Formation Of Nickel Sulfide Research Articles

HDS Activity and Characterization of Zeolite-Supported Nickel Sulfide Catalysts

Catalysts of nickel sulfide supported on zeolite Y have been prepared (by impregnation or ion exchange) and characterized by means of thiophene hydrodesulfurization (HDS), sulfur analysis, temperature-programmed sulfiding, 129Xe-NMR, HREM and dynamic oxygen chemisorption. The catalysts show large differences in catalytic behavior dependent on the preparation method (impregnation vs ion exchange) and the pretreatment conditions (method of sulfidation). Especially the ion-exchanged catalysts show a high initial activity, but due to the presence of acid sites deactivation is very strong. The initial activity of these catalysts can be improved significantly by drying prior to sulfidation. In all cases sulfidation results in quantitative formation of nickel sulfide, with Ni3S2 being the main product. Occasionally, also some NiS appears to be present. The major part of the nickel sulfide phase is invariably located on the outside of the zeolite particles. The fraction of nickel sulfide in the zeolite pores depends on the preparation method and the pretreatment conditions. The differences in catalytic activity are ascribed not only to variations in overall nickel sulfide dispersion but also to the acidity of the support, and the presence of very active small nickel sulfide clusters in the pores of the zeolite can have a strong influence on the thiophene HDS activity.

Corrosion and creep of Alloy 800 H under simulated coal gasification conditions

AbstractWhen the FeNiCr alloy Alloy 800 is exposed to a mixture of H2S, CO and H2O (as well as to a CO free gas of this composition at 800°C and total pressure of 1.5 bar), internal as well as external corrosion takes place and sulfides, oxides and carbides are formed. Corrosion results in a decrease of creep strength under high load while it remains practically unchanged or is even improved under medium and low load. The unexpected absence of nickel sulfide formation in the above gas mixture is attributed to the comparatively low nickel activity in the alloy so that sulfide formation would occur only at sulphur partial pressures exceeding the pressures used in this investigation. The increase rate of crack propagation under load can be interpreted in terms of the cracking of the oxide surface layer on the metal, the cracks allowing the aggressive gas to freely penetrate to the metal surface. The tests with the CO free gas demonstrate that the strength loss is principally caused by sulfidation and oxidation while carburisation which leeds to a strengthening results in somewhat slower destrengthening rate.

Ar-SO<SUB>2</SUB>雰囲気中における鉄-ニッケル合金の高温腐食

The corrosion of Fe-Ni alloys containing up to 40 mass%Ni at 873-1073 K under mainly 104 Pa SO2 partial pressure was studied by thermogravimetry, X-ray diffraction, SEM, and EPMA. The effect of pre-oxidation on the corrosion of the alloys was also determined.The addition of Ni caused sigificant deterioration in the corrosion resistance of these alloys. The linear and parabolic rate constants obtained at given SO2 partial pressures increased with the nickel content.The decreased corrosion resistance was related to the formation of nickel sulfide and the increased transport of nickel ions through the scale.The pre-oxidation treatment for the alloys yielded a remarkable decrease in corrosion rates and sulfide content in the scales was low during the subsequent corrosion in SO2.

ChemInform Abstract: THE STANDARD GIBBS ENERGY OF FORMATION OF NICKEL SULFIDE (NI3.+‐.XS2)

Chemischer InformationsdienstVolume 16, Issue 18 Physical Inorganic Chemistry ChemInform Abstract: THE STANDARD GIBBS ENERGY OF FORMATION OF NICKEL SULFIDE (NI3.+-.XS2) G. M. MEHROTRA, G. M. MEHROTRASearch for more papers by this authorV. B. TARE, V. B. TARESearch for more papers by this authorJ. B. JUN. WAGNER, J. B. JUN. WAGNERSearch for more papers by this author G. M. MEHROTRA, G. M. MEHROTRASearch for more papers by this authorV. B. TARE, V. B. TARESearch for more papers by this authorJ. B. JUN. WAGNER, J. B. JUN. WAGNERSearch for more papers by this author First published: May 7, 1985 https://doi.org/10.1002/chin.198518012AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue18May 7, 1985 RelatedInformation

Na2SO4-induced accelerated oxidation (hot corrosion) of nickel

The Na2SO4-induced accelerated oxidation of nickel has been studied at 1000°C. It has been found that low oxygen activities in the Na2SO4, which are produced by the formation of NiO, cause the sulfur activity of the Na2SO4 to be increased. Nickel and sulfur from the Na2SO4 combine to form nickel sulfide and the oxide ion activity of the Na2SO4 is increased. The accelerated oxidation of nickel occurs because oxide ions react with NiO to form a nonprotective oxide scale. The accelerated oxidation of nickel is not self-sustaining since oxide ions are not produced when conditions in the Na2SO4 are no longer favorable for the formation of nickel sulfide.