36.Loy Yang褐炭の熱分解におけるイオン交換担持ニッケル種の構造と触媒作用

抄録

Catalysis of ion-exchanged nickel species supported on Loy Yang brown coal was studied. The C1 gas evolution profile during pyrolysis of the nickel-exchanged coal depends on the loading. Two peaks of CO evolution appeared, one at 660-770K (α-CO), depending on the amount of exchanged nickel species and the other at around 920K (β-CO), in contrast to a broader single peak at 870K for nickel-unloaded coal. IR spectra showed that the nickel carboxylate groups have bidentate structure at 0.77wt% loading and bridge structure at 6.4wt% loading, respectively. EXAFS analysis showed that nickel cation species are highly dispersed and that the exchanged nickel carboxylate groups decompose and nickel species aggregate to metal particles during pyrolysis. It was also shown that the temperature for the formation of nickel metal particles increased with increasing nickel loading. The catalysis of nickel species to form α-CO is intimately connected with their structure and aggregation behavior.