Copper-zirconia catalyst and method of use and manufacture

Abstract

Catalysts and methods for their manufacture and use for the dehydrogenation of alcohols are disclosed. The catalysts and methods utilize a highly dispersible alumina, for example, boehmite or pseudoboehmite, to form catalysts that exhibit high dehydrogenation activities. Specifically, the catalysts include Cu that is highly dispersed by reaction of an alumina formed by peptizing of boehmite or pseudoboehmite and precursors of ZrO.sub.2, ZnO and CuO.

Claims

1. A dehydrogenation catalyst comprising about 10 to about 75 weight % CuO, about 5 to about 50 weight % ZnO, about 1 to about 30 weight % ZrO.sub.2, and about 5 to about 40 weight % alumina prepared by: peptizing an alumina mixture comprising a nondispersible alumina and a dispersible alumina with a dispersibility of at least about 50% or greater; and reacting the alumina mixture with precursors of CuO, ZnO, and ZrO.sub.2; wherein: the alumina mixture comprising up to 99% by weight of the nondispersible alumina; and the nondispersible alumina is selected from -alumina, -alumina, -alumina, gibbsite, bayerite, and mixtures thereof.

2. The catalyst of claim 1, wherein the dispersible alumina has a dispersibility of at least about 70% or greater.

3. The catalyst of claim 1, wherein the dispersible alumina has a dispersibility of at least about 90% or greater.

4. The catalyst of claim 1, wherein the dispersible alumina is selected from boehmite, pseudoboehmite, and mixtures thereof.

5. The catalyst of claim 1, wherein the catalyst exhibits an XRD pattern containing boehmitic peaks at 2 theta values of about 14.2 and 28.1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an XRD pattern of the copper-zirconia catalyst prepared according to Example 1.

DETAILED DESCRIPTION

(2) Before describing several exemplary embodiments of the invention, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced or being carried out in various ways.

(3) A first aspect of the present invention pertains to a dehydrogenation catalyst comprising Cu, ZnO, ZrO.sub.2 and Al.sub.2O.sub.3. In one embodiment, the catalyst exhibits increased dehydrogenation activity compared to conventional catalysts used in dehydrogenation reactions. In one or more embodiments, the catalyst comprises Cu, ZnO, ZrO.sub.2 and Al.sub.2O.sub.3 and the catalyst can be prepared by using highly dispersible alumina. In specific embodiments, the Cu of the catalyst is highly dispersed by reaction of precursors of ZrO.sub.2, ZnO and CuO and an alumina formed by peptizing of boehmite or pseudoboehmite. In one embodiment, a dehydrogenation catalyst comprises Cu, ZnO, ZrO.sub.2 and Al.sub.2O.sub.3, wherein the CuO is present in an amount of about 10% to about 75% by weight of the catalyst. The catalyst may be prepared by reaction of an alumina formed by peptizing of boehmite or pseudoboehmite and precursors of ZrO.sub.2, ZnO and CuO, wherein the alumina has a dispersibility of at least about 50%. In other specific embodiments, the alumina may have a dispersibility of at least about 70% and at least about 90%.

(4) In one or more specific embodiments, the Cu has a surface area exceeding 15 m.sup.2/g of the catalyst. In an even more specific embodiment, the Cu has a surface area exceeding 20 m.sup.2/g of the catalyst. The catalyst of one or more embodiments may include Cu with a surface area exceeding 25 m.sup.2/g of the catalyst. In one or more embodiment, CuO is present in the catalyst in an amount in the range of from about 30% to about 70% by weight of the catalyst. In a specific embodiment, CuO is present in an amount in the range from about 40% by weight to about 60% by weight. In a more specific embodiment, CuO is present in an amount in the range from about 45% to about 55% by weight. In one or more embodiments, ZnO, ZrO.sub.2 and Al.sub.2O.sub.3 comprise the remaining amount of the catalyst, or more specifically, from the range of about 70% to about 30% by weight of the catalyst, and more specifically in the range of about 60% to about 40% by weight of the catalyst. In one or more specific embodiments, ZnO may be present in an amount in the range from about 5 weight % to about 50 weight %, ZrO.sub.2 may be present in an amount in the range from about 1 weight % to about 30 weight % and Al.sub.2O.sub.3 may be present in an amount in the range from about 5 weight % to about 40 weight %.

