TG-DTA on the Nitriding Process of Nitrided NiW Hydrotreating Catalysts
0
Citation
0
Reference
20
Related Paper
Abstract:
Through the TG-DTA in-situation experiments of single metal oxide, bimetallic oxide, supported or unsupported oxide and industrial catalysts G1 of nickel and tungsten nitrided in the mixture gas of hydrogen and nitrogen and passivated in air, the influence factors such as the react temperature, the ratio of hydrogen and nitrogen, the intermedia and the promoter which had influence on nitriding reaction were studied. The results show that WO_3 can be nitrided in the mixture gas of hydrogen and nitrogen, and that the process of the nitriding reaction can be divided into two steps. WO_3 could be nitrided to W_2N in the mixture gas in which the volume ratio of hydrogen and nitrogen is (4～5)∶1 and at the temperature 650 ℃. At another ratio of hydrogen and nitrogen the intermedia WO_2 and WO_XN_Y could be formed. WO_XN_Y can be easily nitrided to W_2N than WO_2.The nitriding temperature decreases 100 ℃ when Ni is introduced to the catalyst as a promoter.The interaction of the supporter γ-Al_2O_3 and the nitride species can result in the nitriding of the catalyst to be one-step reaction. W_2N is able to be oxided at its surface and can not be burned in the air and at room temperature. So W_2N is not necessary to be passivated. The industrial catalysts G1 can be nitrided by using the method mentioned.Keywords:
Bimetallic strip
Cite
Ammonia production
Cite
Citations (109)
Bimetallic strip
Physisorption
Cite
Citations (24)
Temperature-programmed reduction
Cite
Citations (11)
Cite
Citations (0)
The formation of hydrogen during methane conversion on supported Mo nitride catalysts was studied using a flow microreactor at 973 K and atmospheric pressure. The catalysts before and after the reaction were characterized by XRD, temperature-programmed reduction with H2 (TPR), and temperature- programmed surface reaction with CH4 (CH4-TPSR). Based on the catalytic activity effect of the supports (Al2O3, SiO2, TiO2, and ZSM-5), the ZSM-5 supported Mo nitride catalyst was the most active for hydrogen production. Mo nitride was partially transformed into Mo carbide at 973 K during the CH4 decomposition. The addition of Co and Ni atoms to Mo/Al2O3 promoted the CH4 decomposition activity due to the high hydrogen activation performance by the creation of Co(Ni-) added γ-Mo2N or Co(Ni)–Mo nitride in nitridation and the formation of Co(Ni)-added η-Mo3C2 or Co(Ni)-Mo carbide on the surface during the reaction.
Water-gas shift reaction
Cite
Citations (2)
Cite
Citations (15)
Water-gas shift reaction
Space velocity
Non-blocking I/O
Specific surface area
Sulfidation
Cite
Citations (0)
The ZrO 2 Al 2O 3 supports were prepared by the decomposition precipitation meth od . The sulfur tolerant water gas shift Co Mo K catalysts were prepared by impregnation . The effects of ZrO 2 Al 2O 3 support on the activity and thermal stability of Co Mo K catalyst have been studied through activity evaluation. Using BET, XRD, TG and XPS techniques the structures of the supports and catalysts, the reduction property, sulfur and water adsorbabilities of the catalysts have been investigated. The results show that the ZrO 2 Al 2O 3 supported Co Mo K catalysts exhibit a high activity, especially at low temperatures. The conversion of CO could reach up to 72 8% at 250 ℃ over the Z8 catalyst, being 25% higher than that over γ Al 2O 3 supported catalyst. The thermal stability, water and sulfur adsorbab ility and reduction property of the catalyst are all found improved on the ZrO 2 Al 2O 3 support.
Thermal Stability
Water-gas shift reaction
Cite
Citations (0)
Butane
Acid strength
Tetragonal crystal system
Temperature-programmed reduction
Cite
Citations (2)
Carburizing
Carbon fibers
Tungsten Carbide
Cite
Citations (52)