Single step process for the synthesis of furfuryl ethyl ether

Abstract

The present invention provides a single step process for the synthesis of furfuryl ethyl ether comprises refluxing the reaction mixture of furfuryl alcohol, ethanol and catalyst at temperature in the range of 80 to 120 C. for the period in the range of 3 to 7 hrs to afford furfuryl ethyl ether. The catalyst used in present invention is Zr incorporated SBA-15. Further, the conversion of furfuryl alcohol is in the range of 60 to 90%. The selectivity of reaction towards furfuryl ethyl ether is in the range of 85 to 95%.

Claims

1. A single step process for the synthesis of furfuryl ethyl ether comprises refluxing the reaction mixture of furfuryl alcohol, ethanol and Zr incorporated SBA-15 catalyst at temperature in the range of 80 to 120 C. for the period in the range of 3 to 7 hrs to afford furfuryl ethyl ether, wherein selectivity of said reaction towards furfuryl ethyl ether is in the range of 85 to 95%.

2. The process as claimed in claim 1, wherein said reaction is carried out at temperature in the range of 90 to 100 C.

3. The process as claimed in claim 1, wherein said reaction is carried out for the period in the range of 5 to 6 hrs.

4. The process as claimed in claim 1, wherein conversion of furfuryl alcohol is in the range of 60 to 90%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Powder XRD pattern a) Low angle XRD b) Wide angle XRD for calcined Zr-SBA-15 catalysts.

(2) FIG. 2: Low temperature nitrogen adsorption-desorption isotherms for SBA-15 and Zr-SBA-15 (0.09)

(3) FIG. 3: Scanning electron micrographs for a) SBA-15 b) Zr-SBA-15(0.09) c) Zr-SBA-15(0.14) and d) Zr-SBA-15(0.19)

(4) FIG. 4: Transmission electron micrographs for a) SBA-15 b) Zr-SBA-15(0.09) c) Zr-SBA-15(0.14) and d) Zr-SBA-15(0.19)

(5) FIG. 5: DR-UV-vis spectra.

(6) FIG. 6: NH.sub.3-TPD profiles for SBA-15, Zr-SBA-15(0.09), Zr-SBA-15(0.14) and Zr-SBA-15(0.19)

(7) FIG. 7: FT-IR Spectra for SBA-15 and Zr-SBA-15(0.09)

(8) FIG. 8: py-IR Spectra for SBA-15 and Zr-SBA-15(0.09)

(9) FIG. 9: Solid state .sup.29Si NMR for SBA-15 and Zr-SBA-15(0.09)

(10) FIG. 10: Catalyst screening for etherification of furfuryl alcohol to Furfuryl ethyl ether. Reaction conditions: Furfuryl alcohol: 3 mmol, Ethanol: 5 ml, Catalyst: 0.1 g, Temp.: 100 C., Time: 5 h

(11) FIG. 11: Effect of solvent on etherification of Furfuryl alcohol using Zr-SBA-15(0.09) as catalyst. Reaction conditions: Furfuryl alcohol: 3 mmol, Ethanol: 5 ml, Catalyst: 0.1 g, Temp.: 100 C., Time: 5 h.

(12) FIG. 12: Effect of catalyst loading. Reaction conditions: Furfuryl alcohol: 3 mmol, Ethanol: 5 ml, Temp.: 100 C., Time: 5 h.

DETAILED DESCRIPTION OF THE INVENTION

(13) The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully understood and appreciated.

(14) In view of the above, the present invention provides a single step process for the synthesis of furfuryl alkyl ether from furfuryl alcohol in presence of Zr incorporated SBA-15 catalyst. The synthesis of Zr incorporated SBA-15 is carried out by direct synthesis method in self-generated acidic conditions. Incorporation of Zr improves the acidity of prepared catalyst. The prepared catalysts are tested for the etherification of furfuryl alcohol to give ethers which are proven gasoline fuel blends. Detail studies on the catalyst characterization by XRD, .sup.29Si NMR, TEM-FFT, NH.sub.3-TPD, py-IR along with effect of reaction parameters on furfuryl alcohol conversion and selectivity for ethers have been carried out.

(15) In an embodiment, the present invention provides a single step process for the synthesis of furfuryl ethyl ether comprises refluxing the reaction mixture of furfuryl alcohol, ethanol and catalyst at temperature in the range of 80 to 120 C. for the period in the range of 3 to 7 hrs to afford corresponding furfuryl ethyl ether.

