Istraživanje agregacije asfaltena iz uzoraka teške nafte pomoću spektroskopije DOSY NMR

master's thesis

• Title (english): Investigation of asphaltene agregation in heavy oil samples using DOSY NMR spectroscopy
• Author: Martina Kveštak
• Mentor: Predrag Novak (mentor)
• Mentor: Jelena Parlov Vuković (mentor)
• Committee member: Predrag Novak (predsjednik povjerenstva)
• Committee member: Davor Kovačević (član povjerenstva)
• Committee member: Ivana Biljan (član povjerenstva)
• Committee member: Tomislav Jednačak (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2017-02-21, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

Nafta, naftni derivati i proizvodi predstavljaju najkompleksnije prirodne smjese spojeva. Sastoje se od tisuća komponenata različitih veličina i struktura. U posljednje vrijeme, jedan od glavnih ciljeva u naftnoj industriji je prevesti teške naftne ostatke u lakše destilate, pa je u tom smislu zabilježen značajan napredak u analizi teških nafti i njenih ostataka. Asfalteni su najkompleksniji i najpolarniji spojevi u nafti i teškim ostacima koji uzrokuju probleme u transportu i proizvodnji. Zbog izuzetno složene strukture asfaltena njihova karakterizacija danas predstavlja veliki izazov istraživačima u naftnoj industriji.
U ovome radu istraživana je ovisnost koncentracije uzoraka nafte i translacijskih difuzijskih koeficijenata s ciljem određivanja najniže koncentracije pri kojoj dolazi do stvaranja agregata molekula asfaltena. U tu svrhu koristila se pseudo-dvodimenzijska tehnika DOSY NMR kojom je moguće razdvojiti različite komponente smjese na temelju njihovih difuzijskih koeficijenata. Prema difuzijskim koeficijentima određeni su hidrodinamički radijus i molekulske mase asfaltena. Analizirane su tri vrste uzoraka: sirova nafta i uzorci dobiveni njenom destilacijom, atmosferski i vakuumski ostatak. Praćene su promjene difuzijskih koeficijenata prilikom nastajanja različitih vrsta agregata molekula asfaltena. Očekuje se da će dobiveni rezultati doprinijeti boljem razumijevanju agregacije ove vrste spojeva.

Abstract (english)

Crude oil, crude oil residues and products represent the most complex natural compound mixtures. Crude oil is consisted of thousands of components with different sizes and structures. Over the last couple of years, one of the main goals in oil industry was to transfer heavy crude oil residues into light crude oil distillates. In that respect, a significant progress in the analysis of crude oil and crude oil residues was observed. Asphaltenes, which are the heaviest and least reactive molecules in crude oils, cause many problems during transport and production. Owing to complex asphaltene structures, their characterization posts a challenge in crude oil industry.
In this research, concentration dependent diffusion measurements have been performed in order to determine the lowest aggregation concentration of asphaltenes. Pseudo two-dimensional DOSY NMR technique was used to separate different mixture components according to their diffusion coefficients. Hydrodynamic radius and molecular weight of asphaltenes were determined from diffusion coefficients. Three different samples were analyzed: crude oil and samples obtained from crude oil distillation, atmospheric and vacuum residues. Changes in diffusion coefficients reflected formation of different types of asphaltene. It is expected that the results presented in this research will contribute to better understanding of asphaltene aggregation.

• Keywords: agregati; asfalteni; difuzijski koeficijent; DOSY NMR; nafta
• Keywords (english): aggregates; asphaltenes; crude oil; diffusion coefficient; DOSY NMR
• Language: croatian
• URN:NBN: urn:nbn:hr:217:402320
• Study programme: Title: Graduate university studies in chemistry; specializations in: Research programme; Course: Research programme; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra kemije (magistar/magistra kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-03-01 11:01:11