BI-FUNCTIONAL CATALYST FOR THE PRODUCTION OF OLEFINS FROM SYNTHESIS GAS

Abstract

The present invention relates to a composition comprising a) a molding comprising a zeolitic material having an AEI-type framework structure, wherein the zeolitic material has a framework structure comprising Si, a trivalent element X, and oxygen, wherein the zeolitic material further comprises one or more alkali metals AM and/or one or more alkaline earth metals AEM; and b) a mixed metal oxide comprising chromium, zinc, and aluminum; and to a process for its production, as well as to the molding and the mixed metal oxide as such, respectively, as obtainable or obtained according to the inventive production process, as well as to the composition as obtainable or obtained according to the inventive production process. In addition to these, the present invention further relates to the use of the inventive composition as a catalyst or as a catalyst component, as well as to a process for preparing C2 to C4 olefins from a synthesis gas comprising hydrogen and carbon monoxide.

Claims

1.-15. (canceled)

16. A composition comprising a) a molding comprising a zeolitic material having an AEI-type framework structure, wherein the zeolitic material has a framework structure comprising Si, a trivalent element X, and oxygen, wherein the zeolitic material further comprises one or more alkali metals AM and/or one or more alkaline earth metals AEM; and b) a mixed metal oxide comprising chromium, zinc, and aluminum.

17. The composition of claim 16, wherein X is selected from the group consisting of Al, B, In, Ga, and mixtures of two or more thereof.

18. The composition of claim 16, wherein the one or more alkali metals AM is one or more of Li, Na, K, Rb, and Cs.

19. The composition of claim 16, wherein the one or more alkaline earth metals AEM is one or more of Be, Mg, Ca, Sr and Ba.

20. The composition of claim 16, wherein the one or more alkaline earth metals AEM is present in the zeolitic material at least partly in an oxidic form.

21. The composition of claim 16, wherein the molding according to (a) is obtainable or obtained by a process comprising (i.1) providing a zeolitic material having an AEI-type framework structure, wherein the zeolitic material has a framework structure comprising Si, a trivalent element X, and oxygen; (i.2) optionally impregnating the zeolitic material obtained from (i.1) with a source of the one or more alkaline earth metals AEM; (i.3) preparing a molding comprising the impregnated zeolitic material obtained from (i.2) and optionally a binder material.

22. A process for preparing the composition according to claim 16, the process comprising (i) providing a molding comprising a zeolitic material having an AEI-type framework structure, wherein the zeolitic material has a framework structure comprising Si, a trivalent element X, and oxygen, wherein the zeolitic material further comprises one or more alkali metals AM and/or one or more alkaline earth metals AEM; (ii) providing a mixed metal oxide comprising chromium, zinc, and aluminum; (iii) mixing the molding provided according to (i) with the mixed metal oxide provided according to (ii), obtaining the composition.

23. The process of claim 22, wherein providing a molding according to (i) comprises (i.1) providing a zeolitic material having an AEI-type framework structure, wherein the zeolitic material has a framework structure comprising Si, a trivalent element X, and oxygen; (i.2) optionally impregnating the zeolitic material obtained from (i.1) with a source of the one or more alkaline earth metals AEM; (i.3) preparing a molding comprising the impregnated zeolitic material obtained from (i.2) or the zeolitic material from (i.1) and optionally a binder material.

24. The process of claim 23, wherein preparing a molding according to (i.3) comprises (i.3.1) preparing a mixture of the impregnated zeolitic material obtained from (i.2) and a source of a binder material; (i.3.2) subjecting the mixture prepared according to (i.3.1) to shaping.

25. The process of claim 22, wherein providing the mixed metal oxide according to (ii) comprises (ii.1) co-precipitating a precursor of the mixed metal oxide from sources of the chromium, the zinc, and the aluminum; (ii.2) washing the precursor obtained from (ii.1); (ii.3) drying the washed precursor obtained from (ii.2); (ii.4) calcining the washed precursor obtained from (ii.3).

