Catalyst molded body containing graphite

Abstract

The invention relates to a catalyst molded body, which is produced by deforming a mixture of a metal oxide and a special graphite. The invention further relates to a method for producing the corresponding catalyst molded bodies and to the use of the catalyst molded bodies for catalytic reactions in which hydrogen acts as a reaction reactant or reaction product, in particular hydrogenation, hydrogenolysis, and dehydrogenation reactions. The catalysts are characterized by an improvement in the activity and selectivity in particular in hydrogenation, hydrogenolysis, and dehydrogenation reactions, said improvement being achieved by adding special graphites.

Claims

1. A shaped catalyst body obtained by a process comprising the steps of: (a) Mixing of a metal oxide with graphite, and (b) Shaping the mixture to give a shaped body, where the particle diameter D.sub.90 of the graphite is: 5.0 mD.sub.9017.5 m wherein the shaped catalyst body comprises a metal and/or a metal oxide, where the metal is selected from the group consisting of Cu, Zn, Al, Mn, Cr, Ni and mixtures thereof, the metal oxide is selected from the group consisting of copper oxide, zinc oxide, aluminum oxide, manganese oxide, chromium oxide, nickel oxide and mixtures thereof and the particle diameter D.sub.90 of the graphite in the shaped catalyst body is 5.0 mD.sub.9017.5 m.

2. A shaped catalyst body as claimed in claim 1, wherein the metal is selected from the group consisting of Cu, Zn, Al, Mn and mixtures thereof and the metal oxide is selected from the group consisting of copper oxide, zinc oxide, aluminum oxide, manganese oxide and mixtures thereof.

3. A shaped catalyst body as claimed in claim 1, wherein the amount of graphite in the shaped catalyst body is of from 0.1 to 20% by weight, preferably from 1 to 14% by weight, in particular from 2.0 to 12.0% by weight, particularly preferably from 4.0 to 10.0% by weight, calculated as amount of pure carbon and based on the total weight of the shaped catalyst body.

4. A shaped catalyst obtained by a process, comprising the steps of: (a) Mixing of a metal oxide with graphite, and (b) Shaping the mixture to give a shaped body, wherein the particle diameter D.sub.90 of the graphite is: 5.0 mD.sub.9017.5 m, wherein 95% by weight or more of the weight of graphite remains in the shaped catalyst body obtained after step (b) and wherein the shaped catalyst body comprises a metal and/or a metal oxide, where the metal is selected from the group consisting of Cu, Zn, Al, Mn, Cr, Ni and mixtures thereof, the metal oxide is selected from the group consisting of copper oxide, zinc oxide, aluminum oxide, manganese oxide, chromium oxide, nickel oxide and mixtures thereof and the particle diameter D.sub.90 of the graphite in the shaped catalyst body is 5.0 mD.sub.9017.5 m.

5. A shaped catalyst body as claimed in claim 4, wherein the metal is selected from the group consisting of Cu, Zn, Al, Mn and mixtures thereof and the metal oxide is selected from the group consisting of copper oxide, zinc oxide, aluminum oxide, manganese oxide and mixtures thereof.

6. A shaped catalyst body as claimed in claim 4, wherein the amount of graphite in the shaped catalyst body is of from 0.1 to 20% by weight, preferably from 1 to 14% by weight, in particular from 2.0 to 12.0% by weight, particularly preferably from 4.0 to 10.0% by weight, calculated as amount of pure carbon and based on the total weight of the shaped catalyst body.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the catalytic properties of various shaped catalyst bodies according to the invention as a function of the specific surface area O.sub.G of the graphite used. The conversion of fatty acid methyl ester in percent by weight under the following conditions: temperature: 180 C., pressure: 280 bar, GHSV (H.sub.2): 20000 h.sup.1, LHSV (ester): 1.4 h.sup.1 is shown.

(2) FIG. 2 shows the catalytic properties of various shaped catalyst bodies according to the invention as a function of the specific surface area O.sub.G of the graphite used. The formation of the by-product paraffin in percent by weight under the following conditions: temperature: 180 C., pressure: 280 bar, GHSV (H.sub.2): 20000 h.sup.1, LHSV (ester): 1.4 h.sup.1, is shown.

(3) FIG. 3 shows the catalytic properties of various shaped catalyst bodies according to the invention as a function of the particle size D.sub.90 of the graphite used. The conversion of fatty acid methyl ester in percent by weight under the following conditions: temperature: 180 C., pressure: 280 bar, GHSV (H.sub.2): 20000 h.sup.1, LHSV (ester): 1.4 h.sup.1, is shown.

