Pub Date : 2009-03-19DOI: 10.2174/1876214X00902010021
B. Özdemir, S. Gültekin
Generally, consecutive and/or parallel reactions pose a great deal of difficulty in determining meaningful reaction rate parameters. One way to determine such parameters is to separate the whole reaction network into different regions and to study each region independently through initial rates. This method is not only tedious, but also a waste of money and time. The other method is to use the fact that, if the reaction rates are known at any “t” time then an optimization technique in MATLAB, MATHCAD, LINDO or POLYMATH ready package programs can be used to determine rate parameters. In this study, the POLYMATH program is chosen for a highly complex rate expression for the reaction of CO + 2H 2 catalyst CH 3OH with Langmuir-Hinshelwood kinetic expression rA = kKCOKH 2PH 2PCO (1+ KCO .PCO + KH2 .PH2 + KCH3OH .PCH3OH ) 2 Rate parameters k, KCO, KH2 and KCH3OH were determined. INTRODUCTION In chemical reaction engineering and in purely chemical kinetics, due to the nature of the reaction one may face very complex reaction networks. Among the complex models, the most suitable one must be determined. In this determination, well-established regression techniques are used. These regression techniques are [1] a) Linear regression (such as y = ax + b) b) Multiple regression (such as y = a1x1 + a2x2 + ....+ anxn ) c) Polynomial regression (such as y = anx n + an 1x n 1 + ...+ a1x + a0 ) d) Non-linear regression, (such as y = f (x1, x2 , ..., xn ,a1,a2 , ...,an ) where n = # of experiments, m = # of parameters to be determined providing n > m+1.) This is very common and can be used almost under any condition. In using these techniques, one has to watch for the following criteria [2] 1. Variance must be minimum 2. Correlation coefficient (R) must be as close to unity as possible *Address correspondence to this author at the Do u University, Acıbadem, Kadıköy 34722, Istanbul, Turkey; E-mail: burcuozdemir@dogus.edu.tr 3. Determined rate parameters must be physically meaningful 4. 95 % confidence interval determination is also essential in order to eliminate (ignore) certain parameters Reactions networks such as A B C D [3] E or A B F [4] C D E are not uncommon in reaction engineering. REACTION RATE EXPRESSION Reaction rate expression of rA = KAKBk 'PAPB (1+ KAPA + KBPB + KCPC ) 2 can be observed on a heterogeneous catalytic reaction of such as CO + 2H 2 catalyst CH 3OH Then for the above reaction, we can write dual-site Langmuir-Hinshelwood model as follows: 22 The Open Catalysis Journal, 2009, Volume 2 Özdemir and Gültekin rA = kKCOKH 2PH 2PCO (1+ KCO .PCO + KH2 .PH2 + KCH3OH .PCH3OH ) 2 (dual site assumption is made) In this study, the data given in Table 1 for the above reaction were considered for the determination of rate parameters through POLYMATH [1, 5]. Table 1. Initial Rate of Reaction at Various Partial Pressures of Reactants and Product Experiment No PCO * PH2 PCH3OH Rate** 1 0.5 0.5 0.5 0.0457 2 1.0 0.5 0.5 0.0457 3 2.0 0.5 0.5 0.0384 4 4.0 0.5 0.5
{"title":"Determination of rate parameters of complex reactions by polymath","authors":"B. Özdemir, S. Gültekin","doi":"10.2174/1876214X00902010021","DOIUrl":"https://doi.org/10.2174/1876214X00902010021","url":null,"abstract":"Generally, consecutive and/or parallel reactions pose a great deal of difficulty in determining meaningful reaction rate parameters. One way to determine such parameters is to separate the whole reaction network into different regions and to study each region independently through initial rates. This method is not only tedious, but also a waste of money and time. The other method is to use the fact that, if the reaction rates are known at any “t” time then an optimization technique in MATLAB, MATHCAD, LINDO or POLYMATH ready package programs can be used to determine rate parameters. In this study, the POLYMATH program is chosen for a highly