Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2000-09-28
2003-05-27
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S325000, C502S326000, C502S327000, C502S328000, C502S332000, C502S335000, C502S336000, C502S337000
Reexamination Certificate
active
06569804
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a catalyst used in ammonia synthesis and hydrogen preparation, and the preparation of the same. More particularly, the present invention relates to a chromium-free Fe-based catalyst for CO high-temperature-shift (HTS) reaction, and its preparation.
BACKGROUND OF THE INVENTION
In conventional Fe-Cr-based catalyst for CO HTS reaction, chromium can improve the activity, heat-resistance and life of the catalyst as a main promoter. However, Cr has been proved to be a potent carcinogen, which can bring harmful effect to human health and the environment in the process of preparation, use and disposal of the catalyst. Accordingly, a great of effort has been directed toward the development of chromium-free catalyst for CO HTS reaction in the whole globe.
The followings are the main developments on the catalyst for CO HTS reaction since 1970's.
Soviet Union Ivanov Institution has developed a CTK→KC type Fe-Pb-based catalyst, in which another pollutant, Pb, was involved (with Pb in the range of 10-14% by weight).
ICI Incorporation has developed a 71-1 and a 71-2 type chromium-free catalyst comprising CaO, CeO
2
and ZrO
2
(Hf)
2
). But production process is very complicated, which leads to high cost of the preparation.
Nissan Incorporation has developed a chromium-free catalyst, which is made of Fe
2
O
3
, Al
2
O
3
, CuO, K
2
O and Pt.
A patent application entitled “Chromium-free Fe-based catalyst for high(middle)-temperature-shift reaction and its preparation” (filing number: 95121834.4) filed by China Inner Mongolia Polytechnic University disclosed a NBC type chromium-free catalyst prepared by using Fe
2
O
3
, CeO
2
, Al
2
O
3
, and K
2
O.
However, the catalysts mentioned above have problems, such as complexity of production process, high cost and introduction of new pollutant, which are required to be solved.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a novel chromium-free Fe-based catalyst for CO HTS reaction, which can eliminate the pollution of Cr without introducing new pollutant, and which can be produced simply by using the equipment for producing conventional HTS catalyst. The catalyst comprises FeO, Al, Fe, Si-mixed oxides or aluminum-silicon-sol, vanadium oxides, magnesium oxides, nickel oxides and potassium oxides.
It is another object of the present invention to provide a process for producing the catalyst of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
The object of the present invent is fulfilled by a novel chromium-free Fe-based catalyst for CO HTS reaction comprising from about 65 to about 90% by weight of Ferriate Oxides, from about 1 to about 10% by weight of Al, Fe, Si-mixed oxides (Al:Fe:Si=6:2:1) or aluminum-silicon-sol (Al:Si=8:2), from about 0.5 about 2.0% by weight of vanadium oxides, from about 0.5 to about 3.0% by weight of magnesium oxides, from about 0.5 to about 3.0% by weight of nickel oxides, and from about 0.1 to about 0.6% by weight of potassium oxides, based on the total weight of the catalytic material.
The present invention further provides a process for producing the catalyst of the present invention. Firstly, a precursor ferric oxides are obtained by the following process. FeSO
4
.7H
2
O is dissolved in water at 30-50° C., the density of the solution is 1.2-1.35. A (NH
4
)
2
CO
3
solution (the concentrate of (NH
4
)
2
CO
3
and NH
4
OH is 180 g/L-280 g/L and 20 g/L-100 g/L, respectively) is obtained by adding aqueous ammonia solution in NH
4
HCO
3
solution. Then, the FeSO
4
solution is neutralized with (NH
4
)
2
CO
3
solution until pH is between 6.5-7.5 in about 180 minutes at 65-75° C. The slushy precipitated product is heated at 90-95° C. for 60 minutes, then washed with water at a temperature of 40-60° C. for 4-6 times until no white precipitate is produced by adding 10% BaCl
2
solution to the water after washing. The final product, i.e. the catalyst of the present invention, is obtained by one of the two methods listed below.
Method 1: All the ingredients except K
2
O with the amount indicated above are beaten for 30 minutes, followed by pressure-filtering and drying. Then KOH as the precursor of K
2
O is added. The mixture thus obtained is milled for 60 minutes, followed by graining, and calcining at 300-350° C. for 90-120 minutes. Then 0.5%-1.0% graphite is added. The final product is obtained by pelleting the mixture.
Method 2: The slushy precipitated product as obtained above is pressure-filtered and dried, followed by adding all other ingredients with the amount as indicated. Then the mixture is milled for one hour. After that, the mixture is grained, and calcined at 300-350° C. for 90-120 minutes. Thereafter, 0.5%-1.0% graphite is added. The final product is obtained by pelleting the mixture.
Upon extensive investigation, the inventors of the present invention are aware that Cr plays a role not only as the structure promoter but also as the electron promoter. Based on this, Al, Fe, Si-mixed oxides (aluminum-silicon-sol) were prepared and these elements were entered into the lattice of Fe
3
O
4
, resulting the decrease of the size of the crystallite, increase of the surface area, and substitution for Cr to act as the structure promoter. It was proved by XRD and Mössbauer spectra that vanadium added in the form of vanadium oxides exists as V
4+
in A site of the lattice of spinel Fe
3
O
4
in the reaction system. It was also found that nickel oxides added thereto can increase the density of OH
−
on the surface of the catalyst, thereby improving the activity and anti-sulfur performance of the catalyst under low stream and gas ratio (ac. 1.85) conditions. Thereby, the performance of the chromium-free Fe-based catalyst of the present invention reached the level of traditional Fe-Cr-based catalyst.
REFERENCES:
patent: 3686347 (1972-08-01), Dean et al.
patent: 3872027 (1975-03-01), Christmann et al.
patent: 4234461 (1980-11-01), Suresh et al.
patent: 4235749 (1980-11-01), Gens
patent: 4256654 (1981-03-01), Schlinger et al.
patent: 4329517 (1982-05-01), Taniguchi et al.
patent: 4912077 (1990-03-01), Lachman et al.
patent: 4968661 (1990-11-01), Teller et al.
patent: 5118715 (1992-06-01), Iglesia et al.
patent: 5418201 (1995-05-01), Roberts et al.
patent: 5543437 (1996-08-01), Benham et al.
patent: 6235677 (2001-05-01), Manzer et al.
patent: 0 174 716 (1986-03-01), None
Ling Xingyi
Wei Kemei
Xu Jianben
Zheng Qi
National Engineering, Research Center of Chemical Fertilizer Cat
Nguyen Cam N.
Pennie & Edmonds LLP
Silverman Stanley S.
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