(4) FIG. 4 shows the catalytic properties of various shaped catalyst bodies according to the invention as a function of the particle size D.sub.90 of the graphite used. The formation of the by-product paraffin in percent by weight under the following conditions: temperature: 180 C., pressure: 280 bar, GHSV (H.sub.2): 20000 h.sup.1, LHSV (ester): 1.4 h.sup.1, is shown.

(5) FIG. 5 shows the catalytic properties of various shaped catalyst bodies according to the invention as a function of the amount of graphite for the example of graphite #7. The conversion of fatty acid methyl ester in percent by weight under the following conditions: temperature: 180 C., pressure: 280 bar, GHSV (H.sub.2): 20000 h.sup.1, LHSV (ester): 1.4 h.sup.1, is shown.

(6) FIG. 6 shows the catalytic properties of various shaped catalyst bodies according to the invention as a function of the amount of graphite for the example of graphite #7. The formation of the by-product paraffin in percent by weight under the following conditions: temperature: 180 C., pressure: 280 bar, GHSV (H.sub.2): 20000 h.sup.1, LHSV (ester): 1.4 h.sup.1, is shown.

(7) The invention is illustrated in further detail by the following, nonlimiting examples. Even though these examples describe specific embodiments of the invention, they serve merely to illustrate the invention and should not be interpreted as restricting the invention in any way. As a person skilled in the art will know, numerous modifications can be made thereto without deviating from the scope of protection of the invention, as is defined by the attached claims.

EXAMPLES

Reference Example 1

Preparation of a Metal Oxide

(8) The preparation of the metal oxide is carried out by the process described in EP 0 552 463. The metal oxide is prepared by means of precipitation from the corresponding metal salt solutions and subsequent calcination.

(9) Solution 1 is produced from 1234 g of Cu(NO.sub.3).sub.23 H.sub.2O, 212 g of Mn(NO.sub.3).sub.24 H.sub.2O, 1750 g of Al(NO.sub.3).sub.39 H.sub.2O and 10 l of deionized H.sub.2O. Solution 2 is produced from 1700 g of Na.sub.2CO.sub.3 and 7.6 l of deionized H.sub.2O. The two solutions are heated to 80 C. while stirring. They are subsequently metered into a precipitation vessel. The volume flows of solutions 1 and 2 are set so that the pH in the precipitation vessel is 6.8. As soon as the two solutions have been consumed, the precipitate formed is filtered off and washed with deionized water. The filter cake is then resuspended in about 1 l of water and spray dried. The resulting dried powder is calcined at 750 C. for 2 hours in a convection furnace.

Example 1

Production of the Shaped Catalyst Bodies

(10) To produce the catalysts, the metal oxide obtained in reference example 1 was used in each case and mixed with the amounts indicated in table 1 of the respective graphite and tabletted to give shaped bodies having a diameter of about 3 mm and a height of about 3 mm. Activation is carried out by reduction by means of hydrogen at 230 C. for 2 hours. Since the reduction was carried out directly in the test reactor for the activity test, stabilization of the catalyst was not necessary.

(11) 900 g of the catalyst powder and 18.4 g of the appropriate graphite were in each case introduced into an Eirich mixer and homogenized dry for 15 minutes. The powder was subsequently tabletted on a Korsch tabletting press to give tablets having a diameter of about 3 mm and a height of about 3 mm and a target lateral compressive strength of 85 N. The lateral compressive strength was determined in accordance with DIN EN 1094-5. The lateral compressive strength indicated is the arithmetic mean of 100 measurements.

(12) TABLE-US-00001 TABLE 1 Particle sizes D.sub.90, D.sub.50, D.sub.10 and the specific surface area O.sub.G of the graphites used Graphite D.sub.90 in m D.sub.50 in m D.sub.10 in m O.sub.G in m.sup.2/g #1 43.0 13.2 2.8 115 #2 32.1 6.0 1.2 301 #3 39.6 5.5 0.2 405 #4 27.8 1.9 0.1 470 #5 110.1 36.4 7.3 4 #6 55.8 23.1 5.3 6.5 #7 17.2 8.0 3.1 12 #8 6.5 3.4 1.6 20 #9 4.7 2.4 1.2 26

(13) TABLE-US-00002 TABLE 2 Amount of graphite used in the production of the catalysts Amount in % Catalyst Graphite by weight Catalyst 1 #1 2 Catalyst 2 #2 2 Catalyst 3 #3 2 Catalyst 4 #4 2 Catalyst 5 #5 2 Catalyst 6 #6 2 Catalyst 7 #7 2 Catalyst 8 #8 2 Catalyst 9 #9 2 Catalyst 10 #7 1 Catalyst 11 #7 4 Catalyst 12 #7 8 Catalyst 13 #7 12 Catalyst 14 #7 16

Example 2

Hydrogenation of Fatty Acid Methyl Ester (FAME)

(14) The activity of the catalysts is examined in respect of the hydrogenation of fatty acid methyl ester (FAME).

