Sinteza, karakterizacija i ispitivanje renijum/paladijum aerogel i kserogel katalizatora za reakcije desulfurizacije dibenzotiofena i supstituisanog 4,6-dimetil dibenzotiofena u prisustvu vodonika
Synthesis, characterization and testing of rhenuim/palladium aerogel and xerogel catalysts for desulphurization of dibenzothiophene and substituted 4,6-dimethyl dibenzothiophene with hydrogen
Докторанд
Prokić Vidojević, Dragana T.Ментор
Glišić, SandraЧланови комисије
Orlović, AleksandarKrstić, Jugoslav
Метаподаци
Приказ свих података о дисертацијиСажетак
U ovoj doktorskoj disertaciji je prikazana sinteza i karakterizacija mezoporoznih aerogel i
kserogel katalizatora sa plemenitim metalima Re i Pd na nosaĉu TiO2/SiO2 i kovencionalno
korišćenim metalima Co, Mo na nosaĉima SiO2, Аl2О3, kao katalizatora za reakcije desulfurizacije
(HDS) slaboreaktivnih sumpornih jedinjenja prisutnih u nafti, dibenzotiofena (DBT) i
supstituisanog 4,6-dimetildibenzotiofena (4,6-DMDBT). Svi materijali su sintetisani hidrolitiĉkom
sol-gel metodom, sušeni su termiĉkom evaporacijom rastvaraĉa na povišenoj temperaturi ili u višku
natkritiĉnog rastvaraĉa. Uticaj natkritiĉnog sušenja na katalitiĉku aktivnost materijala je ocenjena
paralelnom sintezom aerogelova i kserogelova za Re/Pd- TiO2/SiO2 katalizatore. Sol-gel metodom i
natkritiĉnim sušenjem u višku rastvaraĉa dobijeni su amorfni aerogelovi, relativno velikog
stepenom homogenosti, i nosaĉa i aktivne faze. Odgovarajući kserogelovi su imali sliĉnu strukturu
ali manju specifiĉnu površinu. Katalitiĉka aktivnost C...o/Mo- Al2O3/SiO2 aerogelova u HDS DBT i
4,6-DMDBT nije bila znaĉajno unapreĊena u odnosu na CoMo/ γ-Al2O3katalizator. Sa druge
strane, Re/Pd- TiO2/SiO2 aerogelovi, dobijeni sa dodatkom mezitilena (1,3,5-trimetilbenzen) ili bez
njega, pokazali su 70 % i 64 % veću konverziju 4,6-DMDBT od komercijalnog CoMo/ γ-Аl2О3
katalizatora. Na povećanu aktivnost katalizatora uticala je dobra disperzija aktivne faze Re i Pd
katalizatora, dobra inkorporacija Ti u silikatnu strukturu, razvijena mezoporozna struktura
materijala i velika apecifiĉna površina.
U poreĊenju sa konvencionalnim Co/Mo katalizatorom, oba Re/Pd katalizatora dobijena
sintezom uz upotrebu mezitilena pokazala su povećan stepen konverzije 4,6-DMDBT u rekaciji
HDS. Da bi kvantifikovali udeo desulfurizacije koji se odvija reakcionim putem hidrogenovanja,
konverzije DBT i 4,6-DMDBT zajedno sa nastalim proizvodima reakcije putem direktne
desulfurizacije i hidrogenovanja korišćena je GC-MS tehnika. Reakcija je ispitana 630 K i 60 bar u
šaržnom reaktoru sa mešanjem. Eksperimentalni rezultati su korišćeni u Hougen-Watson
kinetićkom modelu za opis HDSa DBT i 4,6-DMDBT na σ i τ aktivnim centrima. Kinetiĉki
parametri ove kompleksne kinetike su odreĊeni korišćenjem Genetiĉkog algoritma (GA) i funkcije
minimalnog odstupanja. Vrednosti dobijenih kinetiĉkih parametara su potvrdili da je reakcioni put
hidrogenovanja dominantan kod desulfurizacije 4,6-DMDBT. Prednosti Re/Pd aerogel katalizatora
u konverziji 4,6-DMDBT su potvrĊene rezultatima simulacionog modela za Re/Pd aerogelove i
konvencionalne Co/Mo katalizatore.
The research in this thesis describes synthesis and characterization of mesoporous aerogel and
xerogel catalysts with noble metals Re and Pd supported on TiO2/SiO2 as well as conventional Co,
Mo active metals supported on SiO2, Аl2О3, used as catalysts for desulphurization reactions (HDS)
refractive Sulphur compounds present in naphtha, dibenzothiophene (DBT) and 4,6-
dimethyldibenzotiophene (4,6-DMDBT). All materials are synthesized using hydrolytic sol-gel
method, dried either by thermal evaporation in air or in excess of supercritical solvent. The
influence of supercritical drying on the final catalytic properties of the materials was determined by
parallel synthesis of aerogels and xerogels for Re/Pd-TiO2/SiO2 catalysts. The sol-gel method and
supercritical drying were found to result in amorphous aerogels with relatively high degree of
uniformity, of both supports and active phases. Corresponding xerogels were found to be similar to
aerogels in terms of composition and structure, ...but characterized by lower specific surface areas.
Catalytic activity of Co/Mo-Al2O3/SiO2 aerogel catalysts in HDS of DBT and 4,6-DMDBT has
shown no major improvement in comparison to conventional Co/Mo catalyst. On the other hand,
Re/Pd-TiO2/SiO2 aerogels, obtained with the addition of mesitylene or without it, achieved 70 %
and 64 % higher conversion of 4,6-DMDBT than conventional Co/Mo catalyst, respectively.
Increased catalytic activity can be attributed to well dispersed Re and Pd active phases across the
catalyst structure, good incorporation of Ti within silica matrix, increased mesopore volumes and
high specific surface areas.
Both Re/Pd catalysts, obtained with and without use of mesitylene in the synthesis step, have
shown increased conversion levels in the desulphurization of 4,6-DMDBT when compared to
conventional Co/Mo hydroprocessing catalysts. In order to quantify the extent of desulphurisation
which proceeds via hydrogenation route, conversions of DBT and 4,6-DMDBT along with
evolution of reaction products characteristic for direct desulphurisation route and hydrogenation
route were monitored using GC-MS analytical tecnique. The reaction was performed at 630 K and
60 bar in batch catalytic reactor. The experimental results were used in Hougen-Watson kinetic
model describing DBT and 4,6-DMDBT desulphurisation on σ and τ active sites. Kinetic
parameters of this complex catalytic kinetics were determined in a procedure using Genetic
Algorhythm (GA) method and minimum deviation function. Values of calculated kinetic
parameters have confirmed that hydrogenation route is the dominant route for desulphurisation of
4,6-DMDBT. Potential advantages of the Re/Pd aerogel catalysts in conversion of 4,6-DMDBT are
indicated by the results of model simulations for Re/Pd aerogels and conventional Co/Mo catalysts