Razvoj obstojnih katalizatorjev za postopek priprave glicidola iz glicerola

Knez, Tjaša (author), Likozar, Blaž (mentor), Plazl, Igor (comentor)

Izčrpavanje fosilnih virov, kot so nafta, zemeljski plin in premog, povišane cene nafte in povišanje negativnih vplivov na podnebne spremembe, je spodbudilo strokovnjake iz industrije in znanosti k iskanju biogoriv, kot alternative fosilnim gorivom. Danes so bioetanol, biodizel in bioplin bolj perspektivni in okolju prijazni nadomestki bencina, dizelskega goriva in zemeljskega plina. Biodizel se v osnovi proizvaja s transesterifikacijo živalskih maščob ali rastlinskih olj z biokatalizatorji (encimi), kislimi in bazičnimi katalizatorji, pri čemer je glavni stranski produkt postopka glicerol. Nenehno rastoči trg biodizla je ustvaril znaten presežek proizvodnje glicerola, kar je povzročilo sočasen padec njegove cene. Glicerol je tako postal visoko dostopna in poceni kemikalija, zaradi tega so bile v zadnjih letih predlagane številne nove uporabe glicerola. Je vsestranska surovina, saj je nestrupen, užiten in biorazgradljiv, lahko se uporabi kot surovina za pridobivanje dragocenih derivatov ali pa se neposredno pretvori v kemikalije. Ena izmed kemikalij, ki jo lahko pridobimo iz glicerola je glicidol, ki je pomemben intermediát za pripravo kemikalij, farmacevtskih izdelkov in bioaktivnih spojin. V tem raziskovalnem delu sem se osredotočila na sintezo obstojnih katalizatorjev za pripravo glicidola iz glicerola v plinski fazi. Postopek priprave glicidola sem izvedla v enem koraku v industrijskem neprekinjenem pretočnem reaktorju s strnjenim slojem katalizatorja pod atmosferskim tlakom. Obstojni katalizatorji imajo številne pomembne lastnosti, ki jih naredijo učinkovite in zanesljive za dolgotrajno uporabo v različnih kemijskih procesih, nekatere od teh so stabilnost, visoka aktivnost, selektivnost, možnost regeneracije, dolga življenjska doba in ekonomičnost. Sintetizirala sem enajst različnih katalizatorjev, od tega je šest katalizatorjev vsebovalo različne masne deleže cezija. Po testiranju vseh šestih katalizatorjev ima na podlagi dobljenih rezultatov optimalno sestavo katalizator 15%Cs/ZSM-5(1500). Drugih pet katalizatorjev je vsebovalo različne masne deleže rubidija, tukaj so podatki pokazali, da ima optimalno sestavo katalizator 10%Rb/ZSM-5(1500). S spreminjanjem reakcijskih pogojev, kot so temperatura, koncentracija glicerola, pretok glicerola in pretok dušika, sem poiskala optimalne reakcijske pogoje teh dveh katalizatorjev za postopek priprave glicidola. Preverila sem tudi njuno stabilnost in kako uspešna je regeneracija po njuni deaktivaciji.

• Language: Slovenian
• Keywords: zeolit H-ZSM-5, obstojni katalizatorji, sinteza glicidola, pretvorba glicerola
• Work type: Master's thesis/paper
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2024
• PID: 20.500.12556/RUL-158989
• Publication date in RUL: 27.06.2024

Secondary language

• Language: English
• Title: Development of stable catalysts for the preparation process of glycidol from glycerol

Abstract

The depletion of fossil fuels such as oil, natural gas and coal, increased oil prices and the increasing negative impacts of climate change have encouraged experts from industry and science to search for biofuels as an alternative to fossil fuels. Today, bioethanol, biodiesel and biogas are more promising and environmentally friendly alternatives for petrol, diesel fuel and natural gas. Biodiesel is basically produced by transesterification of animal fats or vegetable oils with biocatalysts (enzymes), acidic or basic catalysts, with glycerol being the main by-product of the process. The steadily growing biodiesel market has created a significant surplus of glycerol production, which has led to a simultaneous drop in its price. Glycerol thus became a highly available and cheap chemical, which is why many new uses of glycerol have been proposed in recent years. Glycerol is a versatile raw material as it is non-toxic, edible, and biodegradable, it can be used as a raw material to produce valuable derivates or it can be directly converted into suitable chemicals. One of the chemicals that can be obtained from glycerol is glycidol, which is an important intermediate for the preparation of chemicals, pharmaceuticals, and bioactive compounds. In this research work, I focused on the synthesis of stable catalysts for the gas-phase preparation of glycidol from glycerol. The glycidol preparation process was carried out in one step in an industrial continuous flow packed bed reactor under atmospheric pressure. Stable catalysts have several important properties that make them efficient and reliable for long-term use in various chemical processes, some of these being stability, high activity, selectivity, possibility of regeneration, long life span and economy. I synthesized eleven different catalysts, six of which contained different weight fractions of cesium. After testing all six catalysts based on the results obtained, the catalyst 15%Cs/ZSM-5(1500) has the optimal composition. The other five catalysts contained different weight fractions of rubidium, and here the obtained data showed that the catalyst with an optimal composition is 10%Rb/ZSM-5(1500). By changing the reaction conditions such as temperature, glycerol concentration, glycerol flow and nitrogen flow, I searched for the optimal reaction conditions of these two catalysts for the glycidol preparation process. I also checked their stability and regeneration success after their deactivation.

• Keywords: zeolite H-ZSM-5, stable catalysts, glycidol synthesis, glycerol conversion