Mirosław Grzesik

Insitute of Chemical Enginering Polish Academy of Sciences

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...

Our commentary refers to errors, misunderstandings, inconsistencies and inaccuracies noted in the work of Xiao et al. Contrary to what authors state, it is not possible to derive the empirical differential equation 1 based on the assumptions they make, or using any other assumptions. The kinetic data used -- not functions or a graphical method appl...

The levulinic acid was esterified with n-hexanol, n-octanol, and 2-ethylhexanol under nonisothermal conditionns at an alcohol to acid molar ratio of 3:1, 5:1, and 10:1 in the presence of a 0.1 wt% methanesulfonic acid catalyst. During esterification, the temperature was changed linearly from 373 to 428 K and its average change was 4.5 K/min. The au...

The main goal of kinetic studies of chemical reactions is to obtain kinetic equations, i.e. the relationship between reactions’ rates; and concentrations of reagents and temperature. Values of equation parameters and forms of equations are equally important. Only when both are obtained, such equations can be used to design and simulate the course o...

Four types of equations are most frequently used to describe kinetic data of batch sorption processes. Unfortunately, all of them are empirical equations and their constants have no physical meaning. Additionally, neither logarithmic equation nor a power one fulfill boundary conditions in infinity. However, there is an alternative in form of equati...

In the last few decades, the structural parameter λ (proposed by Chang and Evans) has been used to describe rheologically unstable food liquids subjected to a constant shear rate. The concept is very simple. It is assumed that λ decreases with time from λ = 1 (unbreaking structure) to λ -> λ∞ (equilibrium or limit state). It seems that the use of a...

Levulinic acid was esterified with n‐hexanol, n‐octanol, and n‐decanol at 393–413 K and at molar ratios of between 3:1 and 10:1 (alcohol: acid) in the presence of the dodecatungstophosphoric acid (H3PW12O40) as catalyst (0.1 wt%) to study the reaction kinetics. The results of such study are the precise form of kinetic equation, which is indispensab...

Eight Cu/Zn/Zr catalysts were modified with Ce, Cr or their mixts., then characterized and used for MeOH synthesis in a tubular fixed-bed reactor at 443–513 K under 8 MPa. The highest yield (200 g/(kg∙h)) and selectivity to methanol (70%) was achived for Cu/Zn/Zr/Ga catalyst.

Laergren equation has been succesfully used from 120 years. It is used to describe the kinetic data of various processes, including batch sorption processes. All subsequnt equations derived from differential form of Lagergren equation are empirical

In the case of the adsorption process, the adsorbent is most important, and in particular its selectivity and adsorption capacity. These features determine the practical use of the adsorbent. From a scientific view point the results of surface chemistry study as well as equilibrium tests in the form of sorption isotherms are very important Also imp...

The levulinic acid was esterified with alcohol at an alcohol to acid molar ratio of 3:1, 5:1, and 10:1 in the presence of a 0.1 wt% methanesulfonic acid catalyst. During esterification, the temperature was changed linearly from 373 to 428 K and its average change was 4.5 K/min. The authors stated that reactions were of second order and that the act...

Lauric acid was esterified with n-hexanol at 393–413 K and molar ratio 3:1 to 10:1 in presence of H2SO4 catalyst (0.025% by mass) to study the reaction kinetics. The esterification reactions were carried out in an experimental, isothermal, semibatch reactor. The flow of nitrogen through the reaction mixture was applied for continuously removing the...

The impact of hydrocoliold concncentration. and stirrer type on rheological parameters of guar gum solution. under long-lasting agitating with anchor, frame and helical ribbon stirrer were determined. The Ostwald-de Waele equation was used to describe experimental. results. No proportionality between shear rate changes, rotational speed of stirrer...

State diagrams were established for the candied orange peel obtained by saturation with sucrose or glucose -fructose syrup. Differential scanning calorimetry was used to determine the freezing points and glass transition temperatures in order to generate freezing curve and glass transition curve. Curves were modelled by the Chen and Gordon -Taylor...

