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Oxidative coupling of methane over NbO (p-type) and Nb2O5 (n-type) semiconductor materials (1996)

Erarslanoglu, Yesim ; Onal, Isik ; Dogu, Timur ; [et al.]

Springer

Catalysis letters 38 (1996), S. 215-218

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ISSN: 1572-879X

Keywords: methane oxidative coupling ; semiconductor-type catalysts ; n-type and p-type semiconductors ; Nb2O5 ; NbO

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract Oxidative coupling of methane to higher hydrocarbons was investigated using two types of semiconductor catalysts, NbO (p-type) and Nb2O5 (n-type) at 1 atm pressure. The ratio of methane partial pressure to oxygen partial pressure was changed from 2 to 112 and the temperature was kept at 1023 K in the experiments conducted in a cofeed mode. The results indicated a strong correlation between C2+ selectivity performance and the electronic properties of the catalyst in terms of p-vs. n-type conductivity. The p-type semiconductor catalyst, NbO, had a larger selectivity (e.g. 95.92%) over the n-type Nb2O5 catalyst (23.08%) both at the same methane conversion of 0.64%. Catalyst characterization via X-ray diffraction, TGA and reaction studies indicated that NbO was transformed to Nb2O5 during the course of the reaction which limits catalyst life.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00806571

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Characterization of activated carbon produced from almond shell and hazelnut shell (1994)

Balci, Suna ; Doǧu, Timur ; Yücel, Hayrettin

Chichester : Wiley-Blackwell

Journal of Chemical Technology AND Biotechnology 60 (1994), S. 419-426

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ISSN: 0268-2575

Keywords: Activated carbon ; NH4Cl activation ; pore structure ; almond shell ; hazelnut shell ; Chemistry ; Biochemistry and Biotechnology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Process Engineering, Biotechnology, Nutrition Technology

Notes: Ammonium chloride-impregnated and untreated almond shell and hazelnut shell samples were carbonized in a flow of nitrogen at relatively low temperatures. Pore structure characterization and sorption capacities of activated carbons prepared from shells of almond and hazelnut indicated that treatment with NH4Cl increased the total surface area and improved sorption characteristics. Chemical activation carried out at 350°C gave products with surface area values above 500 m2 g-1. On the other hand, the surface area values observed for the products obtained from untreated raw materials were about half of this value. The surface area of products obtained from NH4Cl-impregnated samples reached values of over 700 m2 g-1 when the carbonization temperature was increased 700°C.

Additional Material: 4 Ill.