Oksidacija glukoze do aldarnih kislin

Volčanšek, Zala (avtor), Likozar, Blaž (mentor)

Zaradi vse večjega onesnaževanja okolja z izpusti in posega v naravo je vsakršna alternativna možnost za proizvodnjo kemikalij dobrodošla. Ena izmed možnosti, s katero lahko zmanjšamo našo odvisnost od nafte in ublažimo emisije toplogrednih plinov, je uporaba obnovljivih virov. V zadnjem času so ogljikovi hidrati, predvsem glukoza, tisti, ki pritegnejo veliko zanimanja kot obnovljiva surovina, saj se jih lahko pretvori v sladkorne kisline, ki so izhodišče pri proizvodnji kemikalij. Ena izmed pomembnejših sladkornih kislin je glukarna kislina, saj zagotavlja obnovljivo alternativo za sintezo adipinske kisline, ki je potrebna za izdelke v industriji plastike in tekstila ter še marsikje drugje. Trenutno se glukarno kislino pridobiva z elektrokemično ali stehiometrično oksidacijo z uporabo nezaželenih reagentov, kot so NaBr, NaOCl in razna belila. Najpogostejši pa je postopek, ki vključuje oksidacijo glukoze s koncentrirano dušikovo kislino, saj je to najbolj ekonomičen postopek, vendar je zelo škodljiv okolju. V zadnjem času se raziskuje obetaven postopek oksidacije glukoze, ki je okolju prijaznejši. Reakcija poteka ob prisotnosti kovinskih katalizatorjev pri povišani temperaturi okoli 100 °C in tlaku 40 barov, kot oksidant pa se uporabi molekularni kisik. Pri laboratorijskem delu sem najprej sintetizirala katalizator 10 % Ag/ZrO2, ki sem ga kasneje uporabila za oksidacijo glukoze. Njegovo učinkovitost in selektivnost sem primerjala s komercialno dostopnim katalizatorjem 10 % Au/TiO2 (anatas + rutil). Cilj je bil pridobiti glukarno kislino, vendar mi to z omenjenima katalizatorjema ni uspelo. Kot produkt je nastala glukonska kislina, intermediat, ki se oksidira do glukarne kisline. Menim, da pretvorba do glukarne kisline ni uspela zaradi premajhne oksidativne kapacitete katalizatorjev.

• Jezik: Slovenski jezik
• Ključne besede: glukoza, aldarne kisline, glukarna kislina, katalizatorji
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2021
• PID: 20.500.12556/RUL-130157
• COBISS.SI-ID: 84659459
• Datum objave v RUL: 10.09.2021

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Oxidation of glucose to aldaric acids

Izvleček

Due to the increasing pollution of the environment through emissions and invasion on nature, any alternative option for the production of chemicals is welcome. One way we can reduce our dependence on fossil fuels and alleviate greenhouse gas emissions is to use renewable resources. Nowadays carbohydrates and especially glucose, is the one that attracts a lot of interest as a renewable raw material This is due to the fact, that it can be converted into sugar acids, which are the starting point in the production of chemicals. One of the most important sugar acids is glucaric acid, as it provides a renewable alternative in the synthesis of adipic acid, which is needed as a raw material in the plastics and textiles industry, among others. Currently, glucaric acid is obtained by electrochemical or stoichiometric oxidation using undesirable reagents such as NaBr, NaOCl, and various bleaches. The most common, however, is a process that involves the oxidation of glucose with concentrated nitric acid, as this is the most economical process, but it is very harmful to the environment. Recently, however, a promising, more environmentally friendly glucose oxidation process has been developed. The reaction is carried out in the presence of metal catalysts, at an elevated temperature of about 100 °C and a pressure of 40 bar, using molecular oxygen is used as the oxidant. For my study I synthesized a 10 % Ag/ZrO2 catalyst, which I then used in glucose oxidation. I compared its efficiency and selectivity with a commercially available 10 % Au/TiO2 catalyst (anatase + rutile). The goal was to obtain glucaric acid, but I failed to do so with the aforementioned catalysts. As a product, gluconic acid was formed, which is a precursor of glucaric acid. I believe that the conversion to glucaric acid failed due to the low oxidation capacity of the catalysts.

• Ključne besede: glucose, aldaric acid, glucaric acid, catalysts