Soobarjanje kationov Co, Ni, Fe, Ru v vodni raztopini heksametilentetramina (HMTA) kot metoda za sintezo katalizatorjev

Černejšek, Tina (author), Marinšek, Marjan (mentor), Makovec, Darko (comentor)

V magistrskem delu sem raziskovala nanos nanodelcev kovin Co, Ni, Fe in Ru in njihovih zlitin na različne podlage kot možen postopek za sintezo različnih katalizatorjev. Kot podlage smo uporabili nanostrukturiran aluminijev oksid ter nanodelce cerijevega oksida različnih morfologij. Ione sem najprej oborila v prisotnosti heksametilentetramina (HMTA) v vodni suspenziji delcev podlage. Po obarjanju ionov sem produkt posušila in ga reducirala s segrevanjem pri 600 ºC v pretoku vodika. Z optimiziranim postopkom sem uspela sintetizirati sferične nanodelce zlitine CoNi velikosti 6–12 nm, ki so bili homogeno porazdeljeni po celotni površini podlage nanostrukturiranega aluminijevega oksida. Predpostavili smo, da med kovinskimi kationi in HMTA nastane termično občutljiva koordinacijska spojina, ki pri segrevanju razpade, pri čemer se kovinski ioni postopoma sproščajo v raztopino, nastali hidroksidi pa zaradi nizkega prenasičenja heterogeno nukleirajo na površini podlage. Podrobnejše raziskave vpliva dodatka HMTA, vrednosti pH, koncentracije reaktantov in temperature na velikost, morfologijo in porazdelitev sintetiziranih nanodelcev na podlagi pa so pokazale, da HMTA nima odločujočega vpliva na obarjanje. Med obarjanjem Co2+ in Ni2+ so se tanki nanolističi hidroksida homogeno nanesli na podlago že pri sobni temperaturi in brez dodatka HMTA. Ko sem soobarjanju kobalta in niklja dodala še železo, ni bilo mogoče doseči homogene porazdelitve Fe po površini podlage. Prav tako pri soobarjanju Co in Ru ni bila dosežena homogena porazdelitev obeh ionov. V primerjavi z obarjanjem na nanostrukturirano podlago iz aluminijevega oksida so na podlagi iz nanodelcev cerijevega oksida nastali mnogo manj homogeni nanodelci oborjenih ionov.

• Language: Slovenian
• Keywords: soobarjanje, heksametilentetramin (HMTA), nanodelci CoNi, heterogena nukleacija, magnetni katalizatorji
• Work type: Master's thesis/paper
• Organization: FKKT - Faculty of Chemistry and Chemical Technology
• Year: 2026
• Publication date in RUL: 21.08.2026

Secondary language

• Language: English
• Title: Coprecipitation of Co, Ni, Fe, Ru cations in an aqueous solution of hexamethylenetetramine (HMTA) as a method for catalyst synthesis

Abstract

In this master’s thesis, the deposition of Co, Ni, Fe, and Ru metal nanoparticles and their alloys onto different supports was investigated as a potential method for the synthesis of various catalysts. Nanostructured aluminium oxide and cerium oxide nanoparticles with different morphologies were used as supports. The metal ions were first precipitated in the presence of hexamethylenetetramine (HMTA) in an aqueous suspension of the support particles. After precipitation, the product was dried and reduced by heating at 600 °C under a flow of hydrogen. Using the optimised procedure, spherical CoNi alloy nanoparticles with sizes ranging from 6 to 12 nm were successfully synthesised. The nanoparticles were homogeneously distributed over the entire surface of the nanostructured aluminium oxide support. It was assumed that a thermally sensitive coordination compound formed between the metal cations and HMTA. Upon heating, this compound was expected to decompose, gradually releasing the metal ions into the solution. Owing to the resulting low supersaturation, the hydroxide was expected to nucleate heterogeneously on the surface of the support. However, a more detailed investigation of the effects of HMTA addition, pH, reactant concentration, and temperature on the size, morphology, and distribution of the synthesised nanoparticles on the support showed that HMTA did not have a decisive effect on the precipitation process. During the precipitation of Co2+ and Ni2+, thin hydroxide nanosheets were homogeneously deposited onto the support even at room temperature and without the addition of HMTA. When iron was added to the co-precipitation system containing cobalt and nickel, a homogeneous distribution of Fe over the support surface could not be achieved. Similarly, the co-precipitation of Co and Ru did not result in a homogeneous distribution of both ions. Compared with precipitation onto the nanostructured aluminium oxide support, precipitation onto cerium oxide nanoparticles produced considerably less homogeneous deposits of the precipitated ions.

• Keywords: co-precipitation, hexamethylenetetramine (HMTA), CoNi nanoparticles, heterogeneous nucleation, magnetic catalysts