(5) The catalyst according to one or more embodiments may have a BET total surface area of greater than about 140 m.sup.2/g. The catalyst may exhibit an XRD pattern containing boehmitic peaks at 2 theta values of about 14.2 and 28.1.

(6) The alumina utilized in the catalysts described herein is characterized as peptized until the desired dispersibility or a dispersible alumina, as defined above, is achieved. According to one or more specific embodiments, the use of a highly dispersible alumina allows more of the surface area of the Cu to be exposed for reaction and thus provides a higher catalytic activity. In one or more embodiments, the peptized alumina has a particle size of 1 m or less. In one more embodiments, the alumina has 40% or greater dispersibility in water after peptizing at a pH of 2 to 5. In other words, the percentage of alumina having a particle size of 1 m or less in water after peptizing at a pH of 2 to 5 is at least 40%. In one more embodiments, the alumina has 50% or greater dispersibility in water after peptizing at a pH of 2 to 5. In a more specific embodiment, the alumina has 80% or greater dispersibility in water after peptizing at a pH of 2 to 5. Other suitable alumina may have 90% or greater dispersibility in water after peptizing at a pH of 2 to 5. In one or more alternative embodiments, non-dispersible alumina may be used in combination with dispersible alumina. In such embodiments, the non-dispersible alumina is milled into a fine powder before use.

(7) The catalyst includes Al.sub.2O.sub.3 which may be formed or derived from boehmite, pseudoboehmite and combinations thereof. Suitable boehmite and pseudoboehmites have 70% or greater dispersibility in water after peptizing at a pH of 2 to 5. For example, suitable aluminas are available from Sasol North America Inc. of Houston, Tex., under the trademarks Catapal, Pural, Dispersal, and Dispal. Examples of aluminas that may be utilized in the catalysts described herein include aluminas available under the trade names Catapal A, B, Cl, and D and Pural SB. A specific example of a suitable alumina is available under the trade name CATAPAL D and has a particle size d.sub.50 of about 40 m. The alumina available under the trade name CATAPAL D also has a BET surface area of 220 m.sup.2/g and a pore volume of about 0.55 ml/g after activation at 550 C. for 3 hours.

(8) As will be understood, other sources of alumina can be used and include such diverse materials as aluminum nitrate. Some dispersible alumina sources are thought to be unsuitable for industrial scale applications because of their tendency to gel or become solid under normal operating conditions in an industrial or large-scale setting. Accordingly, many known catalysts and methods of making and using such catalysts utilized aluminum nitrate as an alumina source. Modifying these known alumina sources, for example, aluminum nitrate and aluminum powders, were considered, however, none of these yielded the high Cu dispersion and enhanced catalytic activity desired. The dispersible alumina of the present invention is selected, despite the many issues regarding its use, and modified by peptizing to achieve the high Cu dispersion. Specifically, as stated above, the Cu of one or more catalysts described herein is highly dispersed by the reaction of an alumina derived by peptizing of boehmite or pseudoboehmite and precursors of ZrO.sub.2, ZnO and CuO.

(9) In one or more embodiments, at least a portion of the dispersible alumina in the catalyst may be replaced with nondispersible alumina. Suitable nondispersible alumina include -alumina, -alumina, -alumina, other transitional aluminas, boehmite, pseudoboehmite, gibbsite, bayerite, and mixtures thereof.

(10) The catalyst according to one or more embodiments includes ZrO.sub.2, ZnO and CuO which are formed from various precursors. A suitable ZrO.sub.2 precursor includes zirconyl nitrate though other known precursors may be utilized. When zirconyl nitrate is used as the zirconia precursor, the ZrO.sub.2 precursor is provided by forming a slurry of zirconyl nitrate and water. In such embodiments, it is desirable to maintain the reaction mixture or the zirconyl nitrate and water slurry at a pH of less than about 2, and in specific embodiments at a pH of less than about 1.5 or 1. In one or more specific embodiments, the reaction mixture or the zirconyl nitrate slurry is maintained at a pH of about 1. In one or more embodiments, the reaction mixture is maintained or has a temperature in the range from about 20 C. to about 30 C. In one or more embodiments, the temperature of the zirconyl nitrate slurry may be maintained at a temperature of about 25 C.

