Patent Application
20180185827
A material possessing an ordered uni-directional (1D) or two-dimensional (2D) network of micropores (ie pores<2 nm in diameter) containing mesopores (pores with diameters in the range 2-50 nm) connected to the microporores, the mesopores being characterized by an aspect ratio (length to width) higher than 2, a ratio of the volume of the intracrystalline mesopores to the volume of the micropores in the range 0.1 to 2 and an orientation of the mesopores in the direction of the micropores.
Generation of an oriented network of mesopores with adjustable sizes in a microporous material. The mesopores are oriented in the directions of the micropores and connected to the external surface by restrictions. The material is useful for traditional catalysis, sorption, separation, ion-exchange applications as well as for advanced applications based on occlusion chemistry.
The zeolite ferrierite (also named ZSM-35; FER-type), displays unique textural properties advantageously used in some acid-catalyzed reactions, such as skeletal isomerization of n-alkenes to iso-alkenes (J. Catal., 2009, 265, 170-180 and J. Catal. 2002, 211, 366-378), propene oxidative dehydrogenation (Appl. Catal. A 2002, 235, 181-191), NOx reduction (1998, Chem. Commun. 2755-2756), epoxidation of styrene (Catal. Lett. 1999, 62, 209-213), etc. The micropore (<2 nm) architecture of ferrierite, is characterized by 10-membered ring (10-MR) (0.42×0.54 nm, along [001] direction) channels perpendicularly intersected by 8-MR (0.35×0.48 nm, along [010] direction) channels in framework (U.S. Pat. No. 4,016,245).
Ferrierite generally appears as plate-like crystals (J. Catal., 2009, 265, 170-180). The 8- or 10-MR channels, which support the main diffusion path for molecules, run parallel to the plate. 6-MR channels exist along the [101] direction (vertical to the plate), but the aperture of these channels (<0.25 nm) does not allow usual molecules to diffuse in this direction. These characteristics make ferrierite a unique molecular sieve for catalysis, separation, ion exchange applications.
It is well known that the microporous nature of zeolite materials limits their sorption and occlusion ability and the accessibility to their internal surface to reactants or sorbates with sizes equivalent, or smaller, than the size of the micropores. To circumvent this limitation, secondary pore systems in the mesopore range size (2-50 nm) are necessary to increase their intracrystalline volume and improve transport and accessibility to the active surface (Chem. Commun., 2010, 46, 7840-7842).
Over the years many innovative post-synthesis routes, such as dealumination (Catal. Rev. Sci. Eng., 2003, 45, 297-319) and desilication (J. Phys. Chem. B, 2004, 108, 13062-13065), also named as ‘destructive’ approaches (Chem. Commun., 2010, 46, 7840-7842; Chem Cat Chem, 2011, 3, 67-81), have been developed for generating mesopores in zeolites. By 3D-TEM observations (electron tomography), it has been demonstrated (J. Phys. Chem. B, 2004, 108, 13062-13065) that most of the mesopores created upon dealumination by steaming followed by acid leaching of NH4Y zeolite were randomly distributed cavities, with broad distributions of sizes, interconnected by channels and open to the external surface of the zeolite crystal. This pore architecture is commonly found in dealuminated zeolites. Framework desilication by alkaline attack of zeolite crystals is another effective method to generate mesopores in zeolites (J. Phys. Chem. B, 2004, 108, 13062-13065). The mesoporous network thus formed is similar to the one produced by dealumination and is open to the external surface and easily accessible from mercury intrusion porosimetry data (Part. Part. Syst. Charact., 2006, 23, 101-106). The alkaline desilication method has been successfully applied to treat many silica rich zeolites, such as MFI (J. Phys. Chem. B, 2004, 108, 13062-13065), MOR (J. Catal., 2007, 251, 21-27), FAU (Angew. Chem., Int. Ed., 2010, 49, 10074-10078), FER (J. Catal., 2009, 265, 170-180), etc.
