METHOD AND SYSTEM FOR PRODUCING AN OLEFIN

Abstract

There is provided a method for producing an optionally substituted olefin, comprising the steps of: dehydrogenating an optionally substituted alcohol in a first reaction zone comprising a first catalyst supported on a porous silica-based particle to form an optionally substituted carbonyl at a first set of reaction conditions; converting the optionally substituted alcohol and the optionally substituted carbonyl from the first reaction zone in a second reaction zone at a second set of reaction conditions that is different to the first set of reaction conditions and is selected to form the optionally substituted olefin, wherein the second reaction zone comprises a second catalyst supported on a porous silica-based particle. There is also provided a system for producing the optionally substituted olefin.

Claims

1. A method for producing an optionally substituted olefin, comprising the steps of: dehydrogenating an optionally substituted alcohol in a first reaction zone comprising a first catalyst supported on a porous silica-based particle to form an optionally substituted carbonyl at a first set of reaction conditions; converting the optionally substituted alcohol and the optionally substituted carbonyl from the first reaction zone in a second reaction zone at a second set of reaction conditions that is different to the first set of reaction conditions and is selected to form the optionally substituted olefin, wherein the second reaction zone comprises a second catalyst supported on a porous silica-based particle.

2. The method of claim 1, wherein the first set of reaction conditions comprises controlling the alcohol/carbonyl molar ratio provided to the second reaction zone.

3. The method of claim 1, wherein the controlling step comprises fixing the temperature in the second reaction zone, while controlling the temperature in the first reaction zone.

4. The method of claim 1, wherein the first set of reaction conditions comprises conducting the dehydrogenating step at a temperature of between 100° C. to 400° C.

5. The method of claim 1, wherein the second set of reaction conditions comprises conducting the conversion step at a temperature of between 250° C. to 550° C.

6. The method of claim 1, wherein the first catalyst and the second catalyst are different metal catalysts composed of different metals.

7. The method of claim 1, wherein the first catalyst and the second catalyst are independently selected from the group consisting of a single metal catalyst, binary metal catalyst, ternary metal catalyst and metal oxide catalysts thereof.

8. The method of claim 7, wherein the metal or metal oxide of the first catalyst is selected from the group consisting of silver, gold, copper, cobalt, zinc, aluminum, magnesium, manganese, zirconium, tantalum, titanium, vanadium and their combinations thereof; and the metal or metal oxide of the second catalyst is selected from the group consisting of silver, gold, copper, zinc, aluminum, magnesium, zirconium, tantalum, titanium, vanadium and their combinations thereof.

9. The method of claim 7, wherein the first catalyst is copper supported on a mesoporous silica-based particle or wherein the second catalyst is zirconium supported on a mesoporous silica-based particle.

10. The method of claim 1, wherein the optionally substituted olefin is an optionally substituted diene; preferably the optionally substituted olefin comprises 4 to 20 carbon atoms and the optionally substituted alcohol comprises 2 to 20 carbon atoms.

11. (canceled)

12. (canceled)

13. The method of claim 1, wherein the converting step comprises a step of coupling the optionally substituted alcohol with the optionally substituted carbonyl, and a step of dehydrating the coupled optionally substituted alcohol and optionally substituted carbonyl to form the optionally substituted olefin.

14. A system for producing an optionally substituted olefin, the system comprising: a first reaction zone having a first catalyst for dehydrogenating an optionally substituted alcohol to form an optionally substituted carbonyl; and a second reaction zone having a second catalyst for converting the optionally substituted alcohol and the optionally substituted carbonyl from the first reaction zone to form the optionally substituted olefin; wherein the first and second catalysts are supported on a porous silica-based particle.

15. The system of claim 14, wherein the silica-based particle is macroporous or mesoporous; preferably the silica-based particle is mesoporous; or more preferably the mesoporous silica-based particle is a mesocellular siliceous foam.

16. (canceled)

17. (canceled)

18. The system of claim 15, wherein the pore size of the mesocellular siliceous foam is in the range of 1 um to 100 um.

19. The system of claim 14, wherein the porous silica based particle has a surface area of at least 350 m.sup.2/g.

20. The system of 14, wherein the first catalyst and the second catalyst are independently selected from the group consisting of a single metal catalyst, binary metal catalyst, ternary metal catalyst and metal oxide catalysts thereof.

