Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
1999-06-28
2001-01-30
Barts, Samuel (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
C564S480000
Reexamination Certificate
active
06180828
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to modified molecular sieve catalysts which are useful in an amination reaction of alcohols, typically for the production of methylamines from methanol and ammonia, and to methods for producing methylamines using said modified molecular sieve catalysts.
Among alkylamines obtained by the amination reaction of alcohols, methylamines are commercially important products having broad demands as materials for solvents, rubber products, pharmaceuticals and surfactants.
2. Description of the Prior Art
Methylamines are produced usually from methanol and ammonia using solid acid catalysts such as silica-alumina, at a temperature around 400° C. As generally known, the production in the presence of such silica-alumina catalysts is conducted under thermodynamic equilibrium. The main product is trimethylamine which has the least demand among the three amines. Dimethylamine is the most useful. Accordingly, methods for selectively producing dimethylamine in an amount exceeding the thermodynamic proportion have been developed. For example, there are methods using zeolites, such as zeolite A (JP 56-69846 A), FU-1 (JP 54-148708 A), ZSM-5 (U.S. Pat. No. 4,082,805), ferrierite and erionite (JP 56-113747 A), ZK-5, Rho, chabazite and erionite (JP 61-254256 A) and mordenite (JP 56-46846 A, JP 58-49340 A, JP 59-210050 A and JP 59-227841 A). These methods apply, to zeolites having small pore size, ion exchange, a de-aluminum treatment, steam treatment, addition of particular elements, silane-treatment and/or the other well known methods for controlling pore-sizes or modifying outer surfaces of zeolites. They intend to improve form-selectivity for dimethylamine and catalyst activity.
In addition, there is a method for producing monomethylamine in an amount exceeding the thermodynamic equilibrium proportion, by using silicoaluminophosphates, non-zeolite molecular sieves (JP 2-734 A).
The present inventors filed a patent application, on the basis of findings that silica-modified silicoaluminophosphates have a high activity together with a high selectivity for dimethylamine, as compared with prior arts in producing methylamines using zeolite catalysts (JP Application No. 9-197232).
SUMMARY OF THE INVENTION
In the known methods, modification of crystalline molecular sieve catalysts is an important and almost essential procedure in order to improve their activities and selectivities. A method of JP 6-75678 B, for example, mentions a modification by forming precipitations of silicon, aluminum, phosphorus or boron. JP 8-193057 A mentions a silylation by a silane treatment. However, these catalyst modification procedures are troublesome, and such catalyst modification processes are hardly simplified.
The present inventors have further studied to develop non-equilibrium type methylamine catalysts which are free from the disadvantages encountered in the conventional methylamine catalysts.
The present invention provides catalysts for producing methylamines. The catalysts are prepared by mixing a crystalline molecular sieve with one or more members of modifiers selected from the group consisting of titanium oxide, lanthanum oxide, zirconium oxide, yttrium oxide, cerium oxide, thorium oxide, niobium oxide, chromium oxide, molybdenum oxide, ruthenium oxide, rhenium oxide, iron oxide, cobalt oxide, palladium oxide, copper oxide, zinc oxide, gallium oxide, indium oxide, tin oxide, bismuth oxide, nickel oxide, manganese oxide, kaolinite, dickite, nacrite, halloysite, montmorillonite, talc, mica and illite. It further provides a method for producing methylamines from methanol and ammonia in the presence of the catalysts mentioned above. It also provides a method for producing dimethylamine from monmethylamine in the presence of the catalysts mentioned above.