This study investigated the relationships between equilibrium water content and water activity for candied orange peel produced by saturation in sucrose-based and glucose–fructose syrups, and for native orange peel. Dry matter loss due to candying was found to be the highest for glucose–fructose syrup dehydrated products. The greatest amount of sug...

This research study analysed the rheological properties of potato amylose and potato amylopectin in binary solutions of the following water and dimethyl sulfoxide concentrations: 90% DMSO (1), 80% DMSO (2) and 50% DMSO (3), with preparation methodology involving the dissolution at the temperature of 98°C. The studies of dynamic light scattering on...

Autocorrelation functions for solutions of amylose. (EPS)

Autocorrelation functions for solutions of amylopectin. (EPS)

The methods of obtaining and using levulate esters are discussed. Literature has been reviewed for the kinetic studies of esterification of levulinic acid with various alcohols. Levulinic acid esters are highly potent chemical compounds in many industries because of their specific physicochemical properties. The most important of them from the indu...

In the research study, the moisture sorption isotherms were determined for the hydrolysates obtained by the enzymatic hydrolysis of native potato starch, acetylated potato starch, and distarch phosphate. Furthermore, the effect was determined of the dextrose equivalent values obtained (DE 6, 11, 16) on the hygroscopicity of products. The sorption i...

The objective of the research study was to discuss the effect of substituting starch with residues of monocarboxylic or dicarboxylic aliphatic acids on the basic starch properties appearing significant in food technology. The effect was discussed of the degree of substitution and of the chain length of acid residue on the properties of the preparat...

In the food industry a variety of non-starch hydrocolloids are used, whose solutions exhibit complex rheological properties, which depend not only on shear rate but also on shear time. The purpose of the study was to determine the changes in rheological properties of selected non-starch hydrocolloids solutions, subjected to shear under long-term ag...

A review, with 56 refs., of the prepn. methods of the title esters in org. or ionic solvents, under the supercrit. conditions, in absence of solvents as well as by using lipases of microbial origin.

Selected rheological properties of acetylated starch pastes of different amylose content were discussed in the study. The rheological studies were carried out immediately after the preparation of the pastes as well as after their one and seven day storage. For the paste of acetylated potato starch (P-A), a phenomenon of oscillatory changes of visco...

A study of polyaniline (PANI) doping with various cobalt compounds, that is, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) salen, is presented. The catalysts were prepared by depositing cobalt compounds onto the polymer surface. PANI powders containing cobalt ions were obtained by one- or two-step method suspending PANI in the following a...

The paper presents results of studies on the preparation of fresh food foams based on egg white and hydrocolloids (xanthan gum and carrageenan). The basic physical parameters of the obtained foams such as density, gas volume fraction and size of gas bubbles were measured. Rheological measurements were also performed, and continuous Maxwell model wa...

Non-starch hydrocolloids have a number of valuable functional properties that are used in many branches of the food industry. They are mainly used as structure-forming substances, which in turn translates into the appropriate mechanical properties of the finished food product. From a physicochemical point of view, hydrocolloids are biopolymers of m...

In the study paper, flow curves of potato and waxy starch pastes were interpreted. A rheological exponential equation of state for shear thinning systems was adjusted to the experimental data obtained at different temperatures. Distributions of rheological time constants were computed using a regularization method by Tikhonov. It was found that the...

Among other things, shelf life of food products depends on interactions among proteins, polisaccharides, and water. It is possible to assess them based on the measurements of osmotic pressure in model systems: solvent - single biopolymer or a mixture of biopolymers. The initial research material constituted aqueous solutions of protein isolates: wh...

Among other things, shelf life of food products depends on interactions among proteins, polisaccha-rides, and water. It is possible to assess them based on the measurements of osmotic pressure in model systems: solvent - single biopolymer or a mixture of biopolymers. The initial research material constituted aqueous solutions of protein isolates: w...

Succinic acid was esterified with cyclohexanol in presence of Ti(OBu)4 at 120–170°C and alcohol/acid ratio 3:1 to 10:1 to resp. mono- and diesters. The form of kinetic equations were proposed and verified experimentaly. The value of kinetic parameters was determined. The monoester formation was a 2nd order reaction with respect to acid and alcohol...