21. The system of claim 20, wherein the metal or metal oxide of the first catalyst is selected from the group consisting of silver, gold, copper, cobalt, zinc, aluminum, magnesium, manganese, zirconium, tantalum, titanium, vanadium and their combinations thereof; and the metal or metal oxide of the second catalyst is selected from the group consisting of silver, gold, copper, zinc, aluminum, magnesium, zirconium, tantalum, titanium, vanadium and their combinations thereof.

22. The system of claim 20, wherein the first catalyst is copper supported on the porous silica-based particle or wherein the second catalyst is zirconium supported on the porous silica-based particle.

23. (canceled)

24. The system of claim 14, wherein the optionally substituted olefin is an optionally substituted diene; preferably the optionally substituted olefin comprises 4 to 20 carbon atoms; or more preferably the optionally substituted alcohol comprises 2 to 20 carbon atoms.

25. (canceled)

26. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0095] The accompanying drawings illustrate a disclosed embodiment and serves to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

[0096] FIG. 1 is an exemplary reaction scheme for the conversion of ethanol to butadiene.

[0097] FIG. 2 shows the nitrogen isotherms of the prepared catalysts and a blank MCF support referred to in Example 1.

[0098] FIG. 3 shows the X-ray diffraction (XRD) spectrum of the prepared catalysts and a blank MCF support referred to in Example 1.

[0099] FIG. 4 is a schematic illustration of the experimental setup used in Examples 2-4.

[0100] FIG. 5 is a graph of the ethanol conversion and the BD selectivity against the temperature of the catalysts in Example 2.

[0101] FIG. 6 is a graph of the ethanol conversion and the acetaldehyde selectivity against reaction time of the Cu/MCF catalyst in (a) pure ethanol and (b) in aqueous ethanol, in Example 3.

[0102] FIG. 7 is a graph of the ethanol conversion and the butadiene selectivity of entry 1 of Example 4 against reaction time of the dual reaction system in (a) pure ethanol and (b) in aqueous ethanol.

[0103] FIG. 8 is a graph of the ethanol conversion and the BD selectivity against reaction time when regenerated catalyst was used in Example 2.

[0104] FIG. 9 is a schematic illustration of the experimental setup used in Example 5.

[0105] FIG. 10 is a schematic illustration of the experimental setup used in Examples 6 and 8.

EXAMPLES

[0106] Non-limiting examples of the invention will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

Example 1

Preparation of the Cu Catalyst on MCF (Cu/MCF)

[0107] 30 mL of deionized (DI) water was added to 1 g of MCF synthesized according to a known method (Y. Han, S. S. Lee and J. Y. Ying, Chemistry of Materials, 2007, 19, 2292-2298). An appropriate amount of soluble copper precursor (e.g CuNO.sub.3 or CuCl.sub.2) was added into the MCF/water mixture and was rapidly stirred. A solution of aqueous ammonia (4 M) was added dropwise until the pH reached ˜9. At pH 9, the silica surface was negatively-charged and attracted the positively-charged [Cu(NH.sub.3).sub.4].sup.2+ species in the solution.

[0108] The mixture was stirred for 10 min, filtered, washed several times with water, and then dried under vacuum for 12 hours. The resulting powders were heated at 500° C. for 3 hours to obtain the final green coloured Cu/MCF catalyst. Formation of highly-dispersed copper on an MCF support was achieved. The Cu/MCF catalyst did not show any visible peaks in its XRD spectrum (FIG. 3) confirming the highly dispersed copper elements on the surface of MCF.

[0109] However, the Cu-im-MCF catalyst prepared by the prior art impregnation method showed a typical XRD pattern of CuO (not shown), which indicates that relatively big CuO particles were formed on the MCF surface.