complex rate expression for the reaction of CO + 2H 2 catalyst CH 3OH with Langmuir-Hinshelwood kinetic expression rA = kKCOKH 2PH 2PCO (1+ KCO .PCO + KH2 .PH2 + KCH3OH .PCH3OH ) 2 Rate parameters k, KCO, KH2 and KCH3OH were determined. INTRODUCTION In chemical reaction engineering and in purely chemical kinetics, due to the nature of the reaction one may face very complex reaction networks. Among the complex models, the most suitable one must be determined. In this determination, well-established regression techniques are used. These regression techniques are [1] a) Linear regression (such as y = ax + b) b) Multiple regression (such as y = a1x1 + a2x2 + ....+ anxn ) c) Polynomial regression (such as y = anx n + an 1x n 1 + ...+ a1x + a0 ) d) Non-linear regression, (such as y = f (x1, x2 , ..., xn ,a1,a2 , ...,an ) where n = # of experiments, m = # of parameters to be determined providing n > m+1.) This is very common and can be used almost under any condition. In using these techniques, one has to watch for the following criteria [2] 1. Variance must be minimum 2. Correlation coefficient (R) must be as close to unity as possible *Address correspondence to this author at the Do u University, Acıbadem, Kadıköy 34722, Istanbul, Turkey; E-mail: burcuozdemir@dogus.edu.tr 3. Determined rate parameters must be physically meaningful 4. 95 % confidence interval determination is also essential in order to eliminate (ignore) certain parameters Reactions networks such as A B C D [3] E or A B F [4] C D E are not uncommon in reaction engineering. REACTION RATE EXPRESSION Reaction rate expression of rA = KAKBk 'PAPB (1+ KAPA + KBPB + KCPC ) 2 can be observed on a heterogeneous catalytic reaction of such as CO + 2H 2 catalyst CH 3OH Then for the above reaction, we can write dual-site Langmuir-Hinshelwood model as follows: 22 The Open Catalysis Journal, 2009, Volume 2 Özdemir and Gültekin rA = kKCOKH 2PH 2PCO (1+ KCO .PCO + KH2 .PH2 + KCH3OH .PCH3OH ) 2 (dual site assumption is made) In this study, the data given in Table 1 for the above reaction were considered for the determination of rate parameters through POLYMATH [1, 5]. Table 1. Initial Rate of Reaction at Various Partial Pressures of Reactants and Product Experiment No PCO * PH2 PCH3OH Rate** 1 0.5 0.5 0.5 0.0457 2 1.0 0.5 0.5 0.0457 3 2.0 0.5 0.5 0.0384 4 4.0 0.5 0.5","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"6 1","pages":"21-23"},"PeriodicalIF":0.0,"publicationDate":"2009-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88823708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-19DOI: 10.2174/1876214X00902010045
A. El-ShobakyGamil, S. YehiabNaema, A. El-HendawyAbdel-Nasser, Abo-Elenina Reham M.M., Badawy Abdel Rahman A.A.
Copper-zinc mixed oxides treated with small amounts of alumina and having the formula 0.5 CuO: 0.5ZnO: 0.05 Al2O3 were prepared by coprecipitation of their mixed hydroxides from their mixed nitrates solutions using 1 M NaOH solution. The precipitation was carried out at different pH values varying between 7 to 9.5 and at 50 and 70 o C. The results revealed that the bulk of various solids consisted of CuO and ZnO having ratios varying between 0.91 and 1.20. While the surface Cu/Zn ratio was bigger than those present in the bulk and varied between 1.16 to 1.64 depending on the pH value and calcination temperature. The mixed oxide solids existed as nanocrystalline CuO and ZnO phases. The surface characteristics are strongly dependent on both the pH value and calcination temperature. The computed SBET val- ues varied between 21and 108 m 2 /g and all adsorbents are mesoporous solids. The prepared solids showed a good cata- lytic activity in CO oxidation by O2 which proceeds via first order kinetics in all cases. The activation energy of the cata- lyzed reaction was determined for various solids and the computed values were very small indicating the big catalytic ac- tivity of the investigated solids.