(16) The catalyst is Zr incorporated SBA-15 and the conversion of furfuryl alcohol is in the range of 60 to 90%. The selectivity of said reaction towards furfuryl ethyl ether is in the range of 85 to 95%.

(17) In one embodiment, the present invention provides a synthesis of Zr incorporated SBA-15 using direct synthesis method in self-generated acidic conditions. The incorporation of Zr improves the acidity of prepared catalyst. It is observed that the incorporation of Zr generates Lewis acidic sites responsible for etherification of furfuryl alcohol to FEE. It also possesses highly ordered uniform hexagonal mesochannels with high surface area 1084 m.sup.2/g which minimize diffusion constraint for reactant and product. Zr-SBA-15(0.09) showed the highest conversion for furfuryl alcohol 85% with 95% selectivity towards FEE.

(18) The process for the synthesis of furfuryl ethyl ether from furfuryl alcohol is as shown in scheme 1 below:

(19) ##STR00001##
The FIG. 1a) shows low angle powder XRD pattern for of calcined Zr-SBA-15 materials with different Zr loadings. Pure SBA-15 catalyst has strong (100), (110) and (200) diffraction peaks, a strong peak at around 2=0.8 and two small peaks at 2=1.6, 1.8 respectively of 2D-hexagonal p6 mm structure, indicating that the materials possess well-ordered pore arrangement. Low angle XRD pattern of Zr-SBA-15(0.09) shows shifting of these three (100), (200) and (210) planes to lower 20 values. This shift is because of increase in the d-spacing which confirmed the incorporation of Zr into the SBA-15 framework. This indicated that Zr is incorporated in the SBA-15 framework successfully, using one step sol-gel method which did not destroy the mesoporous structure of SBA-15. While further increase in Zr loading in case of Zr-SBA-15(0.14) and Zr-SBA-15(0.19) did not show the characteristic peaks of SBA-15 which indicates that more concentration of Zr affect the pore ordering. Wide angle powder XRD pattern for Zr-SBA-15(0.09) showed a broad diffraction peak at 20 around 15-35, which is corresponding to amorphous silica walls of mesoporous materials. As no any characteristic peaks of ZrO.sub.2 are observed in, it proved that Zr is incorporated into the framework of the SBA-15.

(20) The FIG. 2 shows the nitrogen adsorption-desorption isotherms for SBA-15 and Zr-SBA-15(0.09). Both the samples show typical type IV isotherm with H1 type hysteresis loop which is characteristic of the mesoporous nature of solids. Physicochemical properties of prepared catalysts are given in Table 1. The SBA-15 have surface area 1210 m.sup.2/g while incorporation of Zr decreases the surface area to 1084 m.sup.2/g along with decrease in pore volume and pore diameter from 0.75 to 0.66 (cc/g) and 18.01 to 17.96 () respectively. These results suggest that Zr species are incorporated into the silica framework of SBA-15 without disturbing mesoporous structure.

(21) TABLE-US-00001 TABLE 1 Physicochemical properties of the catalysts Surface Pore Pore Total NH.sub.3 area.sup.a volume.sup.b diameter.sup.b desorbed.sup.c Sr. no. Catalyst (m.sup.2/g) (cc/g) (A.sup.0) (mmol/g) 1 SBA-15 1210 0.75 18.01 2 Zr-SBA15(0.09) 1084 0.66 17.96 0.11 .sup.amultipoint BET surface area; .sup.bBJH method, .sup.cNH.sub.3-TPD: NH.sub.3 desorbed in the range of 200-350 C.
The FE-SEM images of SBA-15 and Zr-incorporated SBA-15 catalysts are showed in FIG. 3. The parent SBA-15 catalyst showed rod like morphology FIG. 3 a). While Zr-SBA-15(0.09) FIG. 3 b) showed rope like morphology due to presence of Zr in the silica matrix. Further increase in zirconia concentration during the synthesis causes shortening of the rod like structure for Zr-SBA-115(0.14) FIG. 3 c), while it completely disrupts for Zr-SBA-15(0.19) FIG. 3 d). Elemental analysis for the SBA-15 and prepared catalyst are given in Table 2. Increase in % incorporation of Zr showed increase in the Zr/Si mole ratio.

