Mathematical modeling of acidolysis of benzyl phenyl ether as a model lignin component and model validation

Oblikovan je bil model za pridobitev kinetičnih parametrov acidolize benzil fenil etra s pomočjo dvomolarne žveplove kisline, ki ima pri reakcijah vlogo homogenega katalizatorja. Poskusi so potekali v treh sistemih topil: etanolu, metanolu in etanolu/vodi. Poskusi so potekali pri temperaturah med 160 in 200 °C v dušikovi atmosferi pri začetnem tlaku 10 bar. Pridobljeni so bili podatki o konstantah hitrosti in aktivacijskih energijah reakcije. Model je bil sestavljen na podlagi poskusov v reaktorju z goščo. Predvideno je bilo popolno premešanje in upoštevano spreminjanje gostot tekoče faze, uparevanje topila in zmanjševanje mase tekoče faze skozi trajanje poskusa zaradi jemanja vzorcev. Funkcije parnih tlakov in gostot tekočih faz so bile pridobljene iz eksperimentalnih podatkov. Vsi modeli so predvideli linearno odvisnost reakcijske hitrosti od koncentracije žveplove kisline, za opis odvisnosti od temperature pa sem uporabil Arrheniusovo zvezo. Ujemanje modela je dobro, do večjih odmikov pride pri temperaturah reakcije 200 °C, kjer pride do negativnih odmikov eksperimentalnih vrednosti od modelnih. Model v etanolu je bil tudi validiran z dvema poskusoma, s katerima sem želel doseči čim višje konverzije. Razpad benzil fenil etra pri obeh reakcijah poteka po z modelom napovedani krivulji.A mathematical model was developed to obtain the kinetic parameters of benzyl phenyl ether acidolysis with two molar sulphuric acid which is the homogenous catalyst in the system in three solvent systems, ethanol, methanol and water/ethanol. The experiments were performed in batch reactor in the temperature range between 160 and 200 °C in the nitrogen athmosphere at the initial pressure of 10 bar. Homogeneity of the mixture was pressumed, density and pressure functions were created with curve fitting of experimental data. The volumetric change due to sampling was also described. Kinetic parameters i.e. reaction rate constants and activation energies were obtained. The reaction rate was linearly proportional to the concentration of sulphuric acid and temperature dependance was described with the Arrhenius equation. The accuracy of the model was verified for the ethanol system