{"title":"Effects of Preparation Conditions on Surface and Catalytic Properties of Copper and Zinc Mixed Oxides System","authors":"A. El-ShobakyGamil, S. YehiabNaema, A. El-HendawyAbdel-Nasser, Abo-Elenina Reham M.M., Badawy Abdel Rahman A.A.","doi":"10.2174/1876214X00902010045","DOIUrl":"https://doi.org/10.2174/1876214X00902010045","url":null,"abstract":"Copper-zinc mixed oxides treated with small amounts of alumina and having the formula 0.5 CuO: 0.5ZnO: 0.05 Al2O3 were prepared by coprecipitation of their mixed hydroxides from their mixed nitrates solutions using 1 M NaOH solution. The precipitation was carried out at different pH values varying between 7 to 9.5 and at 50 and 70 o C. The results revealed that the bulk of various solids consisted of CuO and ZnO having ratios varying between 0.91 and 1.20. While the surface Cu/Zn ratio was bigger than those present in the bulk and varied between 1.16 to 1.64 depending on the pH value and calcination temperature. The mixed oxide solids existed as nanocrystalline CuO and ZnO phases. The surface characteristics are strongly dependent on both the pH value and calcination temperature. The computed SBET val- ues varied between 21and 108 m 2 /g and all adsorbents are mesoporous solids. The prepared solids showed a good cata- lytic activity in CO oxidation by O2 which proceeds via first order kinetics in all cases. The activation energy of the cata- lyzed reaction was determined for various solids and the computed values were very small indicating the big catalytic ac- tivity of the investigated solids.","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"21 1","pages":"45-53"},"PeriodicalIF":0.0,"publicationDate":"2009-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88547718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-17DOI: 10.2174/1876214X00902010033
M. ReddyBenjaram, Thirupathi Boningari, K. PatilMeghshyam
A remarkable acceleration in the synthesis of substituted coumarins via Pechmann reaction catalyzed by silica gel supported sulfuric acid (H2SO4/silica gel) at 120 °C in high yields under solvent-free reaction condition with short re- action times is described. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and sol- vents.
{"title":"One-Pot Synthesis of Substituted Coumarins Catalyzed by Silica Gel Supported Sulfuric Acid Under Solvent-Free Conditions","authors":"M. ReddyBenjaram, Thirupathi Boningari, K. PatilMeghshyam","doi":"10.2174/1876214X00902010033","DOIUrl":"https://doi.org/10.2174/1876214X00902010033","url":null,"abstract":"A remarkable acceleration in the synthesis of substituted coumarins via Pechmann reaction catalyzed by silica gel supported sulfuric acid (H2SO4/silica gel) at 120 °C in high yields under solvent-free reaction condition with short re- action times is described. This methodology offers momentous improvements over various options for the synthesis of coumarins with regard to yield of products, simplicity in operation and green aspects by avoiding toxic catalysts and sol- vents.","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"175 1","pages":"33-39"},"PeriodicalIF":0.0,"publicationDate":"2009-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75986932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-17DOI: 10.2174/1876214X00902010040
M. Amini, Y. Fazaeli, Zahra Yassaee, Shahzad Feizi, A. Bazgir
Polytungstozincate acid was prepared from sodium polytungstozincate and after formulation, Na3H9(WZn3(H2O)2(ZnW9O34)2), was used as an efficient catalyst for the synthesis of xanthene derivatives under solvent- free conditions. The simple experimental procedure, short reaction times (40-120 min.), and excellent yields (81-94%) are the advantages of the present method.
{"title":"Polytungstozincate Acid: A New and Efficient Catalyst for the Synthesis of Xanthenes Under Solvent-Free Conditions","authors":"M. Amini, Y. Fazaeli, Zahra Yassaee, Shahzad Feizi, A. Bazgir","doi":"10.2174/1876214X00902010040","DOIUrl":"https://doi.org/10.2174/1876214X00902010040","url":null,"abstract":"Polytungstozincate acid was prepared from sodium polytungstozincate and after formulation, Na3H9(WZn3(H2O)2(ZnW9O34)2), was used as an efficient catalyst for the synthesis of xanthene derivatives under solvent- free conditions. The simple experimental procedure, short reaction times (40-120 min.), and excellent yields (81-94%) are the advantages of the present method.","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"28 1","pages":"40-44"},"PeriodicalIF":0.0,"publicationDate":"2009-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77558270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-11DOI: 10.2174/1876214X00902010024
S. Sathiyanarayanan, Ravi P.E., A. Ramesh
Zinc oxide nanorods having the size 100 to 250 nm and 1 to 2 � m length were prepared by reacting zinc acetate with triethanolamine. The structure of the nanorods was confirmed by scanning electron microscope analysis. Photocata- lytic activity of zinc oxide nanorods on the new class of ketoenole and chloronicotinyl in secticides spirotetramat and imi- dacloprid was investigated. The decontamination effect of catalyst on the residues of spirotetramat and imidacloprid in water was studied at three different buffer solutions (4.0, 7.0 and 9.0). The catalytic reaction was measured under direct sunlight at two different concentration levels and the optimum concentration of catalyst re quired for the decontamination was also established by varying the amount of catalyst from 0.02 to 0.2 g/L. Residues are quantified by a high perform- ance liquid chromatography UV method (HPLC-UV) and calculated the DT 50 and DT 90 from the dissipation data. The rate of the reaction showed first order ki netics in water. The addition of zinc oxide nanorods induced the photocatalytic reaction contributing significantly to the rapid dissipation of residues. Complete mineralization of the residues was con- firmed by liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS/MS). The method has the limit of quantification 0.1 � g/L in water.