As an alternative to better control the size and the distribution of mesopores in zeolite crystals, “constructive methods” have been introduced more recently, eventually in combination with destructive ones (Chem. Commun., 2010, 46, 7840-7842). A constructive method, also called “zeolite recrystallization” involves first the controlled partial dissolution of the zeolite in alkaline solution and then its re-assembly in the presence of surfactants (i.e. CTAB) through hydrothermal treatment. This method was proposed for the preparation of mesoporous MOR, MFI, BEA, FER, etc., and allows introducing ordered mesopores (MCM-41-type) into zeolite crystals (Pure Appl. Chem., 2004, 76, 1647-1658; Microporous Mesoporous Mater., 2011, 146, 201-207; Appl. Catal. A, 2012, 441-442, 124-135; Chem. Soc. Rev., 42, 3671-3688). The resulting materials generally consist of composite mixtures of mesoporous disordered and ordered portions of the original zeolite.
Until now most of the reported desilication and recrystallization procedures are performed in solutions of strong inorganic or organic bases, including NaOH, TMAOH, etc.
Because all T-sites of ferrierite are bonded to five rings, the framework is very stable and harsh conditions, such as the use of NaOH concentrations of 0.5 mol/L, temperatures of 80° C. and treatment times of 3 h, were required to extract silicon, leading to mesoporosity in H-FER zeolite with Si/Al ratio of 27. Hierarchical micro/mesoporous FER zeolite was also successfully synthesized by dissolution of H-FER (Si/Al=27) first in NaOH solution and then hydrothermal recrystallization in the presence of cethyltrimethylammonium bromide (CTAB). These NaOH desilicated materials led to improved catalytic performance in skeletal isomerization of 1-butene, but with no possibility to control the extent of mesopore creation as well as the pore size and the distribution of the mesopores.
Aqueous sodium carbonate (Na2CO3) solution, also named soda, one of the widely-used mild base salts in industry, was also reported to induce partial selective dissolution of framework silicon in the interior of ZSM-5 zeolite crystals (Zeolite, 1992, 12, 776-779). Recently, ZSM-5 microboxes composed of a thin shell and large hollow core were synthesized by a mild alkaline treatment of ZSM-5 single-crystals in Na2CO3 solution (J. Catal., 2008, 258, 243-249; J. Mater. Chem., 2008, 18, 3496-3500), which can increase the propylene selectivity in methanol-to-propylene reaction and the catalysis activity of cumene cracking and α-pinene isomerization.
Ogura et al in Applied Catalysis A vol 219 no 1-2, 2001 pages 33-43 disclose the alkali treatment of ZSM5 under atmospheric pressure at a maximum temperature of 80° C. The ZSM-5 crystals obtained according to the method described by Ogura present cracks and faults on their surface depending on the operating conditions.
In WO 2012/084276 relates to the desilication of USY zeolite (a 3D zeolite) via alkaline treatment under atmospheric pressure.
Dessau et al. in Zeolites vol 12 no 7 1992 pages 776-779 disclose describe the partial dissolution of the interior of ZSM-5 crystals with the treatment under reflux and under atmospheric pressure of the crystallites with aqueous solution of 0.5M of Na2CO3. Hollowed crystals of ZSM-5 are obtained via this process.
Groen et al. in Microporous and Mesoporous Materials vol 69 no 1-2, 2004 pages 29-34 disclose the production of intracrystalline mesoporosity in zeolites via desilication in alkaline medium. Desilication is performed at a maximum temperature of 85° C. under atmospheric pressure and leads to partial dissolution of the zeolite crystals.
Bonilla et al. in Journal of Catalysis, vol 265 no 2, 2009, pages 170-180 relate to the desilication of ferrierite with alkali treatment under atmospheric pressure and at a maximum temperature of 90° C. The ferrierite obtained do not have a defined mesopore size but instead have a broad distribution of large mesopores.
In US 2008/138274 relates to mesoporisation of USY, a 3D zeolite, with an alkaline solution.
Aguirre et al. in Revista de al Sociedad Quimica del Peru, 74(4), 291-297, 2008 disclose the preparation of zeolite MOR/MCM41 via hydrothermal treatment.
In US 2005/239634 relates to mesoporisation of MCM41, a 3D zeolite, with an alkaline solution.
Though Na2CO3 solution has been reported for the desilication to ZSM-5 at ambient temperature and pressure, until now the method has not been claimed for the preparation of other mesoporous zeolites.
We disclose here a new desilication route for crystalline zeolites with mono-dimensional (1D) and bi-dimensional (2D) microporosity performed under mild hydrothermal conditions and in a basic aqueous medium, using preferably an alkaline metal carbonate solution.
