Process of producing zeolite-based catalysts for converting oxygenates to lower olefins

Abstract

A process of producing a catalyst based on pentasil-type crystalline aluminosilicate is described, including the steps of (a) treating hydrous aluminum oxide with an aqueous, acid-containing medium, (b) mixing the hydrous aluminum oxide treated with aqueous, acid-containing medium from step (a) with an H-zeolite and (c) calcining the mixture obtained in step (b). In addition, a catalyst is disclosed which is obtained by such a process, as well as its use in CMO and OTO processes.

Claims

1. A process for producing a catalyst comprising a pentasil-type crystalline aluminosilicate, comprising the steps of: (a) treating hydrous aluminium oxide with an aqueous, acid-containing medium to provide a plasticized and homogenous mixture, (b) mixing the plasticized and homogenous mixture hydrous aluminium oxide treated with the aqueous, acid-containing medium from step (a) with a pentasil-type H-zeolite with an average diameter of its primary crystallites being 0.01 m and 0.1 m to form a mixture, and (c) calcining the mixture obtained in step (b), wherein at least 95 vol.-% of the particles of hydrous aluminium oxide, relative to an average diameter, are smaller than or equal to 100 m, and wherein the catalyst has a pore volume of 0.31 to 0.44 cm.sup.3/g and an average lateral compressive strength of 0.8 to 1.5 kp/mm (7.8 to 14.7 N/mm).

2. The process according to claim 1, wherein the aqueous, acid-containing medium comprises an aqueous inorganic acid.

3. The process according to claim 1, wherein the acid-containing medium comprises an aqueous organic acid.

4. The process according to claim 1, wherein in step (a) the aqueous, acid-containing medium is added to the hydrous aluminium oxide in a quantity such that an acid concentration of from 0.005 to 2.5 mol H.sup.+/mol Al.sub.2O.sub.3 results.

5. The process according to claim 1, where at least 97 vol.-% of the particles of the hydrous aluminium oxide (relative to the average diameter) are smaller than or equal to 100 m.

6. The process according to claim 1, wherein the hydrous aluminum oxide particles have a particle-size spectrum of 91 vol.-%90 m 51 vol.-%45 m, and 91 vol.-%90 m, in each case relative to the average particle diameter.

7. The process according to claim 1, wherein the hydrous aluminium oxide is present in a quantity of from 10 wt.-% to 40 wt.-% aluminium oxide, relative to the total weight of the product.

8. The process according to claim 1, wherein the calcining takes place at a temperature in the range of from 500 to 700 C. for 6 hours or less.

9. The process according to claim 1, wherein the pentasil-type H-zeolite is obtained by a process comprising the following steps: (i) producing aluminosilicate crystallites with an average diameter of from more than or equal to 0.01 m to less than 0.1 m by reacting a silicon source, an aluminium source, an alkali source and a template at a reaction temperature of more than or equal to 90 C., (ii) separating the crystallites from step (i), (iii) reacting the aluminosilicate crystallites from step (ii) with an ion-exchange compound, (iv) separating and calcining the product obtained from step (iii).

10. The process of claim 1 wherein the acid-containing medium is selected from the group consisting of sulfuric acid and nitric acid.

11. The process of claim 1, wherein the acid-containing medium is selected from the group consisting of acetic acid, citric acid, formic acid and oxalic acid.

12. The process of claim 1 wherein in step (a) the aqueous, acid-containing medium is added to the hydrous aluminium oxide in a quantity such that an acid concentration of from 0.01 to 1.5 mol H.sup.+/mol Al.sub.2O.sub.3 results.

13. The catalyst of claim 1, the pore volume of which, determined using mercury porisometry, is 0.41 to 0.44 cm.sup.3/g.

14. The process of claim 1 wherein in step (a) the aqueous, acid-containing medium is added to the hydrous aluminium oxide in a quantity such that an acid concentration of from 0.05 to 1.0 mol H.sup.+/mol Al.sub.2O.sub.3 results.

Description

EXAMPLES

(1) The average primary crystallite size was ascertained as described above with the help of scanning electron examinations.

(2) The average lateral compressive strength was determined from the force that acts on the lateral face (longest side) of the shaped bodies until they crack. For this, 50 shaped bodies with a length in the range of from 5.5 to 6.5 mm were selected from a representative sample of shaped bodies and measured individually. The shaped bodies were free of cracks and shaped straight. A shaped body was placed between two measuring jaws (one movable and one fixed). The movable measuring jaw was then moved evenly against the shaped body until the shaped body cracked. The crack value in kiloponds (kp), measured with a measuring apparatus from Schleuniger, was divided by the length of the shaped body in order to obtain the lateral compressive strength of the shaped body. The average lateral compressive strength was then determined from 50 individual measurements.