{"title":"Applications of Zinc Oxide Nanorods as Photocatalyst for the Decontamination of Imidacloprid and Spirotetramat Residues in Water","authors":"S. Sathiyanarayanan, Ravi P.E., A. Ramesh","doi":"10.2174/1876214X00902010024","DOIUrl":"https://doi.org/10.2174/1876214X00902010024","url":null,"abstract":"Zinc oxide nanorods having the size 100 to 250 nm and 1 to 2 � m length were prepared by reacting zinc acetate with triethanolamine. The structure of the nanorods was confirmed by scanning electron microscope analysis. Photocata- lytic activity of zinc oxide nanorods on the new class of ketoenole and chloronicotinyl in secticides spirotetramat and imi- dacloprid was investigated. The decontamination effect of catalyst on the residues of spirotetramat and imidacloprid in water was studied at three different buffer solutions (4.0, 7.0 and 9.0). The catalytic reaction was measured under direct sunlight at two different concentration levels and the optimum concentration of catalyst re quired for the decontamination was also established by varying the amount of catalyst from 0.02 to 0.2 g/L. Residues are quantified by a high perform- ance liquid chromatography UV method (HPLC-UV) and calculated the DT 50 and DT 90 from the dissipation data. The rate of the reaction showed first order ki netics in water. The addition of zinc oxide nanorods induced the photocatalytic reaction contributing significantly to the rapid dissipation of residues. Complete mineralization of the residues was con- firmed by liquid chromatography electrospray tandem mass spectrometry (LC-ESI-MS/MS). The method has the limit of quantification 0.1 � g/L in water.","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"24 138 1","pages":"24-32"},"PeriodicalIF":0.0,"publicationDate":"2009-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77094275","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-03-11DOI: 10.2174/1876214X00902010012
S. Kumar, Jain Bhawana, N. Reena, Katre Yokraj, Singh S.P.
Kinetics of Pd(II) catalyzed oxidation of valine has been studied by N-bromophthalimide (NBP) in acidic me- dium at 303 K. The reaction follows first order kinetics with respect to (Pd(II)) while negative effect was observed for the variation of (H + ) on the rate of reaction. The reaction exhibits first order kinetics with respect to (NBP) at its lower con- centrations and tends towards zero order at its higher concentrations. Rate of reaction exhibits zero order and fractional order kinetics with respect to (valine) and (Cl - ) respectively. (Hg(OAc)2), (phthalimide), ionic strength (I) and dielectric constant of the medium did not bring about any significant change on the rate of reaction. The rate constants observed at five different temperatures (298 K-318 K) were utilized to calculate the activation parameters. A plausible mechanism has been proposed from the results of kinetic studies, reaction stoichiometry and product analysis.
用n -溴酞酰亚胺(NBP)在酸性介质303 K下，研究了Pd(II)催化缬氨酸氧化的动力学。与(Pd(II))有关的反应遵循一级动力学，而(H +)的变化对反应速率有负影响。该反应在低浓度下表现为一级动力学，在高浓度下趋向于零级动力学。反应速率对(缬氨酸)和(Cl -)分别表现为零级和分数级动力学。(Hg(OAc)2)、(酞酰亚胺)、离子强度(I)和介质介电常数对反应速率没有显著影响。利用5种不同温度(298 K ~ 318 K)下的速率常数来计算活化参数。从动力学研究、化学计量学和产物分析等方面提出了一种合理的反应机理。
{"title":"Oxidation of Valine by N-Bromophthalimide in Presence of Chloro- Complex of Pd(II) as Homogenous Catalyst: A Kinetic and Mechanistic Study","authors":"S. Kumar, Jain Bhawana, N. Reena, Katre Yokraj, Singh S.P.","doi":"10.2174/1876214X00902010012","DOIUrl":"https://doi.org/10.2174/1876214X00902010012","url":null,"abstract":"Kinetics of Pd(II) catalyzed oxidation of valine has been studied by N-bromophthalimide (NBP) in acidic me- dium at 303 K. The reaction follows first order kinetics with respect to (Pd(II)) while negative effect was observed for the variation of (H + ) on the rate of reaction. The reaction exhibits first order kinetics with respect to (NBP) at its lower con- centrations and tends towards zero order at its higher concentrations. Rate of reaction exhibits zero order and fractional order kinetics with respect to (valine) and (Cl - ) respectively. (Hg(OAc)2), (phthalimide), ionic strength (I) and dielectric constant of the medium did not bring about any significant change on the rate of reaction. The rate constants observed at five different temperatures (298 K-318 K) were utilized to calculate the activation parameters. A plausible mechanism has been proposed from the results of kinetic studies, reaction stoichiometry and product analysis.","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"56 1","pages":"12-20"},"PeriodicalIF":0.0,"publicationDate":"2009-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84779995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-02-10DOI: 10.2174/1876214X00902010007
