Process for the preparation of an aromatic compound from biomass

Abstract

A process for the production of an aromatic compound which comprise reacting a mixture comprising ethylene and a furan compound over a zeolitic material having a BEA-type framework structure is described, wherein the zeolitic material having a BEA-type framework structure comprised in the catalyst is obtainable and/or obtained according to an organotemplate-free synthetic process.

Claims

1. A process for the production of an aromatic compound, comprising: feeding a mixture (M1) comprising ethylene and a compound of formula (I), ##STR00006## into a reactor comprising a catalyst, the catalyst comprising a zeolitic material having a BEA-type framework structure; contacting the mixture (M1) with the catalyst in the reactor for reacting at least a portion of the mixture (M1) to an aromatic compound of formula (II), ##STR00007## and collecting a reacted mixture (M2) comprising the aromatic compound of formula (II) from the reactor; wherein R.sup.1 and R.sup.2 are each independently selected from the group consisting of H, a substituted (C.sub.1-C.sub.3)alkyl, and an unsubstituted (C.sub.1-C.sub.3)alkyl, and wherein the zeolitic material having a BEA-type framework structure is obtained by an organotemplate-free synthetic process.

2. The process of claim 1, wherein the zeolitic material having a BEA-type framework structure displays an X-ray diffraction pattern comprising at least the following reflections: TABLE-US-00004 Intensity (%) Diffraction angle 2θ/° [Cu K(alpha 1)] [12-32]  [21.79-21.99] 100 [22.28-22.48] [8-28] [25.18-25.38] [19-39]  [25.71-25.91] [6-26] [26.96-27.16] [5-25] [28.62-28.82] [5-25] [29.43-29.63] [4-24] [30.23-30.43] [4-24] [33.06-33.47] [4-24] [43.21-43.61] wherein 100% relates to the intensity of the maximum peak in the 20-45° 20 range of the X-ray powder diffraction pattern, and wherein the BEA-type framework structure comprises SiO.sub.2 and X.sub.2O.sub.3, wherein X is a trivalent element.

3. The process of claim 1, wherein the compound of formula (I) is at least one selected from the group consisting of a substituted furan, an unsubstituted furan, a 2-methylfuran, a 2,5-dimethylfuran, and a mixture of two or more thereof.

4. The process of claim 1, wherein the mixture (M1) further comprises a solvent system.

5. The process of claim 1, wherein the compound of formula (I) and/or ethylene are derived from biomass.

6. The process of claim 1, wherein the zeolitic material having a BEA-type framework structure is in the H-form.

7. The process of claim 1, wherein the zeolitic material having a BEA-type framework structure comprises 5 wt.-% or less of Na calculated as the element and based on 100 wt.-% of SiO.sub.2 contained in the framework structure of the zeolitic material having a BEA-type framework structure.

8. The process of claim 1, wherein the zeolitic material having a BEA-type framework structure comprises 5 wt.-% or less of a metal TM calculated as the element and based on 100 wt.-% of SiO.sub.2 contained in the framework structure of the zeolitic material having a BEA-type framework structure, wherein the metal TM stands for at least one selected from the group consisting of Pt, Pd, Rh, and Ir.

9. The process of claim 1, wherein the zeolitic material having a BEA-type framework structure comprises 5 wt. % or less of phosphorous calculated as the element and based on 100 wt.-% of SiO.sub.2 contained in the framework structure of the zeolitic material having a BEA-type framework structure.

10. The process of claim 1, wherein the contacting of the mixture (M1) with the catalyst is conducted at a temperature in the range of from 150 to 350° C.

11. The process of claim 1, which is conducted in a continuous mode and/or in a batch mode.

12. The process of claim 1, wherein the trivalent element X of the zeolitic material having a BEA-type framework structure is at least one selected from the group consisting of Al, B, In, Ga, and a mixture of two or more thereof.

13. The process of claim 1, wherein the ratio BA:LA of the amount of Bronsted acid sites (BA) to the amount of Lewis acid sites (LA) displayed by the zeolitic material having a BEA-type framework structure is in the range of from 0.5 to 8, wherein the amount of Bronsted and Lewis acid sites is determined according to the temperature programmed desorption of ammonia (NH3-TPD) or according to .sup.31P MAS NMR using trimethylphosphine oxide.

