Demircivi, Pelin, and Esra Bilgin Simsek. "Fabrication of Zr-doped TiO2/chitosan composite catalysts with enhanced visible-light-mediated photoactivity for the degradation of Orange II dye." Water Science and Technology 78, no. 3 (July 3, 2018): 487–95. http://dx.doi.org/10.2166/wst.2018.298.

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Abstract Zirconium/titanium/chitosan (Zr/Ti/CHT) composite catalysts were synthesized by sol-gel method using different chitosan amounts (5–20 wt.%) and their activity in the photocatalytic degradation of Orange II dye was evaluated for the first time. The results were compared with Zr/Ti, Zr/CHT and Ti/CHT catalysts. The composite catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray photoelectron spectroscopy analysis. XRD analysis revealed that the Zr/Ti/CHT composite catalyst showed high crystallinity of anatase TiO2 phase. Photocatalytic experiments showed that adding CHT into the catalyst structure increased the photocatalytic degradation under visible light irradiation. Also, the first-order reaction rate constant, kapp, was calculated using the Langmuir–Hinshelwood (L-H) equation. The kapp values were found to be 0.009, 0.0013, 0.012 and 0.014 min−1 for Zr/Ti, Zr/CHT, Ti/CHT and Zr/Ti/CHT, respectively. According to stability tests, after the first cycle Orange II dye degradation was found to be 95%, while it was 37% after the fifth cycle. The results showed that the composite catalyst could be used several times for Orange II dye degradation.

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Mehrizad, Ali, and Parvin Gharbani. "Optimization of operational variables and kinetic modeling for photocatalytic removal of Direct Blue 14 from aqueous media by ZnS nanoparticles." Journal of Water and Health 15, no. 6 (October 9, 2017): 955–65. http://dx.doi.org/10.2166/wh.2017.269.

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Abstract Zinc sulfide nanoparticles (ZnS-NPs) were synthesized via a simple and facile co-precipitation method and were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and diffuse reflectance spectroscopy (DRS). Photocatalytic activity of synthesized nanoparticles was evaluated in removal of double azo dye Direct Blue 14 (DB14) from aqueous media. Optimization of photocatalytic removal of DB14 was studied using response surface methodology (RSM). Based on the results, DB14 removal efficiency increased with increasing intensity and duration of UV light irradiation, whereas the higher pH and higher initial dye concentration were unfavorable. Under optimum conditions (initial DB14 concentration =10 mg L−1, ZnS-NPs amount = 0.7 g L−1, pH = 3.5, UV light intensity =16 W m−2, and irradiation time = 48 min), dye removal efficiency reached up to 88.26%. In continuation of our researches, non-linear regression analysis was used to development a kinetics model based on the Langmuir–Hinshelwood model and an empirical equation was obtained for estimation of apparent pseudo-first-order rate constant (kap) as a function of the operational variables. Findings indicated a high similarity was between the model prediction and experimental results.

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Tao, Ran. "Humic Acids Degradation and Membrane Fouling in Photocatalytic MF Systems for Drinking Water Treatment." Advanced Materials Research 800 (September 2013): 573–75. http://dx.doi.org/10.4028/www.scientific.net/amr.800.573.

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Humic acids (HA) that are one of the major organic components in natural water play an important role in water treatment because they can interact with metals, trace organics, and chlorine while generating toxic complexes and by-products. In this work, photocatalytic degradation of HA and its kinetic behavior were investigated in a photocatalytic microfiltration (MF) system, along with evaluation of membrane permeability at different fluxes. The mechanisms of adsorption and desorption of HA on TiO2 surfaces were elucidated with adsorption isotherm tests of HA before and after photocatalysis of humic water. The kinetic parameters for humic acids, k (rate constant) and K (equilibrium adsorption coefficient) of the Langmuir-Hinshelwood equation, were obtained based on mass balances in continuous stirred tank reactor (CSTR) operations. Regarding membrane fouling, it was assumed that the rate of degree of fouling is disproportional to the fouling resistance. It was found that the fouling rate constant started increasing substantially when the flux increased to a level of greater than 50 L/m2-h. This indicated that the photocatalytic MF system should be operated at a flux below the critical value to prevent serious membrane fouling.

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32

Wiederkehr, Bruna, David Alexander Mitchell, Luiz Fernando de Lima Luz, and Nadia Krieger. "Use of the Langmuir-Hinshelwood-Hougen-Watson equation to describe the ethyl esterification of fatty acids catalyzed by a fermented solid with lipase activity." Biochemical Engineering Journal 168 (April 2021): 107936. http://dx.doi.org/10.1016/j.bej.2021.107936.