K. TandonPraveen, B. DwivediPriy, P. Manisha, Singh Satpal
Oxidation of benzyl alcohol by cerium(IV) sulphate catalyzed by iridium(III) chloride was studied both from the kinetic and synthetic point of views. In the kinetic study reaction followed direct proportionality with respect to catalyst concentrations while first order kinetics at low concentrations becoming to zero order at higher concentrations of both oxidant and organic substrate was observed. Rate decreases sharply with increasing concentrations of H + , Ce III and Cl ions. Potential of cerium(IV)-iridium(III) system in synthesis was checked by changing the concentrations or conditions of various factors, which affect the yield of benzaldehyde. After a certain point increase in the duration of experiment or the concentration of oxidant and catalyst does not increase the yield and under the experimental conditions it was only the temperature, which may further increase the yield. Product was identified by various means.
{"title":"Iridium(III) Catalyzed Oxidation of Benzyl Alcohol by Cerium(IV) Sulphate: A Kinetic and Synthetic Study","authors":"K. TandonPraveen, B. DwivediPriy, P. Manisha, Singh Satpal","doi":"10.2174/1876214X00902010007","DOIUrl":"https://doi.org/10.2174/1876214X00902010007","url":null,"abstract":"Oxidation of benzyl alcohol by cerium(IV) sulphate catalyzed by iridium(III) chloride was studied both from the kinetic and synthetic point of views. In the kinetic study reaction followed direct proportionality with respect to catalyst concentrations while first order kinetics at low concentrations becoming to zero order at higher concentrations of both oxidant and organic substrate was observed. Rate decreases sharply with increasing concentrations of H + , Ce III and Cl ions. Potential of cerium(IV)-iridium(III) system in synthesis was checked by changing the concentrations or conditions of various factors, which affect the yield of benzaldehyde. After a certain point increase in the duration of experiment or the concentration of oxidant and catalyst does not increase the yield and under the experimental conditions it was only the temperature, which may further increase the yield. Product was identified by various means.","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"56 1","pages":"7-11"},"PeriodicalIF":0.0,"publicationDate":"2009-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84846721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2009-01-15DOI: 10.2174/1876214X00902010001
B. Özdemir, S. Gültekin
In studies on chemical kinetics, generally after the rate data have been taken, a mechanism and an associated rate law model are proposed based on the data taken. Frequently, more than one mechanism and rate law may be consis- tent with data. In order to find the correct rate law, regression techniques (model discrimination) are applied to indentify which model equation best fits the data by choosing the one with the smaller sum of squares. With this non-linear regres- sion technique, rate parameters with 95% confidence limits are calculated along with residues. Of course, model parame- ters must be realistic. For example, reaction rate constants, activation energies or adsorption equilibrium constants must be positive by comparing the calculated value of parameters with 95% confidence limits, one can judge about the validity of the model. In this paper, model discrimination will be applied to certain data from the literature along with the suggested heterogene- ous catalytic models such as Langmuir-Hinshelwood Kinetic Model or Rideal-Eley Model. A reaction of A + B C + D type have been selected (like methanation) with the rate laws given below: rA = kPAPB /1 + KAPA + KBPB + KCPC + KDPD () 2 dual-site Langmuir-Hinshelwood Model r A = kP A P B /1 + K A P A + K B P B + K C P C + K D P D () single-site Langmuir-Hinshelwood Model