(11) A suitable CuO precursor includes copper nitrate. A suitable ZnO precursor includes zinc nitrate. In one or more embodiments, the catalyst is formed by first reacting a ZrO.sub.2 precursor with the peptized alumina to provide a first reaction product, a mixed slurry or a new slurry. A second reaction is then performed in which the CuO and ZnO precursors are reacted in a separate vessel to form or provide a second reaction product. The first reaction product and second reaction product are then subsequently mixed together.

(12) A second aspect of the present invention pertains to a method of preparing a catalyst as described herein. In one or more embodiments, the method includes peptizing the highly dispersible alumina to form a peptized alumina and reacting the peptized alumina with precursors of ZrO.sub.2, ZnO and CuO, as described above.

(13) A highly dispersible alumina, as otherwise described herein, is prepared by adding the alumina to water to provide approximately 5 wt % to 35 wt % solids. The alumina and water mixture is mixed at high shear for approximately one hour to form a slurry. In one or more embodiments, the alumina and water mixture is maintained at a pH in the range from about 2 to about 5 during the mixing process at a temperature in the range from about 20 C. to about 30 C. In a specific embodiment, the alumina and water is maintained at a pH of about 3 during the mixing process. In an even more specific embodiment, the temperature of the alumina and water is maintained at about 25 C. The pH of the alumina and water mixture is maintained by adding an amount of acid to the mixture. Examples of suitable acids include nitric acid, formic acid, other known acids and combinations thereof. As described herein, in one or more embodiments the dispersible alumina may be replaced with nondispersible alumina. For example, up to 99% of the dispersible alumina may be replaced with nondispersible alumina that may include -alumina, -alumina, -alumina, other transitional aluminas, boehmite, pseudoboehmite, gibbsite, bayerite, and mixtures thereof.

(14) Prior to a first reaction of the peptized alumina and the ZrO.sub.2 precursor, the ZrO.sub.2 precursor is prepared as a slurry in a separate vessel from the highly dispersible alumina. The process includes maintaining the ZrO.sub.2 precursor a low pH and a controlled temperature. In one or more embodiments, the ZrO.sub.2 precursor is maintained at a pH of less than 2 or less than about 1.5. In one or more specific embodiments, the ZrO.sub.2 precursor is maintained at a pH in the range from about 1.0 to about 2.0. In a more specific embodiment, the ZrO.sub.2 precursor is maintained at a pH of about 1.0. The temperature of the ZrO.sub.2 precursor of one or more embodiments is maintained at a temperature in the range from about 20 C. to about 30 C. prior to the first reaction with the peptized alumina. In one or more specific embodiments, the ZrO.sub.2 precursor is maintained at a temperature in the range from about 22 C. to about 28 C., or, more specifically, in the range from about 24 C. to about 26 C. In one variant, the ZrO.sub.2 precursor is maintained at a temperature of about 25 C.

(15) The dispersed alumina and water slurry is added to the slurry of the ZrO.sub.2 precursor and the alumina slurry and ZrO.sub.2 precursor are well mixed for a duration from about 30 minutes to about 60 minutes to form a first reaction product, new slurry or mixed slurry. While the alumina slurry and the ZrO.sub.2 precursor are mixed, the pH is maintained at less than about 1.5. In one or more embodiments, while the mixed slurry or first reaction product is formed, the process includes maintaining the pH at about 1 or as close to 1 as possible. The temperature is also maintained at a range from about 20 C. and about 30 C. or, more specifically, at 25 C.

