Hydrogenation and desulfurization

The main limitation of this type of reactor is the gradual accumulation of metals when heavy feedstocks are processed. The metals accumulate in the pores of the catalyst and gradually block access for hydrogenation and desulfurization. The length of operation is then dictated by the metal-holding capacity of the catalyst and the nickel and vanadium content of the feed. As the catalyst deactivates, the reactor feed temperature is gradually increased to maintain conversion. 

Sel iiion of Compressor Equipment, Compressors for such gas processes as liquid-air separation, hydrogenation, and desulfurization must be non-lubricated to avoid possible explosive reaction with lubricating oils. Graphite rings are used in reciprocating compressors, and labyrinth or... 

Decomposition, hydrogenation, and desulfurization C talyat Hydrodesulfurization Retidna... 

PROCESSES, CLEANING AND desulfurization). Hydrogen also reacts with other sulfui compounds ... 

Ladle metallurgy, the treatment of Hquid steel in the ladle, is a field in which several new processes, or new combinations of old processes, continue to be developed (19,20). The objectives often include one or more of the following on a given heat more efficient methods for alloy additions and control of final chemistry improved temperature and composition homogenisation inclusion flotation desulfurization and dephosphorization sulfide and oxide shape control and vacuum degassing, especially for hydrogen and carbon monoxide to make interstitial-free (IF) steels. Electric arcs are normally used to raise the temperature of the Hquid metal (ladle arc furnace). 

Two different sets of experimental conditions have been used. Buu-Hoi et al. and Hansen have employed the method introduced by Papa et using Raney nickel alloy directly for the desulfurization in an alkaline medium. Under these conditions most functional groups are removed and this method is most convenient for the preparation of aliphatic acids. The other method uses Raney nickel catalysts of different reactivity in various solvents such as aqueous ammonia, alcohol, ether, or acetone. The solvent and activity of the catalyst can have an appreciable influence on yields and types of compounds formed, but have not yet been investigated in detail. In acetic anhydride, for instance, desulfurization of thiophenes does not occur and these reaction conditions have been employed for reductive acetylation of nitrothiophenes. Even under the mildest conditions, all double bonds are hydrogenated and all halogens removed. Nitro and oxime groups are reduced to amines. 

Progress and prospects in hydrogenation, hydrogenolysis, and desulfurization of thiophenes with soluble metal complexes 98ACR109. 

The low reactivity of alkyl and/or phenyl substituted organosilanes in reduction processes can be ameliorated in the presence of a catalytic amount of alkanethiols. The reaction mechanism is reported in Scheme 5 and shows that alkyl radicals abstract hydrogen from thiols and the resulting thiyl radical abstracts hydrogen from the silane. This procedure, which was coined polarity-reversal catalysis, has been applied to dehalogenation, deoxygenation, and desulfurization reactions.For example, 1-bromoadamantane is quantitatively reduced with 2 equiv of triethylsilane in the presence of a catalytic amount of ferf-dodecanethiol. 

Figure 8.21 shows the scheme for producing ammonia. First, the natural gas is desulfurized and then steam-reformed in the primary reformer into a mixture of unreacted methane (10-13 %), CO, CO2, and FI2 that is then combined with air, which contains the necessary nitrogen for the ammonia process, to react in a secondary reformer. Here the oxygen reacts with hydrogen and methane in strongly... 

The desulfurized natural gas is mixed with the recycled depleted fuel stream containing steam formed in the fuel cell. About 75 percent of the methane is converted to hydrogen and carbon monoxide in the prereformer. The hydrogen-rich fuel is then passed over the... 

V-(Arylsulfonamidino)thioureas (108) afford the expected 5-amino-3-sulfonamido-l,2,4-thiadiazoles (109). The cyclization occurs almost quantitatively under the influence of bromine, but fails with hydrogen peroxide, which cleaves part of the starting material to sulfonylguanidine (110), and desulfurizes part to sulfonamidinourea (111).116. 

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