Preparation of the Zr Catalyst on MCF (Zr/MCF)

[0110] 20 mL of DI water was added to 1 g of MCF. The urea hydrolysis method was used for the preparation of the Zr/MCF catalyst. An appropriate amount of zirconium precursor (ZrOCl.sub.2.8H.sub.2O or ZrONO.sub.3.xH.sub.2O) and urea in a mole ratio of 1 to 10 was added to the MCF/water mixture and was rapidly stirred. The resultant mixture was heated up to 90° C. and stirred for 6 hours. After cooling, the mixture was filtered, washed several times with water, and then dried under vacuum for 12 hours. The resulting powders were heated at 500° C. for 3 hours to obtain the final colourless Zr/MCF catalyst.

Characterization

[0111] The prepared supported catalysts and a blank MCF support were analyzed.

[0112] Nitrogen isotherms were measured at −196° C. and P/Po between 0.01 and 0.995 on a Micromeritics ASAP 2020 (Georgia, USA) after degassing samples of the catalysts at 200° C. under vacuum overnight. The measured nitrogen isotherms are shown in FIG. 2.

[0113] The surface areas of all samples were calculated using the Brunauer-Emmett-Teller (BET) equation. The Barret-Joyner-Halenda (BJH) method was used to calculate the pore size distribution of the samples using data obtained from the nitrogen isotherm. The results are shown below in Table 1.

TABLE-US-00001 TABLE 1 BET Surface BJH BJH Material area (m.sup.2/g) Adsorption (nm) Desorption (nm) MCF 512 31.0 13.3 Cu/MCF 402 30.0 13.3 Zr/MCF 477 28.5 12.8

[0114] Powder X-ray diffraction (XRD) patterns were obtained using a Philips X'pert Pro diffractometer equipped with a CuKα radiation source (1.506 {acute over (Å)}), operating at a 2θ range of 20° to 80°. Inductively coupled plasma mass spectrometry (ICP-MS) analyses were performed using Perkin-Elmer Elan DRC II (Massachusetts, USA) on HF/HNO.sub.3-digested samples and appropriate standard solutions. The XRD data is shown in FIG. 3.

Example 2

Catalytic Reaction by the Dual Reactor System

[0115] Ethanol, acetaldehyde, diethyl ether, crotonaldehyde, crotyl alcohol were calibrated by manual injection (average of five injections) of known amounts into a gas chromatography (GC) machine equipped a thermal conductivity detector (FID). Ethylene and BD were calibrated using a certified gas blend of 2 mol % each in nitrogen balance. Both gases were injected into the GC using a 250 uL gas syringe.

[0116] A liquid chromatography (LC) pump was used to control amount of ethanol in the system as disclosed herein.

[0117] A mass flow controller (MFC) was used to control the rate of nitrogen flow, which delivered vaporized ethanol through a fixed bed reactor packed with 20 mg of Cu/MCF (the first reaction zone). The resultant stream of gas was then delivered to another fixed bed reactor packed with 60 mg of Zr/MCF (the second reaction zone). A schematic illustration of the setup is shown in FIG. 4.

[0118] Initial ethanol amount in the flow was determined via sampling using a gas valve system at 150° C. in both reactors. The reaction was carried out at ambient pressure and monitored at 1 hr intervals. The outlet products were analyzed periodically using GC-FID with a 30 m-long PoraPlot Q column via the gas valve system. Output gas was bubbled into CDCl.sub.3 for .sup.1H NMR spectroscopy and analysed for qualification purposes.

[0119] The reaction temperature of both the supported catalysts in reactors 1 and 2 were optimized by plotting the ethanol conversion and the BD selectivity against the temperature of the catalysts, which represents the temperature of the reactor. The first data point was obtained at 100 mins into the reaction. The Cu loading of the Cu/MCF catalyst was 4.1 mol % and the Zr loading of the Zr/MCF catalyst was 2.0 mol %. The results are shown in FIG. 5.

[0120] From the obtained results, the optimum temperature for Cu/MCF and Zr/MCF is 235° C. and 400° C., respectively.

[0121] The catalyst was regenerated by calcination under air at 500° C. for 3 hours.

[0122] The experiment was repeated with regenerated catalysts and the ethanol conversion and butadiene selectivity were monitored over 110 hours and plotted against reaction time. The results are shown in FIG. 8.

[0123] Carbon balances were determined to give typically more than 95%.

