Catalyst composite comprising an alkaline earth metal containing CHA zeolite and use thereof in a process for the conversion of oxygenates to olefins

Abstract

The present invention relates to catalyst comprising one or more metal oxides and/or metalloid oxides and a zeolitic material having the CHA framework structure comprising YO.sub.2 and X.sub.2O.sub.3, wherein Y is a tetravalent element and X is a trivalent element, wherein the zeolitic material comprises one or more alkaline earth metals selected from the group consisting of Mg, Ca, Sr, Ba, and combinations of two or more thereof, and wherein the framework of the zeolitic material comprised in the catalyst contains substantially no phosphorous, as well as to a process for the preparation of a catalyst comprising one or more alkaline earth metals selected from the group consisting of Mg, Ca, Sr, Ba, and combinations of two or more thereof and to a catalyst obtainable therefrom. Furthermore, the present invention relates to a method for the conversion of oxygenates to olefins employing the inventive catalyst, as well as to the use of the inventive catalyst in specific applications.

Claims

1. A catalyst comprising one or more metal oxides and/or metalloid oxides and a zeolitic material having the CHA framework structure comprising YO.sub.2 and X.sub.2O.sub.3, wherein Y is Si and X is Al, wherein the zeolitic material comprises Mg and wherein the framework of the zeolitic material comprised in the catalyst contains substantially no phosphorous; wherein the one or more metal oxides and/or metalloid oxides comprises, Al.sub.2O.sub.3 and/or SiO.sub.2 and wherein the zeolitic material comprised in the catalyst contains Mg in an amount in the range of from 2 to 7 wt. % calculated as the element and based on 100 wt. % of the YO.sub.2 in the zeolitic material and wherein the zeolitic material contains substantially no phosphorous and wherein the catalyst is in the form of a shaped body in the form of granulates and/or extrudates.

2. The catalyst of claim 1, wherein the zeolite material and the metal oxide and/or metalloid oxide is calcined and the catalyst displays a MO:zeolite weight ratio of the one or more metal oxides and/or metalloid oxides (MO) to the zeolitic material in the range of from 0.05 to 3 as calculated based on the weight of the calcined metal oxides and/or metalloid oxides and of the calcinated zeolitic material.

3. A process for the preparation of the catalyst as claimed in claim 1, comprising YO.sub.2 and X.sub.2O.sub.3, wherein Y is Si and X is Al, (B) mixing the zeolitic material provided in claim 1 with one or more metal oxides and/or metalloid oxides and with a solvent system; (C) optionally homogenizing the mixture obtained in (B); (D) molding of the mixture obtained in (B) or (C); (E) optional drying of the molding obtained in (D); (F) optional calcining of the molding obtained in (D) or (E); (G) impregnation of the molding obtained in (D), (E), or (F) with a solution containing one or more salts of Mg; (H) optional drying of the molding obtained in (G); and (I) optional calcining of the molding obtained in (G) or (H).

4. A catalyst comprising Mg obtained according to the process of claim 3.

5. A method for the conversion of oxygenates to olefins comprising (i) providing the catalyst according to claim 1; (ii) providing a gas stream comprising one or more oxygenates; (iii) contacting the catalyst provided in (i) with the gas stream provided in (ii) and converting one or more oxygenates to one or more olefins.

6. The method of claim 5, wherein the gas stream provided in (ii) comprises one or more oxygenates selected from the group consisting of aliphatic alcohols, ethers, carbonyl compounds and mixtures of two or more thereof.

7. The method of claim 5, wherein the water content in the gas stream provided in (ii) is in the range from 5 to 60% by volume.

8. The method of claim 5, wherein the contacting according to (iii) is effected at a temperature in the range from 200 to 700° C.

9. A process comprising: (i) preparing the catalyst according to claim 1, (ii) providing the catalyst of step (i) to a process selected from the group consisting of conversion of oxygenates to olefins, a methanol-to-olefin process (MTO process), a dimethylether to olefin process (DTO process), methanol-to-gasoline process (MTG process), a methanol-to-hydrocarbon process, a biomass to olefins and/or biomass to aromatics process, a methane to benzene process, and for alkylation of aromatics.

10. The catalyst of claim 1, wherein the catalyst comprises a composite of the zeolitic material and the one or more metalloid oxides.

11. The catalyst of claim 1, wherein the one or more metal oxides and/or metalloid oxides comprises Al.sub.2O.sub.3.

12. The catalyst of claim 1, wherein the one or more metal oxides and/or metalloid oxides comprises SiO.sub.2.

13. The catalyst of claim 1, wherein the one or more metal oxides and/or metalloid oxides comprises Al.sub.2O.sub.3 and SiO.sub.2.