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Lin, Xiao, Ming Li, Youji Li, and Wei Chen. "Enhancement of the catalytic activity of ordered mesoporous TiO2 by using carbon fiber support and appropriate evaluation of synergy between surface adsorption and photocatalysis by Langmuir–Hinshelwood (L–H) integration equation." RSC Advances 5, no. 127 (2015): 105227–38. http://dx.doi.org/10.1039/c5ra21083f.

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34

Zouaghi, Razika, Abdennour Zertal, Bernard David, and Sylvie Guittonneau. "Photocatalytic Degradation of Monolinuron and Linuron in an Aqueous Suspension of Titanium Dioxide Under Simulated Solar Irradiation." Revue des sciences de l'eau 20, no. 2 (May 16, 2007): 163–72. http://dx.doi.org/10.7202/015810ar.

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Abstract The photocatalytic degradation of two phenylurea herbicides, monolinuron (MLN) and linuron (LN), was investigated in an aqueous suspension of TiO2 using simulated solar irradiation. The objective of the study was to compare their photocatalytic reactivity and to assess the influence of various parameters such as initial pesticide concentration, catalyst concentration and photonic flux on the photocatalytic degradation rate of MLN and LN. A comparative study of the photocatalytic degradation kinetics of both herbicides showed that these two compounds have a comparable reactivity with TiO2/simulated sun light. Under the operating conditions of this study, the photocatalytic degradation of MLN and LN followed pseudo first-order decay kinetics. The kobs values indicated an inverse dependence on the initial herbicide concentration and were fitted to the Langmuir-Hinshelwood equation. Photocatalytic degradation rates increased with TiO2 dosage, but overdoses did not necessarily increase the photocatalytic efficiency. The degradation rate of MLN increased with radiant flux until an optimum at 580 W m‑2 was reached and then decreased. Under these conditions, an electron-hole recombination was favored. Finally, the photocatalytic degradation rate depended on pH, where an optimum was found at a pH value close to the pH of the point of zero charge (pH = 6).

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35

Raillard, C., V. Héquet, P. Le Cloirec, and J. Legrand. "Photocatalytic oxidation of methyl ethyl ketone over sol-gel and commercial TiO2 for the improvement of indoor air." Water Science and Technology 53, no. 11 (May 1, 2006): 107–15. http://dx.doi.org/10.2166/wst.2006.343.

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This work focuses on the photocatalytic oxidation of gaseous methyl ethyl ketone chosen as a typical indoor air pollutant. Two types of TiO2 coatings were prepared and deposited on glass plates: one using the commercial Degussa P25 TiO2 and the other one by sol-gel method. The first objective of this study was to compare different ways of preparing thin films of sol-gel TiO2 coated on glass plates, taking into account their general aspect and their photocatalytic efficiency. Several parameters were tested, such as the stabilising agent, the glass type of the support, the number of coatings and the calcination temperature. One of the synthesised materials was then kept to carry out the following study. The study aimed to assess the influence of TiO2 coating types on the effect of water vapour. This was achieved by performing MEK photocatalytic degradation kinetics under two levels of humidity at a fixed temperature. Experimental results were then modelled by the Langmuir-Hinshelwood equation. The obtained parameters gave specific trends in function of the considered catalyst. The second part of this work was to identify MEK degradation byproducts during its photocatalytic oxidation. The main detected intermediate was acetaldehyde, followed by methyl formate. A MEK degradation pathway was then proposed.

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Wang, Shang, Zhaolian Han, Tingting Di, Rui Li, Siyuan Liu, and Zhiqiang Cheng. "Preparation of pod-shaped TiO 2 and Ag@TiO 2 nano burst tubes and their photocatalytic activity." Royal Society Open Science 6, no. 9 (September 4, 2019): 191019. http://dx.doi.org/10.1098/rsos.191019.