(22) TABLE-US-00002 TABLE 2 Element detection using EDAX Zr/Si Molar Zr/Si Molar ratio in Sr. No. Catalyst ratio in gel formed catalyst 1 SBA-15 0 0 2 Zr-SBA-15(0.09) 0.09 0.12 3 Zr-SBA-15(0.14) 0.14 0.15 4 Zr-SBA-15(0.19) 0.19 0.19

(23) The FIG. 4 shows TEM images of SBA-15, Zr-SBA-15(0.09), Zr-SBA-15(0.14), Zr-SBA-15(0.19) catalyst with fast fourier transform images (FFT) inset Zr-SBA-15(0.09). The Zr-SBA-15(0.09) catalyst is found to retain the hexagonally ordered porous structure even after addition of Zr during synthesis. ZrO.sub.2 crystals are not visible in the TEM images of confirming that Zr are not deposited on the external surface but instead are present inside the mesochannels of SBA-15. The FFT images of the high resolution TEM showed single set of six spots suggesting that the pores remained in the ordered structure throughout the volume of particles. Other FFT image viewed in [110] direction with two-fold symmetry confirmed the ordered mesoporous structure with a single dominant direction through the particle. Selected area electron diffraction (SAED) pattern confirmed that the composite matrix is composed of several mesopores which is commonly found in the amorphous materials.

(24) FIG. 5 shows DR-UV-vis spectra of SBA-15, ZrO.sub.2 and Zr incorporated SBA-15 catalysts. In the case of Zr-SBA-15(0.09) catalyst showed sharp absorption band at around 200-210 nm was attributed to the LMCT from O.sup.2 to an isolated Zr.sup.4+ ion in a tetrahedral configuration.

(25) The profiles of NH.sub.3 temperature-programmed desorption are shown in FIG. 6. NH.sub.3-TPD of SBA-15 and composite samples showed two characteristic peaks. The first peak in the region of 100-200 C. is due to the weak acidity corresponding to desorption of weakly held, physisorbed ammonia. A broad peak in the region of 200-350 C. in the Zr incorporated sample indicated the presence of weak acid sites. Zr-SBA-15(0.09) catalyst possess weak acidity 0.11 mmol/g. The FT-IR spectra for Parent SBA-15 and Zr-SBA-15(0.09) are shown in FIG. 7. SBA-15 showed two bands at 1073 cm.sup.1 due to asymmetric stretching mode of SiOSi and at 807 cm.sup.1 ascribed to symmetric stretching mode of SiOSi. Zr incorporated catalyst showed slight red shift to 1049 cm.sup.1 for the band at 1073 cm.sup.1 that evidenced the strong interaction between Zr and SBA-15.

(26) The FIG. 8 represents Py-IR Spectra for SBA-15 and Zr-SBA-15(0.09) catalyst to distinguish between Lewis and Brnsted acid sites. Pure SBA-15 did not show any peak for Brnsted and Lewis acid site confirming SBA-15 lacks acidic nature while Zr-SBA-15(0.09) showed peaks at 1608 cm.sup.1, 1578 cm.sup.1, 1522 cm.sup.1, 1488 cm.sup.1, 1447 cm.sup.1 confirming the Lewis acid sites present in the catalyst. Incorporation of Zr in the silica framework is responsible generation of Lewis acidity in the catalyst.

(27) The FIG. 9 shows that three peaks in the .sup.29Si MAS NMR spectra of SBA-15 and Zr-SBA-15(0.09) catalyst at 90 ppm (Q2), 100 ppm (Q3) and 110 ppm (Q4) which are attributed to (SiO).sub.2Si(OH).sub.2, (SiO).sub.3SiOH and (SiO).sub.4Si, respectively. The corresponding relative peak areas in .sup.29Si MAS NMR spectra. SBA-15 possesses high amount of Q4 species which showed decreasing trend after incorporation of Zr in the framework of SBA-15. The value of (Q3+Q2)/Q4 is higher for Zr-SBA-15(0.09) as compared to SBA-15 i.e. from 18.69 for SBA-15 to 22.60 for Zr-SBA-15(0.09) indicating that the strong interaction existed between SBA-15 framework and Zr.

(28) All these characterization results of XRD, elemental analysis, TEM, .sup.29Si NMR revealed that one can incorporate Zr up to 0.09M concentration successfully in the framework of SBA-15. While further increase in concentration of Zr to 0.14 and 0.19 M will not give the SBA-15 structure which is concluded from low angle XRD patterns. Incorporation of Zr in the silica framework generates Lewis acidity which is responsible for catalytic reaction.