{"title":"Model discrimination in chemical kinetics","authors":"B. Özdemir, S. Gültekin","doi":"10.2174/1876214X00902010001","DOIUrl":"https://doi.org/10.2174/1876214X00902010001","url":null,"abstract":"In studies on chemical kinetics, generally after the rate data have been taken, a mechanism and an associated rate law model are proposed based on the data taken. Frequently, more than one mechanism and rate law may be consis- tent with data. In order to find the correct rate law, regression techniques (model discrimination) are applied to indentify which model equation best fits the data by choosing the one with the smaller sum of squares. With this non-linear regres- sion technique, rate parameters with 95% confidence limits are calculated along with residues. Of course, model parame- ters must be realistic. For example, reaction rate constants, activation energies or adsorption equilibrium constants must be positive by comparing the calculated value of parameters with 95% confidence limits, one can judge about the validity of the model. In this paper, model discrimination will be applied to certain data from the literature along with the suggested heterogene- ous catalytic models such as Langmuir-Hinshelwood Kinetic Model or Rideal-Eley Model. A reaction of A + B C + D type have been selected (like methanation) with the rate laws given below: rA = kPAPB /1 + KAPA + KBPB + KCPC + KDPD () 2 dual-site Langmuir-Hinshelwood Model r A = kP A P B /1 + K A P A + K B P B + K C P C + K D P D () single-site Langmuir-Hinshelwood Model","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"88 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2009-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80614742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-15DOI: 10.2174/1876214X00801010011
Shin Yamamoto, S. Yao, S. Kodama, C. Mine, Y. Fujioka
Seven different transition metal oxides (TiO2, ZnO, V2O5, Fe2O3, Co3O4, MnO2, and CuO) have been investi- gated for oxidation of diesel particulate matter (PM) under plasma discharge conditions. The experiments were carried out by measuring PM oxidation rates over each catalyst using a batch-type dielectric barrier discharge reactor. It was found that TiO2, ZnO, V2O5, and Fe2O3 can promote PM oxidation, among which Fe2O3 is a most desirable catalyst for PM oxi- dative removal as PM oxidation rate promoted by Fe2O3 is highest under plasma discharge conditions. The mechanism of PM catalytic oxidation over the metal oxides has been suggested to follow the redox catalytic cycles from the correlation of the catalytic oxidation rates with the formation enthalpies per oxygen atom of the catalysts. O atoms generated by plasma discharges may play an important role in promoting the re-oxidation of the catalysts. The highest catalytic activity for the PM oxidation with Fe2O3 has been suggested to be due to the balance between the reduction rate and the re- oxidation rate within the redox catalytic cycles.
{"title":"Investigation of Transition Metal Oxide Catalysts for Diesel PM Removal Under Plasma Discharge Conditions","authors":"Shin Yamamoto, S. Yao, S. Kodama, C. Mine, Y. Fujioka","doi":"10.2174/1876214X00801010011","DOIUrl":"https://doi.org/10.2174/1876214X00801010011","url":null,"abstract":"Seven different transition metal oxides (TiO2, ZnO, V2O5, Fe2O3, Co3O4, MnO2, and CuO) have been investi- gated for oxidation of diesel particulate matter (PM) under plasma discharge conditions. The experiments were carried out by measuring PM oxidation rates over each catalyst using a batch-type dielectric barrier discharge reactor. It was found that TiO2, ZnO, V2O5, and Fe2O3 can promote PM oxidation, among which Fe2O3 is a most desirable catalyst for PM oxi- dative removal as PM oxidation rate promoted by Fe2O3 is highest under plasma discharge conditions. The mechanism of PM catalytic oxidation over the metal oxides has been suggested to follow the redox catalytic cycles from the correlation of the catalytic oxidation rates with the formation enthalpies per oxygen atom of the catalysts. O atoms generated by plasma discharges may play an important role in promoting the re-oxidation of the catalysts. The highest catalytic activity for the PM oxidation with Fe2O3 has been suggested to be due to the balance between the reduction rate and the re- oxidation rate within the redox catalytic cycles.","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"220 1","pages":"11-16"},"PeriodicalIF":0.0,"publicationDate":"2008-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86680303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-01DOI: 10.2174/1876214X00801010001
J. Mandal, K. Chowdhury, K. Paul, Bidyut Saha
{"title":"Kinetics and Mechanism of 2,2’-Bipyridyl Promoted Chromic Acid Oxidation of Ethanol and Propan-1-ol in Aqueous Micellar Media~!2008-08-15~!2008-09-26~!2008-11-14~!","authors":"J. Mandal, K. Chowdhury, K. Paul, Bidyut Saha","doi":"10.2174/1876214X00801010001","DOIUrl":"https://doi.org/10.2174/1876214X00801010001","url":null,"abstract":"","PeriodicalId":22755,"journal":{"name":"The Open Catalysis Journal","volume":"16 1","pages":"1-5"},"PeriodicalIF":0.0,"publicationDate":"2008-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78739166","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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