Natural and synthetic nanomaterials: from nacre to organic-inorganic hybrids

AbstractSedef je svjetlucavi sloj u unutrašnjosti nekih puževa i školjkaša, te je jedan od najbolje istraženih prirodnih nanomaterijala. Vedina volumena sedefa otpada na aragonit (95%), dok ostatak otpada na organske spojeve. Sedef je privukao pažnju znanstvenika zbog iznimne čvrstode, koja daleko nadilazi onu čistog aragonita. Uzrok tome je složena struktura koju čine aragonitne ploče i koje se slažu nasumično ili u stupce s organskim slojem kao vezivom između njih. Aragonitne ploče su poligonalne tvorevine kod kojih su nano-zrnca aragonita povezana na organski kostur od hitina. Osim složene strukture po principu cigle (aragonitne ploče) i žbuke (organski sloj), postoje i tzv. nano-mostovi između ploča kroz organski sloj koji uz hrapavost površine aragonitnih ploča pomažu pri raspršenju energije udarca i pridonose čvrstodi strukture. Modifikacijom poznatih materijala sintetiziran je niz materijala strukturno sličnih sedefu čija mehanička svojstva su vidno poboljšana u odnosu na polazne supstance. U posljednje vrijeme kemija nanomaterijala je sve više usmjerena na sintezu organsko-anorganskih hibridnih materijala u ravnotežnim i neravnotežnim uvjetima. Nastali nanomaterijali su izrazito složeni i mogli bi nadi svoju primjenu u elektronici, kao kapsule za lijekove, senzori, katalizatori i sl. Tri su osnovne tehnike sinteze organsko-anorganskih hibridnih materijala (i) Integrativno samoudruživanje (Integrative self-assembly), (ii) Složeno ravnotežno samoudruživanje (higher-order equilibrium self-assembly) i (iii) Samoudruživanje pradeno transformacijom (transformative self-assembly)

The Influence of Inserted Metal Ions on Acid Strength of OH Groups in Faujasite

The number and the strength of acid sites in catalysts have paramount importance on their efficiency. In zeolites chemistry, increased content of framework Al in zeolites gives a higher number of strong acid sites. Their strength can be a disadvantage in catalytic reactions (e.g., methanol to olefins conversion) due to undesired secondary reactions of coke formation. Here, the Faujasite type of zeolite with higher content of Al has been used for investigating the role of defects in structure and inserted (wet impregnation and thermal treatment) metal cations (Mg, Co, Ni, Zn) on the strength of OH acid sites. Desorption of deuterated acetonitrile, as a probe molecule, was used for OH groups acid strength measurements at different temperatures (150, 200, and 300 °C)

Formation reactions of oxalatomolybdates with Co(III) ethylenediamine cations

U okviru ovog diplomskog rada ispitivani su uvijeti nastajanja kompleksnih soli s [Co(EDDA)(en)]+ kationom i oksalatomolibdatima, [Mo2O5(ox)2(H2O)2]2- i [MoO3(ox)]2-, kao anionima. Reakcije su provedene u otopini i to pri sobnoj temperaturi te u uvijetima povišenog tlaka i temperature te mehanokemijski, odnosno u čvrstom stanju s i bez dodatka male količine otapala, vode, odnosno acetona. Reakcije provedene u otopni dale su kao produkte dihidratni i tetrahidratni solvat [Co(EDDA)(en)]2[Mo2O5(ox)2(H2O)2. Reakcije s [MoO3(ox)]2- u vodenoj otopini nisu dale produkt, no mehanokemijskom sintezom uz dodatak male količine acetona u kombinaciji sa starenjem kao produkt reakcije dobiven je [CoEDDA(en)]2(enH2)[CoMo6O24]·3H2O. Svi izolirani produkti identificirani su na osnovi rezultata kemijske analize, termogravimetrijske analize i podataka iz infracrvenih spektara. Izoliranim kompleksima odreĎena je i molekulska i kristalna struktura metodom difrakcije rentgenskih zraka na jediničnom kristalu.In this diploma thesis we researched conditions for formation of complex salts containing [Co(EDDA)(en)]+ as cation and oxalatomolybdates, [Mo2O5(ox)2(H2O)2]2- i [MoO3(ox)]2-, as anions. Reactions were conducted in solution at room temperature, in the conditions of high pressure and high temperature, and in the solid state as liquid assisted grinding with water or acetone. Reactions in the solution resulted in formation of dihydrate and tetrahydrate solvate of [Co(EDDA)(en)]2[Mo2O5(ox)2(H2O)2. Reactions with [MoO3(ox)]2- in water solution didn’t result in the formation of product, but liquid assisted grinding with few drops of acetone in the combination with aging resulted in formation of [CoEDDA(en)]2(enH2)[CoMo6O24]·3H2O. All products were identified by chemical analysis, termogravimetric analysis and infrared spectroscopy. Crystal and molecular structure of isolated products was determined using single crystal X-ray diffraction

