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Effects of thermal treatment and fluoride ion doping on surface and catalytic properties of NiO–ZrO2 catalysts

Reham M. A. F., Kiwan H. A., Ahmed A. I., Mostafa M. R.

Materials Science Poland

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2016

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Vol. 34, No. 1

53--62

EN

ZrO2 and a series of NiO/ZrO2 hydrogels (5 to 25 wt.% NiO) were co-precipitated with the aid of NaOH–Na2 C2 O4 solution. Two fluorinated hydrogels were also prepared by wet impregnation method. The samples were calcined in the temperature range of 550 to 850 °C. The surface properties of the samples were determined using DTA, XRD and nitrogen adsorption at −196 °C. The conversion of isopropanol was tested using microcatalytic pulse technique. DTA measurements showed that the addition of nickel oxide to zirconia influences the phase transition of ZrO2. XRD revealed that the tetragonal phase was formed at T ≤ 650 °C, while a biphasic mixture was obtained at T ≥750 °C. No spinel structure was detected by both DTA and XRD techniques and only traces of cubic NiO were detected for the samples containing ≥ 15 wt.% nickel oxide and calcined at T ≤ 750 °C. Significant changes in texture, surface acidity and catalytic activity were found as a result of the effects of thermal treatment and chemical composition. Incorporation of fluoride ions greatly increased the surface acidity and consequently enhanced the dehydration activity. It has been found that dehydration activity is related to the amount of surface acidity while the dehydrogenation of this alcohol is sensitive to NiO content.

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Reusable Nanocatalyst: Zirconia and Sulfated Zirconia

Gondaliya M. B., Maheta T., Mamtora M. J., Shah M. K.

International Letters of Chemistry, Physics and Astronomy

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2014

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Vol. 17, iss. 3

295--302

EN

1,5-benzodiazepines have been synthesized by Nano Zirconia and Nano Sulfated Zirconia in solvent free conditions. Synthesis was carried out by conventional as well as microwave method. Benzodiazepines were synthesized by reacting o-phenylenediamine and few ketones in the presence of catalytic amount of Nanoparticles. Particles used were sized in between 53-100 nm. Nanoparticles were characterized by FT-IR, DLS and powder XRD analysis.

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Dinitrotoluene Synthesis Using Solid State Catalysts - MoO3/SiO2 and H3PO4/MoO3/SiO2

Adamiak J., Skupiński W.

Central European Journal of Energetic Materials

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2010

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Vol. 7, nr 3

301-311

EN

Dinitrotoluene (DNT) has a lot of applications. It is mainly used in the production of polyurethane forms. Other uses include the explosives industry. It is converted to trinitrotoluene (TNT), or used as an additive in propellants. The main aim of these researches was to obtain DNT in one stage process with solid acid catalyst and nitric acid. The solid catalysts were composed of transition metal oxide (MoO3) and silica gel. One of them was modifed by phosphoric acid (H3PO4/MoO3/SiO2). The addition of phosphoric acid to these catalysts enhances catalytic properties and gives new structures on the surface – mixture of MoO3 and 12-molybdophosphoric acid. The activity of two catalysts in toluene nitration was compared. Higher yields of DNT were obtained in shorter time and with lower excess of HNO3 using modifed catalyst H3PO4/MoO3/SiO2 than using catalyst MoO3/SiO2. The very high yield of DNT (85%) was obtained in the reaction with only tenfold excess of nitric acid with 10 g of H3PO4/MoO3/SiO2. The way of regeneration of the catalyst system H3PO4/MoO3/SiO2 was found and time of storing was examined.