Chenyu Wang,Wei Zhu,Cheng Chen,Hao Zhang,Naixi Lin,Ying Su
Dewatered sewage sludge with different moisture contents was treated with a nickel catalyst in supercritical water in a batch quartz tube micro-reactor at different temperatures and reaction times. The catalytic activity of the nickel wire catalyst was investigated. Because of the gradual deactivation of the catalyst, the hydrogen yield decreased by 8–72% after five catalytic cycles. The temperature has the largest influence on the deactivation rate of the nickel catalyst. The decline rate of the hydrogen yield decreased from 67% to 8% when the temperature was increased from 400 °C to 500 °C. SEM, EDS and TPO were used to characterize the spent catalyst. The results showed that the deactivation of the nickel catalyst is caused by the deposition of char/coke on the catalyst surface. Finally, the relationship between the reaction conditions and catalyst deactivation was investigated from the viewpoint of the organic matter degradation pathway.
Yi Lin,Zaixing Wang,Lina Tang,Shi Jiang,Yu Guo,Xiaoqin Liu
Ni-based catalysts supported on composite metal oxides (NiO-Al 2 O 3 , MgO-Al 2 O 3 , Co 3 O 4 -Al 2 O 3 ) were synthesized via coprecipitation followed by Ni impregnation to investigate the influence of support composition on catalyst stability in methane steam reforming. Accelerated deactivation protocols (methane decomposition, high-temperature sintering, hydrothermal oxidation) revealed hydrothermal oxidation as the primary cause of irreversible deactivation. The 10Ni/NiAl catalyst (10 wt% Ni/10 wt% NiO-Al 2 O 3 ) showed remarkable regenerability after 923 K hydrothermal treatment, fully restoring its activity. This was attributed to coexisting reduced Ni species and readily reducible NiO, facilitating rapid reactivation. Other catalysts formed thermally stable NiAl 2 O 4 , leading to permanent deactivation. Methane cracking at 973 K had negligible effect, and 10Ni/NiAl catalyst exhibited the lowest carbon deposition (17.02 %). Under extreme hydrogen purged at 1223 K, only the 10Ni/CoAl catalyst exhibited a minor activity decline. The superior stability of 10Ni/NiAl was attributed to an in situ-formed NiAl composite metal oxides during 973 K calcination, which effectively anchored Ni particles, suppressed sintering, and prevented extensive oxidation.
危险品化学品经营许可证（带存储）