(16) In one or more embodiments, the CuO and ZnO precursors are prepared separately for reaction with the first reaction product, new slurry or mixed slurry. In a separate vessel, a solution of the CuO precursor and ZnO precursor is prepared to form a second reaction product. In one or more specific embodiments, the second reaction product is provided by forming a solution of copper nitrate and zinc nitrate in a separate vessel. The temperature of second reaction product is maintained at a temperature in the range from about 30 C. to about 50 C. In one or more specific embodiments the temperature of the second reaction product is maintained at about 40 C. In one variant, the pH of the second reaction product is maintained at a pH of less than about 1.5 or, in a more specific variant, at about 1. In one or more specific embodiments, the second reaction product is maintained at this pH by the addition of soda ash, or other suitable sodium source, for example, sodium hydroxide, sodium carbonate or sodium bicarbonate.

(17) The second reaction product is then added to the first reaction product or mixed slurry. The first reaction product and the second reaction product are well mixed for a duration from about 30 minutes to about 60 minutes. The temperature and/or pH may be adjusted or controlled to create an acidic slurry. The acidic slurry may containing copper nitrate, zinc nitrate, zirconyl nitrate and alumina.

(18) In one or more embodiments, the first reaction product and the second reaction product are maintained at a pH of less than about 1.5, or in a more specific embodiment, at about 1 or as close to about 1 as possible. The temperature may also be controlled. For example, in one variant, the temperature of the first reaction product and the second reaction product is raised and maintained at a temperature in the range from about 30 C. to about 50 C. In one or more specific embodiments, the temperature of the first reaction product and the second reaction product is raised and maintained at a temperature of about 40 C.

(19) The acidic slurry formed from the first reaction product and the second reaction product is then combined with a precipitation solution and a heel of water to form a precipitate slurry. The precipitation solution may include a basic solution of one or more of sodium carbonate and sodium bicarbonate and is formed separately from the heel of water. The precipitation solution may be formed at a temperature and/or have a temperature in the range from about 30 C. to about 50 C. or, in one or more specific embodiments, a temperature of about 40 C. In one or more embodiments, the slurry is formed by adding the acidic slurry and the precipitate solution simultaneously and slowly to a separate vessel containing a heel of water to form a precipitate slurry. The heel of water may have a temperature in the range from about 30 C. to about 50 C. or, in one or more specific embodiments, a temperature of about 40 C. This simultaneous addition of the acidic slurry and the precipitation solution improves the consistency in the precipitation of the carbonates.

(20) After addition, the first and second reaction products and the precipitation solution are well stirred for a duration of about 90 minutes. In one or more embodiments, precipitation reaction is performed or carried out at a pH that is controlled, for example, by adjusting the flow of the first and second reaction product and/or the flow of the precipitation solution. In one or more embodiments, the pH is controlled to an amount in the range from about 6 to about 7 or, more specifically, in the range from about 6.5 to about 6.7. In one or more specific embodiments, the pH is controlled at about 6.5. The temperature of the precipitation may be carried out at a temperature in the range from about 30 C. to about 50 C., or more specifically, a temperature of about 40 C.

(21) In one or more embodiments, the precipitate slurry is digested or aged for a duration of about 15 minutes to about 15 hours. In a specific embodiment, the precipitate slurry is digested or aged for a duration of about 1 hour to about 3 hours. In an even more specific embodiment, the precipitate slurry is digested or aged for a duration of about 2 hours. The temperature of the precipitate slurry is increased to a temperature in the range from about 30 C. to about 70 C. during aging or, more specifically, to a temperature of about 60 C. In one variant, the pH of the precipitate slurry during digestion or aging is not controlled. In such embodiments, the pH of the precipitate slurry undergoes some changes by cyclically increasing and decreasing, though the amount of increase and decrease may not be uniform. During the digestion or aging process, the color of the slurry changes from blue to green. In one variant, the method includes filtering and washing the slurry to form a filter cake. The method may also include drying the filter cake to form a dry filter cake or dried powder. The dry filter cake or dried powder may then be calcined to decompose any carbonates to oxides. In one or more embodiments, the dry filter cake or dried powder may be calcined for a duration of about 2 hours at a temperature of about 350 C.