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The pod-shaped TiO 2 nano burst tubes (TiO 2 NBTs) were prepared by the combination of electrospinning and impregnation calcination with oxalic acid (H 2 C 2 O 4 ), polystyrene (PS) and tetrabutyl titanate. The silver nanoparticles (AgNPs) were loaded onto the surface of TiO 2 NBTs by ultraviolet light reduction method to prepare pod-shaped Ag@TiO 2 NBTs. In this work, we analysed the effect of the amount of oxalic acid on the cracking degree of TiO 2 NBTs; the effect of the concentration of AgNO 3 solution on the particle size and loading of AgNPs on the surface of TiO 2 NBTs. Scanning electron microscopy and transmission electron microscopy investigated the surface morphology of samples. X-ray diffraction and X-ray photoelectron spectroscopy characterized the structure and composition of samples. Rhodamine B (RhB) solution was used to evaluate the photocatalytic activity of pod-shaped TiO 2 NBTs and Ag@TiO 2 NBTs. The results showed that TiO 2 NBTs degraded 91.0% of RhB under ultraviolet light, Ag@TiO 2 NBTs degraded 95.5% under visible light for 75 and 60 min, respectively. The degradation process of both samples was consistent with the Langmuir–Hinshelwood first-order kinetic equation. Therefore, the catalytic performance of the sample is: Ag@TiO 2 NBTs > TiO 2 NBTs > TiO 2 nanotubes.

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37

Bouzek, Karel, and Ivo Roušar. "Comparison of the Effectiveness Factors for a Reaction at a Pore Wall Calculated on the Assumption of the Langmuir-Hinshelwood Mechanism and According to a Power Equation." Journal of Chemical Technology & Biotechnology 66, no. 2 (June 1996): 131–34. http://dx.doi.org/10.1002/(sici)1097-4660(199606)66:2<131::aid-jctb490>3.0.co;2-k.

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38

Oladipo, Gabriel O., Akinola K. Akinlabi, Samson O. Alayande, Titus A. M. Msagati, Hlengilizwe H. Nyoni, and Opeyemi O. Ogunyinka. "Synthesis, characterization, and photocatalytic activity of silver and zinc co-doped TiO2 nanoparticle for photodegradation of methyl orange dye in aqueous solution." Canadian Journal of Chemistry 97, no. 9 (September 2019): 642–50. http://dx.doi.org/10.1139/cjc-2018-0308.

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In this study, TiO2 nanocrystals, 1 mol% Ag-doped TiO2, and 1 mol% Ag and 0.6 mol% Zn co-doped TiO2 powders were synthesized by the sol–gel route. Their photocatalytic activities on methyl orange dye under visible irradiation were investigated. The powders were characterized by X-ray diffraction (XRD), UV–visible spectroscopy (UV–vis), Brunauer–Emmett–Teller (BET), and Fourier transform infrared spectroscopy (FTIR). The XRD results revealed the presence of a rutile phase with an average crystallite size of 9 and 11 nm. The UV–vis spectra showed a red-shift towards a longer wavelength with the corresponding decrease in band gap from 2.9 to 2.5 eV. The BET surface areas of the nanoparticles ranged from 4.7 to 11.8 m2 g−1 with an average pore size between 18.9 and 56.6 nm. The Ag-doped TiO2 has the largest surface area of 11.8 m2 g−1, whereas the Ag–Zn co-doped TiO2 was found to have the highest pore size and volume. The absorption bands at 750–500 cm−1 were attributed to the –O–Ti–O– bond in the TiO2 lattice. The photocatalytic efficiency was highest at an optimum pH of 4.1 for Ag–Zn co-doped TiO2. The results confirmed that Ag-doped and Ag–Zn co-doped TiO2 were more effective than pure TiO2. The kinetic data were fitted into a pseudo first-order equation using a Langmuir–Hinshelwood kinetic model.

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Uyguner, Ceyda Senem, and Miray Bekbolet. "Photocatalytic degradation of natural organic matter: Kinetic considerations and light intensity dependence." International Journal of Photoenergy 6, no. 2 (2004): 73–80. http://dx.doi.org/10.1155/s1110662x0400011x.

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The current study was conducted to investigate the photocatalytic degradation kinetics of humic acid at different light intensities using commercialTiO2powders. The pseudo first order kinetic model and Langmuir-Hinshelwood (L-H) rate equation in modified forms were used to compare the photocatalytic activities ofTiO2materials as a function of light intensity. Under constant irradiation conditions, the pseudo first order reaction rates as well as L-H rates were found to be decreasing in the following trend; Degussa P-25, Millennium PC-500 and Millennium PC-100. The pseudo first order rate constants showed the same decreasing trend as the pseudo first order reaction rates while L-H rate constants exhibited a light intensity related change in the ordering of the photocatalysts. At the lowest light intensity, L-H rate constants decreased as follows: Millennium PC-500>Millennium PC-100>Degussa P-25. However, increasing the light intensity changed the order to; Millennium PC-100>Millennium PC-500>Degussa P-25 revealing the significance of the L-H adsorption constant. Under constant irradiation conditions, ionic strength dependent changes in the structure of humic acid did not alter degradation efficiency trend of the photocatalyst specimens and they were ordered such as; Degussa P-25>Millennium PC-500>Hombikat UV-100>Millennium PC-100 > Merck. The results presented in this research also confirmed the effectiveness of Degussa P-25 as a photocatalyst for the degradation of humic acid.