Pimelic and subaric acids were esterified to the resp. diesters with cyciohexanol in presence of H2SO4 in a laboratory, isothermal semibatch reactor at 120-150°C (alcohol-to-acid ratios 3:1 to 10:1) to study the reaction kinetics. The reaction had two-step course. The formation of resp. monoesters was 1st order reaction with respect to the acid and...

Glutaric acid was esterified with 2-ethylhexanol to corresponding mono- and diesters in a laboratory. isothermal semibatch reactor to study the reaction kinetics. In the presence of H2SO4 catalyst, the reaction of monoester formation was 1st order reaction while the reaction of the diester formation was a 2nd order reaction. Lack of catalyst result...

Glutaric acid was esterified with cyclohexanol to respective mono- and diesters in lab. semibatch reactor under isothermal conditions to study the reaction kinetics. In the presence of H2S04 catalyst both reaction were on first order with respect to the acid and the second reaction was first order with respect to monoester. Without any catalyst, th...

The possibility of scaling viscoelastic properties of starch solutions in relation to biopolymer concentration was presented in this study. An application of this empirical method enabled to widen the observation horizon of viscoelastic properties. It was also determined that the scope of its applicability is limited by amylose content in the solut...

H form of ZSM-5 zeolite with composition H2.4:Na0.2:Al2.6:Si93.4:O192 and SiO2/Al2O3 ratio = 90.5. was prepared. This catalyst had good activity, and almost 100 percent. selectivity (no formation of hydrocarbons). The X-ray characteristics showed that it is highly crystalline without the presence of a different crystalline phase and impurities with...

DME is an important chemical industry product. Many research centers are working on obtaining it from synthesis gas or from carbon dioxide and hydrogen. Promising seems to be the synthesis of DME on hybrid catalysts, via an intermediate like methanol. The efficiency of such a process is large. This favors the conjugated reactions system of the synt...

Rheological measurements of highly concentrated dimethylsulfoxide (DMSO) starch solutions were performed. For all experiments commercial maize starch with different AM content was used. The research covered a wide range of polymer concentrations depending on linear fraction contribution and allowed to obtain a starch content up to 40% w/w. The anal...

In the viscoelasticity science usually there are performed two experiments: oscillatory, where deformation (stress) is sinusoidally changed in function of time (frequency domain), and step function, where deformation (stress) is constant in time domain. As a result of experiment conducted in frequency domain, the most often the complex viscoelastic...

Modification of starch led to new product with new desirable properties. Oat starch was subjected to different chemical modifications (acetylation, oxidation and phosphorylation). These processes greatly influenced physico-chemical properties of starch. There were observed shifts in molecular mass, as well as in amylose, lipid and phosphorus conten...

The esterification kinetics of methacrylic acid with methanol in the presence of H3PW12O40 or H3MoW 12O40 as a catalyst was studied with isothermal batch experimental reactor. The catalyst concentration was varied between 14.4 and 57.7 mol/m3. The experiments were carried out at temperatures from 316 K to 333 K and at initial molar ratios of alcoho...

Methanol dehydration is carried out on acid catalysts with Broensted and Lewis type active sites. γ-Al2O3, Ti2O / Al2O3, Ti2O / Zr2O2, and zeolites may be included in this group. Methanol adsorption occurs on acid and alkaline centers with simultaneous dissociation with the formation of ions (i.e. carbocations) and water. Water formation is a major...

Research report on the kinetics of methanol synthesis on a copper catalyst with the addition of Ga and Zr, kinetics of synthesis of dimethyl ether on the H-ZSM-5 catalyst and modeling and optimization of direct synthesis of dimethyl ether on hybrid catalyst. The conclusions presented concern separately the synthesis of methanol, methanol dehydratio...

Polysaccharides play a significant role in food systems as texture forming agent. Their solutions posses some peculiar rheological behaviors. Some information about structure of these biopolymers and relaxation processes occurring in their solutions may be obtained by investigation of linear viscoelasticity properties. The aim of this research was...

