Temperature sulfide

Nickel sulfide, NiS, can be prepared by the fusion of nickel powder with molten sulfur or by precipitation usiag hydrogen sulfide treatment of a buffered solution of a nickel(II) salt. The behavior of nickel sulfides ia the pure state and ia mixtures with other sulfides is of iaterest ia the recovery of nickel from ores, ia the high temperature sulfide corrosion of nickel alloys, and ia the behavior of nickel-containing catalysts. 

Furnace tubes, piping, and exchanger tubing with metal temperatures above 800°F now tend to be an austenitic stainless steel, e.g., Type 304, 321, and 347, although the chromium-molybdenum steels are still used extensively. The stainless steels are favored beeause not only are their creep and stress-rupture properties superior at temperatures over 900°F, but more importantly because of their vastly superior resistance to high-temperature sulfide corrosion and oxidation. Where corrosion is not a significant factor, e.g., steam generation, the low alloys, and in some applications, carbon steel may be used. 

Fig. 9.15 XPS spectra of a Mo03/Si02/Si(100) model catalyst after sulfidation in H2S + H2 at the indicated temperatures show that considerable uptake of sulfur occurs already at room temperature, accompanied by reduction of Mo6+ to Mo4+. The S 2p spectra show the presence of at least two sulfur species after low-temperature sulfidation. (From [64]).

Fig. 1. Illustration of tube-in-tube-in-tube reaction vessels applicable for high-temperature sulfide experimentation. The inner reaction vessel (A) is 2 to 4 mm l.D. (wall thickness 1 mm) with a total length not exceeding 25 to 30 mm. The dimensions of the closely fitting second tube and the outside vessel are consequently larger...

Fig. 2. High-temperature sulfide experimentation vessel as described in the text. The inner tube (A) normally does not exceed 3 mm I.D. (1 mm wall thickness) with a length of approx. 50 mm. The tube is surrounded by the silica glass vessel and graphite crucible...

Corrosion, stress, temperature Sulfide stress cracking... 

Reprinted from High Temperature Sulfide Corrosion in Hydrogen Free Environment, API Proceedings—Division of Refining, vol. 43, May 1963, American Petroleum Institute, Washington, DC.)... 

NaY (Katalistiksj Si/Al=2 56) was used as a starting material for preparation of NH, K, Cs exchanged samples and three series of stab.lliJed Y-zeolites. Nickel was introduced before molybdenum by ion-exchange from Wi(NO )2 solution. Molybdenum was incorporated into the zeolite by sublimation of Mo(CO) in hydrogen stream at room temperature. Sulfided and non-sulfided Mo Y and Ni-Mo-Y samples were characterized with XRD, ND sorption capacity and FTIR spectroscopy. Each sample (0.25 g. 0.5-1 mm grains) was partially decarbonylated at 425 K before the WGS reaction and next presulfided with 1 2 vo1 %)/H2 mixture at 675 K, Catalysts after pre-... 

Alloying steels for improved corrosion resistance in chemical and hydrocarbon plants is based on chromium and molybdenum additions. The lowest of these alloys, lCr-l/2Mo and l-l/4Cr-l/2Mo, are often used above 800°F (425°C). Low-aUoy Cr-Mo steels (with 5% or greater Cr) are resistant to high-temperature sulfidic corrosion. However, the Cr-Mo alloys find their most critical use in high-temperature, high-pressure hydrogen service. The most commonly used alloys are the... 

If hydrogen is involved in the process, the material selected for resistance to sulfur must also meet the minimum requirements, based on the Nelson curves. In many cases, combined hydrogen-sulfur or hydrogen-hydrogen sulfide service require cladding or overlays, to provide resistance to the effects of high-temperature sulfidic corrosion and hydrogen attack, at an affordable cost. 

McConomy, H.E. 1963. High Temperature Sulfidic Corrosion in Hydrogen Eree Environment. API Subcommittee on Corrosion, May 12. 

---