Kinetika in transportni pojavi pri katalitski hidrogenaciji glukarne kisline do adipinske kisline

Hočevar, Brigita (author), Likozar, Blaž (mentor)

Trenutna proizvodnja adipinske kisline (enega izmed najpomembnejših monomerov polimerne industrije) temelji na skoraj 80 let starem procesu oksidacije cikloheksana, pri čemer nastajajo okolju škodljive NOx komponente. V predstavljeni doktorski disertaciji sem želela razviti bolj trajnosten proces pridobivanja bioosnovane adipinske kisline iz celuloznih virov. Doktorsko delo je bilo razdeljeno na študijo hidrodeoksigenacije modelnih komponent z eno funkcionalno skupino ter na študijo dehidroksilacije aldarnih kislin (mucinske in glukarne kisline) do končnega produkta adipinske kisline (oziroma njenih estrov). Na podlagi študije hidrodeoksigenacije (HDO) modelnih komponent (heksanojske kisline, 1-,2- in 3-heksanola, 2- in 3-heksanona, heksanala, metil heksanoata in diheksil etra), izvajane v trifaznem šaržnem reaktorju in katalizirane preko NiMo/γ-Al2O3 katalizatorja, sem razvila mikrokinetični matematični model, ki opisuje dogajanje v vseh treh fazah in na površini katalizatorja. V drugem delu sem na podlagi razvitega matematičnega modela predpostavila reakcijske pogoje za HDO kompleksnejšega sistema, torej HDO aldarne kisline, ki na terminalnih mestih vsebuje karboksilno kislino, na vmesnih C atomih pa po eno hidroksilno skupino. V tem sklopu sem testirala reakcijske pogoje ter kovinske katalizatorje na različnih nosilcih za HDO mucinske kisline v vodnem mediju. Izkazalo se je, da v vodnem mediju mucinska kislina tvori lakton. Poleg tega so bili testirani katalizatorji premalo ali preveč (poleg HDO potekala tudi cepitev C-C vezi) aktivni. V zadnjem sklopu sem se osredotočila na selektivno odstranjevanje –OH skupin iz aldarne kisline preko homogenih in heterogenih Re katalizatorjev na različnih nosilcih. Izkazalo se je, da homogeni katalizatorji uspešno odstranjujejo hidroksilne skupine, saj je dobitek dehidroksiliranih produktov (z dvema, eno ali nobeno dvojno vezjo) znašal več kot 50 mol%. Reducirani Re/C katalizator se je izkazal kot najbolj učinkovit, saj se je pri temperaturi 175 °C in po 60 urah reakcije v metanolu kot topilu pridobilo kar 98 mol% dehidroksiliranih produktov, kar je najvišji objavljeni dobitek do sedaj. Razviti proces sem uspešno opisala tudi z matematičnim modelom, ki je vključeval raztapljanje aldarne kisline, transportne pojave, adsorpcijo in desorpcijo ter kinetično pretvorbo na površini katalizatorja.

• Language: Slovenian
• Keywords: ignocelulozna biomasa, aldarna kislina, adipinska kislina, katalitska hidrodeoksigenacija, dehidroksilacija, matematično modeliranje, reakcijska kinetika
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2020
• PID: 20.500.12556/RUL-116896
• COBISS.SI-ID: 1538553027
• Publication date in RUL: 15.06.2020

Secondary language

• Language: English
• Title: Kinetics and transport phenomena in catalytic hydrogenation of glucaric acid to adipic acid

Abstract

Current production of adipic acid (one of the most important monomer building blocks in the polymer industry) is based on the nearly 80-year-old oxidation process of cyclohexane, producing environmentally harmful NOx compounds. The aim of the presented doctoral dissertation was to develop a sustainable process for the production of bio-based adipic acid from cellulosic sources. This doctoral thesis is divided into two studies; hydrodeoxygenation of model compounds with one oxygen-containing functional group, followed by dehydroxylation of aldaric acids (mucic and glucaric acid) into the final product, adipic acid (or its esters). Based on the hydrodeoxygenation (HDO) study of model compounds (hexanoic acid, 1-, 2- and 3-hexanol, 2- and 3-hexanone, hexanal, methyl hexanoate and dihexyl ether) carried out in a three-phase batch reactor and catalyzed via NiMo/γ-Al2O3 catalyst, a micro-kinetic mathematical model describing the phenomena in all three phases and on the catalyst surface was developed. In the second part, based on the developed mathematical model, initial assumptions were proposed for HDO of a more complex system, i.e. HDO of aldaric acid, which has free carboxylic groups at the terminal sites and one hydroxyl group on each intermediate C atom. In this experimental study, various reaction conditions and metal catalysts on different supports were tested for HDO of aqueous mucic acid. In aqueous media mucic acid readily forms a lactone while the tested catalysts showed negligible or too high (resulting in C-C bond cleavage) activity. The final section was focused on selective removal of –OH groups from aldaric acids via homogeneous and heterogeneous Re catalysts on different supports. Presence of homogeneous catalysts resulted in successful removal of –OH groups as a 50 mol% yield of dehydroxylated products (with two, one or no double bonds) was obtained. The reduced Re/C catalyst proved to be the most effective as a yield of dehydroxylated products, obtained at 175 °C after 60 h of reaction in methanol as solvent, was 98 mol%, the highest published yield ever reported. The developed process was successfully described by the mathematical model, which included dissolution of aldaric acid, transport phenomena, adsorption, desorption, and kinetic reactions on the catalyst surface.

• Keywords: lignocellulosic biomass, aldaric acid, adipic acid, catalytic hydrodeoxygenation, dehydroxylation, mathematical modeling, reaction kinetics