(22) In one or more embodiments, the resulting catalyst, before reduction of the copper oxide to form copper metal, includes cupric oxide in an amount in the range from about 10% by weight to about 75% by weight. In one variant, ZnO was present in the resulting catalyst, before reduction, in an amount in the range from about 5% by weight to about 70% by weight. In one or more embodiments, the catalyst includes ZrO.sub.2 in an amount in the range from about 1% by weight to about 50% by weight, before reduction. In one or more embodiments, the catalyst includes alumina in an amount in the range from about 5% by weight to about 70% by weight, before reduction.

(23) In one or embodiments, the prepared catalyst is further reduced. A variant of the reducing step utilizes a hydrogen-containing gas. Specifically, such methods may include heating the catalyst to a temperature in the range from about 150 C. to about 200 C. while flowing nitrogen gas at atmospheric pressure over the catalyst in a reactor. In one or more specific embodiments, the catalyst is heated to a temperature in the range from about 165 C. to about 185 C. in flowing N.sub.2. In a more specific embodiment, the catalyst is heated to a temperature of about 170 C. in flowing N.sub.2. The nitrogen is replaced incrementally by hydrogen. The temperature may be slowly and incrementally increased to a maximum of about 220 C.

(24) The resulting catalyst includes copper metal, formed form the reduction of the CuO precursor. The catalyst also includes ZrO.sub.2, which functions as a chemical promoter, while ZnO and alumina function as structural promoters. In one or more embodiments, at least the ZnO and ZrO.sub.2 are closely associated with the copper metal.

(25) A third aspect of the present invention pertains to a method of converting alcohol to an ester or otherwise dehydrogenating an alcohol. One or more embodiments of the method include contacting an alcohol-containing fluid stream with a catalyst as described herein and dehydrogenating the alcohol to an ester. The alcohol-containing fluid stream may be flowed at 1 h.sup.1 LHSV with a hydrogen-containing gas that is flowed at 4.2 h.sup.1 GHSV. The catalyst utilized in the method to convert alcohol may be reduced in a stream containing hydrogen. In one or more embodiments, the alcohol may include ethanol and the ester that is formed may include ethyl acetate.

(26) Without intending to limit the invention in any manner, embodiments of the present invention will be more fully described by the following examples.

EXAMPLES

(27) Two catalysts were prepared and the catalytic activity of each catalyst was measured. Both catalysts, Example 1 and Comparative Example 2, included CuO, ZnO, ZrO.sub.2 and Al.sub.2O.sub.3. Example 1 was made with highly dispersible alumina having a dispersibility greater than about 90%, available under the trade name Catapal D from Sasol North America, Inc. Comparative Example 2 was made with aluminum nitrate. The components and quantities of the components used to make the final catalyst of Example 1 and Comparative Example 2 catalyst in the oxide or unreduced form are provided in Table 1.

(28) TABLE-US-00001 TABLE 1 Example 1 Comparative Example 2 Reagents (solutions) Amount, g Reagents (solutions) Amount, g 16% Copper in Nitrate 1919.6 16% Copper in Nitrate 1919.6 solution solution 16.5% Zinc in Nitrate 579.4 17% Zinc in Nitrate 562.4 solution solution Al Nitrate solution N/A 7.2% Al in Nitrate 927.4 solution 14.6% Zirconia in 510.2 26.7% Zirconia in 262.7 Nitrate Nitrate Al.sub.2O.sub.3 (@19% VF 663.2 Al.sub.2O.sub.3 (@19% VF N/A solids) solids) Water to be added for 2841.3 Water to be added for 2994.1 dilution dilution Sodium Carbonate 1146.7 Sodium Carbonate 1146.7 Water 3631.1 Water 3631.1 Total carbonate 4777.8 Total carbonate 4777.8 solution solution Water Heel 2124.6 Water Heel 2124.6 Total wt of solution 4461.6 Total wt of solution 3672.1 Water in mix 1853.0 Water in mix 1700.2 % total metal concen- 25.3 % total metal concen- 27.6 tration in solution tration in solution Water for required 4694.3 Water for required 4694.3 concentration concentration Grams of metal in Grams of metal in final catalyst final catalyst Cu 307.1 Cu 307.1 Zn 95.6 Zn 95.6 Al from nitrate N/A Al from nitrate 66.7 Al from solid alumina 66.7 Al from solid alumina N/A Zr 74.3 Zr 52.0 Total g of metal 543.8 Total g of metal 521.4