Esterification reactions of acrylic acid with n-propanol and n-butanol were carried out in the liquid phase in the presence of H3PW12O40 or H3PMo12O40 as a catalyst, at various temperatures, molar ratios of the reactants, and concentrations of the catalyst. The kinetic equations had a nonelementary form. © 2008 Wiley Periodicals, Inc. Int J Chem Ki...

The results of investigations of kinetics of esterification of methacrylic acid with n-butanol and butanol-2 in the presence of some heteropolyacids as catalysts have been presented. In the study, the effects of temperature, initial concentration and concentration of the catalyst on the course of the esterification process have also been determined...

The aim of present work was to study viscoelastic properties of maize starch–guar gum–water systems. The investigations were performed using two techniques: rheological measurements in frequency domain and structural studies with AFM method. Interpretation of results was based on time–temperature superposition principle and phenomenological theory...

The influence of the catalyst on the kinetics of ethyl metacrylate synthesis The synthesis of ethyl metacrylate in the liquid phase was studied. Tungstophosphoric and molybdophosphoric acids, which belong to heteropolyacids group, were used as a catalyst. The chemical compounds from this group are often utilized in the catalysis with regard to thei...

The presented research covers the investigation on the interaction of basic mono- (D-glucose, D-fructose) and a disaccharide (saccharose) with two of the most used hydrocolloids, i.e. guar gum and xanthan. As a basic model the 50% water solution of an appropriate carbohydrate with 1%wt. of a hydrocolloid was chosen. Viscoelastic measurements were c...

Summary Polyaniline (PANI) as one of the conducting polymers focuses intensive research on both scientific and practical field. There are quite a lot of known hybrid materials of PANI and other polymer systems with various synthetic polymers, which results in blends with various properties. The presented research covers the blends of polyaniline wi...

Polysaccharides are one of the basic components of food. They are also used to shape its mechanical and textural properties. Because of biodegradability and renewability, they are used in the pharmaceutical, ceramic, paper, textile and biotech industries. The complex hydrodynamic behavior of polysaccharides and their solutions allow them to be used...

A review covering the structure, properties, and catalytic performance of heteropoly acids In the homo (liq.) and hetero systems with particular ref. to esterification of acrylic acid with BuOH.

Extended abstract: Esters of acrylic acid are the group of chemical compounds widely spread in many aspects of life. Basing on methyl and ethyl acrylates, used as monomers in synthesis of various polymers and co-polymers, plastic material, varnishes, binding and coating agents and also super absorbents are produced. They can also be used as auxilia...

Extended abstract: The esters of methacrylic acid with aliphatic alcohols of low molecular weight have an important place in organic syntheses.They are commonly used for the production of organic glasses, resins, adhesives, sealants, thickeners, dispersing agents and surfactants. The kinetics of the esterification of methacrylic acid with methanol...

Extended abstract: Dimethyl ether (DME) is a gas with similar properties to propane and butane. It can be used as LPG substitute. Furthermore, DME has been sugested as an alternative fuel for diesel engines. DME can be produced directly from z H2, CO2 i CO (using bifunctional catalyst bed) as well as from methanol in methanol dehydration process. T...

Effect of limited proteolysis of extruded soy flour on rheological properties and microstructure of the obtained hydrolysates was investigated. Flow curves with a controlled shear rate and time-dependent curves with a constant shear rate were determined. The surface of investigated material was studied with atomic force microscope Quesant "Nomad" m...

The optimum temperature profiles in a fixed-bed catalytic reactor for the methanol synthesis from H2, CO2 and CO were determined. The mass balance equations with Vanden Bussche and Froment kinetic equations were used to describe the coures of chemical reactions (CO2 + 3H2 <=> CH3OH + H2O with a side reaction: CO2 + H2 <=> CO + H2O). To find the opt...

Extended abstract: The paper deals with stress relaxation and linear viscoelasticity behavior of guar gum water solutions. Frequently, the determination of material characteristic function, such as the molecular mass distribution of a polymeric sample, or the relaxation spectrum of a viscoelastic fluid, leads to an ill-posed problem. The determinat...