(15) For this purpose, an electrically heated fixed-bed reactor having a reactor volume of 25 ml is used. Methyl laurate (C12-methyl ester) is used for the test.

(16) To evaluate the ester conversion and the selectivity to the fatty alcohol and/or the formation of by-products, the reaction product formed is analyzed by gas chromatography. The conversion is calculated from the molar amount of ester used and the remaining molar amount of ester in the product. The selectivity to the by-product paraffin is calculated from the molar amount of ester which has been converted into paraffin.

(17) For the analysis by means of gas chromatography, 6.0000 g of the product formed are mixed with 0.2000 g of 5-nonanol (internal standard). The sample is subsequently analyzed twice by means of a gas chromatograph.

(18) Equipment used: GC: Agilent 7890A with FID Column: ZB-1, 60 m0.25 mm from Phenomenex Software: EZ Chrom Elite Version 3.3.2 SP1

(19) Test conditions in the hydrogenation of methyl laurate: Temperature: 180 C. Pressure: 280 bar GHSV (H.sub.2): 20000 h.sup.1 LHSV (ester): 1.4 h.sup.1

(20) Values for the activity and the selectivity obtained by the above-described method are shown in table 3 for the catalysts 1 to 4. The activity is reported as percentage conversion of the ester. The selectivity is reported as percentage value in respect of the formation of paraffins as undesirable by-product.

(21) TABLE-US-00003 TABLE 3 FAME conversion and formation of the by-product paraffin at 180 C. specific Formation of surface area the by- O.sub.G of the FAME product graphite conversion paraffin at used [m.sup.2/g] at 180 C. [%] 180 C. [%] Catalyst 1 115 55.1 0.091 Catalyst 2 301 73.2 0.048 Catalyst 3 405 80.5 0.028 Catalyst 4 470 90.9 0.019

(22) The results as a function of the specific surface area O.sub.G of the graphites are shown in graph form in FIGS. 1 and 2. It can be seen that the activity (ester conversion) increases and the selectivity (formation of the undesirable by-product of the paraffins) decreases with increasing surface area.

(23) The values for the activity and the selectivity obtained by the above-described method are shown in table 4 for the catalysts 5 to 9. The activity is reported as percentage conversion of the ester. The selectivity is reported as percentage value in respect of the formation of paraffins as undesirable by-product.

(24) TABLE-US-00004 TABLE 4 FAME conversion and formation of the by-product paraffin at 180 C. FAME Formation of conversion the by-product at 180 C. paraffin at D.sub.90 [m] D.sub.50 [m] D.sub.10 [m] [%] 180 C. [%] Catalyst 5 121.6 31.6 4.8 70.6 0.05 Catalyst 6 71.6 24.5 6.4 79.9 0.03 Catalyst 7 17.2 8 3.1 82.3 0.026 Catalyst 8 6.5 3.5 1.6 83.8 0.022 Catalyst 9 4.7 2.4 1.2 76.9 0.029

(25) The results in respect of the particle size D.sub.90 are shown in graph form in FIGS. 3 and 4. It can be seen that the activity (ester conversion) increases with decreasing D.sub.90 values. A similar behavior can be observed in respect of the D.sub.50 and D.sub.10 values. A particularly high activity can be observed for the catalysts 7 and 8. The activity goes through a maximum in this range of the catalyst compositions and the graphites used.

(26) The values for the activity and the selectivity obtained by the above-described method are shown in table 5 for the catalysts 7 and 10 to 14. These catalysts differ only in the amounts of graphite which are mixed in. The activity is once again reported as percentage conversion of the ester and the selectivity is reported as percentage value in respect of the formation of paraffins as undesirable by-product.

(27) TABLE-US-00005 TABLE 5 FAME conversion and formation of the by-product paraffin at 180 C. Selectivity to FAME paraffin at Proportion conversion at 180 C. Graphite [% by weight] 180 C. [%] [%] Catalyst 10 #7 1 77.1 0.039 Catalyst 7 #7 2 82.3 0.026 Catalyst 11 #7 4 85.2 0.022 Catalyst 12 #7 8 88.1 0.02 Catalyst 13 #7 12 85.9 0.019 Catalyst 14 #7 16 84 0.023

(28) The results as a function of the amount of graphite used are shown in graph form in FIGS. 5 and 6. It can be seen that the activity and selectivity can be increased by increasing the amount of graphite. The activity of the catalysts is greatest at a proportion of about 8% by weight of graphite. The selectivity behaves analogously. The least by-product (paraffins) is formed in a range from 8 to 12% by weight of graphite.