26. A molding, obtainable or obtained by a process according to claim 23.

27. A mixed metal oxide, obtainable or obtained by a process according to claim 25.

28. A composition, obtainable or obtained by a process according to claim 22.

29. A catalyst or as a catalyst component which comprises the composition according to claim 16.

30. A process for preparing C2 to C4 olefins from a synthesis gas comprising hydrogen and carbon monoxide, the process comprising (1) providing a gas stream which comprises a synthesis gas stream comprising hydrogen and carbon monoxide; (2) providing a catalyst comprising a composition according to claim 16; (3) bringing the gas stream provided in (1) in contact with the catalyst provided in (2), obtaining a reaction mixture stream comprising C2 to C4 olefins.

Description

DESCRIPTION OF THE FIGURES

[0243] FIG. 1 displays the results from catalytic testing of the mixed metal oxide catalysts from Reference Example 1 “CrZn” and Comparative Example 1 “ZrZn” in the conversion of synthesis gas to methanol and dimethylether.

[0244] FIG. 2 displays the results from extended catalytic testing of the mixed metal oxide catalyst from Reference Example 1 in the conversion of synthesis gas to methanol and dimethylether.

[0245] FIG. 3 displays the results from catalytic testing of the zeolite catalysts from Reference Example 2 and Comparative Example 2 in the conversion of synthesis gas and methanol to C2 to C4 olefins.

[0246] FIG. 4 displays the results from extended catalytic testing of the zeolite catalyst from Reference Example 2 in the conversion of synthesis gas and methanol to olefins.

EXAMPLES

Determination of the BET Specific Surface Area

[0247] The BET specific surface area was determined via nitrogen physisorption at 77 K according to the method disclosed in DIN 66131.

Determination of Selectivities and Yields

[0248] The selectivity of a given product compound, in %, referred to in the following as “S.sub.N_SubstanceA”, is a normalized selectivity S.sub.N and is calculated as follows:

S.sub.N_SubstanceA/%=S_SubstanceA/%*Fact_normS

wherein [0249] S_SubstanceA/%=selectivity of substance A [0250] Fact_normS=normalization factor, used to achieve a sum of the selectivities of 100%

a) S_SubstanceA

[0251] The selectivity of substance A, S_SubstanceA, is defined as

S_SubstanceA/%=(Y_SubstanceA/X_CO(IntStd))*100

wherein [0252] Y_SubstanceA=yield of substance A [0253] X_CO(IntStd)=conversion of CO calculated based on an internal standard, in the present case an inert liner (Argon)

a.1) Y_SubstanceA

[0254] The yield of substance A, Y_SubstanceA, is defined

Y_SubstanceA/%=(R(C)_SubstanceA/R(C)_CO_in)*100

wherein [0255] R(C)_SubstanceA=the rate of carbon of substance A, determined in g/h via gas chromatography [0256] R(C)_CO_in =the rate of carbon monoxide CO which is fed to the reactor, determined in (g carbon)/h

a.2) X_CO(IntStd)

[0257] The conversion of CO, X_CO(IntStd), is defined as

X_CO(IntStd)=(1−(RA_CO/Arout)/(RA_CO/AroutRef))*100

wherein [0258] RA_CO/Arout=rate of CO determined via gas chromatography, divided by the rate of the inert liner Ar determined via GC [0259] RA_CO/AroutRef=rate of CO/reference determined via gas chromatography, divided by the rate of inert liner Ar/reference determined via gas chromatography (i.e. rate of CO at the inlet divided by rate of Ar at the inlet

b) Fact_normS

[0260] The normalization factor, Fact_normS, is defined as

Fact_normS=100/((Sum of all S)−(S_starting material))

wherein [0261] Sum of all S=sum of all selectivities measured at the outlet of the reactor (which would include the selectivites of starting material at the out let of the conversion is not 100%) [0262] S_starting material=selectivites of the starting materials (if conversion is 100%, the value would be 0%)

Temperature Programmed Desorption of Ammonia (NH.SUB.3.-TPD)