(29) Example 1 is prepared according to the methods of preparing a catalyst composition described herein. As Comparative Example 2 utilized aluminum nitrate as an alumina source and thus, did not contain any solid alumina. Accordingly, a different preparation procedure was utilized to form Comparative Example 2. Comparative Example 2 was formed using copper nitrate, zinc nitrate, zirconyl nitrate, and aluminum nitrate precursors, which were all mixed together without the need for the initial interaction of zirconyl nitrate with aluminum nitrate. The mixture had a pH of 2.5. A slurry was formed by precipitating the mixture with soda ash at a pH of 7 and temperature of 60 C. The slurry was then digested at a temperature of about 60 C. for a duration of about 90 minutes. The filtration, washing, drying, and calcination steps for preparing Comparative Example 2 were the same as for Example 1. Example 1 and Comparative Example 2 were reduced at approximately 210 C. using a gas containing 5% hydrogen in nitrogen, as described herein. Table 2 provides the analyses of Example 1 and Comparative Example 2 before and after reduction.

(30) TABLE-US-00002 TABLE 2 Analyses of Example 1 and Comparative Example 2 Example Comparative Example 1 Example 2 Analyses % CuO 48.0 51.0 % ZnO 16.0 15.5 % ZrO2 12.1 11.5 % Al2O3 23.9 22.0 % Na2O 0.02 0.04 After reduction % Cu 42.5 45.5 % rest of components as 57.5 54.5 oxides BET total surface area, m.sup.2/g 142 134

(31) The Cu surface areas of reduced Example 1 and reduced Comparative Example 2 as prepared in Example 1 were measured by a standard procedure described by G. C. Chinchen et al. in Journal of Catalysis (1987), vol 103, pages 79 to 86. After reducing, a reduced metallic Cu surface is obtained on both Example 1 and Comparative Example 2. A gas containing 2 wt % N.sub.2O in helium at a temperature of 60 C. is flow through reduced Example 1 and Comparative Example 2 for 10 minutes. It is believed that the nitrous oxide decomposes on the copper surface of the catalysts and the resulting N.sub.2 evolved is measured via a thermal conductivity detector, while the oxygen atoms remain attached to the copper. Each oxygen atom is attached to two surface Cu atoms. The amount of nitrogen evolved gives a measure of the number of number of oxygen atoms, and thus copper atoms available on the surface of the catalyst. The surface area of a Cu atom is 6.810.sup.16 cm.sup.2/atom. By multiplying the number of Cu atoms by the area of each atom the copper surface area of the catalyst is derived. The Cu dispersion, which is defined as surface copper atoms as a percentage of all copper atoms, and Cu surface areas of Example 1 and Comparative Example 2 are shown in Table 3.

(32) TABLE-US-00003 TABLE 3 Cu dispersion and Cu surface area Cu surface area, % Cu dispersion m.sup.2/g of catalyst Example 1 10.4 28.4 Comparative 3.0 8.8 Example 2

(33) As is evident from Table 3, Example 1 made with dispersible alumina and with the method described above exhibits a significant increase in the Cu dispersion and surface area compared to Comparative Example 2, which was made with aluminum nitrate instead of a dispersible alumina.

(34) A sample made in accordance with Example 1 was submitted for X-ray diffraction analysis using standard techniques. The sample was ground in a mortar and pestle. The resultant powder was then backpacked into a flat plate mount for use in reflection mode. X-ray diffraction was performed on a - PANalytical X'Pert Pro MPD X-ray diffractometer with Cu.sub.k radiation. The generator settings were voltage 45 kV and current 40 mA. The diffractometer optics utilized Bragg-Brentano geometry, a divergence slit, 0.04 radian soller slits, 15 mm beam mask and anti-scatter slit. The data collection range was 8 to 80 two theta (2) using a step size of 0.0334 and counting for 240 seconds per step. As illustrated in FIG. 1, the catalyst exhibits an XRD pattern containing boehmitic peaks at 2 theta values of about 14.2 and 28.1.

