Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: ZnAl2O4

Sortuj według:

Ogranicz wyniki do:

Nano-ZnAl2O4 - hydrothermal mw assisted synthesis in a stop-flow reactor and characterization

Sibera D., Strachowski T., Łojkowski W., Narkiewicz U., Chudoba T., Jędrzejewski R., Majcher A., Presz A.

Problemy Eksploatacji

2010

nr 4

91-102

The aim of the study was to obtain nanometric zinc-alumina spinel in a stop-flow reactor with microwave emission. The water solution of zinc and aluminium nitrates was used as a reaction substrate. The mole ratio of Al:Zn = 2:1. A 2M water solution of potassium hydroxide was used as mineraliser. The process was carried out under the pressure of 3.9 MPa for 15, 30 and 60 min. The obtained product had grains of about 6 nm, determined on the basis of the specific surface area and density measurements, observed using SEM and TEM microscopes. According to XRD analysis, a pure phase of Al-Zn spinel was obtained for optimum reaction time of 30 min. The specific surface area measured using BET method was in the range of 230-270 m2/g. For the first time a nanocrystalline zinc aluminate spinel of high specific surface area and high phase purity was obtained in a stop flow microwave solvothermal reactor.

Celem prac było uzyskanie manometrycznego spineklu cynkowo-aluminiowego w mikrofalowym reaktorze pracującym w cyklu stop-flow. Jako substratów reakcji użyto azotków cynku i aluminium w stosunku molowym Al:Zn = 2:1. Jako mineralizator zastosowano 2M wodny roztwór wodorotlenku potasu. Procesy prowadzone były przy ciśnieniu 3.9 MPa przez 15, 30 i 60 minut. Otrzymano produkt o rozmiarze ziaren około 6 nm. Rozmiar ziaren określono z wykorzystaniem pomiarów powierzchni właściwej i gęstości oraz obserwacji wykonywanych z użyciem mikroskopów SEM i TEM. Przepro-wadzona analiza XRD wykazała, że czystą fazę Al-Zn uzyskano dla czasu reakcji wynoszącego 30 minut. Powierzchnia właściwa, określona metodą BET, zawierała się w zakresie 230-270 m2/g. Po raz pierwszy uzyskano, w reaktorze mikrofalowym typu stop-flow, nanokrystaliczny spinel cynkowo-aluminiowy o dużej powierzchni właściwej i dużej czystości fazowej.

Methanol Synthesis from CO2 and H2 Mixture over 60 per cent Cu/support (FeAlO3, ZnAl2O4) Catalysts

Maniecki T. P., Mierczyński P., Bawolak-Olczak K., Jóźwiak W. K.

Polish Journal of Chemistry

2009

Vol. 83, nr 9

1653-1662

The aim of this work was to determine the correlation between catalytical activity of copper supported catalysts 60 per cent Cu/support (FeAlO3, ZnAl2O4) in methanol synthesis and their physicochemical properties. Surface area measurements (BET), X-ray diffraction (XRD) and temperature-programmed reduction (TPR-H2) techniques were used to study the physicochemical properties of Cu/support catalysts. The activity tests in methanol synthesis were carried out over copper catalysts in the temperature range 180–260 graduate C at elevated pressure (4 MPa) in a fixed bed reactor. Monometallic supported catalyst 60 per cent Cu/FeAlO3 was more active, but less selective in comparison with 60 per cent Cu/ZnAl2O4 catalyst in methanol synthesis. The XRD results confirmed the presence of binary oxide (ZnAl2O4 and FeAlO3), copper oxide, alfa-Fe2O3 and ZnO for appreciate copper supported catalysts. A reduction study of copper catalyst confirmed two step of copper oxide reduction (Cu2+ rightwards arrow Cu+rightwards arrow Cu0).

Catalytic properties of Fe2O3/ZnAl2O4 system in alkylation reactions of chosen hydroxyarenes with methanol

Grabowska H., Miśta W., Zawadzki M., Wrzyszcz J.

Polish Journal of Chemical Technology

2003

Vol. 5, nr 3

32-34

The influence of iron oxide supported on zinc aluminate on catalytic activity and physicochemical properties of the samples was investigated. Zinc aluminate was prepared by coprecipitation followed by hydrothermal treatment at elevated temperatures and iron as Fe(NO3)3 was supported on ZnAl2O4 by wet impregnation method. The obtained samples were characterized by X-ray diffraction, textural measurements (SBET, Vp, pore size distribution), and temperature programmed reduction (TPR-H2). Activities and selectivities obtained in the catalytic alkylation of phenol and anisole with methanol, performed in the presence of ZnAl2O4 and 8%Fe2O3/ZnAl2O4, were studied and compared. Experimental data show that the addition of Fe2O3 into ZnAl2O4 does improve the selectivity of alkylation. As a result of phenol methylation there were obtained its ort/zo-derivatives (ortho-creso\ and 2,6-xylenol) over ZnAl2O4 and 8%Fe2O3/ZnAl2O4 with selectivities 54.9 and 61.5%, respectively. The application of anisole as raw material in studied reaction of methylation led to obtain of 2,3,5-trimethylphenol with 76.5% selectivity at 342°C K in the presence of 8%Fe2O3/ZnAl2O4.