Example 3

[0124] In this example, the dehydrogenation reaction was investigated.

[0125] A feedstock of pure ethanol having a water content of less than 0.005 vol % was compared with a feedstock of 90 v/v % ethanol/H.sub.2O. The temperature of the reaction was held at 300° C. The WHSV of the pure ethanol was 7.7 hr.sup.−1, while the WHSV of the aqueous ethanol was 5.3 hr.sup.−1.

[0126] The ethanol conversion and acetaldehyde selectivity of pure ethanol and aqueous ethanol are shown in FIG. 6a and FIG. 6b, respectively.

Example 4

[0127] Different catalyst systems at different WHSV and time were investigated in this example.

[0128] The dual catalyst system illustrated in FIG. 4 was used and the results are shown in Table 2 below.

TABLE-US-00002 TABLE 2 Reactor 1 Reactor 2 EtOH BD WHSV Entry catalyst catalyst conversion (%) Selectivity (%) (hr.sup.−1) 1 Cu/MCF Zr/MCF 99 73 1.5 2 Cu/MCF Zr/MCF 99 70 1.5 3 Cu/MCF Zr/MCF 99 72 1.5 4 Cu/MCF Zr/MCF 96 69 3.7 5 Cu/MCF Zr/MCF 85 71 6.5 6 Cu/MCF Zr/MCF 92 71 1.5

[0129] The ethanol conversion and butadiene selectivity were calculated as an average over 20 hours.

[0130] In entries 1, 4 and 5, the Zr/MCF catalyst had an ICP loading of 2.0 mol %. In entry 2, the Zr/MCF catalyst had an ICP loading of 1.0 mol %. In entry 3, the Zr/MCF catalyst had an ICP loading of 3.0 mol %. In entries 1 to 4, pure ethanol having a water content of less than 0.005 vol % was used.

[0131] In entry 6, 4 mol % Cu and 2.0 mol % Zr were used as catalysts and wet ethanol was used (10 vol % H.sub.2O).

[0132] The optimum temperatures for reactors 1 and 2 were 240° C. and 375° C., respectively

[0133] From entries 1, 2 and 3 in Table 2 above, it can be seen that the optimum ICP loading of the Zr/MCF catalyst was 2.0 mol %.

[0134] The ethanol conversion and butadiene selectivity of entry 1 were plotted against reaction time and is shown in FIG. 7a. The ethanol conversion and butadiene selectivity of entry 6 were plotted against reaction time and is shown in FIG. 7b. Upon comparison of FIG. 7a and FIG. 7b, it is shown that BD selectivity was comparable when pure ethanol or wet ethanol was used. However, it can be seen that ethanol conversion was slightly higher when pure ethanol was used as compared to when wet ethanol was used.

[0135] An average BD selectivity of 73% at an ethanol conversion of 96% was achieved in entry 1. BD productivity of 0.62 g.sub.BDg.sub.cat.sup.−1 hr.sup.−1 at a concentration of 1.7×10.sup.4 Vppm over a time-on-stream of 15 hours was also achieved. Accordingly, the catalytic performance of the present system surpassed all reported results known to the inventors, e.g. a BD productivity of at least 0.15 g.sub.BDg.sub.cat.sup.−1 hr.sup.−1 and a concentration of 1×10.sup.4 Vppm in the product stream reported in E. V. Makshina, W. Janssens, B. F. Sels and P. a. Jacobs, Catalysis Today, 2012, 198, 338-344.

Example 5

[0136] The use of a different silica support for reactor 2 was investigated in this example. The dual catalyst system as illustrated in FIG. 9 was used.

[0137] The synthesis of this catalyst was identical to that for Zr/MCF in Example 1, except that three different silica supports (Merck, Davisil 60 Å grade 635 and 150 Å grade 645) were used in place of MCF.

[0138] The catalyst for reactor 1 remained as Cu/MCF.

[0139] The optimum temperatures of reactors 1 and 2 were 235° C. and 400° C., respectively.

[0140] Ethanol conversion and butadiene selectivity were averaged over 15 hrs at WHSV of 1.5 hr.sup.−1. The results are shown in Table 3 below.