Formation reactions of oxalatomolybdates with Co(III) ethylenediamine cations

U okviru ovog diplomskog rada ispitivani su uvijeti nastajanja kompleksnih soli s [Co(EDDA)(en)]+ kationom i oksalatomolibdatima, [Mo2O5(ox)2(H2O)2]2- i [MoO3(ox)]2-, kao anionima. Reakcije su provedene u otopini i to pri sobnoj temperaturi te u uvijetima povišenog tlaka i temperature te mehanokemijski, odnosno u čvrstom stanju s i bez dodatka male količine otapala, vode, odnosno acetona. Reakcije provedene u otopni dale su kao produkte dihidratni i tetrahidratni solvat [Co(EDDA)(en)]2[Mo2O5(ox)2(H2O)2. Reakcije s [MoO3(ox)]2- u vodenoj otopini nisu dale produkt, no mehanokemijskom sintezom uz dodatak male količine acetona u kombinaciji sa starenjem kao produkt reakcije dobiven je [CoEDDA(en)]2(enH2)[CoMo6O24]·3H2O. Svi izolirani produkti identificirani su na osnovi rezultata kemijske analize, termogravimetrijske analize i podataka iz infracrvenih spektara. Izoliranim kompleksima odreĎena je i molekulska i kristalna struktura metodom difrakcije rentgenskih zraka na jediničnom kristalu.In this diploma thesis we researched conditions for formation of complex salts containing [Co(EDDA)(en)]+ as cation and oxalatomolybdates, [Mo2O5(ox)2(H2O)2]2- i [MoO3(ox)]2-, as anions. Reactions were conducted in solution at room temperature, in the conditions of high pressure and high temperature, and in the solid state as liquid assisted grinding with water or acetone. Reactions in the solution resulted in formation of dihydrate and tetrahydrate solvate of [Co(EDDA)(en)]2[Mo2O5(ox)2(H2O)2. Reactions with [MoO3(ox)]2- in water solution didn’t result in the formation of product, but liquid assisted grinding with few drops of acetone in the combination with aging resulted in formation of [CoEDDA(en)]2(enH2)[CoMo6O24]·3H2O. All products were identified by chemical analysis, termogravimetric analysis and infrared spectroscopy. Crystal and molecular structure of isolated products was determined using single crystal X-ray diffraction

