Thermally modified active carbon as a support for catalysts for NH3 synthesis

✍ Scribed by Zbigniew Kowalczyk; Jan Sentek; Slawomir Jodzis; Ryszard Diduszko; Adam Presz; Artur Terzyk; Zbigniew Kucharski; Jan Suwalski

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 765 KB
• Volume: 34
• Category: Article
• ISSN: 0008-6223
• DOI: 10.1016/0008-6223(95)00199-9

✦ Synopsis

The effect of thermal treatment of a typical active carbon at 1300°C and 1900°C on its structural properties was investigated. It has been found that only a high-temperature heating (1900°C) produced substantial changes in the structure of the carbon used: a disappearance of a considerable part of open micropores and formation of a turbostratic structure. The prepared materials were used as a support in catalysts for NH, synthesis. The precursor of the active phase was Fe(NO,), .9H,O. The iron nitrate deposited on the raw amorphous carbon decomposes to finely dispersed, hardly reducible iron oxides on heating to 470°C in a H, + N, mixture. Even if reduced to more than 33%, iron is inactive in NH, synthesis (400-47o"C, p = 10 MPa). When deposited on the turbostratic, low-surface area carbon, iron forms, however, well developed crystallites (-60 nm), and is active in ammonia synthesis. Potassium activates strongly the surface of Fe, and, in the case of the amorphous support, it stimulates the reduction of iron oxides.