(3) The pore volume was measured using the mercury porosimetry method and the pore diameter calculated according to DIN 66133.

(4) The average methanol conversion rate was measured as described in application example 1 below.

Reference Example 1: Production of an H-zeolite with an Average Primary Crystallite Size of 0.03 m

(5) A reaction mixture was produced by intimate mixing of two solutions at room temperature in a 40-liter autoclave. The two solutions were called solution A and solution B. Solution A was produced by dissolving 2218 g tetrapropylammonium bromide in 11 kg deionized water. 5000 g of a silicic acid customary in the trade was added to this solution. Solution B was produced by dissolving 766 g NaOH and then 45.6 g NaAlO.sub.2 in 5.5 liters of deionized water. The still warm solution B was added to solution A. The autoclave was then closed and taken to the reaction temperature accompanied by stirring at approximately 60 rpm. The reaction was ended once the average particle diameter of the primary crystallites was 0.03 m. After cooling, the autoclave was opened, the product removed from the reaction vessel and filtered. The filter cake was suspended in approximately 40 liters of deionized water, mixed with approximately 5 liters of a 0.4 wt.-% aqueous suspension of a flocculant customary in the trade, followed by decanting after stirring and settling of the pre-agglomerates of the solid. The described wash process was repeated until the wash water had a pH of from 7 to 8 and a Br concentration of less than 1 ppm. The suspension in which pre-agglomerates of primary crystallites were to be seen, which were clearly held together by the flocculant, was filtered. The filter cake was then dried at 120 C. for 12 hours.

(6) The dried filter cake was reduced to a particle size of 2 mm with a granulator customary in the trade.

(7) The granules were taken to 350 C. at a heating rate of 1 C./minute under nitrogen (1000 Nl/h) and calcined at 350 C. for 15 hours under nitrogen (1000 Nl/h). The temperature was then increased to 540 C. at a heating rate of 1 C./minute and the granules were calcined in air for 24 hours at this temperature in order to burn off the remaining tetrapropylammonium bromide.

(8) The calcined Na zeolite was suspended in 5 times the quantity of a 1-molar aqueous HCl solution and taken to 80 C. Stirring was carried out at this temperature for an hour. Then approximately 1 liter of a 0.4 wt.-% suspension of the flocculant was added, and the supernatant acid was decanted after the solid had settled. The thus-described procedure was repeated once more. In approximately 10 wash procedures the solid was suspended each time in 60 liters of deionized water accompanied by stirring and mixed with an average of 100 ml of a 0.4 wt.-% suspension of the flocculant. After the zeolite had settled, the remaining solution was decanted. When the level of Cl.sup. in the wash water was <5 ppm, the suspension was filtered off and dried for 15 hours at 120 C.

(9) The dried H-zeolite was reduced to 2 mm with a granulator customary in the trade and taken to 540 C. in air at a heating rate of 1 C./minute and calcined in air for 10 hours at this temperature.

Example 1: Catalyst 1

(10) In a kneader-mixer customary in the trade, 61 kg demineralized water and 57 kg of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 69 kg of a solution consisting of 39 kg 57.2% nitric acid and 30 kg demineralized water were added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 235 kg of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, was then added. Mixing was carried out for a further 30 minutes and another approximately 25 kg water was added to improve the consistency of the material. After mixing in 20 kg steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(11) Average lateral compressive strength: 1.5 kp/mm (14.7 N/mm)

(12) Mercury pore volume: 0.31 cm.sup.3/g

(13) Average methanol conversion rate a): 95.2%

(14) a) averaged over 200-400 hours-on-stream (HOS)

Example 2: Catalyst 2

(15) In a kneader-mixer customary in the trade, 54 kg demineralized water and 50 kg of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 60 kg of a solution consisting of 33 kg 58.2% nitric acid and 27 kg demineralized water were added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 200 kg of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, was then added. Mixing was carried out for a further 30 minutes and another approximately 18 kg water was added to improve the consistency of the material. After mixing in 17 kg steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(16) Average lateral compressive strength: 1.5 kp/mm (14.7 N/mm)

(17) Mercury pore volume: 0.33 cm.sup.3/g

(18) Average methanol conversion rate a): 95.1%

(19) a) averaged over 200-400 hours-on-stream (HOS)