Formation reactions of oxalatomolybdates with Co(III) ethylenediamine cations

U okviru ovog diplomskog rada ispitivani su uvijeti nastajanja kompleksnih soli s [Co(EDDA)(en)]+ kationom i oksalatomolibdatima, [Mo2O5(ox)2(H2O)2]2- i [MoO3(ox)]2-, kao anionima. Reakcije su provedene u otopini i to pri sobnoj temperaturi te u uvijetima povišenog tlaka i temperature te mehanokemijski, odnosno u čvrstom stanju s i bez dodatka male količine otapala, vode, odnosno acetona. Reakcije provedene u otopni dale su kao produkte dihidratni i tetrahidratni solvat [Co(EDDA)(en)]2[Mo2O5(ox)2(H2O)2. Reakcije s [MoO3(ox)]2- u vodenoj otopini nisu dale produkt, no mehanokemijskom sintezom uz dodatak male količine acetona u kombinaciji sa starenjem kao produkt reakcije dobiven je [CoEDDA(en)]2(enH2)[CoMo6O24]·3H2O. Svi izolirani produkti identificirani su na osnovi rezultata kemijske analize, termogravimetrijske analize i podataka iz infracrvenih spektara. Izoliranim kompleksima odreĎena je i molekulska i kristalna struktura metodom difrakcije rentgenskih zraka na jediničnom kristalu.In this diploma thesis we researched conditions for formation of complex salts containing [Co(EDDA)(en)]+ as cation and oxalatomolybdates, [Mo2O5(ox)2(H2O)2]2- i [MoO3(ox)]2-, as anions. Reactions were conducted in solution at room temperature, in the conditions of high pressure and high temperature, and in the solid state as liquid assisted grinding with water or acetone. Reactions in the solution resulted in formation of dihydrate and tetrahydrate solvate of [Co(EDDA)(en)]2[Mo2O5(ox)2(H2O)2. Reactions with [MoO3(ox)]2- in water solution didn’t result in the formation of product, but liquid assisted grinding with few drops of acetone in the combination with aging resulted in formation of [CoEDDA(en)]2(enH2)[CoMo6O24]·3H2O. All products were identified by chemical analysis, termogravimetric analysis and infrared spectroscopy. Crystal and molecular structure of isolated products was determined using single crystal X-ray diffraction

Influence of acid sites strength on conversion of methanol to olefines

Na zeolitima strukturnih tipova FAU i MFI (ZSM-5) napravljene su modifikacije tijekom ili nakon sinteze kao bi se poboljšala njihova katalitička aktivnost. Pripremljeni uzorci su modificirani dodatkom mezoporoznog templata N,N,N-trimetilheksadekan-1-amonijeva bromida (CTAB) ili jetkani vodenom otopinom natrijeva hidroksida, kako bi se povećao broj mezopora u kristalima i olakšala difuzija reaktanata do aktivnog mjesta. Jakost aktivnog mjesta ugađana je kationskom zamjenom s ionima Mg2+ , Co2+, Ni2+ i Zn2+ (u vodenoj otopini i mehanokemijski). Utjecaj pojedinog metalnog kationa na broj i jakost Lewisovih i Brønstedovih kiselih mjesta u materijalu praćen je infracrvenom spektroskopijom u vakuumu pomoću adsorpcije probne molekule (deuterirani acetonitril). Broj pojedinih kiselih mjesta dobiven je integriranjem pojedinih krivulja nakon dekonvolucije spektra vezanog D3-acetonitrila, anjihova jakost određena je iz količine nakon zagrijavanja na 150, 200 i 300 °C. Na odabranim uzorcima napravljeni su katalitički testovi konverzije metanola u olefine.Modifications during and after sythesis were made on FAU and MFI (ZSM-5) zeolite type samples in order to enhance their catalytic activity. Prepared samples were modified with mesoporosity template N,N,N-Trimethylhexadecan-1-aminium bromide (CTAB) or etched with water solution of sodium hydroxide to increase the volume of mesopores in crystals and faciliate diffusion of reactnats to the active site. The strength of active sites was modified by cationic exchange with Mg2+ , Co2+ , Ni2+ and Zn2+ ions (in water solution and mechanochemicaly). Effect of metal cation on number and strength of Lewis and Brønsted acid sites was studied by infrared spectroscopy in vacuum with the adsorption of probe molecule (deuterated acetonitrile). The number of various types of acid sites was calculated from the integrated curves after deconvolution of spectra of adsorbed D3-acetonitrile, while their strength is determined after heating at 150, 200 and 300 °C. Catalytic tests of methanol to olefine conversion (MTO) were preformed on selected samples