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40

Asenjo, Natalia G., Ricardo Santamaría, Clara Blanco, Marcos Granda, Patricia Álvarez, and Rosa Menéndez. "Correct use of the Langmuir–Hinshelwood equation for proving the absence of a synergy effect in the photocatalytic degradation of phenol on a suspended mixture of titania and activated carbon." Carbon 55 (April 2013): 62–69. http://dx.doi.org/10.1016/j.carbon.2012.12.010.

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41

Mohammad, Bepari, Aravamudhan, and Kuila. "Kinetics of Fischer–Tropsch Synthesis in a 3-D Printed Stainless Steel Microreactor Using Different Mesoporous Silica Supported Co-Ru Catalysts." Catalysts 9, no. 10 (October 21, 2019): 872. http://dx.doi.org/10.3390/catal9100872.

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Fischer–Tropsch (FT) synthesis was carried out in a 3D printed stainless steel (SS) microchannel microreactor using bimetallic Co-Ru catalysts on three different mesoporous silica supports. CoRu-MCM-41, CoRu-SBA-15, and CoRu-KIT-6 were synthesized using a one-pot hydrothermal method and characterized by Brunner–Emmett–Teller (BET), temperature programmed reduction (TPR), SEM-EDX, TEM, and X-ray photoelectron spectroscopy (XPS) techniques. The mesoporous catalysts show the long-range ordered structure as supported by BET and low-angle XRD studies. The TPR profiles of metal oxides with H2 varied significantly depending on the support. These catalysts were coated inside the microchannels using polyvinyl alcohol and kinetic performance was evaluated at three different temperatures, in the low-temperature FT regime (210–270 °C), at different Weight Hourly Space Velocity (WHSV) in the range of 3.15–25.2 kgcat.h/kmol using a syngas ratio of H2/CO = 2. The mesoporous supports have a significant effect on the FT kinetics and stability of the catalyst. The kinetic models (FT-3, FT-6), based on the Langmuir–Hinshelwood mechanism, were found to be statistically and physically relevant for FT synthesis using CoRu-MCM-41 and CoRu-KIT-6. The kinetic model equation (FT-2), derived using Eley–Rideal mechanism, is found to be relevant for CoRu-SBA-15 in the SS microchannel microreactor. CoRu-KIT-6 was found to be 2.5 times more active than Co-Ru-MCM-41 and slightly more active than CoRu-SBA-15, based on activation energy calculations. CoRu-KIT-6 was ~3 and ~1.5 times more stable than CoRu-SBA-15 and CoRu-MCM-41, respectively, based on CO conversion in the deactivation studies.

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42

Mashentseva, Anastassiya A., Nurgulim A. Aimanova, Nursanat Parmanbek, Bakhtiyar S. Temirgaziyev, Murat Barsbay, and Maxim V. Zdorovets. "Serratula coronata L. Mediated Synthesis of ZnO Nanoparticles and Their Application for the Removal of Alizarin Yellow R by Photocatalytic Degradation and Adsorption." Nanomaterials 12, no. 19 (September 22, 2022): 3293. http://dx.doi.org/10.3390/nano12193293.

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In this study, the potential of biogenic zinc oxide nanoparticles (ZnO NPs) in the removal of alizarin yellow R (AY) from aqueous solutions by photocatalytic degradation, as well as adsorption, was investigated. The synthesized ZnO NPs were prepared by the simple wet-combustion method using the plant extract of Serratula coronata L. as a reducing and stabilizing agent and characterized by powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray and X-ray photoelectron spectroscopy. Photocatalytic degradation of AY was monitored by UV–visible spectroscopy and the effects of parameters, such as light source type (UV-, visible- and sunlight), incubation time, pH, catalyst dosage and temperature on degradation were investigated. It was demonstrated that the source of light plays an important role in the efficiency of the reaction and the UV-assisted degradation of AY was the most effective, compared to the others. The degradation reaction of AY was found to follow the Langmuir-Hinshelwood mechanism and a pseudo-first-order kinetic model. The degradation kinetics of AY accelerated with increasing temperature, and the lowest activation energy (Ea) was calculated as 3.4 kJ/mol for the UV-light irradiation system, while the Ea values were 4.18 and 7.37 kJ/mol for visible light and sunlight, respectively. The dye removal by the adsorption process was also affected by several parameters, such as pH, sorbent amount and contact time. The data obtained in the kinetics study fit the pseudo-second-order equation best model and the rate constant was calculated as 0.001 g/mg·min. The isotherm analysis indicated that the equilibrium data fit well with the Freundlich isotherm model. The maximum adsorption capacity of AY on biogenic ZnO NPs was 5.34 mg/g.

