Catalyst – solid sorbent – or support therefor: product or process – Solid sorbent – Free carbon containing
Patent
1997-08-11
1998-11-24
Lewis, Michael L.
Catalyst, solid sorbent, or support therefor: product or process
Solid sorbent
Free carbon containing
502433, 423445R, 423460, B01J 2002
Patent
active
058406514
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a technique on an activated coke for simultaneous desulfurization and denitrification, and especially to a technique for producing a useful activated coke for concurrent desulfurization and denitrification, said coke being suitable for use as a denitrification catalyst in a dry desulfurization and denitrification process.
BACKGROUND ART
For the removal of sulfur oxides and nitrogen oxides which are contained in flue gas, many wet and dry, desulfurization and denitrification processes have been proposed and practiced. Among these desulfurization and denitrification processes, the dry processes have been attracting increasing interests in recent years owing to the merits that they do not require complex waste water treatment facilities, whose maintenance and control are difficult, and they do not need a large area for plant installation.
In these dry desulfurization and denitrification processes, various adsorbents and catalysts are employed. Among these, carbonaceous materials obtained by granulating or otherwise forming activated carbon as a principal raw material are used especially widely by using abilities for desulfurization and denitrification of the activated carbon.
As plants for practicing dry desulfurization and denitrification, those of the moving bed system have been predominantly adopted. In these plants, a carbonaceous adsorbent is generally recycled and reused. Conventional granulated or otherwise formed carbonaceous adsorbents are however accompanied by such practical problems to be resolved that they are low in compressive strength, abrasiveness, shatter strength and the like and are hence worn out or otherwise lost considerably when repeatedly used through adsorption and regeneration.
There is known, for example, a production process in which a coal, whose caking property has been eliminated by subjecting it beforehand to carbonization or oxidation treatment in a temperature range of 250.degree.-600.degree. C., is added and mixed with another coal having caking property and a binder to adjust the caking property, the resultant mixture is formed, the thus-formed material is carbonized at a temperature of 800.degree.-900.degree. C. (heating efficiency: 10.degree. C./min or less) and an oxygen concentration of 0 vol. %, and the thus-carbonized formed material is then activated with steam at a temperature of 800.degree.-900.degree. C. to obtain an activated coke. By treating the coal in advance and hence eliminating its caking property, this process achieves prevention of deformation, breakage or the like of the formed material due to its expansion or the like in the carbonization step and also formation of uniform pores upon conversion into the activated coke. The activated coke obtained as described above, however, has contributed extremely little to an improvement in the denitrification efficiency despite the specific surface area has been increased by conducting the activation treatment.
Further, research and development work are under way on adsorptive carbonaceous materials to further enhance their desulfurization and denitrification performance. This approach include, for example, to increase surface functional groups on a carbonaceous material. This approach may be able to improve abilities for desulfurization and denitrification but, due to a substantial reduction in strength by the activating treatment itself, it can obtain only a low-strength carbonaceous adsorbent. On the other hand, carbonaceous adsorbents developed with a primary object focused at their strength are accompanied by the problem that their initial desulfurization and denitrification performance is not sufficient.
Also developed are those obtained by having a metal or the like carried on an activated coke so that their performance for nitrogen oxides have been enhanced. To employ them in a dry desulfurization and denitrification process of the moving bed system, however, their poisoning by sulfur oxides, worn-out or loss, reduction in performance after regeneration, and t
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Hanashita Kazuhiko
Matsuoka Masahiro
Suenaga Hiroyasu
Umeno Katsuhiko
Yuda Toshihisa
Hendrickson Stuart L.
Lewis Michael L.
Mitsui Mining Co. Ltd.
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