Influence of acid sites strength on conversion of methanol to olefines

Na zeolitima strukturnih tipova FAU i MFI (ZSM-5) napravljene su modifikacije tijekom ili nakon sinteze kao bi se poboljšala njihova katalitička aktivnost. Pripremljeni uzorci su modificirani dodatkom mezoporoznog templata N,N,N-trimetilheksadekan-1-amonijeva bromida (CTAB) ili jetkani vodenom otopinom natrijeva hidroksida, kako bi se povećao broj mezopora u kristalima i olakšala difuzija reaktanata do aktivnog mjesta. Jakost aktivnog mjesta ugađana je kationskom zamjenom s ionima Mg2+ , Co2+, Ni2+ i Zn2+ (u vodenoj otopini i mehanokemijski). Utjecaj pojedinog metalnog kationa na broj i jakost Lewisovih i Brønstedovih kiselih mjesta u materijalu praćen je infracrvenom spektroskopijom u vakuumu pomoću adsorpcije probne molekule (deuterirani acetonitril). Broj pojedinih kiselih mjesta dobiven je integriranjem pojedinih krivulja nakon dekonvolucije spektra vezanog D3-acetonitrila, anjihova jakost određena je iz količine nakon zagrijavanja na 150, 200 i 300 °C. Na odabranim uzorcima napravljeni su katalitički testovi konverzije metanola u olefine.Modifications during and after sythesis were made on FAU and MFI (ZSM-5) zeolite type samples in order to enhance their catalytic activity. Prepared samples were modified with mesoporosity template N,N,N-Trimethylhexadecan-1-aminium bromide (CTAB) or etched with water solution of sodium hydroxide to increase the volume of mesopores in crystals and faciliate diffusion of reactnats to the active site. The strength of active sites was modified by cationic exchange with Mg2+ , Co2+ , Ni2+ and Zn2+ ions (in water solution and mechanochemicaly). Effect of metal cation on number and strength of Lewis and Brønsted acid sites was studied by infrared spectroscopy in vacuum with the adsorption of probe molecule (deuterated acetonitrile). The number of various types of acid sites was calculated from the integrated curves after deconvolution of spectra of adsorbed D3-acetonitrile, while their strength is determined after heating at 150, 200 and 300 °C. Catalytic tests of methanol to olefine conversion (MTO) were preformed on selected samples

Influence of acid sites strength on conversion of methanol to olefines

Na zeolitima strukturnih tipova FAU i MFI (ZSM-5) napravljene su modifikacije tijekom ili nakon sinteze kao bi se poboljšala njihova katalitička aktivnost. Pripremljeni uzorci su modificirani dodatkom mezoporoznog templata N,N,N-trimetilheksadekan-1-amonijeva bromida (CTAB) ili jetkani vodenom otopinom natrijeva hidroksida, kako bi se povećao broj mezopora u kristalima i olakšala difuzija reaktanata do aktivnog mjesta. Jakost aktivnog mjesta ugađana je kationskom zamjenom s ionima Mg2+ , Co2+, Ni2+ i Zn2+ (u vodenoj otopini i mehanokemijski). Utjecaj pojedinog metalnog kationa na broj i jakost Lewisovih i Brønstedovih kiselih mjesta u materijalu praćen je infracrvenom spektroskopijom u vakuumu pomoću adsorpcije probne molekule (deuterirani acetonitril). Broj pojedinih kiselih mjesta dobiven je integriranjem pojedinih krivulja nakon dekonvolucije spektra vezanog D3-acetonitrila, anjihova jakost određena je iz količine nakon zagrijavanja na 150, 200 i 300 °C. Na odabranim uzorcima napravljeni su katalitički testovi konverzije metanola u olefine.Modifications during and after sythesis were made on FAU and MFI (ZSM-5) zeolite type samples in order to enhance their catalytic activity. Prepared samples were modified with mesoporosity template N,N,N-Trimethylhexadecan-1-aminium bromide (CTAB) or etched with water solution of sodium hydroxide to increase the volume of mesopores in crystals and faciliate diffusion of reactnats to the active site. The strength of active sites was modified by cationic exchange with Mg2+ , Co2+ , Ni2+ and Zn2+ ions (in water solution and mechanochemicaly). Effect of metal cation on number and strength of Lewis and Brønsted acid sites was studied by infrared spectroscopy in vacuum with the adsorption of probe molecule (deuterated acetonitrile). The number of various types of acid sites was calculated from the integrated curves after deconvolution of spectra of adsorbed D3-acetonitrile, while their strength is determined after heating at 150, 200 and 300 °C. Catalytic tests of methanol to olefine conversion (MTO) were preformed on selected samples