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Staelens, N., M. F. Reyniers, and G. B. Marin. "Langmuir–Hinshelwood–Hougen–Watson rate equations for the transalkylation of methylamines." Chemical Engineering Journal 90, no. 1-2 (November 2002): 185–93. http://dx.doi.org/10.1016/s1385-8947(02)00079-7.

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Morávek, Vladimír, and Miloš Kraus. "Kinetics of individual steps in reaction network ethanol-diethyl ether-ethylene-water on alumina." Collection of Czechoslovak Chemical Communications 51, no. 4 (1986): 763–73. http://dx.doi.org/10.1135/cccc19860763.

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The rates of single reactions have been measured at 250 °C in the complex reaction of ethanol dehydration to ethylene and to diethyl ether involving also hydrolysis of the ether, its disproportionation to ethanol and ethylene and its dehydration to ethylene. The found dependences of the initial reaction rates on partial pressures of the reactants were correlated by semiempirical Langmuir-Hinshelwood type rate equations.

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MACHIDA, Motoi, Shigeyoshi ONO, and Hideshi HATTORI. "Quantitative Prediction of Aniline and Pyridine Hydrodenitrogenation Reactions by Use of Langmuir-Hinshelwood Equations." Journal of The Japan Petroleum Institute 40, no. 4 (1997): 263–71. http://dx.doi.org/10.1627/jpi1958.40.263.

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Letková, Zuzana, Alena Brunovská, and Josef Markoš. "Study of Activity Distribution for Consecutive Reactions." Collection of Czechoslovak Chemical Communications 59, no. 8 (1994): 1788–99. http://dx.doi.org/10.1135/cccc19941788.

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The optimal pellet activity distribution for a system of consecutive reactions is analyzed numerically. Two cases are studied: the case of unconstrained activity (without predescribed maximal concentration of active component) leading to a Dirac delta activity distribution and the case with upper bound for the activity distribution (concentration of active component can not exceed given maximal value) which leads to a step function profile. As the objective function global selectivity is chosen. Examples of both cases are given. The reaction kinetics is described by Langmuir-Hinshelwood type of equations.

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Hamryszak, Łukasz, Maria Madej-Lachowska, Mirosław Grzesik, and Michał Śliwa. "Cu/Zn/Zr/Ga Catalyst for Utilisation of Carbon Dioxide to Methanol—Kinetic Equations." Catalysts 12, no. 7 (July 9, 2022): 757. http://dx.doi.org/10.3390/catal12070757.

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This paper presents the kinetics of methanol synthesis from carbon dioxide and hydrogen over a Cu/Zn/Zr/Ga catalyst. Kinetic studies were carried out in a continuous-flow fixed-bed reactor in a temperature range from 433 to 513 K, pressures from 3 to 8 MPa, and GHSV from 1660 to 10,000 1/h for initial molar fractions of hydrogen from about 0.48 to 0.70, carbon dioxide from 0.05 to about 0.22, and carbon monoxide from 0 to about 0.07. Significant effects of temperature and the composition of the reaction mixture on the conversion degrees α1 and α2 were found. The Cu/Zn/Zr/Ga catalyst showed good stability over 960 h. XRD and CO2TPD characterisation were performed. Thefinally obtained results of kinetic tests were developed in the form of Langmuir–Hinshelwood kinetic equations. The numerical Levenberg–Marquardt method was used to estimate the kinetic equations. The average relative error of fitting the kinetic equations to the experimental data was 18%.

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Feng, X. G., F. Rong, Tao Wei, and Chun Wei Yuan. "Studies of Photocatalytic Degradation of Trace-Level MC-LR in Water on Thin Film of Titanium Dioxide." Solid State Phenomena 121-123 (March 2007): 951–54. http://dx.doi.org/10.4028/www.scientific.net/ssp.121-123.951.