(29) The catalysts are screened for the etherification of furfuryl alcohol using ethanol as solvent in order to evaluate the effect of Zr loading on the conversion of furfuryl alcohol to FEE and data is as presented in FIG. 10. The furfuryl alcohol conversion to FEE did not proceed in absence of the catalyst as well as in presence of parent SBA-15. Pure ZrO.sub.2 showed very low conversion for furfuryl alcohol 7% and no FEE product is detected. One pot synthesized Zr-SBA-15 found to be very efficient catalyst for etherification of furfuryl alcohol. For the lowest Zr loading Zr-SBA-15(0.09) it showed the highest conversion for furfuryl alcohol 85% with 92% selectivity towards FEE. As the Zr loading increases for Zr-SBA-15(0.14) and Zr-SBA-15(0.19) it showed decrease in conversion from 77% to 66% along with marginal decrease in selectivity from 86% and 89% respectively. The decrease in conversion of furfuryl alcohol as increase in Zr loading is attributable to less acidity of these catalyst as compare to Zr-SBA-15(0.09). Presence of Lewis acid sites along with uniform mesoporous structure in the Zr-SBA-15(0.09) catalyst are responsible for the better conversion of furfuryl alcohol and selectivity towards FEE. Further optimization of reaction parameters viz. solvent effect and catalyst loading effect are carried out using Zr-SBA-15(0.09) as catalyst.

(30) The FIG. 11 shows the effect of various alcohols form C1-C4 on etherification of furfuryl alcohol. It is observed that solvent have very significant role in the etherification of furfuryl alcohol as it alters the conversion and selectivity for the desired product ethers. Methanol as a solvent gives 33% conversion of furfuryl alcohol with 14% selectivity to furfuryl methyl ether. When ethanol is used as solvent the conversion is increased dramatically to 85% with 92% selectivity for desired product. Aggregation of catalyst after adding methanol as the solvent which hinders the interaction between substrate and catalytic active sites must be responsible for lowering the catalytic activity. n-propanol and iso-propanol solvents gives 73% and 77% conversion respectively using Zr-SBA-15(0.09) as catalyst but ether formation is not observed in this case. It is observed that when n-butanol is used as solvent it showed 99% conversion of furfuryl alcohol with 55% selectivity towards ether and 27% selectivity towards butyl levulinate.

(31) The FIG. 12 shows the effect of catalyst loading in the range of 0.05 to 0.12 g on the etherification of furfuryl alcohol using ethanol as a solvent. 0.05 g loading of Zr-SBA-15(0.09) catalyst gives 33% conversion of furfuryl alcohol with almost complete selectivity towards FEE. It is observed that the increased in catalyst loading results increase in conversion of furfuryl alcohol. For 0.08 g loading it showed 55% conversion and selectively gives FEE as product. Further, it is observed that increase in loading to 0.1 g results in enhanced conversion to 85% with 92% selectivity towards FEE. Further increase in catalyst loading to 0.12 g showed marginal increase in conversion i.e. 87% with 95% selectivity for desired product.

(32) The following examples, which include preferred embodiments, will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purpose of illustrative discussion of preferred embodiments of the invention.

EXAMPLES

Example 1: Catalyst Preparation

(33) SBA-15 was prepared according to previously published [Science. 1998, 279, 548-552]. Compositions for Zr incorporated synthesis solution was 0.013 P123:1 TEOS: 1NaCl: 0.09-0.19 ZrOCl.sub.2.8H.sub.2O:221 H.sub.2O. In a typical procedure 1.5 g of pluronic P123 and 1.8 g of NaCl was dissolved in 70 g de-ionized water, stirred for 3 h at 35 C. in teflon beaker. 4.2 g of TEOS was added. After hydrolysis for 4 h, a pale white colloidal solution with a pH value of 4-5 was obtained. To this solution 10 ml of ZrOCl.sub.2.8H.sub.2O solution concentration ranging from 0.09 to 0.19 M was added. The pH value of the synthesis solution dropped to 2 and solutions became transparent. The solution was stirred for 24 h at 35 C. The milky suspension was aged at 90 C. for 24 h in teflon lined steel autoclave. The solid product was filtered, washed, dried at 100 C. for 12 h and calcined at 500 C. for 6 h (heating rate @ 1 C. min.sup.1). The resulting samples were labeled as Zr-SBA-15(0.09), Zr-SBA-15(0.14), and Zr-SBA-15(0.19) where bracketed figures indicate molarity of ZrOCl.sub.2.8H.sub.2O added during preparation.