In one embodiment, the invention relates to a mesoporous zeolitic material being preferably FER possessing an ordered mono-dimensional (1D) or two-dimensional (2D) network of micropores (i.e. pores<2 nm in diameter) containing mesopores (i.e. pores with diameters in the range 2-50 nm) connected to the microporores, the mesopores being characterized by an aspect ratio (length to width) higher than 2, a ratio of the volume of the intracrystalline mesopores to the volume of the micropores in the range 0.1 to 2 and an orientation of the mesopores in the direction of the micropores. Such mesoporous zeolitic can preferably be characterized by their adsorption isotherm of the type IV or V according to the IUPAC classification being preferably measured using N2 BET adsorption method. The orientation of the mesopores is preferably determined via TEM.
Ordered mono-dimensional (1D) micropore architecture or two-dimensional (2D) interconnecting micropore architecture networks refer to the channel system of the mesoporous zeolitic material. It is known in the art and can be found for instance on the Zeolite database structures (see for instance www.iza-structure.org/databases/).
The composition can preferably be determined by elemental analysis using the EDX method. Crystal structure can preferably be analyzed by X-Ray diffraction with Bragg-Brentano geometry. Pore volumes can be calculated from the analysis of the sorption-desorption isotherms for nitrogen recorded at 77 K. The total pore volume (including micropore volume, volume of intracrystalline mesopores and volume of intercrystalline mespores) can be calculated from the total amount adsorbed at a relative pressure p/p0 of 0.95. The volume of micropores plus intracrystalline mesopores can be calculated using the as plots method applied to the desorption branch of the isotherm at p/p0=0.5. The micropore volume can be calculated using the as plots method applied to the fraction of the isotherm below p/p0=0.3. The distribution, the size and the orientation of the intracrystalline mesopores can be determined by Transmission Electron Microscopy (TEM).
Moreover, different from the previous art where H-type ferrierite with a Si/Al ratio of 27 (obtained by previous dealumination) is usually reported to be used as the starting material due to the easy extraction of silicon atoms from the framework, we report here the selective desilication of a as-synthesized low-silica Na/K-type ferrierite (NaKFER) with a Si/Al ratio of 9.2.
Finally, for the first time, we report a resulting material exhibiting a unique distribution of oriented 3D short cylinder-like mesopores or tablet-like mesopores, due to the selective dissolution of the crystal along both the 8-([010]) and 10-MR ([001]) channel directions, with a narrow and tunable distribution of sizes.
The term “zeolite” as used herein refers to both natural and synthetic microporous crystalline silicate silicate materials having a definite crystalline structure as determined by X-ray diffraction. Crystalline silicates (also called zeolites) are microporous crystalline inorganic polymers based on a framework of XO4 tetrahedra linked to each other by sharing of oxygen ions, where X may be trivalent (e.g. Al, B, . . . ) or tetravalent (e.g. Ge, Si, . . . ). A zeolite comprises a system of channels which may be interconnected with other channel systems or cavities such as side-pockets or cages. The channel systems may be three-dimensional, two-dimensional or one-dimensional.
The term “intracrystalline mesopore” as used herein corresponds to mesopores which are located within a zeolite crystal.
The term “intercrystalline mesopore” as used herein corresponds to mesopores which are located between zeolite crystals.
The pore volume and the pore diameter are preferably measured via isotherm adsorption method (BET) for instance according to ASTM D4365.
The type of zeolite suitable for use in the process as the parent zeolite can be selected from the group consisting of:
In a preferred embodiment, suitable parent zeolites for use in the process having mono-dimensional (1D) micropore architecture comprise a topology selected from the groups MTT (ZSM-23), TON (ZSM-22, Theta-1, NU-10), EUO (ZSM-50, EU-1), MOR.
In a preferred embodiment, suitable parent zeolites for use in the process having two-dimensional (2D) interconnecting micropore architecture comprise a topology selected from the groups FER (ferrierite, FU-9, ZSM-35), MWW (MCM-22, PSH-3, ITQ-1, MCM-49), MFS (ZSM-57), ZSM-48. The FER group is the most preferred group.
In a preferred embodiment, suitable parent materials are zeolites not subjected to modification treatments such as, and without being limited to, dealumination, steaming, acid leaching, desilication treatments.