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MCs are produced by cyanobacteria and cause concerns in potable water due to toxicity. Conventional treatments are poor at removing MCs. In the present study, the photocatalytic degradation of MC-LR was conducted using nano-TiO2 thin film, prepared by sol-gel and dip-coating method, with UV 365nm irradiation. According to analysis results from solid-phase extraction combined with HPLC method, the trace-level MC-LR is easily to be removed by photocatalytic system. The degradation efficiency of MC-LR is influenced by the pH conditions, initial concentration due to adsorption of MC-LR on TiO2 thin film. The maximum initial rate of photocatalytic degradation occurs at pH 4 and over 95% of 20μg/L MC-LR is decomposed within 120min. The kinetic equations and parameters revealed that degradation reaction of trace level MC-LR, which depicted by pseudo first order kinetics process in appearance, was in accordance with Langmuir-Hinshelwood kinetics model well, the corresponding rate constant k and Langmuir adsorption constant K were determined to be 19.72μg/l·min-1 and 6.57×10-4l/μg, respectively.

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Shinde, Sunil B., and Raj M. Deshpande. "Kinetic Study for Chemoselective Hydrogenation of Benzoic Acid to Benzyl Alcohol in a Batch Slurry Reactor using Ru-Sn/Al2O3 Catalyst." Asian Journal of Chemistry 34, no. 10 (2022): 2538–44. http://dx.doi.org/10.14233/ajchem.2022.23817.

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Chemoselective hydrogenation of benzoic acid was carried out using Ru-Sn/Al2O3 catalyst at temperature and hydrogen pressure range of 473-513 K and 3.8-8.8 MPa, respectively. The Sn/Ru ratio in Ru-Sn/Al2O3 catalyst was 5. The initial rates for multiphasic hydrogenation reaction were observed to be first order with respect to catalyst loading, hydrogen partial pressure and benzoic acid. The initial rate data obtained were fitted to different rate equations based on Langmuir-Hinshelwood (L-H) type model and a rate model was obtained which predicted the rate of reaction with an error less than ± 5%. Rate model suggests two different type of active site on Ru-Sn/Al2O3 catalyst for hydrogenation of benzoic acid. The activation energy for hydrogenation of benzoic acid to benzyl alcohol using Ru-Sn/Al2O3 was found to be 81.64 kJ/mol.

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Williams, Almoruf Olajide Fasola. "Modelling and Dynamic Simulation of One-Dimensional Isothermal Axial Dispersion Tubular Reactors with Power Law and Langmuir-Hinshelwood-Hougen Watson Kinetics." Journal of Applied Science & Process Engineering 8, no. 2 (October 31, 2021): 834–58. http://dx.doi.org/10.33736/jaspe.3328.2021.

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In this paper, the modelling, numerical lumping and simulation of the dynamics of one-dimensional, isothermal axial dispersion tubular reactors for single, irreversible reactions with Power Law (PL) and Langmuir-Hinshelwood-Hougen-Watson (LHHW)-type kinetics are presented. For the PL-type kinetics, first-order and second-order reactions are considered, while Michaelis-Menten and ethylene hydrogenation or enzyme substrate-inhibited reactions are considered for the LHHW-type kinetics. The partial differential equations (PDEs) developed for the one-dimensional, isothermal axial dispersion tubular reactors with both the PL and LHHW-type kinetics are lumped to ordinary differential equations (ODEs) using the global orthogonal collocation technique. For the nominal design/operating parameters considered, using only 3 or 4 collocation points, are found to adequately simulate the dynamic response of the systems. On the other hand, simulations over a range of the design/operating parameters require between 5 to 7 collocations points for better results, especially as the Peclet number for mass transfer is increased from the nominal value to 100. The orthogonal collocation models are used to carry out parametric studies of the dynamic response behaviours of the one-dimensional, isothermal axial dispersion tubular reactors for the four reaction kinetics. For each of the four types of reaction kinetics considered, graphical plots are presented to show the effects of the inlet feed concentration, Peclet number for mass transfer and the Damköhler number on the reactor exit concentration dynamics to step-change in the inlet feed concentration. The internal dynamics of the linear (or linearized) systems are examined by computing the eigenvalues of the linear (or linearized) lumped orthogonal collocation models. The relatively small order of the lumped orthogonal collocation dynamic models make them attractive and useful for dynamic resilience analysis and control system analysis/design studies.

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