When methylamines are produced from methanol and ammonia using the catalysts according to the invention, conversion of methanol is large and a satisfactory selectivity is obtained wherein a much more amount of dimethylamine and a less amount of trimethylamine are produced. In addition, excellent catalyst activities are sustained for a long period of time. The catalysts according to the invention can be prepared by a simple procedure in which a crystalline molecular sieve is mixed with a modifier such as the oxides mentioned above, followed by calcination, if required, and the mixture is extruded, compressed, or pelletized for shaping.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Preferable structures of the crystalline molecular sieves of the present invention are those having effective micropore size ranging from 0.3 to 0.6 nm. According to the IUPAC structural code of zeolites and their analogous compounds, for example, 8-membered ring-structural ABW, AEI, AFX, APC, ATN, ATT, ATV, AWW, CHA, DDR, EAB, ERI, GIS, JBW, KFI, LEV, LTA, MER, MON, PAU, PHI, RHO, RTE, RTH and VNI; 9-membered ring-structural CHI, LOV, RSN and VSV; 10-membered ring-structural DAC, EPI, FER, LAU, MEL, MFI, MFS, MTT, NES, TON and WEI; and 12-membered ring-structural AFS, AFY, ATO, CAN, GME, MAZ, MEI, MTW, OFF, RON and VET; and the like, are mentioned. The crystalline molecular sieves of the present invention also include crystalline silicoaluminophosphates and crystalline aluminosilicates.
The crystalline silicoaluminophosphates used in the present invention are so-called SAPO. They are prepared by an isomorphic replacement of a part of P or Al—P bonds with Si, in a crystalline aluminum phosphate compound (ALPO) having a chemical composition of the formula 1:
Al
2
O
3
·(1.0±0.2)P
2
O
5
(1)
which is represented by oxide mole ratios, excluding crystalline water and organic bases of structure directing agents (for example, JP 57-77015 A). Such crystalline silicoaluminophosphates include, for example, SAPO-5, 11, 17, 18, 31, 34, 35, 37, 40, 41, 42, 43, 44, 47 and 56, RUW-18, UTD-2, 3, 5 and 6, and those prepared from these compounds by an isomorphic replacement with Li, Ti, Zr, V, Cr, Mn, Fe, Co, Zn, Be, Mg, Ca, B, Ga, Ge, or the like. Herein, the relationship between the SAPO numbers and their structures is mentioned in, for example, Encyclopedia of Inorganic Chemistry, Vol. 8, 4369 (1994). The crystalline silicoaluminophosphates may be of H-type or those in which a part of the H-type has been replaced with an atom selected from Li, Ti, Zr, V, Cr., Mn, Fe, Co, Zn, Be, Mg, Ca, B, Ga and Ge. These crystalline silicoaluminophosphates can readily be prepared using an aluminum compound, an aqueous phosphoric acid solution, and an Si-source agent, together with an amine or quaternary ammonium compound as a structure directing agent. In order to prepare the crystalline silicoaluminophosphates, there are already known methods as described in, for example, JP 59-35018 A and the other improved methods. As the crystalline aluminosilicates of the present invention, there are, for example, chabazite, mordenite, erionite, ferrierite, offretite, gmelinite, paulingite, clinoptilolite, epistilbite, phillipsite, levynite, zeolite-A, rho, ZK-5, EU-1, FU-1, ZSM-5, 11, 12, 20, 22 and 23, and NU-3. Among these crystalline molecular sieves, crystalline silicoaluminophosphates, mordenite and chabazite are preferably used, because of their higher catalytic activities which are sustained for a longer period of time.
Each of the crystalline molecular sieves may be used singly or as mixtures of them. They may be not only as a simple mixture of them, but as an intergrowth, for example, of offretite and erionite as in U.S. Pat. No. 4,086,186, namely an intergrowth of two kinds of crystalline molecular sieves having different topologies from each other.
These crystalline molecular sieves may be subjected to ion-exchange or metal replacement, in order to intensify the acidity or activity. To this effect, are adequately used Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, Ga, Zn, Fe, Co, B, P, Ge or others.
Modifiers used for the preparation of the present catalysts are, for exampe, titanium oxide, lanthanum oxide, zirconium oxide, yttrium
Hidaka Toshio
Higuchi Katsumi
Koike Nobuyuki
Miki Yasushi
Barts Samuel
Mitsubishi Gas Chemical Company Inc.
Pillsbury Madison & Sutro LLP
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