Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Patent
1996-12-02
1999-03-09
Lewis, Michael L.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
502355, B01J 2332
Patent
active
058800590
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to chemistry and concerns the chemical and phase composition of catalysts for a deep oxidation of organic compounds and carbon oxide. The latter are present in industrial exhaust gases, exhausts of inner combustion engines, natural gas. The invention can be used to clean industrial and exhaust gases before their ejection into the atmosphere and to obtain calorific heat.
STATE OF ART
There are several well known catalysts that help to perform the oxidation of organics and carbon oxide. Such catalysts should exhibit a high thermal shock resistance, since heat evolves during the reaction and catalyst bed temperature attains 400.degree.-1000.degree. C. With this regard catalysts based on aluminium-manganese system are quite promising.
The known manganese oxide based catalysts contain phase oxides, mostly MnO.sub.2, mixed or not mixed with the oxides of other elements (e.g., the hopkalite catalysts, see the FRG patent No 2010449, MKI BO1J 23/34). These catalysts are prepared either via support impregnation by the Mn(II) salts solutions or by moulding (e.g., extrusion) conditioned paste or charge containing the oxides of aluminium, copper or such compounds as calcium aluminate (Bakhtadze V. Sh. Manganese and Manganese-Copper Catalysts, PhD thesis, Tbilisi, 1971).
Such catalysts are calcined in special furnaces at 550.degree.-850.degree. C. They, however, exhibit a low activity. Thus, in a model reaction of n-pentane oxidation a catalyst sample prepared via alumina impregnation by manganese nitrate solution shows activity lower than 6.times.10.sup.-4 cm.sup.3 /(g s) at 30020 C. and current pentane concentration equal to 0.05 vol. %. X-ray phase analysis data and electron microscopy show that the phase composition of this sample includes rather large (up to 500 .ANG.) particles of .beta.-MnO2 and .gamma.-Al.sub.2 O.sub.3.
It is possible to obtain aluminium-manganese catalyst for the deep oxidation of organic compounds and carbon oxide peptizing an acid mixture of a phase oxide Mn2O.sub.3 with .gamma.-Al.sub.2 O.sub.3, then extruding it, drying and calcining at 800.degree. C. (Japan patent No 52-38977 MKI BO1 D 53/34). This catalyst also shows a low catalytic activity, since its active component has a low dispersity and is well crystallized.
Therefore, the known aluminium-manganese catalysts, though exhibiting a good thermal stability necessary for the process performance, have a low activity caused by a large size and thus small surface of the active component.
DISCLOSURE OF THE INVENTION
The present invention aims at designing a catalyst for the deep oxidation of organic compounds and carbon oxide. The catalyst should be resistant to heat and show a high activity. For the purpose the catalyst suggested has the following composition: 2.7-11.5 mass. % of manganese, balance alumina.
Manganese (Mn) in the active component is represented by a defect non-stoichiometric oxide .beta.-Mn.sub.3 O.sub.4+x, where 0.1<.times.<0.25, containing 80-95% of all manganese atoms and by manganese aluminate containing 20-5% of all manganese atoms. Alumina Al.sub.2 O.sub.3 is presented by the high temperature forms .alpha. and (.delta.+.theta.).
The catalyst of such phase and chemical composition is obtained via a high temperature treatment of moulded (extrudated) or impregnated catalyst at 900.degree.-1000.degree. C. During the thermal treatment initial solid solution Mn.sub.y O.gamma.-Al.sub.2 O.sub.3 decomposes, and a disperse defect spinel phase Mn.sub.3 O.sub.4+x forms on the surface of generated high temperature aluminas as well as a solid solution based on manganese aluminate of non-identified composition.
The high temperature forms of alumina in the catalyst are represented by particles of irregular but round spatial configuration with a size of about 1000 .ANG.. The defect spinel dispersed at the surface of the above particles consists of round agglomerated particles of non-stiochiometric manganese oxide having size of 400-500 .ANG.. The two types of particles are fixed b
REFERENCES:
patent: 3764564 (1973-10-01), Maselli et al.
patent: 4310717 (1982-01-01), Eastman et al.
patent: 4353815 (1982-10-01), Antos
Carbon Oxide Removal From Exhaust Gases Using Manganese and Manganese-Copper Catalysts (0.5.340 -inorganic material technology), V.Sh. Bakhtadze, 1971 with English translation (no month.
Atamanchuk Oleg Vasilievich
Balashov Vladimir Aleksandrovich
Kachkina Olga Aleksandrovna
Kudrya Elena Nikolaevna
Lyubushkin Vladimir Alekseevivh
Ghyka Alexander G.
Institut Kataliza imeni G.K. Boreskova Sibirskogo otdelenia Ross
Lewis Michael L.
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