Esterificatfon of n-Butanol with Acetic Acid Catalyzed by a Cation Exchange Resin

The kinetics of the esterification of n-butanol with acetic acid have been studied in a batch and in a tubular reactor. The best model for obtaining the esterification rate with a partially wet ion exchanger (270/o water contents) is obtained by assuming a pseudohomogeneous system, while the kinetics of dry ion exchangers is best represented by a model derived from assumptions based on a heterogeneous system. A separate study of the induction period in a tubular reactor shows the considerable influence of the water content on reaction kinetics. This is manifested by a change of the catalytic activity during the reaction. Change of the catalytic activity can lead to erroneous interpretation of experimental results and to derivations of inadequate kinetic expression. It is shown that change of ion exchanger activity in the induction period is caused by diffusion of reactants into resin particle

Experimental Methods for Catalyst Testing

Katalizatori su sastavni dio većine industrijskih reaktora koji se koriste u kemijskoj, petrokemijskoj i srodnim industrijama. Osim što ubrzavaju reakcije između tvari koje bi inače reagirale vrlo sporo, maksimiraju nastajanje željenog i minimiziraju nastajanje neželjenog produkta, omogućavaju bolju kontrolu procesa, provedbu procesa pri nižoj temperaturi i/ili tlaku, smanjujuai tako utrošak energije, sirovina i nastajanje otpada. Njihova funkcionalna svojstva ne utječu samo na odvijanje kemijske reakcije u reaktoru, vea i na procese koji prethode i slijede samoj reakciji. Stoga je izvedba katalizatora ključna za razvoj novih kao i za unapređenje postojećih katalitičkih procesa. Prvi korak u inženjerstvu novo pripravljenih katalizatora je određivanje stupnja koji određuje brzinu reakcije. Zbog složenosti reakcijskog puta te interakcije kemijske reakcije i fizičkih procesa prijenosa u radu se posebice razmatraju kriteriji za procjenu utjecaja pojedinih procesa na ukupnu brzinu reakcije. Također je dan kratki pregled osnovnih tipova eksperimentalnih reaktora u kojima se istražuje i određuje brzina katalitičke reakcije.Catalysis plays a critical role in virtually every industry. Often it is the key to making an entirely new technology or breathing new life into otherwise, mature technology. In addition to continued needs for productivity improvements, efficient use of energy and raw materials, minimal impact on the environment, and heightened industrial safety add a new aspect to the importance of catalytic innovation. In the development of catalysts various stages can be distinguished. This development process cover the whole range from the new idea for a process or catalyst via the catalyst preparation, catalyst screening, establishing reaction networks, kinetic studies, and life tests to scale up on pilot plant level, before a new or modified process is introduced. The first step in the engineering of a newly discovered catalyst is to quantify the phenomena that govern its performance. These fall into two broad categories: transport phenomena (i. e. heat, mass, and momentum transfer) and reaction kinetics. The paper presents correlations that describe these phenomena, along with guidance for obtaining, from experimental data, the values for the constants in the correlating equations. Various types of laboratory reactors for catalyst testing, in order to obtain the relevant information with regard to intrinsic activity, selectivity, deactivation, is also described

Esterificatfon of n-Butanol with Acetic Acid Catalyzed by a Cation Exchange Resin

The kinetics of the esterification of n-butanol with acetic acid have been studied in a batch and in a tubular reactor. The best model for obtaining the esterification rate with a partially wet ion exchanger (270/o water contents) is obtained by assuming a pseudohomogeneous system, while the kinetics of dry ion exchangers is best represented by a model derived from assumptions based on a heterogeneous system. A separate study of the induction period in a tubular reactor shows the considerable influence of the water content on reaction kinetics. This is manifested by a change of the catalytic activity during the reaction. Change of the catalytic activity can lead to erroneous interpretation of experimental results and to derivations of inadequate kinetic expression. It is shown that change of ion exchanger activity in the induction period is caused by diffusion of reactants into resin particle

Modeling-based Development of an Enantioselective Hydrogenation Reaction of a Sitagliptine Intermediate

This work presents a quality by design (QbD) driven approach to the plan of experiments and reaction modeling that was effective in obtaining enhanced process knowledge and defining a design space for an active pharmaceutical ingredient (API) manufacturing process. Engineering aspects of the process were explored by process modeling using computer predictive process simulators. QbD approach is presented on a case study of the process development of the sitagliptine synthesis step. The process involves an enantioselective hydrogenation step. Based on the proposed reaction mechanism and by combining the heat and mass transfer, thermodynamics, and the kinetics of the reactions, the API quality specifications (enantiomeric purity, impurity levels) are described across the modeling of process space. This process space was defined through target specifications, practical operating conditions for scale-up, and plant control capabilities. Model predictions were verified with results obtained in the laboratory, and at pilot plant scale

