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J N Sahu - One of the best experts on this subject based on the ideXlab platform.
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experimental and modeling of a non isothermal cstr to find out parameter regions and conditions causing input multiplicity for acid catalyzed hydrolysis of Acetic Anhydride
Chemometrics and Intelligent Laboratory Systems, 2014Co-Authors: N S Jayakumar, J N Sahu, Merlin ThomasAbstract:Abstract The continuous stirred tank reactor (CSTR) presents challenging operational problems due to its complex open-loop non-linear behavior such as input and output multiplicities, ignition/extinction, parametric sensitivity, non-linear oscillations and perhaps even chaos. Many researchers have studied the non-linear dynamic behavior of CSTR for several reaction schemes from a theoretical stand point. The present experimental studies are carried out to identify the existence of input multiplicity in a non-isothermal CSTR. The sulfuric acid catalyzed hydrolysis of Acetic Anhydride reaction system has been chosen and the regions of existence of input multiplicity are theoretically identified. The reactor showed the same steady state temperature for two input flow rates of reaction mixtures into the CSTR reactor and thus confirming the existence of input multiplicity for the sulfuric acid catalyzed hydrolysis of Acetic Anhydride reaction system. It was observed that the time taken by the reactor was too long at a low feed flow rate of reaction mixture than at a higher feed flow rate reaction mixture. The model simulations of steady state temperatures were in close agreement with experimental data for the above feed flow rates of reaction mixture conditions.
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experimental and theoretical investigation of parametric sensitivity and dynamics of a continuous stirred tank reactor for acid catalyzed hydrolysis of Acetic Anhydride
Computers & Chemical Engineering, 2011Co-Authors: N S Jayakumar, Mohd Ali Hashim, Anurag Agrawal, J N SahuAbstract:The continuous stirred tank reactor is a dynamic system exhibiting nonlinear behavior such as multiplicity and oscillations and, in certain range of operating conditions, may exhibit a parametric sensitivity where small changes in one or more of the input parameters lead to large changes in the output variable. In the present work, hydrolysis of Acetic Anhydride reaction system was used to demonstrate the existence of parametric sensitivity with respect to the input parameter, the cooling water flow rate. The applications of parametric sensitivity analysis were used for detection of parametric sensitivity in a continuous stirred tank reactor using catalyses hydrolysis of Acetic Anhydride reaction system. Also, theoretical investigation revealed that the effect of wall capacitance has definite influence on the dynamics of continuous stirred tank reactor. The continuous stirred tank reactor showed parametric sensitivity both in the regions of uniqueness and multiplicity, and a mathematical model was developed for the reactor. The numerically simulated results are in satisfactory agreement with the experimental data.
Zhimin Zong - One of the best experts on this subject based on the ideXlab platform.
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oxidation of shenmu char powder with aqueous hydrogen peroxide Acetic Anhydride
Fuel Processing Technology, 2015Co-Authors: Yugao Wang, Yan Li, Peng Li, Zhimin ZongAbstract:Abstract The mild oxidation of Shenmu char powder (SCP) with aqueous hydrogen peroxide (AHPO)–Acetic Anhydride (AAH) was carried out under different conditions, including volume-to-mass ratio of AAH to SCP (AAH/SCP), temperature, volume ratio of AHPO to AAH (AHPO/AAH), and time. Each reaction mixture was filtrated and then extracted with methanol to afford residue and extract. The optimal conditions were determined to be 60/1 of AAH/SCP, 50 °C, 2 of AHPO/AAH and 60 h based on the extract yield. The extracts from SCP oxidation after different periods of time ranging from 12 to 72 h were analyzed with a gas chromatograph/mass spectrometer (GC/MS) and atmospheric pressure solid analysis probe/time-of-flight mass spectrometer (ASAP/TOF-MS). In total, 46 compounds were identified in the extracts by GC/MS analysis and carboxylic acids are predominant. Malonic acid and succinic acid were detected in the extracts and their total mass content in the extracts is up to 56.5%. A series of long-chain alkenedioic acids or long-chain cycloalkanedioic acids with molecular formulae C 29 H 56 (CH 2 ) n (COOH) 2 (n = 0–6) were detected in the extracts with ASAP/ TOF-MS.
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mild oxidation of xiaolongtan lignite in aqueous hydrogen peroxide Acetic Anhydride
Fuel, 2015Co-Authors: Jing Liu, Xianyong Wei, Yugao Wang, Dongdong Zhang, Tiemin Wang, Juan Gui, Zhimin ZongAbstract:Abstract Xiaolongtan lignite (XL) was subjected to the mild oxidation with aqueous hydrogen peroxide–Acetic Anhydride (AAH) under different conditions, including temperature, the amount of AAH, and time. Each reaction mixture was separated by filtration and subsequent treatments, including extraction with ethyl acetate (EA), to afford the EA-extractable portion (EAEP), which was analyzed with a gas chromatograph/mass spectrometer. The optimal conditions were determined to be 2 mL AAH, 50 °C, and 9 h for the oxidation of 0.1 g XL, based on the yields and product distributions of the EAEPs. In total, 47 carboxylic acids (CAs) were detected in the EAEPs under optimized conditions and aliphatic acids are the predominant species. Malonic and succinic acids account for more than 41% of all the CAs, suggesting that dominant linkages connecting aromatic rings (ARs) are –CH 2 – and –CH 2 CH 2 – along with less amounts of polymethylene linkages such as –(CH 2 ) n – ( n = 3–7). Meanwhile, naphthalenecarboxylic acids and aliphatic linkages connecting three ARs are speculated to exist in XL. The investigation provides an effective approach for understanding the structural features of lignites and obtaining aliphatic acids, especially malonic and succinic acids.