The parent crystalline silicate is such that the Si/Al ratio ranges more advantageously from 5 to 100, preferably from 9 to 90.
In another embodiment, the invention relates to a process for preparing a mesoporous zeolitic material possessing a mono-dimensional or bi-dimensional channel system and being preferably FER, comprising the following steps:
In another embodiment, the invention relates to a process for preparing the mesoporous zeolitic material possessing a mono-dimensional or bi-dimensional channel system and being preferably FER, comprising the following steps:
A process for preparing the mesoporous zeolitic material possessing a mono-dimensional or bi-dimensional channel system and being preferably FER, comprising the following steps:
In a most preferred embodiment, said mesoporous zeolitic material prepared according to any of the above process possesses an ordered mono-dimensional (1D) or two-dimensional (2D) network of micropores (i.e. pores<2 nm in diameter) containing mesopores (i.e. pores with diameters in the range 2-50 nm) connected to the microporores, the mesopores being characterized by an aspect ratio (length to width) higher than 2, a ratio of the volume of the intracrystalline mesopores to the volume of the micropores in the range 0.1 to 2 and an orientation of the mesopores in the direction of the micropores.
In a most preferred embodiment, said mesoporous zeolitic material prepared according to any of the above process possesses, has a network of micropores has a geometry consistent with one of MTT (ZSM-23), TON (ZSM-22, Theta-1, NU-10), EUO (ZSM-50, EU-1), FER (ferrierite, FU-9, ZSM-35), MWW (MCM-22, PSH-3, ITQ-1, MCM-49), MFS (ZSM-57), and ZSM-48.
Autogeneous pressure refers to a pressure at least higher than the atmospheric pressure and self generated by the heating. Autogeneous pressure is generally obtained via heating of a closed vessel.
The gist of the invention lies in a particularly versatile desilication process of zeolite leading to mesoporous materials with unique properties. Either a strong or a weak base can be used in the processes described above. The processes described above are particularly suitable for zeolite such as FER. Indeed FER are known to be difficult to desilicate: depending on the operating condition FER is either not desilicated at all or fully dissolved. The processes described above allow a controlled desilication of zeolite and in particular of FER.
In one embodiment, the base used for the desilication route according to the invention is a strong base and/or a weak base. Preferably the base is a weak base having a pKa above 9, more preferably above 10, even more preferably chosen among an alkaline metal carbonate, such as sodium, potassium, lithium ammonium carbonate. In a more preferred embodiment, the weak base used in the disclosed invention is sodium carbonate i.e. Na2CO3. The alkaline metal carbonate is preferably chosen among Na2CO3, (NH4)2CO3, NaHCO3 or K2CO3 or any mixture thereof.
In one embodiment, heating of the composition is done at a temperature from 101 to 150° C., preferably from 120 to 150° C., more preferably from 130° C. to 150° C., under optionally autogenous pressure from 1 preferably 2 to 20 bara, preferably between 1 preferably 2 and 15 bara.
The unit “bara” refers to “bar absolute”. Measurement of the pressure can be “absolute” or “relative”. Relative pressure is made by comparison with the atmospheric pressure. It is the measure made by most nanometers; when the nanometer indicates zero the pressure is equal to the atmospheric pressure. On the other hand, the absolute pressure is the pressure usually used in thermodynamic. The difference between the relative and the absolute pressure is the atmospheric pressure (1 bar).
Alternatively the base is a strong base, preferably an alkaline hydroxide, alkaline earth hydroxide, tetraalkylammonium hydroxide; more preferably sodium hydroxide. In one embodiment, the organic structure directing agent is typically a surfactant, which is solid under ambient temperature and pressure conditions. Suitable surfactant that can be employed include cationic, ionic, neutral surfactants and/or combinations of these. Exemplary surfactants include for example, hexadecyltrimethylammonium bromide, or cetyltrimethylammonium bromide (CTAB). Another type of suitable surfactant includes recyclable surfactants, characterized in that they are able to generate a micellization upon the effect of the variation of a physico-chemical parameter (pH, temperature, ionic strength). A non limiting example of mesopore structure directing agent is an oligomeric or polymeric chain bearing at least one ionic function and rendered amphiphilic upon the effect of the variation of a physico-chemical parameter, preferably chosen among pH, temperature and ionic strength and is preferably selected among:
is preferably a Jeffamine selected among Jeffamine M600 and Jeffamine M2005 wherein the amino group of the mesopore-templating agent is preferably quaternized, most preferably with chloride or bromide or hydroxide. None limited examples of recyclable surfactants can be found in WO2016005277 which is thereby incorporated by reference.
