메탄의 수증기 개질 반응과 이산화탄소 개질 반응의 비교 연구를 통한 Ni-YSZ 촉매의 비활성화에 관한 연구
- 메탄의 수증기 개질 반응과 이산화탄소 개질 반응의 비교 연구를 통한 Ni-YSZ 촉매의 비활성화에 관한 연구
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- A Ni-YSZ cermet catalyst with or without K2Ti2O5 additives was studied under various types of methane reforming condition
steam reforming, CO2 reforming, mixed reforming. The appearance of deactivation of Ni-YSZ is quite different. The amount of deposited carbon is much larger after steam reforming than CO2 reforming, but Ni-YSZ catalyst deactivated continuously during CO2 reforming. The addition of K2Ti2O5 additives definitely lower carbon deposition on both types of reforming, but can not improve stability on CO2 reforming, and even reduce Ni-YSZ activity. Mixed reforming on Ni-YSZ and with 10wt% K2Ti2O5 was also performed. The addition of steam decreased deactivation rate of Ni-YSZ, but it can not prevent deactivation totally.
Switching test of steam and CO2 reforming over Ni-YSZ tell us its reaction mechanism is different. The deactivation and regeneration of the catalyst independently occurs on steam and CO2 reforming condition respectively. In view of the results so far achieved, steam reforming might follow mono-site mechanism, while CO2 reforming might follow dual-site mechanism. The carbon deposition, mainly considered as reasons for catalyst deactivation on reforming reaction, seems not a critical factor on CO2 reforming of methane over Ni-YSZ.
From the result of switching test, poisoning occurs in two ways, one is on Ni active site which could be regenerated on steam reforming, the other occurs on Ni and ZrO2 perimeter, possibly responsible for catalyst deactivation on CO2 reforming. It revealed CO2 treatment can regenerate catalytic activity of Ni-YSZ while steam wasn’t effective at all for removal of poisoning reason. The process of both deactivation of Ni-YSZ on CO2 reforming reaction and its regeneration by CO2 treatment are not clear. Poisoning on Ni and ZrO2 perimeter might be possible cause so far, but it was not clearly examined in the present study.
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