We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina(OMA) with confined Ni in the pore wall(Ni-OMA) wa...We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina(OMA) with confined Ni in the pore wall(Ni-OMA) was prepared via the one-pot evaporation induced self-assembly method. By using the incipient impregnation method, different amounts of free Ni were loaded over Ni-OMA(Ni/NiOMA) at a fixed total NiO content of 15 wt%. Characterization results confirmed the formation of wellstructured Ni-OMA, and the ordered structure was still well preserved even after impregnating NiO at a content of as high as 12 wt%. The catalysts were evaluated for the CO methanation as a model reaction under varied conditions. Importantly, the activity and stability of Ni/Ni-OMA for the titled reaction were significantly regulated by simply changing the ratio of the confined to free Ni. Over the optimum catalyst of NiO(2 wt%)/NiO(13 wt%)-OMA, the high activity at a temperature of as low as 300 ℃ was achieved with the space-time yield of methane over 7.6 g gcat-1 h-1 while a long-term stability for a time-onstream of 400 h was confirmed without an observable deactivation under the conditions of 600 ℃ and an extremely high gas hourly space velocity of 120,000 mL g-1 h-1. The results were well explained as the integrated merits of the free Ni for a high dispersion and the confined Ni in OMA for the anti-sintering property.展开更多
The loading-dispersion-reducibility dependence has always been one of the most critical issues in the development of high-performance supported metal catalysts.Herein,up to 40 wt%NiO over ordered mesoporous alumina(OM...The loading-dispersion-reducibility dependence has always been one of the most critical issues in the development of high-performance supported metal catalysts.Herein,up to 40 wt%NiO over ordered mesoporous alumina(OMA)was prepared by co-grinding the hybrid of template-containing OMA and Ni(NO_(3))2:6H_(2)O.Characterization results confirmed that the OMA mesostructure was still preserved even after loading NiO at a content as high as 40 wt%.More importantly,the reduction extent,dispersion,and average particle size of the Ni/OMA catalysts were maintained at≥91.0%,~13.5%,and~4.0-5.0 nm,respectively,when the Ni0 loading was increased from 20 to 40 wt%.The catalysts were evaluated for the CO methanation as a model reaction,and the similarly high turnover frequency of 24.0 h^(-1) was achieved at 300℃ for all of the Ni/OMA catalysts.For the catalyst with the highest NiO loading of 40 wt%(40Ni/OMA),the low-temperature activity at 300℃ indexed by the space-time yield of methane(over 325.8 molCH_(4)·kg_(cat)^(-1)·h^(-1))was achieved,while the catalyst was operated without an observable deactivation for a time on stream of 120 h under severe reaction conditions of 600℃ and a very high gas hourly space velocity of 240000 mL·g^(-1).h^(-1).With these significant results,this work paves the way for a rational and controllable design of supported Ni catalysts by breaking the loadingdispersion-reducibility dependence and stabilizing Ni nanoparticles under harsh reaction conditions.展开更多
基金the National Natural Science Foundation of China(U1862116)the National Key Research and Development Program of China(2018YFB0604600-04)the Fundamental Research Funds for the Central Universities(GK201901001)。
文摘We propose a new strategy to make an active and stable Ni-based catalyst which can be operated in a wide range of reaction temperatures. The ordered mesoporous alumina(OMA) with confined Ni in the pore wall(Ni-OMA) was prepared via the one-pot evaporation induced self-assembly method. By using the incipient impregnation method, different amounts of free Ni were loaded over Ni-OMA(Ni/NiOMA) at a fixed total NiO content of 15 wt%. Characterization results confirmed the formation of wellstructured Ni-OMA, and the ordered structure was still well preserved even after impregnating NiO at a content of as high as 12 wt%. The catalysts were evaluated for the CO methanation as a model reaction under varied conditions. Importantly, the activity and stability of Ni/Ni-OMA for the titled reaction were significantly regulated by simply changing the ratio of the confined to free Ni. Over the optimum catalyst of NiO(2 wt%)/NiO(13 wt%)-OMA, the high activity at a temperature of as low as 300 ℃ was achieved with the space-time yield of methane over 7.6 g gcat-1 h-1 while a long-term stability for a time-onstream of 400 h was confirmed without an observable deactivation under the conditions of 600 ℃ and an extremely high gas hourly space velocity of 120,000 mL g-1 h-1. The results were well explained as the integrated merits of the free Ni for a high dispersion and the confined Ni in OMA for the anti-sintering property.
基金This work was supported by the National Natural Science Foundation of China(Grant No.22208205)the Fundamental Research Funds for the Central Universities(Grant No.GK202304042)the Key Research and Development Program of Shaanxi Province(Grant No.2024SF-YBXM-613).
文摘The loading-dispersion-reducibility dependence has always been one of the most critical issues in the development of high-performance supported metal catalysts.Herein,up to 40 wt%NiO over ordered mesoporous alumina(OMA)was prepared by co-grinding the hybrid of template-containing OMA and Ni(NO_(3))2:6H_(2)O.Characterization results confirmed that the OMA mesostructure was still preserved even after loading NiO at a content as high as 40 wt%.More importantly,the reduction extent,dispersion,and average particle size of the Ni/OMA catalysts were maintained at≥91.0%,~13.5%,and~4.0-5.0 nm,respectively,when the Ni0 loading was increased from 20 to 40 wt%.The catalysts were evaluated for the CO methanation as a model reaction,and the similarly high turnover frequency of 24.0 h^(-1) was achieved at 300℃ for all of the Ni/OMA catalysts.For the catalyst with the highest NiO loading of 40 wt%(40Ni/OMA),the low-temperature activity at 300℃ indexed by the space-time yield of methane(over 325.8 molCH_(4)·kg_(cat)^(-1)·h^(-1))was achieved,while the catalyst was operated without an observable deactivation for a time on stream of 120 h under severe reaction conditions of 600℃ and a very high gas hourly space velocity of 240000 mL·g^(-1).h^(-1).With these significant results,this work paves the way for a rational and controllable design of supported Ni catalysts by breaking the loadingdispersion-reducibility dependence and stabilizing Ni nanoparticles under harsh reaction conditions.