[0263] The temperature-programmed desorption of ammonia (NH.sub.3-TPD) was conducted in an automated chemisorption analysis unit (Micromeritics AutoChem II 2920) having a thermal conductivity detector. Continuous analysis of the desorbed species was accomplished using an online mass spectrometer (OmniStar QMG200 from Pfeiffer Vacuum). The sample (0.1 g) was introduced into a quartz tube and analysed using the program described below. The temperature was measured by means of a Ni/Cr/Ni thermocouple immediately above the sample in the quartz tube. For the analyses, He of purity 5.0 was used. Before any measurement, a blank sample was analysed for calibration. [0264] 1. Preparation: Commencement of recording; one measurement per second. Wait for 10 minutes at 25° C. and a He flow rate of 30 cm.sup.3/min (room temperature (about 25° C.) and 1 atm); heat up to 600° C. at a heating rate of 20 K/min; hold for 10 minutes. Cool down under a He flow (30 cm.sup.3/min) to 100° C. at a cooling rate of 20 K/min (furnace ramp temperature); Cool down under a He flow (30 cm.sup.3/min) to 100° C. at a cooling rate of 3 K/min (sample ramp temperature). [0265] 2. Saturation with NH.sub.3: Commencement of recording; one measurement per second. Change the gas flow to a mixture of 10% NH.sub.3 in He (75 cm.sup.3/min; 100° C. and 1 atm) at 100° C.; hold for 30 minutes. [0266] 3. Removal of the excess: Commencement of recording; one measurement per second.

[0267] Change the gas flow to a He flow of 75 cm.sup.3/min (100° C. and 1 atm) at 100° C.; hold for 60 min. [0268] 4. NH.sub.3-TPD: Commencement of recording; one measurement per second. Heat up under a He flow (flow rate: 30 cm.sup.3/min) to 600° C. at a heating rate of 10 K/min; hold for 30 minutes. [0269] 5. End of measurement.

[0270] Desorbed ammonia was measured by means of the online mass spectrometer, which demonstrates that the signal from the thermal conductivity detector was caused by desorbed ammonia. This involved utilizing the m/z=16 signal from ammonia in order to monitor the desorption of the ammonia. The amount of ammonia adsorbed (mmol/g of sample) was ascertained by means of the Micromeritics software through integration of the TPD signal with a horizontal baseline.

Catalyst Testing Setup

[0271] The catalytic conversions in the examples were investigated in a fixed catalyst bed consisting of catalyst split fraction (oxide or zeolite). The reactions were performed in the gas phase using a 16-fold unit with stainless steel reactors. Catalysts were tested with a particle size fraction of 250-315 μm and catalyst volumes of 1 mL, 0.9 mL, 0.6 mL, and 0.4 mL.

[0272] The reactions temperatures were varied from 350-425° C., the pressure varied between 25, 30, and 35 bar. Composition of feedstock included a mixtures of H.sub.2/CO/MeOH/DME for zeolites, and H.sub.2/CO for oxide catalysts.

Reference Example 1: Preparation of a Mixed Metal Oxide of Cr, Zn, and Al

[0273] 108 g of Al(NO.sub.3).sub.3*9 H.sub.2O (Honeywell, 98%) and 40 g Zn(NO.sub.3).sub.2*6 H.sub.2O (Honeywell, 98%) were dissolved in 1 L of distilled water under stirring. The solution displaying a pH of 1.68 was then placed in a vessel and heated under stirring to 70° C. 388 g of a 20 wt % aqueous solution of (NH.sub.4).sub.2CO.sub.3 (Aldrich) were then added dropwise to the mixture over 1 h until a pH of 7 was reached. The mixture was then further stirred at 70° C. for 2.5 h, during which a white solid precipitated from the solution. The solid was then filtered off and washed with 9 liters of distilled water until the washwater displayed a conductivity of <10 pS. The filter cake was then dried over night at 110° C., and then heated in a muffle oven in 4 h to 500° C. and calcined at that temperature for 1 h for obtaining a Zn/AI mixed metal oxide.