Kinetics and Mass Transfer in the Hydrogenation of 2-((1-benzyl-1,2,3,6-tetrahydropyridin-4-yl)methylene)-5,6-dimethoxy-2,3-dihydroinden-1-one hydrochloride over Pt/C Catalyst

The liquid phase hydrogenation of 2-((1-benzyl-1,2,3,6-tetrahydropyridin-4-yl)methylene)-5,6-dimethoxy-2,3-dihydroinden-1-one hydrochloride (1) over a 5 % Pt/C industrial catalyst was studied experimentally in a batch slurry reactor using methanol as a solvent. The catalyst was characterized by the adsorption techniques for specific surface area and pore volume, and by XRD for crystallinity. To investigate the intrinsic kinetics of the reaction, the effect of temperature, catalyst loading, hydrogen partial pressure and (1) concentration on the initial rate of hydrogenation was studied. The analysis of initial rate data showed that the gas-liquid, liquid-solid, and intraparticle mass-transfer resistances were not significant. The reaction scheme of (1) hydrogenation was proposed for the kinetic modelling. Apparent rate constants for all hydrogenation steps were calculated using a first order kinetic approach resulting in good agreement between the experimentally obtained and predicted concentrations. From the temperature dependence of rate constants, the activation energies of various reaction steps were calculated. The averaged activation energy of these steps was found to be 31.1 kJ mol–1

Combustion of Active Carbon as a Model Carbon Material: Comparison of Non-catalytic and Catalytic Oxidation

Kinetics of non-catalytic and Pt-catalysed oxidation of active carbon, selected as a model carbon material was investigated using thermogravimetric analysis (TGA). Investigations were performed in the temperature range from 40 °C to 1000 °C at different heating rates (5–25 °C min–1). The influence of Pt-based catalyst on the combustion kinetics was examined as well. Values of the kinetic parameters, such as activation energy, Ea and Arrhenius pre-exponential factor, A were determined using isoconversional method proposed by Kissinger-Akahira-Sunose. The obtained values were in good agreement with the literature data

Eksperimentalne metode ispitivanja katalizatora

Catalysis plays a critical role in virtually every industry. Often it is the key to making an entirely new technology or breathing new life into otherwise, mature technology. In addition to continued needs for productivity improvements, efficient use of energy and raw materials, minimal impacton the environment, and heightened industrial safety add a new aspect to the importance of catalytic innovation. In the development of catalysts various stages can be distinguished. This development process cover the whole range from the new idea for a process or catalyst via the catalyst preparation, catalyst screening, establishing reaction networks, kinetic studies, and life tests to scale up on pilotplant level, before a new or modified process is introduced. The first step in the engineering of a newly discovered catalyst is to quantify the phenomena that govern its performance. These fall into two broad categories: transport phenomena (i. e. heat, mass, and momentum transfer) and reaction kinetics. The paper presents correlations that describe these phenomena, along with guidance for obtaining, from experimental data, the values for the constants in the correlating equations. Various types of laboratory reactors for catalyst testing, in order to obtain the relevant information withregard to intrinsic activity, selectivity, deactivation, is also described

Phenol oxidation with hydrogen peroxide using Cu/ZSM5 and Cu/Y5 catalysts

In this work, catalytic activity and stability of Cu/Y5 and Cu/ZSM5 zeolites in phenol oxidation with hydrogen peroxide were examined. The catalyst samples were prepared by the ion exchange method of the protonic form of commercial zeolites. The catalysts were characterized by the powder X-ray diffraction (XRD), AAS, while the adsorption techniques were used to measure the specific surface area. The thermal programmed desorption of NH3 (NH3-TPD) was used for measuring the total number of acid sites formed on the surface of zeolites. Catalytic performance of the prepared samples was monitored in terms of phenol, hydrogen peroxide and total organic carbon (TOC) conversion, by-product distribution and a degree of copper leached into the aqueous solution. It was found that the activity of Cu/Y5 catalyst was generally higher than that of Cu/ZSM5 and that unlike Cu/ZSM5, Cu/Y5 catalyzed phenol oxidation more completely

Modeling-based Development of an Enantioselective Hydrogenation Reaction of a Sitagliptine Intermediate

This work presents a quality by design (QbD) driven approach to the plan of experiments and reaction modeling that was effective in obtaining enhanced process knowledge and defining a design space for an active pharmaceutical ingredient (API) manufacturing process. Engineering aspects of the process were explored by process modeling using computer predictive process simulators. QbD approach is presented on a case study of the process development of the sitagliptine synthesis step. The process involves an enantioselective hydrogenation step. Based on the proposed reaction mechanism and by combining the heat and mass transfer, thermodynamics, and the kinetics of the reactions, the API quality specifications (enantiomeric purity, impurity levels) are described across the modeling of process space. This process space was defined through target specifications, practical operating conditions for scale-up, and plant control capabilities. Model predictions were verified with results obtained in the laboratory, and at pilot plant scale