Biološka priprava različnih aldarnih kislin

Simčič Zuljan, Ana (avtor), Likozar, Blaž (mentor)

Želja po lepši in bolj čisti prihodnosti ter potreba po nadomestitvi neobnovljivih virov je pripeljala do razvoja okolju prijaznejših kemikalij. Med njimi so tudi aldarne kisline, sladkorne kisline, ki se jih pridobiva iz celuloze. Ker gre za obnovljiv vir, je idealen nadomestek fosilnim gorivom za pripravo vsestranskega najlona-6,6. V preteklosti se je za pripravo glukarne kisline, vmesnega produkta pri pridobivanju adipinske kisline, uporabljala oksidacija s pomočjo dušika. Pri tem procesu so se v okolje izpuščale ogromne količine N2O, ki je še bolj problematičen za globalno segrevanje kot CO2. Možna je tudi priprava glukarne kisline s pomočjo biološke katalize, pri kateri se kot katalizatorji uporabljajo encimi. To so proteini, ki jih proizvajajo živi organizmi. Encimi so za razliko od kemijskih katalizatorjev bolj specifični, saj lahko katalizirajo le določeno kemijsko reakcijo. Ker pa so večji izkoristki doseženi z uporabo anorganskih katalizatorjev, je trenutno biosinteza še vedno v fazi razvoja in zaenkrat še ne obstaja industrijski proces, pri katerem se glukarno kislino pridobiva s pomočjo encimov. Nove raziskave so pokazale, da je oksidacija glukoze do glukarne kisline uspešna tudi z uporabo kisika pri povišanem tlaku (okoli 40 bar) in višji temperaturi (100 °C). Pomemben del samega procesa pa je uporaba primernega katalizatorja, s katerim lahko dosežemo največjo aktivnost in selektivnost. Cilj diplomske naloge je bila raziskava teoretičnega ozadja biološke katalize. Sledil je eksperimentalni del, pri katerem sem se posvetila kemijski katalizi ter v tem okviru pripravila svoj bimetalni katalizator Ag-Cu/ZrO2. Izvedla sem dve oksidaciji, kjer sem po primerjavi rezultatov ugotovila, da je najboljši katalizator zlato. Bimetalni katalizator, ki sem ga sama pripravila, je imel slabe izkoristke. V nobenem primeru nisem prišla do željenega končnega produkta – glukarne kisline. Analiza katalizatorja je pokazala, da je bila sinteza uspešna. Torej lahko sklepam, da katalizator, ki je kombinacija srebra in bakra, ni dovolj selektiven, da bi vodil do nastanka glukarne kisline.

• Jezik: Slovenski jezik
• Ključne besede: glukoza, glukarna kislina, biosinteza, encimi, katalizatorji
• Vrsta gradiva: Diplomsko delo/naloga
• Tipologija: 2.11 - Diplomsko delo
• Organizacija: FKKT - Fakulteta za kemijo in kemijsko tehnologijo
• Leto izida: 2020
• PID: 20.500.12556/RUL-119537
• COBISS.SI-ID: 28403971
• Datum objave v RUL: 09.09.2020

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Biological synthesis of different aldaric acids

Izvleček

The desire for a better and cleaner future and the need to replace a non-renewable resource have led to the development of more sustainable chemicals. Some of them are aldaric acids, sugar acids derived from cellulose. Since this is a renewable resource, it is an ideal substitute for fossil fuels in the preparation of the wildly used nylon-6,6. In the past, oxidation of glucose with nitrogen has been used to prepare glucaric acid. The latter is an intermediate in the production of adipic acid. In this process, huge amounts of N2O are released into the environment, which is a greenhouse gas 180 times more potent than CO2. An interesting alternative to oxidation of glucose with nitrogen, is biological catalysis, in which enzymes are used as catalysts. These are proteins produced by living organisms, and unlike chemical catalysts, enzymes are more specific because they can only catalyse a certain chemical reaction. As higher efficiencies are achieved through the use of inorganic catalysts, biosynthesis is currently still in the development stage and, for the time being, there is no industrial process where enzymes are used for the production of glucaric acid. New research has shown that the oxidation of glucose to glucaric acid is also successful with the use of oxygen as an oxidant at elevated pressures (about 40 bar) and higher temperature (100 °C). An important part of the process itself is also the use of a suitable catalyst with which we can achieve maximum activity and selectivity. The aim of the thesis was to investigate the theoretical background of biological catalysis, followed by the experimental part, where I focused on chemical catalysis. As already mentioned, an important element of oxidation is the catalyst, so I prepared my bimetallic catalyst Ag-Cu/ZrO2 as part of the experimental work. Two oxidation experiments were performed, where, after comparing the results, it was found that the gold catalyst was more active. In no case did I get the desired end product – glucaric acid. Catalyst analysis showed that the synthesis was successful, so we can conclude that the silver and copper bimetallic catalyst is not selective enough to lead to the formation of glucaric acid.

• Ključne besede: glucose, glucaric acid, biosynthesis, enzymes, catalysts