Extended abstract: N-octyl acrylate is an important organic ester used especially in polymer industry. The emphasis of the current work is to study in detail the kinetics of esterification of acrylic acid with n-octanol in the presence of two heteropolyacids as a catalyst: H3PW12O40 and H3PMo12O40. Kinetic experiments were carried out in the semiba...

The optimum temperature profiles in a fixed-bed catalytic reactor for the system of three consecutive-competing reactions with external diffusion were determined. The shape of optimum temperature profiles can be decreasing curve, increasing curve or decreasing-increasing curve. They do not need to begin or end by maximum limiting value of temperatu...

The heterogeneous autocatalytic reactions described by stoichiometric equations A → B, A + (n - 1)B → nB, B → C was analysed in details. The mass balance equations were written separately for the processes on a surface of pellet and for the processes occurring in a chemical or biochemical reactor. The optimum distributions of size of pellets in a t...

The equilibrium of the synthesis of methyl acrylate was studied in a batch reactor. The reaction equilibrium constant was determined experimentally in the range 39-60°C. The standard molar reaction properties were obtained at 298 K: ΔH 0 = 26698.2 J·mol -1, ΔG 0 = -3765.7 J·mol -1 and ΔS 0 = 102.18 J·mol -1·K -1. The standard molar properties of fo...

Extended abstract: The rheological behaviour of potato starch in water solution has an impotrant role in thermal processing and mixing of food. Thixotropy, attributed to a structure breakdown under shear stress, plays a significant role. In the present work, an attempt has been made to study the interaction of potato starch with xanthan in water so...

Extended abstract: The kinetics of esterification of methacrylic acid with n-heksanol and n-octanol catalysed by the dodeca tungstophosphoric acid has been investigated. Kinetic experiments were carried out in an isothermal, laboratory-scale, semibatch reactor. To avoid the influence of the hydrolysis on process, the flow of nitrogen through the re...

Extended abstract: Industry development, shrinking energy resources and increasing ecological awareness of societies force search for new technological solutions. One such method is reactive distillation. This process combines chemical reactions with pre-separation in one device. The aim of the study was the use of reactive distillation for the syn...

The paper presents the results of viscoelastic studies of aqueous solutions of maize starch with the addition of guar gum. Modeled starch and hydrocolloid systems of various concentrations were subjected to a creep test. The results are desribed with the Burgers continuous model, which allowed to determine the retardation spectra. The computations...

The optimum temperature profiles in fixed-bed catalytic reactors for the system of two consecutive-competing reactions accompanied by external energy transport have been determined. The shape of optimum temperature profiles can be a decreasing curve, increasing curve or a decreasing-increasing one. They do not need to begin or end by maximum limiti...

The system of heterogeneous autocatalytic reactions described by stoichiometric equations: A → B, A + (n - 1)B → nB, B → C was analysed in details. The possibility of increase in the yield of product B by controlled change in resistance of intraparticle diffusion in a fixed-bed catalytic reactor or bioreactor was shown.

The kinetics of the esterification of acrylic acid with methyl and ethyl alcohols using sulphuric acid as a catalyst (0,5-3 wt %) has been investigated. The study was conducted in an experimental, isothermal batch reactor with the initial molar ratio of alcohol to acrylic acid equal to 1:1, 2:1, 3:1 and 4:1. The temperature was varied in the range...

The kinetics of esterification of methacrylic acid with methyl and ethyl alcohols using sulphuric acid as a catalyst (0.5-4 wt. %) has been studied. The experiments were carried out in an isothermal batch reactor with the initial molar ratio of alcohol to acrylic acid equal to 1:1, 2:1, 3:1 and 4:1, within the range of temperatures from 25 to 85°C....

The objective of the present work is the evaluation, modeling, and optimization of heterogenic autocatalytic reactions that show the Langmuir−Hinshelwood kinetics with accompanying external diffusion for nonporous catalyst pellets or intraparticle diffusion and external energy transport for porous pellets in a fixed-bed tubular reactor. Both cases...