N S Jayakumar - One of the best experts on this subject based on the ideXlab platform.
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experimental and modeling of a non isothermal cstr to find out parameter regions and conditions causing input multiplicity for acid catalyzed hydrolysis of Acetic Anhydride
Chemometrics and Intelligent Laboratory Systems, 2014Co-Authors: N S Jayakumar, J N Sahu, Merlin ThomasAbstract:Abstract The continuous stirred tank reactor (CSTR) presents challenging operational problems due to its complex open-loop non-linear behavior such as input and output multiplicities, ignition/extinction, parametric sensitivity, non-linear oscillations and perhaps even chaos. Many researchers have studied the non-linear dynamic behavior of CSTR for several reaction schemes from a theoretical stand point. The present experimental studies are carried out to identify the existence of input multiplicity in a non-isothermal CSTR. The sulfuric acid catalyzed hydrolysis of Acetic Anhydride reaction system has been chosen and the regions of existence of input multiplicity are theoretically identified. The reactor showed the same steady state temperature for two input flow rates of reaction mixtures into the CSTR reactor and thus confirming the existence of input multiplicity for the sulfuric acid catalyzed hydrolysis of Acetic Anhydride reaction system. It was observed that the time taken by the reactor was too long at a low feed flow rate of reaction mixture than at a higher feed flow rate reaction mixture. The model simulations of steady state temperatures were in close agreement with experimental data for the above feed flow rates of reaction mixture conditions.
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experimental and theoretical investigation of parametric sensitivity and dynamics of a continuous stirred tank reactor for acid catalyzed hydrolysis of Acetic Anhydride
Computers & Chemical Engineering, 2011Co-Authors: N S Jayakumar, Mohd Ali Hashim, Anurag Agrawal, J N SahuAbstract:The continuous stirred tank reactor is a dynamic system exhibiting nonlinear behavior such as multiplicity and oscillations and, in certain range of operating conditions, may exhibit a parametric sensitivity where small changes in one or more of the input parameters lead to large changes in the output variable. In the present work, hydrolysis of Acetic Anhydride reaction system was used to demonstrate the existence of parametric sensitivity with respect to the input parameter, the cooling water flow rate. The applications of parametric sensitivity analysis were used for detection of parametric sensitivity in a continuous stirred tank reactor using catalyses hydrolysis of Acetic Anhydride reaction system. Also, theoretical investigation revealed that the effect of wall capacitance has definite influence on the dynamics of continuous stirred tank reactor. The continuous stirred tank reactor showed parametric sensitivity both in the regions of uniqueness and multiplicity, and a mathematical model was developed for the reactor. The numerically simulated results are in satisfactory agreement with the experimental data.
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input multiplicity analysis in a non isothermal cstr for acid catalyzed hydrolysis of Acetic Anhydride
Chemical Engineering & Technology, 2010Co-Authors: N S Jayakumar, Mohd Ali Hashim, Merlin T ThomasAbstract:Multiplicity analysis gives practical guidance for process design to eliminate difficult operating regions associated with input and output multiplicities. Continuous stirred tank reactors (CSTRs) present challenging operational problems due to complex behavior such as input and output multiplicities, ignition/extinction, parametric sensitivity, and nonlinear oscillations. In the absence of a unified mathematical theory for representing various nonlinear system characteristics, the present study was aimed at understanding the dynamic behavior of CSTRs by means of experiments and to link the experimental data to theoretical considerations for further detection and elimination of operating problems. Theoretical modeling and analysis of a non-isothermal CSTR with acid-catalyzed hydrolysis of an Acetic Anhydride system for input multiplicity are discussed. Theoretical modeling of a non-isothermal CSTR using a root-finding technique was carried out for predicting steady-state temperatures. Alternatively, a mathematical model for a non-isothermal CSTR using unsteady-state mass and energy balance equations is proposed. Computer-based simulation was carried out using a program developed in MATLAB for final transient temperature and time-temperature data of the CSTR system under investigation. The results of a theoretical analysis conducted for confirming the existence of input multiplicity in non-isothermal CSTRs with acid-catalyzed hydrolysis of Acetic Anhydride were compared with experimental investigations for validation.
Rene Peters - One of the best experts on this subject based on the ideXlab platform.
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pd ii catalyzed regio enantio and diastereoselective 1 4 addition of azlactones formed in situ from racemic unprotected amino acids and Acetic Anhydride
Journal of Organic Chemistry, 2012Co-Authors: Manuel Weber, Rene PetersAbstract:A multicomponent reaction is reported generating highly enantioenriched and diastereomerically pure quaternary amino acid derivatives via 1,4-addition of azlactones to enones. The azlactone intermediates are generated in situ from unprotected α-amino acids and Acetic Anhydride. Previous attempts using bis-palladacycle catalysts required the use of a large excess of benzoic Anhydride (which is very difficult to remove from the products), since Acetic Anhydride provided regioisomeric product mixtures. Key for the high regioselectivity is a pentaphenylferrocene monopalladacycle catalyst.
Yian Shi - One of the best experts on this subject based on the ideXlab platform.
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an atom economic approach to carboxylic acids via pd catalyzed direct addition of formic acid to olefins with Acetic Anhydride as a co catalyst
Organic and Biomolecular Chemistry, 2015Co-Authors: Yang Wang, Wenlong Ren, Yian ShiAbstract:An effective Pd-catalyzed hydrocarboxylation of olefins using formic acid with Acetic Anhydride as a co-catalyst is described. A variety of carboxylic acids are obtained in good yields with high regioselectivities under mild reaction conditions without the use of toxic CO gas.
