キレート剤を用いた高活性Co/SiO₂ Fischer-Tropsch合成触媒の調製: 調製の各過程におけるCo種の構造に及ぼすキレート剤の影響

Improvement of the Fischer–Tropsch Synthesis Activity of Co/SiO2 Catalyst by the Stepwise Impregnation Method with Chelating Agents

“…It is noted that this result is in contrast with our previous results, where the higher conversion was obtained by the catalyst with NTA rather than CyDTA when the catalyst is prepared from the aqueous solution containing Co nitrate and these chelating agents [18,19]. The increasing conversion over Co (20)/NTA/SiO 2 catalyst with decreasing the Co 2+ /NTA molar ratio is consistent with the dependency observed for NTA-Co(5)/ SiO 2 catalyst upon the Co 2+ /NTA molar ratio. On the contrary, the conversion over Co (20)/CyDTA/SiO 2 catalyst shows a broad maximum in the wide range of the Co 2+ / CyDTA molar ratio (8 to 2 mol mol -1 ).…”

“…Concerning effects of the chelating agents, the C 5+ selectivities over Co (20)/NTA/SiO 2 and Co(20)/CyDTA/ SiO 2 catalysts are comparable with that over Co(20)/SiO 2 catalyst, whereas the a values over Co (20)/NTA/SiO 2 and Co(20)/CyDTA/SiO 2 catalysts are slightly lower. Besides, the use of these chelating agents greatly improves the STY of hydrocarbons.…”

“…Over Co(20)/NTA/SiO 2 catalyst, CO conversion gradually increases with increasing NTA loading (Co 2+ /NTA molar ratio from 15 to 2 mol mol -1 ). On the contrary, CO conversion over Co (20)/CyDTA/SiO 2 catalyst steeply increases at CyDTA loading of 8 mass% (Co 2+ /Cy-DTA = 15 mol mol -1 ). The conversion over this catalyst shows a broad maximum in a wide range of CyDTA loading (Co 2+ /CyDTA molar ratio from 8 to 2 mol mol -1 ).…”

“…Besides, the use of these chelating agents greatly improves the STY of hydrocarbons. 608 and 1,500 g kg-cat -1 h -1 of C 5+ hydrocarbon are obtained with Co(20)/NTA/SiO 2 and Co(20)/CyDTA/SiO 2 catalysts, respectively, whereas the STY of C 5+ hydrocarbon over Co (20)/SiO 2 catalyst is no more than 360 g kg-cat -1 h -1 . Furthermore, the STY of C 10-20 hydrocarbon (equivalent to the diesel fraction) reaches 815 g kg-cat -1 h -1 over Co (20) In open literatures, the champion data for the STY of C 5+ and C 10-20 hydrocarbons has been reported to be 710 and 350 g kg-cat -1 h -1 , respectively, over SBA-15 supported Co catalyst (Co loading: 20 mass% as metallic Co) at 503 K and 2.0 MPa with W/F of 2.4 g h mol -1 [22].…”

“…In our previous studies, it was found that the FTS activity and selectivity of the NTA-Co(5)/SiO 2 and Cy-DTA-Co(5)/SiO 2 catalysts depend on various preparation conditions such as the type of SiO 2 support, pH of the impregnating solution, calcination temperature and so on [20,21]. The type of SiO 2 support and other preparation conditions for Co(X)/L/SiO 2 catalysts mentioned above were chosen according to these previous studies.…”