Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2000-04-25
2001-02-20
Nazario-Gonzalez, Porfirio (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S772000, C568S885000, C423S326000, C423S705000, C423S713000, C423S714000, C423SDIG002, C502S085000
Reexamination Certificate
active
06191323
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for the reduction of ketones or aldehydes to alcohols. The process involves contacting the ketone or aldehyde with a secondary or primary alcohol and a catalyst which comprises a tin substituted zeolite beta at reduction conditions to form the corresponding alcohol.
BACKGROUND OF THE INVENTION
There is an increasing demand for organic compounds containing oxygen in the structure, e.g., ketones, aldehydes, alcohols, etc. and therefore, a demand for processes which are more efficient, selective and environmentally friendly. Since alcohols is one family of desired organic compounds, one selective reaction route is the Meerwein-Pondorf-Verley reduction of aldehydes and ketones and the Oppenauer oxidation of alcohols denoted as MPVO. The MPVO reactions do not reduce C═C double bonds nor C-halogen bonds and can be carried out under mild conditions. In MPV reduction a secondary alcohols is the reductant whereas in Oppenauer oxidations, a ketone is the oxidant.
The art discloses a number of references which address either the mechanism of the MPVO reaction or various catalysts for the reaction. For example, R. Anwander et al., in
Chem. Communic.
(1998) 1811 disclose a catalyst for MPV reduction which is an aluminum isopropoxide grafted onto purely siliceous MCM-41. R. Anwander and C. Palm in
Studies in Surface Science and Catalysis,
vol. 117; 413, L. Bonneviot, F. Beland, C. Danumah, S. Giasson and S. Kaliaguine, editors, (1998) Elsevier Science Press disclose grafting lanthanide alkoxide onto MCM-41; M. A. Aramendia et al. in
Catalysis Letters,
discloses the use of magnesium phosphates to catalyze the MPVO reaction. J. C. van der Waal et al. in
Topics in Catalysis,
4 (1997), 261-268 (and references therein) disclose that zeolite beta and titanium containing beta can catalyze the MPVO reaction.
In contrast to the above art, applicants have carried out the MPVO reaction using a tin substituted molecular sieve which has the formula on an anhydrous basis of:
(M
w
Sn
x
Ti
y
Si
1-x-y-z
Ge
z
)O
2
M is a metal having a +3 valence (trivalent metal) such as aluminum or boron, “w” has a value of about zero to about 2x, “x” can be from about 0.001 to about 0.1 while “y” and “z” have respectively values of zero to about 0.1 and 0 to about 0.08. As will be shown in detail in the examples, a tin containing zeolite beta catalyst is able to convert cyclohexanone to cyclohexanol using isopropanol or 2-butanol as the reductant. The tin-beta catalyst also has better activity and selectivity than zeolite beta or titanium zeolite beta.
SUMMARY OF THE INVENTION
One embodiment of this invention comprises a process for the reduction of organic oxygenates selected from the group consisting of ketones, aldehydes and mixtures thereof comprising contacting the oxygenate with a secondary or primary alcohol and a catalyst at reduction conditions to reduce the oxygenate to its corresponding alcohol, the catalyst comprising a molecular sieve having an empirical formula on a calcined and anhydrous basis of:
(M
w
Sn
x
Ti
y
Si
1-x-y-z
Ge
z
)O
2
where M is a metal having a +3 valence, “w” is the mole fraction of M and varies from zero to about 2x, “x” is the mole fraction of tin and varies from about 0.001 to about 0.1, “y” is the mole fraction of titanium and varies from zero to about 0.1 and “z” is the mole fraction of germanium and varies from zero to less than about 0.08 and characterized in that the composition has the characteristic x-ray diffraction pattern of zeolite beta, and when “w”, “y” and “z” are all zero, then the molecular sieve is amorphous with short range order or has the charateristic x-ray diffraction pattern of zeolite beta.
