The role of sulfur trapped in micropores in the catalytic partial oxidation of hydrogen sulfide with oxygen

Steijns, M.; Mars, P.

doi:10.1016/0021-9517(74)90177-8

Cited by 130 publications

(117 citation statements)

References 7 publications

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“…In that sense, the higher reactivity of some samples (samples PN1 and PTI with respect to sample SB1, Figure 2) can be explained. As sulfurization progresses, be-cause the deposited terminal sulfur acts as a catalyst for the oxidation reaction (Steijns and Mars, 1974), no difference should be expected in the demercuriating behavior of all fibrous silicates, except that derived from sulfurization temperature and accessibility of the active sulfur present. Especially long particles, as in micronized sepiolite samples, which are quite suitable for sulfur retention, produce a deletereous effect on mercury retention by forming a "shell" of sulfur, which hinders the diffusion of reacting gases inside the adsorbent mass.…”

Section: Discussionmentioning

confidence: 99%

“…Sulfurized active carbon has been extensively studied as an adsorbent (Sinha and Walker, 1972;Lovett and Cunniff, 1974;Steijns and Mars, 1974) and developed by companies, such as Norit and Montedison, but drawbacks are its high cost and low possibilities of mercury recovery once the adsorbent is saturated. In the development of a less expensive and more recoverable adsorbent, some natural or slightly treated silicates appear to be promising materials, because they possess a developed network of pores and a large surface area.…”

Section: Introductionmentioning

confidence: 99%

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Mercury Adsorption by Sulfurized Fibrous Silicates

Daza

Mendioroz

Pajares

1991

Clays and clay miner.

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Abstract--To eliminate mercury vapor from gas streams, three major methods are used: condensation, absorption, and adsorption. This work deals with adsorption, using elemental sulfur as an active phase supported on sepiolite and palygorskite fibrous clays. Sulfur loads of 5-30% were deposited by catalytic oxidation of hydrogen sulfide at temperatures of < 200~ the clays acting first as a catalyst of the reaction and then as a carder of the obtained sulfur. The ability of the sulfurized clay adsorbents to retain mercury was studied at 45"C and 1 mrn Hg pressure. The high values found, about 4 g Hg/g S supported on clays, compared with 1.69 g Hg/g S on activated carbon under the same conditions are related to a more appropriate pore size distribution, with more of the pore widths > 6 nm for the sulfurized silicates. Also, the allotropic state of the deposited sulfur, where S~r (octo-catena) is better than SX (octo-cycle), may also be a contributing factor.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mercury Adsorption by Sulfurized Fibrous Silicates

Daza

Mendioroz

Pajares

1991

Clays and clay miner.

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“…A possible explanation for the observations mentioned above, might be that the concentration of radicals per volume of sulfur is dependent on the type of microporous material and the degree of filling of the micropore volume of a material with sulfur. The high initial oxidation rates are probably caused by impurities like ironoxide (1) (Figs. 3c and 4c).…”

Section: Comparison Of the Mercury Chemisorption With The Activity Fomentioning

confidence: 99%

“…Studying the selective oxidation of hydrogen sulfide we found that the product sulfur catalyses the reaction (1). This sulfur deposits during the reaction in the pores of a material and it may possess a high surface area, causing autocatalysis.…”

Section: Introductionmentioning

confidence: 99%

Mercury chemisorption by sulfur adsorbed in porous materials

Steijns

Peppelenbos

Mars

1976

Journal of Colloid and Interface Science

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The sorption of mercury vapor by adsorbed sulfur in the zeolites CaA (=5A) and NaX (= 13X) and two types of active carbon has been measured at a temperature of 50°C. With increasing degree of micropore filling by sulfur the fraction of sulfur accessible to mercury atoms decreased for CaA and NaX. The sulfur chemisorbed on carbon (only less than 0.05 g sulfur per g) is not very active for mercury chemisorption. The mercury uptake shows a sharp maximum as a function of the amount of sorbed sulfur in the case of CaA, NaX and activated sugar charcoal. The oxidation rate of H2S with oxygen on NaX and activated sugar charcoal correlates with the capacity for mercury chemisorption, both as a function of the amount of sorbed sulfur. From the amount of sorbed mercury an estimate of the specific sulfur surface area may be given. When sulfur impregnated CaA, NaX or activated sugar charcoal are used as adsorbents for mercury traces out of gas streams, the mercury sorption capacity may be maximized by using materials ~vith a micropore volume approximately half filled with sulfur.

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“…The selective-oxidation method with molecular 0, has been shown to be more effective for treating lower concentration H , S (<lo volume %) especially removing trace quantities of H,S from a gas stream rather than for producing a large amount of sulfur, which could be efficiently accomplished by the Claus process (Steijns and Mars, 1974;Ghosh and Tollefson, 1986). …”

Section: Oxidization Of H2s By 0mentioning

confidence: 99%