The paper presents results of rheological studies of potato starch paste and with the addition of xanthan gum The pastes were tested with a rotary reomether RS150L (Haake) using a qualitative hysteresis loop test and equilibrium curve test (apparent viscosity vs. time at constant shear rate). Applying the Chang and Evans theory of structural parame...

The kinetics of the esterification of levulinic acid with various alcohols: n-hexanol and n-decanol, in the presence of sulfuric acid as a catalyst has been investigated in an experimental, isothermal semibatch reactor. The range of reaction temperatures was 383-413 K, initial molar ratios of aliphatic alcohol to levulinic acid were 3:1, 5:1, 10:1...

Application of the pseudo-homogenous and steady-state adsorption model (SSAM) was analyzed for the description of the oxidative dehydrogenation (ODH) of propane over vanadia-titania catalyst, using an extensive set of the experimental data. It has been shown that the SSAM model adequately describes the kinetics of the studied reaction for a broad r...

The esterificaion of benzoic acid has been studied in an experimental, isothermal, semi-batch reactor using sulfuric acid catalyst. The reaction appears to be the first order with respect to benzoic acid and does not depend on the concentration of octyl alcohol. The kinetic parameters are given.

The kinetics of the esterification of crotonic acid with octyl, decyl, and dodecyl alcohol has been investigated in an isothermal semibatch reactor using sulfuric acid as the catalyst. The reaction kinetics appeared to be of the second order when it was dependent on the concentrations of both reactants. The temperature dependence of the kinetic par...

The kinetics of the esterification of maleic anhydride with hexan-1-ol using various catalysts has been investigated in an isothermal semibatch reactor. It was found that the second stage of the esterification of maleic anhydride with hexan-1-ol in the presence of sulfuric acid is of the first order in a relationship to the monoester. The reaction...

The work deals with modelling and optimization of complex systems as autocatalytic and pseudoautocatalytic reactions accompanied by mass transport phenomena in the fixed-bed catalytic reactors. L-H kinetic equations are used .Both isotherma and nonisothermal reactiones are considered. Control variable is reactor diameter influencing directly interp...

Theoretical and numerical work focused on determination of optimum temperature profiles in complex systems as systems of chemical reactions accompanied by mass and energy trasport phenomena in fixed-bed catalytic reactor. L-H type kinetic equations were used. Optimum control problem was solved using Pontriagin's maksimum principle. From numerical v...

Extended abstract: The kinetics of the esterification of crotonic acid with n-decyl alcohol and n-dodecyl alcohol in the presence sulfuric acid asa catalyst has been investigated in an experimental, isothermal, semibatch reactor. Prior to the start of the process, a carefully weighed amount of alcohol mixed with a suitable amount of sulfuric acid w...

Extended abstract: Phthalates of aliphatic alcohols are primarily used as intermediates in organic synthesis, particularly in polymer industry. One of important is di-n-hexyl phthalate. Its synthesis from phthalic anhydride proceeds in two stages: phthalic anhydride + n-hexanol ==> monoester, monoester + n-hexanol ==> diester + water. The first sta...

The kinetics of the esterification of crotonic acid with n-octyl alcohol and its isomer 2-ethylhexyl alcohol has been investigated in an experimental, isothermal, semibatch reactor. When using sulfuric acid catalyst, the reaction in both cases appears to be the second order with respect to crotonic acid and to octyl alcohol. The kinetic parameters...

A detailed analysis was carried out concerning the autocatalytic reactions of the type: A → B, A + (n-1)B → nB, occurring in chemical reactors and accompanied by intraparticle diffusion and external energy transport. The optimum distribution of the sizes of catalyst pellet was found leading to a maximum extent of the non isothermal, heterogeneous a...

The esterification process of methacrylic acid with n-propanol and isopropanol have been studied in an experimental, isothermal batch reactor. Basing on experimental results, the rigorous kinetic models were derived including the reversible reactions. The equilibrium constants and kinetic parameters have been determined.