Example 3: Catalyst 3

(20) In a double-Z-kneader customary in the trade, 198 g demineralized water and 145 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 130 g of a solution consisting of 31 g 52.2% nitric acid and 99 g demineralized water were added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 600 g of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, was then added. Mixing was carried out for a further 30 minutes and another approximately 11 g water was added to improve the consistency of the material. After mixing in 50 g steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(21) Average lateral compressive strength: 0.8 kp/mm (7.8 N/mm)

(22) Mercury pore volume: 0.38 cm.sup.3/g

(23) Average methanol conversion rate a): 97.6%

(24) a) averaged over 200-400 hours-on-stream (HOS)

Example 4: Catalyst 4

(25) In a double-Z-kneader customary in the trade, 104 g demineralized water and 102 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 127 g of a solution consisting of 75 g 52.5% nitric acid and 52 g demineralized water were added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 400 g of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, was then added. Mixing was carried out for a further 30 minutes and another approximately 150 g water was added to improve the consistency of the material. After mixing in 34 g steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(26) Average lateral compressive strength: 0.8 kp/mm (7.8 N/mm)

(27) Mercury pore volume: 0.41 cm.sup.3/g

(28) Average methanol conversion rate a): 99.1% Average olefin selectivity a): Propylene: 43.7% Butenes: 21.6%

(29) C.sub.2-4 olefins: 72.0%

(30) a) averaged over 200-400 hours-on-stream (HOS)

Example 5: Catalyst 5

(31) In a double-Z-kneader customary in the trade, 25 kg demineralized water and 23 kg of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 28 kg of a solution consisting of 16 kg 57.2% nitric acid and 12 kg demineralized water was added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 94 kg of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, and 2 kg hollow microspheres as burnout substance were then added. Mixing was carried out for a further 30 minutes and another approximately 10 kg water was added to improve the consistency of the material. After mixing in 8 kg steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(32) Average lateral compressive strength: 0.9 kp/mm (8.8 N/mm)

(33) Mercury pore volume: 0.44 cm.sup.3/g

(34) Average methanol conversion rate a): 99.0%

(35) a) averaged over 200-400 hours-on-stream (HOS)

Example 6: (Comparison Example): Catalyst 6

(36) 750 g of the calcined H-zeolite from reference example 1 was ground to a particle size of less than approximately 500 m with the help of a laboratory mill and dry mixed in a double-Z-kneader customary in the trade with 220 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 98 vol.-%90 m; 95 vol.-%45 m and 55 vol.-%25 m for 15 minutes. 487.5 g of a 1.5 wt.-% aqueous acetic acid solution and 50 g steatite oil were added slowly to this mixture. After adding 55 g of a 1.5 wt.-% aqueous acetic acid solution, subsequent kneading was carried out for 30 minutes and the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(37) Average lateral compressive strength: 0.6 kp/mm (5.9 N/mm)

(38) Mercury pore volume: 0.46 cm.sup.3/g

(39) Because of the low lateral compressive strength, the average methanol conversion rate could not be measured; but it can be estimated at over 99%.

Example 7: (Comparison Example): Catalyst 7

(40) 700 g of the calcined H-zeolite from reference example 1 was ground to a particle size of less than approximately 500 m with the help of a laboratory mill and dry mixed in a double-Z-kneader customary in the trade with 303 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m and 105 g paraffin wax for 15 minutes. 245 g demineralized water and 127 g of a 25 wt.-% aqueous citric acid solution and a further 135 g demineralized water were added slowly to this mixture. After adding 56 g steatite oil, subsequent kneading was carried out for 5 minutes and the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(41) Average lateral compressive strength: 0.7 kp/mm (6.9 N/mm)

(42) Mercury pore volume: 0.47 cm.sup.3/g

(43) Because of the low lateral compressive strength, the average methanol conversion rate could not be measured; but it can be estimated at over 99%.

Example 8: (Comparison Example): Catalyst 8

(44) 700 g of the calcined H-zeolite from reference example 1 was ground to a particle size of less than approximately 500 m with the help of a laboratory mill and dry mixed in a double-Z-kneader customary in the trade with 302 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m and 136 g paraffin wax for 15 minutes. 245 g demineralized water and 127 g of a 25 wt.-% aqueous citric acid solution and a further 206 g demineralized water were added slowly to this mixture. After adding 56 g steatite oil, subsequent kneading was carried out for 5 minutes and the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(45) Average lateral compressive strength: 0.4 kp/mm (3.9 N/mm)

(46) Mercury pore volume: 0.51 cm.sup.3/g

(47) Because of the low lateral compressive strength, the average methanol conversion rate could not be measured; but it can be estimated at over 99%.