(34) a) Catalyst Characterization

(35) Low angle powder X-ray diffractograms were collected on a Rigaku D MAX III VC diffraction system using Ni-filtered Cu K radiation (X, =1.5404 ) over a 2 range of 0.5-5 with a scan speed of 2 per minute. Wide-angle X-ray diffraction (WA-XRD) were recorded on a PANalytical PXRD model X-Pert PRO-1712, using Ni filtered Cu K radiation (=0.154 nm) as a source (current intensity, 30 mA; voltage, 40 kV) and a X-celerator detector. The specific surface area, total pore volume, and average pore diameter were measured by N.sub.2 adsorption-desorption method using a Quantachrome Autosorb-1C sorption unit. Diffuse reflectance UV-Vis measurements were carried out on a Shimadzu spectrophotometer (model UV-2550) with spectral-grade BaSO4 as reference material. NH.sub.3-TPD experiments were carried out on a Micromeritics-2720 (ChemisoftTPx) instrument. Transmission electron microscopy (TEM) analysis was performed on a Jeol Model JEM 1200 electron microscope operated at an accelerating voltage of 120 kV. Morphology of SBA-15 and Zr incorporated SBA-15 catalysts were examined by scanning electron microscopy (SEM), and the presence of Zr was confirmed by EDX analysis on a LEO-LEICA STEREO SCAN 440 instrument. FT-IR was performed on a PerkinElmer Frontier instrument in ATR (PIKE Tech) mode at room temperature. Pyridine IR was conducted using a Harrick diffuse reflectance praying mantis assembly. The reaction was monitored by analyzing the liquid products using a Shimadzu QP-2010 Ultra GC-MS. Solid-state MAS CP-NMR of the catalyst samples were carried out using a JEOL-400 MHz instrument.

Example 2: Etherification of Furfuryl Alcohol to FEE

(36) Etherification of furfuryl alcohol was carried out in a two necked 100 ml round bottom flask equipped with reflux condenser. In one pot reaction, 3 mmol of furfuryl alcohol (296 mg), ethanol (5 ml) and catalyst (100 mg) was added and the reaction was continued at 100 C. for 5 h after which, the catalyst was recovered by filtration. The reaction mixtures were quantified by GC (Shimadzu 2025) using FFAP column equipped with flame ionization detector. Identification of products was done by GC-MS. The conversion of furfuryl alcohol and selectivity of FEE were calculated by the following equations,

(37) $\begin{array}{cc}\left(\%\right)\mathrm{Conversion}\mathrm{of}\mathrm{furfuryl}\mathrm{alcohol}=\frac{\begin{array}{c}(\mathrm{Initial}\mathrm{moles}\mathrm{of}\mathrm{furfuryl}\mathrm{alcohol}-\\ \mathrm{moles}\mathrm{of}\mathrm{furfuryl}\mathrm{alcohol}\mathrm{unreacted})\end{array}}{\mathrm{Initial}\mathrm{moles}\mathrm{of}\mathrm{furfuryl}\mathrm{alcohol}}*100& \left(I\right)\\ \left(\%\right)\mathrm{Selectivity}\mathrm{of}\mathrm{product}=\frac{\mathrm{moles}\mathrm{of}\mathrm{desired}\mathrm{product}\mathrm{formed}}{\mathrm{Total}\mathrm{moles}\mathrm{of}\mathrm{product}\mathrm{formed}}*100& \left(\mathrm{II}\right)\end{array}$

(38) a) Recycling of Catalyst

(39) At the end of reaction, the catalyst was recovered by filtration. The recovered catalyst was washed three times with 10 ml ethanol and dried at 120 C. overnight in a vacuum oven. Catalyst was calcined at 400 C. for 4 h. The recycled catalyst was used for the same reaction study.

Example 3: Etherification of Furfuryl Alcohol with Different Alcohols

(40) Etherification of furfuryl alcohol was carried out in a two necked 100 ml round bottom flask equipped with reflux condenser. In one pot reaction, 3 mmol of furfuryl alcohol (296 mg), methanol or n-propanol or iso-propanol or n-butanol (5 ml) and catalyst (100 mg) was added and the reaction was continued at 100 C. for 5 h after which, the catalyst was recovered by filtration. The reaction mixtures were quantified by GC (Shimadzu 2025) using FFAP column equipped with flame ionization detector.

Advantages of Invention

(41) 1. An environmentally friendly provided.

(42) 2. Single step process

(43) 3. Biomass utilization

(44) 4. Efficient catalyst system

(45) 5. Excellent selectivity to FEE which can be used as gasoline component.

(46) 6. High conversion of furfuryl alcohol achieved.