14. The process of claim 1, wherein the zeolitic material having a BEA-type framework structure is obtained by an organotemplate-free synthetic process comprising: crystallizing a mixture comprising one or more sources for SiO.sub.2, one or more sources for X.sub.2O.sub.3, and seed crystals to obtain the zeolitic material having a BEA-type framework structure; wherein the seed crystals comprise one or more zeolitic materials having a BEA-type framework structure, wherein X is a trivalent element, and wherein the mixture does not contain an organotemplate as a structure-directing agent.

15. The process of claim 14, wherein the mixture comprises 5 wt.-% or less of carbon calculated as the element, based on 100 wt-% of SiO.sub.2 contained in the mixture.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 displays the reaction scheme of 2,5-dimethylfuran (2,5-DMF) via Diels-Alder cycloaddition of ethylene to a cycloadduct intermediate, which the converts to p-xylene by elimination of water. The main side reactions to 3-methylcyclopentanone as well as the further alkylation to 1-n-propyl-4-methylbenzene are also displayed.

(2) FIG. 2 displays the reaction scheme of 2-methylfuran via Diels-Alder cycloaddition of ethylene to a cycloadduct intermediate, which the converts to toluene by elimination of water. The main side reactions to the oligomer, to the epoxide via isomerization of the cycloadduct, to 1-ethyl-4-methylbenzene via further alkylation of the product as well as to the oligomer via dimerization are also displayed.

(3) FIG. 3 displays the reaction scheme of furan via Diels-Alder cycloaddition of ethylene to a cycloadduct intermediate, which the converts to benzene by elimination of water. The main side reactions to the oligomer via dimerization, to the ketone via isomerization of the cycloadduct as well as the further alkylation to ethylbenzene are also displayed.

(4) FIG. 4 displays the reaction products and selectivities in the conversion of 2,5-dimethylfuran and ethylene of zeolite beta catalysts according to Reference Example 1 (Si/Al=7), Reference Example 2 (Si/Al=22), Reference Example 3 (Si/Al=36), and a commercial zeolite beta (Si/Al=19). In the figure, the conversion, the selectivities towards p-xylene and the alkylated product 1-n-propyl-4-methylbenzene, and the yield in p-xylene (indicated by “.star-solid.”) are displayed in %.

(5) FIG. 5 displays the reaction products and selectivities in the conversion of ethylene and 2,5-dimethyl furan (2,5-DMF), 2-methylfuran (2-MF), and furan, respectively, over a zeolite beta catalyst according to Reference Example 2 (Si/Al=22). In the figure, the conversion, the selectivities towards p-xylene and the side products (alkylated and isomerized side products as well as oligomers), and the yield in p-xylene (indicated by “.star-solid.”) are displayed in %.

EXPERIMENTAL SECTION

(6) Determination of Porosity

(7) Surface areas, pore volumes and pore size distributions were determined by the N.sub.2 adsorption/desorption experiments at −196° C. on a Micromeritics ASAP-2020 analyzer. Before each measurement the samples were outgassed at 400° C. and below 10.sup.−3 Pa for 6 h.

(8) Temperature Programmed Desorption of Ammonia (NH.sub.3-TPD) and Determination of Acidity

(9) NH.sub.3 temperature-programmed desorption (NH.sub.3-TPD) was carried out using a chemisorption analyzer (FINETECH, Finesorb 3010C, China) to detect the effluent gases using TCD. Before the measurements, the samples were pretreated in He stream at 500° C. and cooled down to the desired temperature. 5000 ppm NH.sub.3 in He (100 ml/min) was introduced at 100° C. for 0.5 h, followed by He purging for 1.5 h, then the temperature was ramped from 100 to 700° C. at a rate of 10° C./min.

(10) After deconvoluting the NH.sub.3 temperature-programmed desorption (TPD) profiles, all samples showed three desorption peaks centered at ca. 200° C. (low temperature), 250° C. (middle temperature) and 340° C. (high temperature), respectively. The latter two peaks could be roughly attributed to NH.sub.3 desorption on strong and weak Bronsted acid sites (BA), while the low-temperature peak could be assigned to NH.sub.3 desorption on Lewis acid sites (LA). Based thereon, the respective amounts of Bronsted (BA) and Lewis (LA) acid sites as well as the B/L ratios were calculated through the integration of desorption signals.

(11) .sup.31P MAS NMR Measurements and Determination of Acidity Using TMPO

(12) All solid-state magic-angle-spinning (MAS) NMR experiments were carried out on an Agilent DD2-500 MHz spectrometer. .sup.31P MAS NMR single-pulse spectra were measured at 202.3 MHz with a speed of 14 kHz, π/4 excitation pulse of 1.2 μs and recycle delay of 10 s. The chemical shifts were referenced to 85% H.sub.3PO.sub.4.