[0274] 21.76 g of Cr(NO.sub.3).sub.3*9 H.sub.2O [[2.83 g Cr]] (Sigma Aldrich, 99%) were dissolved in 30.6 ml of distilled water. 26.5 g of the calcined Zn/AI mixed metal oxide were then mixed with the aqueous chrome nitrate solution for impregnation thereof, and the resulting slurry was then dried over night at 110° C., wherein the slurry was repeatedly mixed during the drying step for ensuring the impregnation of the mixed metal oxide with the chrome nitrate solution. The impregnated mixed metal oxide was then heated in a muffle oven in 4 h to 500° C. and calcined at that temperature for 1 h. The calcined powder was then sieved through a 1 mm sieve and the powder then pressed with 35 bar pressure in a Shell-Test press to platelets with a diameter of 2 cm. The platelets were then processed to a fraction of 315-500 μm.

[0275] Elemental analysis of the resulting Zn/Al/Cr mixed metal oxide afforded values of 24.7 wt.-% of Zn, 24.0 wt.-% of Al, and 11.3 wt.-% of Cr.

[0276] The BET surface area of the resulting Zn/Al/Cr mixed metal oxide was 113.45 m.sup.2/g.

Comparative Example 1: Preparation of a Mixed Metal Oxide of Zr and Zn

[0277] 130 g of zirconium(IV)oxynitrate hydrate (Sigma Aldrich 99%) and 48.5 g Zn(NO.sub.3).sub.2*6 H.sub.2O (Honeywell, 98%) were dissolved in 0.8 L of distilled water under stirring. The solution displaying a pH of 0.03 was then placed in a vessel and heated under stirring to 70° C. 422 g of a 20 wt % aqueous solution of Na.sub.2CO.sub.3 (Bernd Kraft) were then added dropwise to the mixture, wherein after 80 min of precipitation (pH=1.6) to solution turned into a gel, after which the precipitation was interrupted and the gel was further mixed with the aid of a spatula, and 100 ml of distilled water were stirred in, followed by further precipitating while stirring the mixture at a high stirring rate (450 rm) until a pH of 7 was eventually reached after 2.5 h of precipitation. The mixture was then further stirred at 100 rpm over night at room temperature. The solid was then filtered off and washed with 52 liters of distilled water until the washwater displayed a conductivity of <10 μS. The filter cake was then dried for 12 h at 110° C., and then heated in a muffle oven in 4 h to 500° C. and calcined at that temperature for 5 h for obtaining a Zr/Zn mixed metal oxide.

[0278] The Zr/Zn mixed metal oxide powder was then sieved through a 1 mm sieve and the powder then pressed with 35 bar pressure in a Shell-Test press to platelets with a diameter of 2 cm. The platelets were then processed to a fraction of 315-500 μm.

[0279] Elemental analysis of the resulting Zr/Zn mixed metal oxide afforded values of 53 wt.-% of Zr and 16.4 wt.-% of Zn.

[0280] The BET surface area of the resulting Zr/Zn mixed metal oxide was 29.97 m.sup.2/g.

Reference Example 2: Preparation of Extrudate of an AEI Zeolitic Material Calcined at 800° C.