14. The catalyst of claim 1, wherein the catalyst contains Mg in an amount in the range of from 3.5 to 5.5 wt. % calculated as the element and based on 100 wt. % of the YO.sub.2.

15. The catalyst of claim 1, wherein the catalyst contains Mg in an amount in the range of from 4.3 to 4.9 wt. % calculated as the element and based on 100 wt. % of the YO.sub.2.

16. The catalyst of claim 1, wherein the Mg is present in the catalyst as extra-framework ions.

17. The catalyst of claim 1, wherein the specific surface area of the catalyst is in the range of from 250 to 500 m.sup.2/g.

18. The catalyst of claim 1, wherein the specific pore volume of the catalyst is in the range of from 0.2 to 0.5 ml/g.

19. The catalyst of claim 1, wherein the specific surface area of the catalyst is in the range of from 350 to 375 m.sup.2/g, the specific pore volume of the catalyst is in the range of from 0.36 to 0.37 ml/g and the catalyst is in the form of a shaped body in the form of extrudates.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the isobutene isotherms as obtained for the extrudates from Reference Example 2, Example 1, and Comparative Examples 1 and 2, respectively. In the figure, the pressure in mbar is shown along the abscissa and the absorption in mg/g are plotted along the ordinate.

(2) FIG. 2 shows the yields of methanol, dimethylether and C2-C4 olefins as obtained from the conversion of dimethylether to olefins using the extrudates from Example 1. In the figure, the time on stream in hours is shown along the abscissa and the yield of methanol “.box-tangle-solidup.” and dimethylether “.diamond-solid.” in grey lines and the yield of C.sub.2H.sub.4 “.square-solid.”, C.sub.3H.sub.6 “.box-tangle-solidup.” and C.sub.4H.sub.8 “.circle-solid.” in black lines are respectively plotted along the ordinate in %.

(3) FIG. 3 shows the yields of methanol, dimethylether and C.sub.2-C.sub.4 olefins as obtained from the conversion of dimethylether to olefins using the extrudates from Reference Example 1. In the figure, the time on stream in hours is shown along the abscissa and the yield of methanol “.box-tangle-solidup.” and dimethylether “.diamond-solid.” in grey lines and the yield of C.sub.2H.sub.4 “.square-solid.”, C.sub.3H.sub.6 “.box-tangle-solidup.”, and C.sub.4H.sub.8 “.circle-solid.” in black lines are respectively plotted along the ordinate in %.

(4) FIG. 4 shows the yields of methanol, dimethylether and C.sub.2-C.sub.4 olefins as obtained from the conversion of dimethylether to olefins using the extrudates from Comparative Example 1. In the figure, the time on stream in hours is shown along the abscissa and the yield of methanol “.box-tangle-solidup.” and dimethylether “.diamond-solid.” in grey lines and the yield of C.sub.2H.sub.4 “.square-solid.”, C.sub.3H.sub.6 “.box-tangle-solidup.”, and C.sub.4H.sub.8 “.circle-solid.” in black lines are respectively plotted along the ordinate in %.

(5) FIG. 5 shows the yields of methanol, dimethylether and C.sub.2-C.sub.4 olefins as obtained from the conversion of dimethylether to olefins using the extrudates from Comparative Example 2. In the figure, the time on stream in hours is shown along the abscissa and the yield of methanol “.box-tangle-solidup.” and dimethylether “.diamond-solid.” in grey lines and the yield of C.sub.2H.sub.4 “.square-solid.”, C.sub.3H.sub.6 “.box-tangle-solidup.”, and C.sub.4H.sub.8 “.circle-solid.” in black lines are respectively plotted along the ordinate in %.

EXAMPLES

Reference Example 1: Synthesis of Chabazite

(6) 2,040 kg of water were placed in a stirring vessel and 3,924 kg of a solution of 1-adamantyltrimethylammoniumhydroxide (20% aqueous solution) are added thereto under stirring. 415.6 kg of a solution of sodium hydroxide (20% aqueous solution) were then added, followed by 679 kg of aluminum triisopropylate (Dorox D 10, Ineos), after which the resulting mixture was stirred for 5 min. 7800.5 kg of a solution of colloidal silica (40% aqueous solution; Ludox AS 40, Sigma Aldrich) were then added and the resulting mixture stirred for 15 min before being transferred to an autoclave. 1,000 kg of distilled water used for washing out the stirring vessel were added to the mixture in the autoclave, and the final mixture was then heated under stirring for 19 h at 170° C. The solid product was then filtered off and the filter cake washed with distilled water. The resulting filter cake was then dispersed in distilled water in a spray dryer mix tank to obtain a slurry with a solids concentration of approximately 24% and the spray dried, wherein the inlet temperature was set to 477-482° C. and the outlet temperature was measured to be 127-129° C., thus affording a spray dried powder of SSZ-13 zeolite having the CHA framework structure.