(13) To get more insights into the acid amount and strength of H-Beta zeolites with different Si/Al ratios, .sup.31P MAS NMR experiments are conducted, which is an effective tool to investigate the acidic properties using trimethylphosphine oxide (TMPO) as a probe molecule. Not only the acid sites types (Bronsted acid or Lewis acid) can be distinguished, .sup.31P-TMPO MAS NMR approach is also more useful for discriminating the Bronsted acid strength of zeolite catalysts and capable of covering the whole range from weak, medium, strong to superacidity.

(14) For the quantitative measurement of acidity, all samples were weighed, and the spectra were calibrated by measuring a known amount of (NH.sub.4).sub.2HPO.sub.4 performed in the same conditions except for the longer pulse delay of 90 s. For the adsorption of trimethylphosphine oxide (TMPO, 99%, Alfa) during preparation of the samples for the measurement, the samples were firstly subjected to a full dehydration under vacuum for 20 h. Subsequently, a known amount of TMPO dissolved in anhydrous CH.sub.2Cl.sub.2 was introduced into a vessel containing the dehydrated solid samples in a N.sub.2 atmosphere, followed by removal of the CH.sub.2Cl.sub.2 solvent by evacuation at ca. 50° C. To ensure a uniform adsorption of probe molecules in the zeolites, they were further subjected to thermal treatment at 165° C. for 1 h. Finally, the samples were transferred into an NMR rotor and then sealed by a gas-tight endcap in the N.sub.2 glove box.

(15) After deconvolution of the .sup.31P MAS NMR, seven peaks appeared from the low to high field. Besides the physisorbed TMPO at around 43 ppm, the .sup.31P NMR chemical shifts from 50 to 84 ppm are ascribed to chemical adsorbed TMPO on Bronsted or Lewis acid sites. More specifically, the peaks at ca. 83, 69 and 55-62 ppm are assigned to TMPO adsorbed on the strongest, medium-strength and weakest Bronsted acid sites, respectively, while those at 65 and 50 ppm are ascribed to TMPO adsorbed on the Lewis acid sites. Based on said classification, the total amount of Bronsted (BA) and Lewis (LA) acid sites were quantified the B/L ratios were calculated based on the obtained values.

(16) .sup.29Si MAS NMR Measurements

(17) All solid-state magic-angle-spinning (MAS) NMR experiments were carried out on an Agilent DD2-500 MHz spectrometer. .sup.29Si MAS NMR spectra were collected at 99.3 MHz using a 6 mm MAS probe with a speed of 4 kHz, 400 scans and recycle delay of 4 s. Chemical shifts were referenced to 4,4-dimethyl-4-silapentane sulfonate sodium (DSS).

(18) The Si/Al molar ratios in the framework of the respective materials was determined by deconvolution of the corresponding .sup.29Si MAS NMR spectra.

Reference Example 1: Organotemplate-Free Synthesis of H-BEA

(19) 12.693 kg of distilled water were placed in a 60 L autoclave with stirring means. 0.955 kg of NaAlO.sub.2 were dissolved in 5 L of distilled water and added to the water in the autoclave while stirring. 21.447 kg of sodium waterglass (26 wt.-% SiO.sub.2, 8 wt.-% Na.sub.2O, and 66 wt.-% H.sub.2O) were then added under stirring, wherein the viscosity of the mixture sharply increased and then decreased again. 3.762 kg of Ludox® AS40 (40 wt.-% SiO.sub.2 and 60 wt.-% H.sub.2O) were then added and the resulting gel was stirred at 200 rpm for 3 h, followed by addition of a suspension of 0.717 kg of zeolite Beta seeds (commercially available from Zeolyst International, Valley Forge, Pa. 19482, USA, under the tradename CP814C, CAS Registry Number 1318-02-1, which was converted to the H-form by calcination at 550° C. for 5 h, wherein a heat ramp of 1° C./min was used for attaining the calcination temperature) in 1 L of distilled water under stirring at 100 rpm. The resulting mixture thus contained an aluminosilicate gel with a molar ratio of 1.00 SiO.sub.2:0.0422 Al.sub.2O.sub.3:0.291 Na.sub.2O: 17.50 H.sub.2O. The reaction mixture was heated under stirring at 100 rpm in 3 h to a temperature of 120° C. using a constant heat ramp, wherein said temperature was then maintained under the same stirring speed for 60 h. After having let the reaction mixture cool to room temperature, the solid was separated by filtration, repeatedly washed with distilled water and then dried at 120° C. for 16 h for affording Na-zeolite beta. X-ray diffraction of the product confirmed the BEA-type framework structure of the crystalline material obtained. The resulting white crystalline material displayed a crystallinity of 93% compared to the crystallinity of the zeolite beta seed material (CP814C from Zeolyst) in the 2° Theta range od 18 to 25°.

