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

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 μm and 0.1 μm 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 μm, and

wherein the catalyst has a pore volume of 0.31 to 0.44 cm 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 + /mol Al 2 O 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 μm.

6. The process according to claim 1 , wherein the hydrous aluminum oxide particles have a particle-size spectrum of

91 vol.-%≤90 μm

51 vol.-%≤45 μm, and

91 vol.-%≤90 μm,

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 μm to less than 0.1 μm 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 + /mol Al 2 O 3 results.

13. The catalyst of claim 1 , the pore volume of which, determined using mercury porisometry, is 0.41 to 0.44 cm 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 + /mol Al 2 O 3 results.