(7) The resulting material displayed a particle size distribution affording a D10 value of 1.4 μm, a D50 value of 5.0 μm, and a D90 value of 16.2 μm. The material displayed a surface area of 558 m.sup.2/g, a silica to alumina ratio of 34, a crystallinity of 105% as determined by powder X-ray diffraction. The sodium content of the product was determined to be 0.75 wt.-% calculated as Na.sub.2O.

Reference Example 2: Molding of Chabazite from Reference Example 1

(8) 100 g of chabazite from reference example 1 was placed in a kneader, together with 5 g of hydroxyethyl methyl cellulose (Walocel), after which the components were kneaded for 5 min. 107.1 g of an aqueous solution of colloidal silica (40 wt.-%; Ludox AS 40) were then added and the mixture kneaded for 5 min. 45 g of distilled water were then continually added over a period of 40 min while kneading. The kneaded mass was then extruded to extrudates with a diameter of 2.5 mm. The extrudates thus obtained were dried for 4 h at 120° C. and subsequently heated under air at a rate of 2° C./min to 500° C. and calcined at that temperature for 5 h for obtaining 139.5 g of extrudates.

(9) The extrudates displayed a BET surface area of 404 m.sup.2/g and a pore volume of 0.436 ml/g as obtained from mercury porosimetry. Elemental analysis of the extrudates afforded 1.8 wt.-% Al and 42 wt.-% Si.

Example 1: Impregnation of Molding of Reference Example 2 with Mg

(10) 65 g of extrudate from reference example 2 were placed in a 500 ml round bottom flask in a rotary evaporator. 20.5 g of Mg(NO.sub.3).sub.2×6H.sub.2O were dissolved in 12.4 g of water and the resulting solution sprayed via a glass injector directly onto the extrudate in the rotary evaporator within 10 min employing 100 norm liters of air during operation thereof. The impregnated extrudates were then subject to rotary evaporation a further 15 min and the extrudates subsequently removed from the rotary evaporator for drying in a convention drying cabinet at 80° C. for 4 h and subsequently at 120° C. for 4 h. The dried extrudates were then heated at 2° C./min to 500° C. under air and calcined at that temperature for 5 h for obtaining 68.2 g of the impregnated extrudates.

(11) The extrudates displayed a BET surface area of 361 m.sup.2/g and a pore volume of 0.365 ml/g as obtained from mercury porosimetry. Elemental analysis of the extrudates afforded 1.6 wt.-% Al, 2.7 wt.-% Mg, and 38 wt.-% Si.

Comparative Example 1: Molding of Commercial SPAO-34

(12) 124 g of SAPO-34 (Zeolyst, Lot.-Nr. 2548-109) were placed in a kneader, together with 6.2 g of hydroxyethyl methyl cellulose (Walocel), after which the components were kneaded for 5 min. 133 g of an aqueous solution of colloidal silica (40 wt.-%; Ludox AS 40) were then added and the mixture kneaded for 5 min. 40 g of distilled water were then continually added over a period of 40 min while kneading. The kneaded mass was then extruded to extrudates with a diameter of 2.5 mm. The extrudates thus obtained were dried for 4 h at 120° C. and subsequently heated under air at a rate of 2° C./min to 500° C. and calcined at that temperature for 5 h for obtaining 186.14 g of extrudates.

(13) The extrudates displayed a BET surface area of 389 m.sup.2/g and a pore volume of 0.3078 ml/g. Elemental analysis of the extrudates afforded 11.8 wt.-% Al and 16.2 wt.-% Si.

Comparative Example 2: Impregnation of Molding of Comparative Example 1 with Mg

(14) 60 g of extrudate from comparative example 1 were placed in a 500 ml round bottom flask in a rotary evaporator. 18.69 g of Mg(NO.sub.3).sub.2×6H.sub.2O were dissolved in 9.6 g of water and the resulting solution sprayed via a glass injector directly onto the extrudate in the rotary evaporator within 10 min employing 100 norm liters of air during operation thereof. The impregnated extrudates were then subject to rotary evaporation a further 15 min and the extrudates subsequently removed from the rotary evaporator for drying in a convention drying cabinet at 80° C. for 4 h and subsequently at 120° C. for 4 h. The dried extrudates were then heated at 2° C./min to 500° C. under air and calcined at that temperature for 5 h for obtaining 55.8 g of the impregnated extrudates.