(20) 1,000 g of distilled water were placed in a 2 L reaction vessel. 125 g ammonium nitrate and 125 g of Na-zeolite beta obtained according to Reference Example 1 were then added to the mixture over a funnel, which was then rinsed with 125 g of distilled water. The resulting suspension was then heated to 80° C. and kept at this temperature under continuous stirring for 2 h. The solid was filtered, and the filter cake was then washed with distilled water until the conductivity of the wash water was below 20 microSiemens/cm. The filter cake was dried over night at 120° C. affording 138.5 g of zeolite beta in its ammonium form. This procedure was repeated with a further 125 g of Na-zeolite beta from Reference Examples 1, affording a further 131.5 g of zeolite beta in its ammonium form. Finally, a calcination step of both batches at 500° C. for 5 h (heat ramp 2 K/min) afforded 236 g of zeolite beta in its H-form.

(21) 1,000 g of distilled water were placed in a 2 L reaction vessel. 118 g ammonium nitrate and 118 g of H-zeolite beta obtained from the first ammonium ion-exchange procedure were then added to the mixture over a funnel, which was then rinsed with 118 g of distilled water. The resulting suspension was then heated to 80° C. and kept at this temperature under continuous stirring for 2 h. The solid was filtered, and the filter cake was then washed with distilled water until the conductivity of the wash water was below 10 microSiemens/cm. The filter cake was dried over night at 120° C. affording 111 g of zeolite beta in its ammonium form. This procedure was repeated with 125 g of ammonium nitrate and a further 125 g of H-zeolite beta obtained from the first ammonium ion-exchange procedure, thus affording a further 110 g of zeolite beta in its ammonium form. The samples of H-zeolite beta were united, and a sample of 65 g thereof was subject to a calcination step at 750° C. for 5 h (heat ramp 2 K/min) affording 59.5 g of zeolite beta in its H-form. The Si:Al molar ratio of the H-zeolite beta as determined from .sup.29Si MAS NMR spectra was 7.

Reference Example 2: Dealumination of H-BEA Obtained from Organotemplate-Free Synthesis

(22) 1,250 ml of a 1 M solution of nitric acid were placed in a beaker equipped with a stirrer. 25 g of H-zeolite beta obtained from Reference Example 1 were added and the mixture was stirred for 2 h at room temperature. The solid was the filtered off and washed with distilled water until the conductivity of the wash water was 165 microSiemens/cm. The solid was then dried over night at 120° C. to afford 23.7 g of zeolite beta, wherein elemental analysis afforded a Si:Al weight ratio of 40:2.6. The Si:Al molar ratio of the dealuminated zeolite beta as determined from .sup.29Si MAS NMR spectra was 22.

Reference Example 3: Dealumination of H-BEA Obtained from Organotemplate-Free Synthesis

(23) 1,219 ml of a 1 M solution of nitric acid were placed in a beaker equipped with a stirrer. 24.38 g of H-zeolite beta obtained from Reference Example 1 were added and the mixture was stirred for 5 h at room temperature. The solid was the filtered off and washed with distilled water until the conductivity of the wash water was 65 microSiemens/cm. The solid was then dried over night at 120° C. to afford 21.4 g of zeolite beta, wherein elemental analysis afforded a Si:Al weight ratio of 40:2.1. The Si:Al molar ratio of the dealuminated zeolite beta as determined from .sup.29Si MAS NMR spectra was 36.