TABLE-US-00003 TABLE 3 Zr/support EtOH Conversion (%) BD Selectivity (%) Merck silica gel 60 91 65 Davisil 60 Å grade 635 94 65 Davisil 150 Å grade 645 90 64

Example 6

[0141] The use of a binary catalyst for reactor 2 was investigated in this example. The dual catalyst system as illustrated in FIG. 10 was used.

[0142] The ethanol to butadiene reaction using M/Zr/MCF supported catalyst, where M is either cerium (Ce), copper (Cu), magnesium (Mg) or zinc (Zn) of various loadings, for the second reactor were carried out.

[0143] The catalyst for reactor 1 remained as Cu/MCF.

[0144] The optimum temperatures of reactors 1 and 2 were 235° C. and 400° C., respectively.

[0145] Conversion and selectivity values were obtained after 100 minutes into the reaction at WHSV of 1.5 hr.sup.−1. The carbon balance was typically more than 95%. The results are shown in Table 4 below.

TABLE-US-00004 TABLE 4 EtOH Conversion (%) BD Selectivity (%) Mol ratio Zn/Zr/MCF 0.01/2/98 99 75 0.05/2/98 99 76 0.1/2/98 98 70 Mol ratio Mg/Zr/MCF 0.01/2/98 99 74 0.05/2/98 98 75 0.1/2/98 99 71 Mol ratio Cu/Zr/MCF 0.01/2/98 88 71 0.05/2/98 99 71 0.1/2/98 99 72 Mol ratio Ce/Zr/MCF 0.01/2/98 97 73 0.05/2/98 98 73 0.1/2/98 99 72

Example 7

Preparation of a Binary Catalyst on MCF

[0146] 20 mL of DI water was added to 1 g of MCF. The urea hydrolysis method was used for the preparation of the M/Zr/MCF catalyst. An appropriate amount of zirconium precursor (ZrOCl.sub.2.8H.sub.2O or ZrONO.sub.3.xH.sub.2O), M precursor (where M=cerium, copper, magnesium or zinc) precursor and urea in a mole ratio of 1 to 10 was added to the MCF/water mixture and was rapidly stirred. The resultant mixture was heated up to 90° C. and stirred for 6 hours. After cooling, the mixture was filtered, washed several times with water, and then dried under vacuum for 12 hours. The resulting powders were heated at 500° C. for 3 hours to obtain the final colourless M/Zr/MCF catalyst.

Example 8

[0147] Scale-up experiments were investigated in this example.

[0148] The method of Example 6 was carried out at a larger scale, with the use of the dual catalyst system as illustrated in FIG. 10.

[0149] In reactor 1, 125 mg of Cu/MCF was used. In reactor 2, 375 mg of Zr/MCF was used.

[0150] At a temperature of 240° C. for reactor 1 and 385° C. for reactor 2, the average ethanol conversion was 84% and butadiene selectivity was 76% over 15 hrs, at a WHSV of 2.1 hr.sup.−1. The nitrogen flow was 35 ml/min.

[0151] Two other M/Zr/MCF catalysts (M=Zn or Mg) were also used as catalyst in reactor 2.

[0152] The mol ratio of Zn/Zr/MCF and Mg/Zr/MCF are 0.05Zn/2Zr/98MCF and 0.05Mg/2Zr/98MCF respectively. Values of ethanol conversion and butadiene selectivity obtained are averaged over 15 hours. Results are shown in Table 5 below.

TABLE-US-00005 TABLE 5 EtOH BD Reactor 2 Reactor 1 Conversion Selectivity Reactor 2 catalyst temp. (° C.) temp. (° C.) (%) (%) Zr/MCF 385 240 84 76 Zn/Zr/MCF 385 240 90 74 Mg/Zr/MCF 385 240 95 79

INDUSTRIAL APPLICABILITY

[0153] The disclosed system and method may be useful to produce an optionally substituted olefin at high conversion yield and selectivity.

[0154] The first reaction zone is designed for efficient dehydrogenation reaction of the optionally substituted alcohol to an intermediate and the second reaction zone is designed for efficient coupling of the alcohol and intermediate and subsequent dehydration of the product to produce the optionally substituted olefin.

[0155] It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.