Example 9: (Comparison Example): Catalyst 9

(48) 750 g of the calcined H-zeolite from reference example 1 was ground to a particle size of less than approximately 500 m with the help of a laboratory mill and dry mixed in a double-Z-kneader customary in the trade with 225 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m for 15 minutes. 583 g of a 1.5 wt.-% aqueous nitric acid solution and 50 g steatite oil were added slowly to this mixture. Subsequent kneading was carried out for 30 minutes and the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 6 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(49) Average lateral compressive strength: 2.0 kp/mm (19.5 N/mm)

(50) Mercury pore volume: 0.32 cm.sup.3/g

Example 10: Catalyst 10

(51) In a double-Z-kneader customary in the trade, 175 g demineralized water and 170 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 199 g of a solution consisting of 64 g 99-100% acetic acid and 135 g demineralized water were added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 700 g of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, was then added. Mixing was carried out for a further 30 minutes and another approximately 80 g water was added to improve the consistency of the material. After mixing in 59 g steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 6 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(52) Average lateral compressive strength: 0.90 kp/mm (8.8 N/mm)

(53) Mercury pore volume: 0.36 cm.sup.3/g

Example 11: Catalyst 11

(54) In a kneader-mixer customary in the trade, 910 g demineralized water and 889 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 1108 g of a solution consisting of 653 g 52.5% nitric acid and 455 g demineralized water were added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 3000 g of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, was then added. Mixing was carried out for a further 30 minutes and another approximately 350 g water was added to improve the consistency of the material. After mixing in 252 g steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(55) Average lateral compressive strength: 1.3 kp/mm (12.7 N/mm)

(56) Mercury pore volume: 0.36 cm.sup.3/g

(57) Average methanol conversion rate a): 97.2%

(58) Average olefin selectivity a): Propylene: 43.2% Butenes: 20.3% C.sub.2-4 olefins: 70.0%

(59) a) averaged over 200-400 hours-on-stream (HOS)

Example 12: Catalyst 12

(60) In a kneader-mixer customary in the trade, 1869 g demineralized water and 1827 g of a hydrous aluminium oxide, customary in the trade and capable of being peptized, with a particle-size spectrum of 91 vol.-%90 m; 51 vol.-%45 m and 27 vol.-%25 m were mixed. 2276 g of a solution consisting of 1342 g 52.5% nitric acid and 934 g demineralized water were added slowly to this mixture. This mixture was kneaded for 60 minutes until plasticization and homogenization occurred. 3000 g of the calcined H-zeolite from reference example 1, which was ground to a particle size of less than approximately 500 m on a mill customary in the trade, was then added to 2986 g of the plasticized material obtained. Mixing was carried out for a further 30 minutes and another approximately 200 g water was added to improve the consistency of the material. After mixing in 252 g steatite oil and mixing for 10 minutes, the plasticized material was extruded in an extruder customary in the trade to form shaped bodies with a diameter of approximately 3 mm and a length of approximately 5 mm. The shaped bodies were then dried for 16 hours at 120 C. and calcined for 5 hours at 600 C.

(61) Average lateral compressive strength: 1.4 kp/mm (13.7 N/mm)

(62) Mercury pore volume: 0.31 cm.sup.3/g

(63) Average methanol conversion rate a): 96.1%

(64) Average olefin selectivity a): Propylene: 42.2% Butenes: 19.4% C.sub.2-4 olefins: 68.3%

(65) a) averaged over 200-400 hours-on-stream (HOS)

Application Example 1

(66) This application example shows the advantages of the catalyst according to the invention using catalytic data of the CMO process (conversion of methanol to olefins process) in an isothermal fixed-bed reactor.

(67) All catalysts tested were treated for 48 hours with steam before the methanol/water mixture was released. The methanol/water feed was then passed over the CMO catalyst in an isothermal fixed-bed reactor with a WHSV of 3 (kg/(kg.Math.h), i.e. three kilograms total feed per kilogram of catalyst and per hour at a pressure of 1 bar for the conversion of methanol. The methanol contents of the gas phase and of the liquid phase at the outlet of the CMO catalyst reactor were determined with gas-chromatography analysis processes. Table 1 shows the catalytic properties of the examined catalysts in the isothermal reactor under the following conditions: T.sup.R.sub.OUT (temperature of the reactor at the outlet)=450 C.; load: WHSV=1 h.sup.1 (kg methanol/kg catalyst and hour), weight ratio (MeOH:H.sub.2O)=1:2, for 200-400 HOS (hours-on-stream).