Examples of recyclable surfactants include for example commercially available Jeffamines, which can be quaternized or not.
The final material obtained according to the present invention can be subjected to various treatments before use in catalysis including, ion exchange, modification with metals (in a not restrictive manner alkali, alkali-earth, transition, rare earth elements or noble metals), external surface passivation, modification with P-compounds, steaming, acid treatment or other dealumination methods, or combination thereof.
In another first embodiment, the invention can be described as a mesoporous zeolitic material possessing an ordered mono-dimensional (1D) or two-dimensional (2D) network of micropores (ie pores<2 nm in diameter) containing mesopores (pores with diameters in the range 2-50 nm) connected to the microporores, the mesopores being characterized by an aspect ratio (length to width) higher than 2, a ratio of the volume of the intracrystalline mesopores to the volume of the micropores in the range 0.1 to 2 and an orientation of the mesopores in the direction of the micropores.
In a second embodiment, the invention relates to a mesoporous zeolitic material according to the embodiment 1, which network of micropores has a geometry consistent with one of MTT (ZSM-23), TON (ZSM-22, Theta-1, NU-10), EUO (ZSM-50, EU-1), FER (ferrierite, FU-9, ZSM-35), MWW (MCM-22, PSH-3, ITQ-1, MCM-49), MFS (ZSM-57), and ZSM-48.
In embodiment 3, the invention relates to a process for preparing the mesoporous zeolitic material of embodiments 1 or 2, comprising the following steps:
In embodiment 4, the invention relates to a process for preparing the mesoporous zeolitic material of embodiments 1 or 2, comprising the following steps:
In embodiment 5, the invention relates to a process for preparing the mesoporous zeolitic material of embodiments 1 or 2, comprising the following steps:
In embodiment 6, the invention relates to a process according to embodiment 5, wherein the mesopore structure directing agent is a surfactant, preferably cetyltrimethylammonium bromide (CTAB).
In embodiment 7, the invention relates to a process according to embodiment 5, wherein the mesopore structure directing agent is a recyclable surfactant able to generate a micellization upon the effect of the variation of a physico-chemical parameter (pH, temperature, ionic strength).
In embodiment 8, the invention relates to a process according to embodiment 5, in wherein the mesopore structure directing agent is selected among optionally quaternized Jeffamines.
In embodiment 9, the invention relates to a process according to one any of embodiments 3 and 5-8, wherein the alkaline metal in the alkaline metal carbonate is selected among ammonium, sodium and potassium, and/or their mixtures.
In embodiment 10, the invention relates to a process according to one any of embodiments 4-8, wherein the alkaline hydroxide is selected among ammonium, sodium and potassium hydroxides, and their mixtures.
In embodiment 11, the invention relates to a process according to one any of embodiments 3-10, wherein the parent zeolitic material is a mono-dimensional (1D) micropore architecture zeolite selected from the groups MTT (ZSM-23), TON (ZSM-22, Theta-1, NU-10), EUO (ZSM-50, EU-1).
In embodiment 12, the invention relates to a process according to one any of embodiments 3-10, wherein the parent zeolitic material is two-dimensional (2D) inter-connecting micropore architecture zeolite selected from the groups FER (ferrierite, FU-9, ZSM-35), MWW (MCM-22, PSH-3, ITQ-1, MCM-49), MFS (ZSM-57), ZSM-48.
In embodiment 13, the invention relates to a process according to embodiments 12, wherein the parent zeolitic material belongs to the FER group.
In embodiment 14, the invention relates to the use of an optionally formulated material obtained according to one any of embodiments 3-13, as refining or petrochemical catalyst.
In embodiment 15, the invention relates to the use of a material according to embodiment 1 or 2 as refining or petrochemical catalyst.