(15) The extrudates displayed a BET surface area of 282 m.sup.2/g and a pore volume of 0.331 ml/g. Elemental analysis of the extrudates afforded 12.9 wt.-% Al, 3.2 wt.-% Mg, and 17.4 wt.-% Si.

Example 2: Measurement of Isobutene Isotherms

(16) The isobutene absorption isotherms of the extrudates obtained from Reference Example 2, Example 1, and Comparative Examples 1 and 2 were respectively measured. The results are displayed in FIG. 1. The adsorption isotherms were measured with isobutene, using a magnetic suspension balance from Rubotherm. The samples were filled in a sample container and activated for 4 h at 0.01 bar at 150° C., then the temperature was cooled to 80° C. The test gas was introduced step-by-step from 0.1 bar to 2.5 bar at 80° C. After the adsorption, the pressure was reduced in equivalent steps to desorb the sample. The software used to investigate the results was MessPro.

Example 3: Catalytic Testing for the Conversion of Dimethylether to Olefins (DTO)

(17) 2.35 g of the extrudate from Example 1 (chabazite-containing extrudates impregnated with Mg) were loaded into a fixed bed reactor with an inner diameter of 15 mm. The fresh catalyst was exposed to multiple reaction/regeneration cycles. In the second reaction cycle the reaction temperature was set to 450° C. and the reactor pressure at the outlet to 2.5 bar. The gaseous hourly space velocity GHSV was 2500 1/h. The concentrations of the gases at the reactor inlet were DME/H.sub.2O/N.sub.2=10/35/55 Vol %. The catalyst was two hours on reaction stream. The yields of methanol, dimethylether and C2-C4 olefins are shown in FIG. 2 as a function of reaction time.

(18) The testing was repeated using 2.25 g of extrudate from Reference Example 1 (chabazite-containing extrudates). The yields of methanol, dimethylether and C2-C4 olefins are shown in FIG. 3 as a function of the reaction time.

(19) The testing was repeated using 2.72 g of extrudate from Comparative Example 1 (SAPO-34-containing extrudates). The yields of methanol, dimethylether and C2-C4 olefins are shown in FIG. 4 as a function of the reaction time.

(20) The testing was finally repeated using 2.57 g of extrudate from Comparative Example 2 (chabazite-containing extrudates impregnated with Mg). The yields of methanol, dimethylether and C2-C4 olefins are shown in FIG. 5 as a function of the reaction time.

(21) As may be taken from the results displayed in FIGS. 2-5 it has surprisingly been found that the impregnation of extrudates respectively containing chabazite and SAPO-34 with Mg leads to completely different results. Thus, as may be taken from FIGS. 3 and 4 displaying the nonimpregnated extrudates, SAPO-34 (see FIG. 4) displays a relatively high yield in ethylene and propylene and a lower yield in butylene, wherein the yield in ethylene increases and the yield in butylene gradually decreases during the time on stream. Chabazite (see FIG. 3), on the other hand, displays high yields in ethylene and propylene and a lower yield in butylene as well, wherein the extrudates however display high variations in yield and only poor catalyst lifetime compared to the SAPO-34 extrudates. Impregnation of the SAPO-34 extrudates with Mg (see FIG. 5) leads to a rapid deactivation of the catalyst, such that it may find no application among the known SAPO-34 catalysts. Quite unexpectedly, however, the impregnation of chabazite containing extrudates with Mg (see FIG. 2) leads to a considerable improvement of both the catalyst lifetime, as well as with respect to the constance of the product distribution pattern. In particular, impregnation of the chabazite extrudates with Mg not only leads to a high and constant level of the yields in ethylene and propylene comparable to those obtained with the SAPO-34 extrudates, but further leads to a yield in butylene which exceeds those obtained with the latter in function of the time on stream of the respective catalyst.

(22) Thus, it has quite surprisingly been found that chabazite loaded with Mg affords a highly efficient and durable catalyst for the conversion of dimethylether to C2-C4 olefins, wherein the inventive catalyst even outperforms the SAPO-34 catalysts known in the art, in particular with respect to the yield in butylene. Said results are highly unexpected, in particular considering the poor performance of the chabazite extrudates and furthermore considering the highly detrimental effect of Mg-impregnation on SAPO-34 extrudates. Consequently, the skilled person would by no means have expected that results achieved by the present invention.

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