This and other objects and embodiments of the invention will become more apparent after a detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
As stated, the present application deals with a process for practicing the MPVO reaction. One essential part of this process is a catalyst which comprises a tin containing molecular sieve having the characteristic x-ray diffraction pattern of zeolite beta and an empirical formula on a calcined and anhydrous basis of:
(M
w
Sn
x
Ti
y
Si
1-x-y-z
Ge
z
)O
2
“x” is the mole fraction of tin and varies from about 0.001 to about 0.1, “y” is the mole fraction of titanium and varies from zero to about 0.1 and “z” is the mole fraction of germanium and varies from zero to less than about 0.08. When “w”, “y” and “z” are all zero, the molecular sieve can be amorphous with short range order or have the characteristic x-ray diffraction pattern of zeolite beta. The M metals which can be used include but are not limited to aluminum, boron, gallium, and iron; and “w” is the mole fraction of M and varies from 0 to about 2x. These molecular sieves have a microporous three dimensional framework structure of at least SiO
2
and SnO
2
tetrahedral units, and a crystallographically regular pore system.
These molecular sieves are prepared using a hydrothermal crystallization process in which a reaction mixture is prepared by combining reactive sources of tin, silicon, an organic templating agent, optionally germanium, optionally titanium, optionally a M metal, a fluoride or hydroxide source, optionally hydrogen peroxide and water. The sources of silicon include but are not limited to colloidal silica, amorphous silica, fumed silica, silica gel and tetraalkylorthosilicate. Sources of tin include but are not limited to tin halides, tin alkoxides, tin oxide, metallic tin, alkaline and alkaline earth stannates and alkyl tin compounds. A preferred source is tin tetrachloride. Examples of tin alkoxides include tin butoxide, tin ethoxide and tin propoxide. The organic templating agents include, without limitation, tetraalkylammonium ions such as tetraethylammonium ions, aza-polycyclic compounds such as 1,4-diazabicyclo 2,2,2, octane; dialkyldibenzylammonium ions such as dimethyldibenzyl ammonium ion and bis-piperidinium ions such as 4,4′ trimethylene bis (N-benzyl N-methyl piperidinium) ion. These ions may be added as the hydroxide or halide compounds. Germanium sources include germanium halides, germanium alkoxides and germanium oxides. Titanium sources include titanium alkoxides and titanium halides. Preferred titanium alkoxides are titanium tetraethoxide, titanium isopropoxide and titanium tetrabutoxide. When M is Al, the sources of aluminum include but are not limited to alumina, aluminum oxides, such as pseudo-boehmite, aluminum alkoxides such as aluminum isopropoxide, sodium aluminate and aluminum trichloride, with pseudo-boehmite and aluminum alkoxides being preferred. Sources of boron, gallium and iron include oxides, hydroxides, alkoxides, nitrates, sulfates, halides, carboxylates and mixtures thereof. Representative compounds include, without limitation, boron alkoxides, gallium alkoxides, iron (II) acetate, etc.
The reaction mixture will also contain either a fluoride source such as hydrofluoric acid or ammonium fluoride or a hydroxide source such as sodium hydroxide or potassium hydroxide. The hydroxide source may also be added by using the hydroxide compound of the templating agent. Water is also added to the mixture and optionally hydrogen peroxide.
Generally, the hydrothermal process used to prepare the tin containing molecular sieves involves forming a reaction mixture, using the sources stated above, which is expressed by the formula:
SiO
2
:kM
2
O
3
:aR
2
O:bSnO
2
:cGeO
2
:dTiO
2
:eF:fH
2
O
2
:gH
2
O
where “k” has a value from zero to about 0.1, “a” has a value from about 0.06 to about 0.5, “b” has a value from about 0.001 to about 0.1, “c” has a value from zero to about 0.08, “d” has a value from 0 to about 0.1, “e” has a value from about 0.1 to about 2, “f” has a value from zero to about 0.5 and “g” has a value from about 4 to about 50. The reaction mixture is prepared by mixing the desired sources of tin, silicon, optionally titanium, optionally germanium, optionally a M metal, an organic templating agent, water, optionally hydrogen peroxi
Canos Avelino Corma
Domine Marcelo Eduardo
Moscoso Jaime G.
Nemeth Laszlo T.
Valencia Susana Valencia
Molinaro Frank S.
Nazario-Gonzalez Porfirio
Tolomei John G.
UOP LLC
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