[0281] a) Providing an AEI zeolitic material. [0282] 20.194 kg of distilled water were placed in a 60 L autoclave reactor and stirred at 200 rpm. 2.405 kg of a solution of 50 wt.-% NaOH in distilled water were then added followed by the addition of 6.670 kg of 1,1,3,5-tetramethylpiperidinium hydroxide. 560 g of zeolite Y seeds (NH.sub.4-zeolite Y; CBV-500 from Zeolyst) were then suspended in 3 L of distilled water and the suspension was the added to the reactor while stirring, after which 7.473 kg of Ludox® AS40 (Grace; colloidal silica; aqueous solution, 40 weight-%) were added. The resulting mixture displaying molar ratios of 1.00 SiO.sub.2: 0.30 Na.sub.2O: 0.17 template: 0.19 zeolite Y: 41.5H.sub.2O was further stirred for 30 min at room temperature, after which the reactor was closed and the reaction mixture was heated under autogenous pressure in 1.5 h to 160° C. and subsequently maintained at that temperature for 48 h while further stirring. [0283] The resulting suspension was filled into five 10 L canisters and the suspension allowed to settle, after which the clear supernatant was decanted off. The solid residue was placed in a filter and washed with distilled water to <200 μS. The filter cake was then dried at 120° C. over night to afford 1.1848 kg of a crystalline solid, which was subsequently heated at 2° C./min to 500° C. and calcined at that temperature for 5 hours under air. After said calcination, the calcined zeolitic material was subject to a further calcination step, wherein it was heated at 2° C./min to 550° C. and calcined at that temperature for 5 h to afford 1.0810 kg of the sodium form of a zeolitic material. X-ray diffraction analysis of the zeolitic material revealed an AEI type framework structure. The Na-AEI zeolite displayed a BET surface area as obtained from the nitrogen isotherms of 506 m.sup.2/g and a Langmuir surface area of 685 m.sup.2/g. [0284] Elemental analysis of the resulting Na-AEI zeolite afforded values of 34 wt.-% of Si, 5.1 wt.-% of Al, and 2 wt.-% of Na. Accordingly the zeolite displayed an SiO.sub.2: Al.sub.2O.sub.3 molar ratio of 12.9. [0285] NH.sub.3-TPD analysis of the Na-AEI zeolite afforded a total amount of acid sites of 1.4 mmol/g, wherein the deconvoluted desorption spectrum included a peak at 515° C. having an amount of acid sites of 0.6 mmol/g.

b) Preparing an Extrudate Comprising the AEI Zeolitic Material

[0286] Materials Used:

TABLE-US-00001 Na-AEI zeolitic material, according to a) above: 80.0 g Ludox ® AS40 (Grace; colloidal silica; aqueous 50.0 g solution, 40 weight-%): Walocel 5.0 g Deionized water 92.0 g [0287] The zeolitic material, the Ludox®, and the Walocel were kneaded for 1 h, wherein the distilled water was added to the mixture in portions during kneading. The material obtained was extruded and strands of 1 mm diameter were formed. The strands obtained were dried over night at 120° C. and then calcined for 5 hours in air at 800° C. 92 g of product were obtained. [0288] NH.sub.3-TPD analysis of the extrudate afforded a total amount of acid sites of 0.871 mmol/g, wherein the deconvoluted desorption spectrum included a peak at 418° C. having an amount of acid sites of 0.07 mmol/g.

Comparative Example 2: Preparation of Extrudate of a CHA Zeolitic Material Containing 1% Mg

a) Providing an Na-CHA Zeolitic Material.

[0289] A zeolitic material having framework type CHA was prepared as follows: [0290] 2,040 kg of water were placed in a stirring vessel and 3,924 kg of a solution of 1-adamantyltrimethyl ammoniumhydroxide (20 weight-% aqueous solution) were added thereto under stirring. 415.6 kg of a solution of sodium hydroxide (20 weight-% 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 weight-% 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 weight-% and then 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 a zeolite having the CHA framework structure. The resulting material had a particle size distribution affording a Dv10 value of 1.4 micrometer, a Dv50 value of 5.0 micrometer, and a Dv90 value of 16.2 micrometer. The material displayed a BET specific 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 weight-% calculated as Na.sub.2O.

b) Providing a Mg-CHA Zeolitic Material

[0291]

TABLE-US-00002 Na-CHA 80 g Mg(NO.sub.3).sub.2 × H.sub.2O 8.8 g Deionized water 120 g [0292] Mg(NO.sub.3).sub.2×H.sub.2O was dissolved in water and homogenized. The solution was added dropwise to the zeolitic material contained in a beaker, and the solution homogeneously distributed with the aid of a spatula. The impregnated zeolite was transferred in a porcelain bowl. The material was dried over night at 120° C. and then calcined for 5 hours at 500° C. 82 g of product were obtained. Elemental analysis of the zeolitic material showed an Mg content of 0.96 weight-%.

c) Preparing an Extrudate Comprising the 1 Weight-% Mg-CHA Zeolitic Material

[0293] Materials Used:

TABLE-US-00003 1% Mg-CHA zeolitic material, according to b) above: 80.0 g Ludox ® AS40 (Grace; colloidal silica; aqueous 50.0 g solution, 40 weight-%): Walocel 5.0 g Deionized water 50 g [0294] The zeolitic material, the Ludox®, the Walocel, and the water were kneaded for 1 h. The material obtained was extruded and strands of 1 mm diameter were formed. The strands obtained were dried over night at 120° C. and then calcined for 5 hours at 500° C. 94 g of product were obtained.