Example 1: Synthesis of Aromatic Compounds

(24) The catalytic conversion of 2,5-dimethyl furan, 2-methylfuran or furan with ethylene was carried out in a 50 ml stainless steel autoclave. Before reactions, the autoclave was purged by nitrogen, then 0.3 g of H-Beta zeolite was placed in the reactor, and the desired amounts of 2,5-dimethyl furan, 2-methylfuran or furan with solvent were transferred into the autoclave. More specifically, a 1.56 M solution of the respective compound in heptane was employed. The reactor was then pressurized with ethylene gas, and the mixture was stirred at 1000 rpm with a mechanical stirrer to ensure facile mass transfer in the system, and heated up to the final temperature. In the reaction, the molar the ratio of ethylene to 2,5-dimethyl furan was 0.18, of ethylene to 2-methyl furan was 0.18, and of ethylene to furan was 0.16.

(25) After reactions, the liquid products and solid catalyst were separated by centrifugation. The products were analyzed using the gas chromatograph (Shimadzu, GC-2014C) equipped with a 30 m HP-5 capillary column and the flame ionization detector. The products were identified based on the retention times and response factors of the standard chemicals, and quantified using a known amount of n-decane as the external standard. The products were further identified by GC/MS (Agilent, HP6890/5973MSD) equipped with a 30 m HP-5 MS column.

(26) For comparison, commercial zeolite Beta with Si/Al=19 from organotemplate mediated synthesis (CP814C, NH.sub.4.sup.+-form, Zeolyst) was converted to the H.sup.+-form by calcination at 550° C. for 4 h and subsequently used for the comparative test runs. The Si:Al molar ratio of the commercial zeolite beta as determined from .sup.29Si MAS NMR spectra was 19.

(27) The characteristics of the zeolite beta catalysts used in the testing experiments are displayed in Table 1. In particular, the molar Si:Al ratios as determined from the Si MAS NMR spectra, the ratio BA:LA of the amount of Bronsted acid sites (BA) to the amount of Lewis acid sites (LA) determined by the temperature programmed desorption of ammonia (NH.sub.3-TPD) and according to .sup.31P MAS NMR using trimethylphosphine oxide, respectively, the absolute amounts of Bronsted acid sites and Lewis acid sites according to NH.sub.3-TPD, and the BET surface area and total pore volume are shown.

(28) TABLE-US-00003 TABLE 1 Characteristics of the zeolite beta catalysts used in the testing experiments. BET BA/LA Bronsted Lewis surface pore Si/Al from .sup.31P acid acid BA/LA from area volume Catalyst ratio MAS NMR [μmol/g] [μmol/g] NH.sub.3-TPD [m.sup.2/g] [cm.sup.3/g] Ref. Ex. 1 7 7.0 956 110 8.7 449 0.31 Commercial 19 4.0 527 136 4.0 520 0.36 Ref. Ex. 2 22 2.3 448 185 2.4 500 0.36 Ref. Ex. 3 36 3.0 289 106 2.7 548 0.38

(29) The results from comparative testing of the different zeolite beta catalysts in the reaction of 2,5-dimethyl furan with ethylene are displayed in FIG. 4. The reaction was conducted at 300° C. for 20 h, wherein prior to the reaction, the reactor was pressurized with ethylene to afford an initial pressure of 4.0 MPa prior to heating. Thus, as may be taken from the results, it has quite unexpectedly been found that the conversion over zeolite beta as obtained from organotemplate free synthesis is substantially higher than for commercial zeolite beta obtained from templated synthesis. In particular, as may be taken from the results, it has quite surprisingly been found that the higher conversion rates are not linked to the Si/Al molar ratio, but that the improved results of the catalysts used in the inventive process result from the fact that they are obtained from an organotemplate-free synthetic process. Thus, as may be taken from the results obtained using the zeolite beta samples obtained from organotemplate-free synthesis displaying Si/Al molar ratios of 7 and 22, respectively, both display substantially higher conversion rates than commercial zeolite beta as obtained from templated synthesis having an Si/Al molar ratio of 19, i.e. lying in between the aforementioned Si/Al molar ratios.

(30) In addition to the aforementioned testing, zeolite beta from Reference Example 2 was used in the reaction of ethylene with 2,5-dimethyl furan, 2-methylfuran, and furan, respectively, the results of which are displayed in FIG. 5. The reaction pathways to the desired aromatic products of the Diels-Alder cycloaddition and subsequent elimination of water as well as to the main side products are displayed in FIGS. 1-3, respectively. As may be taken from the results displayed in FIG. 5, the conversion and the selectivity of the reaction towards the desired product is almost 100%, respectively, in the reaction of 2,5-dimethylfuran, whereas the conversion rate and selectivities considerably decrease when reacting ethylene with 2-methylfuran and furan, respectively.

LIST OF CITED DOCUMENTS

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