A Study of the HCN Formation Mechanism during the Coal Char Gasification by O_2

摘要

The HCN formation mechanism during the O_2 gasification of Blair Athol coal char is examined at 600℃. A nitrogen-free phenol resin char is also used as a reference char sample, to examine HCN formation during the reaction with NO/O_2 mixed gas at the same temperature. It is concluded that, in both systems, the nitrogen-containing surface species (C(N)) has an important role as a reaction intermediate for HCN formation. The HCN formation temperature, 600℃, is much lower than that for the reaction without O_2. In the temperature-programmed desorption experiment, a high temperature (>900℃) is also necessary for HCN formation. An important role of O_2 in enhancing HCN formation is to activate C(N) via breakdown of the carbon network. In the resin char/NO/O_2 reaction, the evolution of HCN is not influenced by the removal of NO from the feed gas. This result shows the importance of C(N) as an intermediate for the HCN formation.