The composition of the samples has been determined by elemental analysis using the EDX method. EDX method is a global method allowing the titration of all elements form ppm level. Crystal structure was analyzed by X-Ray diffraction on a Bruker Lynx Eye diffractometer with Bragg-Brentano geometry and CuKα radiation (λ=0.15406 nm) as incident beam. Data were recorded by continuous scanning in the range 4-50°/2θ for studying the crystalline zeolite structure and in the range of 0.5-6°/2θ for the mesoporous structure, with an angular step size of 0.0197°/2θ and a counting time of 0.2 second per step. Pore volumes were calculated from the analysis of the sorption-desorption isotherms for nitrogen recorded at 77 K using a Micromeritics TriStar 3000. Prior to the isotherms acquisition, the samples were degassed under vacuum at 250° C. for 7 h. The total pore volume (including micropore volume, volume of intracrystalline mesopores and volume of intercrystalline mespores) was calculated from the total amount adsorbed at a relative pressure p/p0 of 0.95. The volume of micropores plus intracrystalline mesopores was calculated using the as plots method applied to the desorption branch of the isotherm at p/p0=0.5. The micropore volume was calculated using the as plots method applied to the fraction of the isotherm below p/p0=0.3.
The distribution, the size and the orientation of the intracrystalline mesopores was determined by Transmission Electron Microscopy (TEM) equipped with microdiffraction patterning using a Jeol 1200 electron microscope.
Starting Materials
The following samples of ferrierite have been used as starting materials
The XRD spectrum of FER1 is shown in
The XRD, sorption isotherms and TEM images of samples FER1 are given in
Abbreviations used in the examples, Micro=Micropores; Inter. Meso=Intercrystalline Mesopores, i.e. mesopores located between zeolite crystals; Intra. Meso=Intracrystalline Mesopores, i.e. mesopores located within a zeolite crystal.
In a typical synthesis, 1.67 g of commercial NaKFER (FER1, Si/Al=9.2) was first mixed with 50 mL of 1.25 mol/L Na2CO3 solution (solid/solution=0.0334 g/mL), and then stirred for 30 min. The suspension was hydrothermally treated at 130° C. in a Teflon-lined stainless autoclave for 3 days. After cooling the autoclave to room temperature, the solid was filtered under vacuum and washed with de-ionized water repeatedly until pH=7. Finally the product was dried overnight at 80° C. to get the sample of DeFER1-1.25-130/3. Yields of the preparation were calculated from the ratio between the amount of solid recovered to the amount of parent solid engaged in the reaction.
The as-synthesized DeFER1-1.25-130/3 sample was ion-exchanged in 1.0 mol/L NH4NO3 solution for 6 h at room temperature, after dryness, the sample was calcined in air flow (100 mL/min) in a tubular furnace at 550° C. for 8 h, and the sample denoted as H-DeFER1-1.25-130/3 was obtained.
The XRD diffractogram of DeFER1-1.25-130/3 (
The same procedure as in example 1 has been applied by using Na2CO3 solutions with a different concentration of 0.5 mol/L. Thus 1.67 g of commercial NaKFER (FER1, Si/Al=9.2) was mixed with 50 mL of 0.5 mol/L Na2CO3 solution to yield DeFER1-0.5-130/3.
Decreasing the concentration of the Na2CO3 solution down to 0.5 mol/L leads to a crystalline material (
The same procedure as in example 1 has been applied by using Na2CO3 solutions with a different concentration of 2 mol/L. Thus, 1.67 g of commercial NaKFER (FER1, Si/Al=9.2) was mixed with 50 mL of 2 mol/L Na2CO3 solution to yield DeFER1-2-130/3 (Example 3).
This example shows that by increasing the concentration of the Na2CO3 solution to 2 mol/L, a significant volume of intracystalline occluded mesopores can be created without loss of crystallinity (
The same procedure used in example 1 has been applied to FER2 in order to produce DeHFER2-1.25-130/3.
The procedure applied to a H form ferrierite allows to generate 0.04 mL/g of intracystalline occluded mesopores as shown by Table 5 and
In the example, the same procedure as in example 1 has been applied by using Na2CO3 solutions with the concentration of 1.25 mol/L at 80° C. for 3 days. Thus 1.67 g of commercial NaKFER (FER1, Si/Al=9.2) was mixed with 50 mL of 1.25 mol/L Na2CO3 solution to yield DeFER1-1.25-80-3 (Example 5).
