Selektivna katalitička oksidacija propena do akroleina

master's thesis

• Title (english): Selective catalytic oxidation of propene to acrolein
• Author: Biljana Gojković
• Mentor: Vesna Tomašić (mentor)
• Committee member: Vesna Tomašić (predsjednik povjerenstva)
• Committee member: Vanja Kosar (član povjerenstva)
• Committee member: Aleksandra Sander (član povjerenstva)
• Granter: University of Zagreb; Faculty of Chemical Engineering and Technology; Zagreb
• Defense date and country: 2015-07-15, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Chemical Engineering; Reaction Engineering

Abstract

Reakcije selektivne oksidacije ugljikovodika imaju važnu ulogu u današnjem društvu s obzirom na činjenicu da se na njima zasniva četvrtina proizvodnje najvažnijih industrijskih organskih kemikalija i njihovih međuprodukata koji se koriste u proizvodnji različitih industrijskih proizvoda i robe široke potrošnje. Zbog toga, one značajno doprinose nacionalnom dohotku industrijskih zemalja u razvoju, a s druge strane još uvijek su temelj istraživanja.
Cilj ovog rada bilo je izučavanje selektivne katalitičke oksidacije propena u akrolein u cijevnom reaktoru s nepokretnim slojem katalizatora. Kao katalizatori korišteni su bizmutovi molibdati pripremljeni različitim metodama. Od konvencionalnih metoda korištena je metoda precipitacije, dok je od novijih metoda korištena metoda sušenja s raspršivanjem iz suspenzije i otopine. Reakcije su provedene pri atmosferskom tlaku, konstantnom omjeru propena i kisika, pri različitim ukupnim protocima reakcijske smjese (40 – 160 cm^3 min^-1) te pri različitim temperaturama (350 – 450 °C). Istraživanja su provedena s ciljem povezivanja fizičko – kemijskih značajki katalizatora koje nastaju kao rezultat primjene odgovarajuće metode pripreme i katalitičkih značajki, primarno aktivnosti i selektivnosti katalizatora.
Predloženi su kinetički modeli reakcije, te odgovarajući matematički model za opisivanje reaktora s nepokretnim slojem katalizatora. Na temelju usporedbe eksperimentalnih rezultata s vrijednostima dobivenim prema pretpostavljenom modelu izvedeni su zaključci o prihvatljivosti predloženog modela. Jednadžbe modela reaktora riješene su numerički metodom Runge Kutta IV, uz istovremeni postupak procjene parametara modela. Analiza kinetičkih rezultata provedena je izmijenjenom diferencijalnom metodom (ID), a kao kriterij slaganja korišten je korijen srednjeg kvadratnog odstupanja (SD).
Također, nađeno je da pri radnim uvjetima primijenjenim u ovom radu, osim akroleina kao željenog produkta reakcije, nastaju i sporedni produkti, vjerojatno uslijed naknadne oksidacije reakcijskih intermedijera. Ustanovljeno je i da s porastom temperature raste ukupna konverzija propena, dok se istovremeno smanjuje selektivnost s obzirom na željeni produkt reakcije. Dobiveno je vrlo dobro slaganje eksperimentalnih rezultata s vrijednostima dobivenim prema pretpostavljenom modelu što ukazuje na prihvatljivost predloženog modela.

Abstract (english)

Selective oxidation reactions of hydrocarbons play an important role in today's society since the production of one quater of the most important industrial chemicals and intermediates used in the manufacture of industrial products is based on these reactions. They contribute significantly to the gross national products of industrial countries and they also present opportunities for significant fundamental research.
The aim of this work was to study the catalytic oxidation of propene to acrolein in the fixed bed tubular reactor. Bismuth molybdate, which was used as a catalyst, was prepared using two different methods. Method of precipitation was used as an traditional method for catalyst preparation, , and the spray-drying method from the appropriate suspension or solution was used as a new method of preparation. The catalytic reaction was conducted at the atmospheric pressure, at constant ratio of propene and oxygen, at different total flow rates of the reaction mixture at the inlet of the reactor (40-160 cm^3 min^-1) and at different temperatures (350 - 450 °C). Research was carried out with the aim of connecting the physico- chemical properties of the catalyst occurred as result of applying appropriate methods of preparation, and catalytic properties, primary activity and selectivity.
Kinetic models of the reaction and corresponding mathematical model were proposed to describe the fixed-bed reactor employed in this study. Conclusions about the acceptability of the proposed model were drawn out based on the comparison of experimental results and proposed model. Reactor model equations were solved using the numerical method of Runge Kutta IV, with simultaneous estimation of the model parameters. Analysis of kinetic results was conducted using modified differential method (ID). The root of mean square deviation (SD) was used as a criterion of correlation. .
It was found out that under the reaction conditions employed in this work, some other products are formed, except of acrolein as desired reaction product, probably due to the subsequent oxidation of reaction intermediates. The overall conversion of propene increased with the increase of the reaction temperature, but the selectivity with respect to acrolein as the desired product simultaneously decreased. A good agreement between experimental results and the predicted model of the fixed-bed reactor has been observed, indicating its acceptability.

• Keywords: selektivna katalitička oksidacija; Bi-Mo katalizatori; sušenje s raspršivanjem
• Keywords (english): selective oxidation reactions; Bi-Mo catalysts; spray drying method
• Language: croatian
• URN:NBN: urn:nbn:hr:149:373026
• Study programme: Title: Chemical Engineering - Graduate study; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka kemijskog inženjerstva (magistar/magistra inženjer/inženjerka kemijskog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2016-12-20 11:51:57