Example 1: Catalytic Process for Preparing Methanol and Dimethylether from a Gas Stream Comprising Synthesis Gas

[0295] The conversion of synthesis gas over the mixed metal oxides of Reference Example 1 and Comparative Example 1 was tested in the catalyst testing setup described above. To this effect, an inlet gas stream containing 50 vol.-% of CO, 25 vol.-% of H.sub.2, 9 vol.-% Ar, and N.sub.2 gas make up was employed, wherein the reaction over the mixed metal oxide was conducted at a temperature of 350° C. and a pressure of 30 bara.

[0296] As may be taken from the results displayed in FIG. 1, the Zn/Al/Cr mixed metal oxide from Reference Example 1 provides a high conversion efficiency and a high selectivity towards dimethylether and methanol compared to the Zr/Zn mixed metal oxide from Comparative Example 1, which affords only a fraction of the yield of dimethylehter and methanol.

[0297] An extended test was performed with the Zn/Al/Cr mixed metal oxide from Reference Example 1, wherein the inlet gas stream contained 50 vol.-% of CO, 15 vol.-% of H.sub.2, 9 vol.-% Ar, and N.sub.2 gas make up, and the reaction was conducted at a temperature of 375° C. and at a pressure of 30 bara.

[0298] As may be taken from FIG. 2 displaying extended testing performed using the Zn/Al/Cr mixed metal oxide from Reference Example 1, the high selectivity towards methanol and dimethylether remains constant and even increases to a certain extent after long times on stream.

Example 2: Process for Preparing C2 to C4 Olefins from a Gas Stream Comprising Synthesis Gas and Methanol

[0299] The conversion of synthesis gas and methanol over the zeolitic materials of Reference Example 2 and Comparative Example 2 was tested in the catalyst testing setup described above. To this effect, an inlet gas stream containing 44.95 vol.-% of CO, 44.95 vol.-% of H.sub.2, 1 vol.-% of methanol, 9 vol.-% Ar, and N.sub.2 gas make up was employed, wherein the reaction over the zeolitic material was conducted at a temperature of 400° C. and a pressure of 30 bara. The testing was performed at gas hourly space velocities of 1,500 and 2,500 h.sup.−1.

[0300] As may be taken from the results displayed in FIG. 3, although the zeolitic materials from Reference Example 2 and Comparative Example 2 both afforded high yields in ethylene, propene, and butene, the AEI zeolitic material from Reference Example 2 surprisingly showed higher yields than the Mg-CHA zeolitic material, in particular at the lower gas hourly space velocity of 1,500 h.sup.−1. Said results are particularly unexpected given the fact that the AEI zeolitic material of Reference Example 2 does not contain any magnesium, which is known to improve the selectivity in C2 to C4 olefins.

[0301] An extended test was performed with the AEI zeolitic material from Reference Example 2 under the same conditions as above. As may be taken from the results displayed in FIG. 4, the high yields in olefins are first achieved after a start up phase in which the reaction initially affords mainly alkanes. After said start up phase, the conversion rate of practically 100% and the high selectivity towards olefins remains constant for an extended period of time.

CITED PRIOR ART

[0302] U.S. Pat. No. 4,049,573 [0303] Goryainova et al., in: Petroleum Chemistry, vol. 51, no. 3 (2011) pp. 169-173 [0304] Wan, V. Y., Methanol to Olefins/Propylene Technologies in China, Process Economics Programm, 261A (2013) [0305] Li, J., X. Pan and X. Bao, Direct conversion of syngas into hydrocarbons over a core-shell Cr—Zn@SiO2@SAPO-34 catalyst, Chinese Journal of Catalysis vol. 36 no. 7 (2015), pp. 1131-1135 [0306] Unpublished patent application EP 17185280.9