Mirosław Grzesik

Thermodynamics and kinetics of low pressure methanol synthesis

Abstract The results of our investigations on methanol synthesis, carried out over a number of years, have been presented in the form of an interpretative review. The present article is an attempt to summarize this research against the background of what has already been done in this area in the world. Special attention was focused on the role of CO2 in the process.

Theoretical analysis of two parallel and consecutive reactions in isothermal symmetrical catalyst pellets using the dusty-gas model

Abstract The courses of the simplest multiple reactions such as two parallel reactions and two consecutive reactions proceeding in the isothermal symmetrical ca

The Effect of the Catalyst Used on the Kinetics of Di-2-Ethylhexyl Maleate Synthesis

Kinetics of the esterification of maleic anhydride with 2-ethylhexanol in the presence of sulfuric acid, amphoteric tetrabutyl titanate or in the absence of external catalyst has been studied. The kinetic equations and kinetic parameters have been determined.

Kinetics of the esterification of benzoic acid with n-octyl alcohol or isooctyl (2-ethylhexyl) alcohol using sulfuric acid catalyst

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.

Time-on-stream catalyst decay behaviour in a fixed-bed catalytic reactor under the influence of intraparticle diffusion: intraparticle diffusion affects only catalytic reactions

The time-on-stream theory of catalyst decay developed by Wojciechowski is used to describe the behaviour of diffusion-limited aging catalyst under the assumption that the intraparticle diffusion can affect only catalytic reactions. It is shown that the presence of internal mass transport does not preclude the existence of three classes of catalyst decay behavoiur depeding on the parameter N in the aging function, a(t =(1+Gt-N. By evaluating XA=XA(tf), WB = WB(tf) and WB = WB(XA profiles, the morphologies of some interesting effect are also revealed and discussed.

Modelling of intraparticle diffusion affected by the time-on-stream catalyst decay

The problem of modelling of the intraparticle diffusion affected by the time-on-stream catalyst decay is considered. Independently of the value of n (number of active catalyst sites involved in a single reaction event), a crosseffect is attained consisting in a higher average conversion in the catalyst bed of higher internal diffusion resistance at a sufficiently long deactivation time. If Φ d >Φ dcr = {2(ν+1)} 1/2 , then a non-uniform profile of the fraction of unpoisoned active sites appears in a catalyst pellet, although only concentration-independent deactivation is examined

Enhancement of heterogeneous autocatalytic reactions by external diffusion

Abstract The present analysis deals with the selected heterogeneous autocatalytic reactions of the type A → B,A + B → 2B and A → B,A + 2B → 3B, occurring in chemical reactors and accompanied by external diffusion. The dependence of the overall process rate on the mass transfer coefficient is determined both analytically and numerically, for some chosen values of the operating parameters and for various conversion degrees. It was found that the presence of an external resistance to mass transport may lead to an increase in the overall rate of the process compared with the values obtained for the vanishing resistance. An analytical method is proposed to calculate the optimum distribution of the size of catalyst pellets in some selected types of chemical reactors, which leads to a maximum extent of the heterogeneous autocatalytic reactions.

Enhancement of heterogeneous autocatalytic reactions by intraparticle diffusion

Abstract A detailed analysis was carried out concerning the heterogeneous autocatalytic reactions of the type A → B,A + (n − 1)B → nB, occurring in chemical reactors and accompanied by intraparticle diffusion. The effect of internal diffusion was studied for three basic geometries of a catalyst pellet. The regions were determined in which the effectiveness factor is much larger than unity. In these regions the presence of an internal resistance to mass transport may lead to serious increase in the overall rate of the heterogeneous autocatalytic reactions. The optimum distribution of the sizes of catalyst pellet was found for some selected reactors, leading to a maximum extent of the heterogeneous autocatalytic reactions.

Liquid-Phase Esterification of Methacrylic Acid with Methanol Catalyzed by Heteropolyacid

The esterification kinetics of methacrylic acid with methanol in the presence of H3PW12O40 or H3MoW12O40 as a catalyst was studied with isothermal batch experimental. The catalyst concentration was varied between 14.4 and 57.7 mol/m3. The experiences were carried out at temperatures from 316 to 333 K and initial molar ratios of the reactants from 3 to 10. The non-ideality of the liquid phase was accounted for by using activities instead of molar. The activity coefficients were determined using the UNIFAC method. The kinetic equations developed had a non-elementary form, and the order of the reaction was a fraction.

Chemical equilibria in direct synthesis of dimethyl ether

Abstract The effect of the initial feed composition, temperature and pressure on the equilibrium conversions were examined for direct synthesis of dimethyl ether from CO 2 and H 2 or from CO and H 2 . The three-reaction system was analysed for both considered cases. From a thermodynamic point of view, direct synthesis of dimethyl ether from CO 2 and H 2 or from CO and H 2 seems to be quite promising for industrial applications.