(68) When the catalytic properties are compared (Table 1), it becomes clear that the catalysts according to the invention have a high MeOH conversion rate with, at the same time, a high average lateral compressive strength. Although catalyst 6, which corresponds to the catalyst of Example 1 of EP 1 424 128, has a high MeOH conversion rate, it has a lateral compressive strength which, at 0.6 kp/mm, lies below the threshold of 0.8 kp/mm as the acceptable minimum lateral compressive strength. The catalysts 7 and 8 also have unacceptable lateral compressive strengths. The average methanol conversion rate was not determined here, in order to avoid a clogging of the reactor by a catalyst that is breaking up.

(69) TABLE-US-00001 TABLE 1 Average MeOH conversion rate Average lateral Pore volume (200-400 HOS) compressive Catalyst [cm.sup.3/g] [%] strength [kp/mm] 1 0.31 95.2 1.5 2 0.33 95.1 1.5 3 0.38 97.6 0.8 4 0.41 99.1 0.8 5 0.44 99.0 0.9 6 0.46 >99*.sup.1 0.6 (comparison) 7 0.47 >99*.sup.1 0.7 (comparison) 8 0.51 >99*.sup.1 0.4 (comparison) *.sup.1: estimated

(70) The catalysts can be regenerated after a first cycle ends by first stopping the MeOH stream. Nitrogen is then fed in to expel the remaining MeOH. Finally, oxygen is slowly added to the nitrogen in gradually increasing concentrations in order to burn off the hydrocarbon deposited on the catalysts. The temperature of the catalysts is usually kept below 480 C. The regeneration of the catalysts is ended when the oxygen content of the nitrogen stream is the same at the inlet and at the outlet of the catalyst bed.

Application Example 2

(71) This application example serves to determine the selectivity of the catalysts according to the invention in the CMO process.

(72) The catalysts were pre-treated and tested in the same way as described in application example 1. The compositions of the gas phase and of the liquid phase at the outlet of the CMO catalyst reactor were determined with gas-chromatography analysis processes.

(73) The selectivity S.sub.i results from the molar carbon content of component i relative to the converted carbon:

(74) $S_i=\frac{{\stackrel{.}{n}}_{i\mathrm{out}}.Math.{\mathrm{.Math.}}_i^C}{{\stackrel{.}{n}}_{\mathrm{MeOH}in}.Math.{\mathrm{.Math.}}_{\mathrm{MeOH}}^C-{\stackrel{.}{n}}_{\mathrm{MeOH}\mathrm{out}}.Math.{\mathrm{.Math.}}_{\mathrm{MeOH}}^C}$

(75) In order to rule out the influence of the carbon balance, the selectivity was normalized to 100% as follows:

(76) ${\stackrel{\_}{S}}_i=100\%*\frac{{\stackrel{.}{n}}_{i\mathrm{out}}.Math.{\mathrm{.Math.}}_i^C}{\underset{i}{\overset{i=N}{.Math.}}{\stackrel{.}{n}}_{i\mathrm{out}}.Math.{\mathrm{.Math.}}_i^C}$

(77) For this calculation, dimethyl ether was not taken into account as product.

(78) S.sub.i: selectivity of component i

(79) S.sub.i: normalized selectivity of component i

(80) .sub.i.sup.C: number of carbon atoms of component

(81) {dot over (n)}.sub.i: molar flux of component i

(82) Table 2 shows the methanol conversion rate and the olefin selectivity of the examined catalysts in the isothermal reactor under the same conditions as described in application example 1.

(83) TABLE-US-00002 TABLE 2 Average MeOH Average conversion lateral Average olefin selectivity Pore rate compressive Propylene Butylenes C.sub.2-4 olefins volume (200-400 HOS) strength (200-400 HOS) (200-400 HOS) (200-400 HOS) Catalyst [cm.sup.3/g] [%] [kp/mm] [%] [%] [%] 4 0.41 99.1 0.8 43.7 21.6 72.0 11 0.36 97.2 1.3 43.2 20.3 70.0 12 0.31 96.1 1.4 42.2 19.4 68.3

(84) When the catalytic properties of Table 2 are compared, it becomes clear that all catalysts 4, 11 and 12 according to the invention have high average olefin selectivities.

(85) Catalyst 4, which has the largest pore volume, displays the best catalytic performance.