(35) As an example of the dehydrogenation catalysis of the catalysts described herein, ethanol was reacted with Catalysts 1 and Comparative Example 2, to form ethyl acetate. Before use Example 1 and Comparative Example 2 were reduced in a hydrogen containing gas to obtain the final catalyst comprising of Cu, ZnO, ZrO.sub.2, and Al.sub.2O.sub.3, as described herein. The catalyst reduction procedure utilized includes heating Example 1 and Comparative Example 2 to a temperature of about 170 C. in 250 sccm flowing nitrogen gas at atmospheric pressure. Subsequently hydrogen is introduced to the nitrogen flow in a step-wise fashion for up to about 1 hour for each step, starting at low concentration as outlined below:

(36) 1. 12 cc/min H.sub.2 in 238 cc/min N.sub.2

(37) 2. 25 cc/min H.sub.2 in 225 cc/min N.sub.2

(38) 3. 50 cc/min H.sub.2 in 200 cc/min N.sub.2

(39) 4. 125 cc/min H.sub.2 in 125 cc/min N.sub.2

(40) 5. 200 cc/min H.sub.2

(41) Once reduction was completed, the temperature was increased to 220 C. in 200 sccm hydrogen, and then reactor was pressurized to 10 bars absolute. Once temperature and pressure was stable, the ethanol feed stream was introduced to the reactor at 1 h.sup.1 LHSV (23.7 g/h) while maintaining hydrogen flow at 4.2 h.sup.1 GHSV (2 sccm).

(42) To measure the catalytic activity of Example 1 and Comparative Example 2, a stainless steel reactor tube having dimensions of approximately 84 cm in length, 2.5 cm outer diameter and 2.1 cm inner diameter was utilized. The reactor tube was equipped with a thermocouple well having an outer diameter of 0.47 cm. The thermocouple well ran through the center of the tube and housed 5 thermocouples. The thermocouples were spaced evenly from the top to the bottom of the catalyst bed. The average temperature of the thermocouples was used to control temperature. Thirty cc of each of Example 1 and Comparative Example 2 having a particle size in the range from about 30 mesh to about 50 mesh was mixed with 30 cc of interstitial packing for a total bed volume of 60 cc. The interstitial packing included -alumina granules having a particle size in the range from about 28 to 48 mesh. The bed volume corresponded to a reaction zone of about 18 cm length. -alumina granules having a particle size in the range from about 14 to about 28 mesh was utilized as a preheat inert material and Denstone 57 tablets ceramic bead support media having a length and width of 3 mm3 mm was utilized as a post catalyst inert material. The preheat zone was about 35 cm long and the post catalyst zone was about 30 cm long. The reactor was jacketed to accommodate a recirculating hot oil bath which heated the reactor, and ISCO Model 2350 HPLC pumps were used to pump a feed into the reactor. The feed included a synthetic blend of 95% ethanol and 5% isopropanol.

(43) An on-line Agilent 6890 series gas chromatograph with DB-1701 capillary column having dimensions 60 m0.32 mm1 m, both available from Agilent Technologies of Santa Clara, Calif., and an FID detector were utilized to analyze the conversion of the feed. The heated lines to the gas chromatograph were maintained at a temperature in the range from about 130 C. to about 150 C. The conversion, reaction rate and yield results of the feed using Example 1 and Comparative Example 2 are provided in Table 4.

(44) TABLE-US-00004 TABLE 4 Reaction rate and yield results at constant conversion after 50 hours reaction time on a feed stream at 220 C., 10 bars absolute, 1 liquid hourly space-velocity. Reaction rate, % Ethanol mols ethanol Ethyl acetate yield, conversion reacted/kg catalyst/h g/kg catalyst/h Example 1 25.7 23.1 957 Comparative 25.5 12.6 529 Example 2

(45) Reference throughout this specification to one embodiment, certain embodiments, one or more embodiments or an embodiment means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as in one or more embodiments, in certain embodiments, in one embodiment or in an embodiment in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

(46) Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made to the method and apparatus of the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention include modifications and variations that are within the scope of the appended claims and their equivalents.