In the example, the same procedure as in example 1 has been applied by using Na2CO3 solutions with the concentration of 1.25 mol/L at 150° C. for 3 days. Thus 1.67 g of commercial NaKFER (FER1, Si/Al=9.2) was mixed with 50 mL of 1.25 mol/L Na2CO3 solution to yield DeFER1-1.25-150-3 (Example 6).
In the example, the same procedure as in example 1 has been applied by using Na2CO3 solutions with the concentration of 1.25 mol/L at 130° C. for different duration (6 hours, 24 hours, 72 hours). Thus 1.67 g of commercial NaKFER (FER1, Si/Al=9.2) was mixed with 50 mL of 1.25 mol/L Na2CO3 solution to yield DeFER1-1.25-130/x, x being the duration of the hydrothermal treatment in hours (Example 7).
Example 7 shows that even after 6 hours of hydrothermal treatment under the applied conditions, we obtain a mesoporous FER exhibiting occluded mesopores which are oriented in the same direction as the micropores of the FER starting material.
The examples 1 to 7 clearly show that a mesoporous FER exhibiting the following characteristics:
The mesopore sizes and their relative proportions have been determined for three different concentrations of Na2CO3 (0.5M, 1.25M and 2M) in the (100) and (010) directions as reported below:
0.83 grams of FER1 (NaKFER, Si/Al=9.2) were used as the parent zeolite, which were treated in 0.05 mol/L of NaOH solution (25 mL, solid/solution=0.0334 g/mL) under the conditions of example 1. The same treatment was performed at 130° C. for 3 days and led to the sample DeFER1/NaOH-0.05-130-3.
0.83 grams of FER1 (NaKFER, Si/Al=9.2) were used as the parent zeolite, which were treated in 0.25 mol/L of NaOH solution (25 mL, solid/solution=0.0334 g/mL) under the conditions of example 1. The same treatment was performed at 130° C. for 3 days and led to the sample DeFER1/NaOH-0.25-130-3.
0.83 grams of FER1 (NaKFER, Si/Al=9.2) were used as the parent zeolite, which were treated in 0.50 mol/L of NaOH solution (25 mL, solid/solution=0.0334 g/mL) under the conditions of example 1. The same treatment was performed at 130° C. for 3 days and led to the sample FER1/NaOH-0.50-130-3.
0.83 grams of FER1 (NaKFER, Si/Al=9.2) were used as the parent zeolite, which were treated in 0.5 mol/L of NaOH solution (25 mL, solid/solution=0.0334 g/mL) and then stirred for 30 min. The suspension was hydrothermally treated at 80° C. in a Teflon-lined stainless autoclave for 3 hours. After cooling the autoclave to room temperature, the solid was filtered under vacuum and washed with de-ionized water repeatedly until pH=7. Finally the product was dried overnight at 80° C. to get the sample of DeFER1/NaOH-0.5-80-3 h.
The as-synthesized DeFER1/NaOH-0.5-80-3 h sample was ion-exchanged in 1.0 mol/L NH4NO3 solution for 6 h at room temperature, after dryness, the sample was calcined in air flow (100 mL/min) in a tubular furnace at 550° C. for 8 h, and the sample denoted as H-DeFER1/NaOH-0.5-80-3 h was obtained.
The reaction of FER1 in the presence of NaOH allowed to generate some intracrystalline mesopores (
1.67 g of commercial NaKFER (FER1, Si/Al=9.2) was first mixed with 50 mL of 1.25 mol/L Na2CO3 solution, and then stirred for 30 min. To this mixture cetyltrimethylammonium bromide (CTAB) was added in order to obtain a mass ratio CTAB/FER1 equal to 0.5. The mixture was then treated according to the same procedure as in example 1 to yield DeFER1-1.25-130/3-CTAB and H-DeFER1-1.25-130/3-CTAB.
This example shows that the addition of a surfactant to the reaction mixtures allows a remarkable increase of the volume of the intracystalline occluded mesopores (Table 6,
0.83 grams of FER1 (NaKFER, Si/Al=9.2) were used as the parent zeolite, which were treated in 0.05 mol/L of NaOH solution (25 mL, solid/solution=0.0334 g/mL) under the conditions of example 1, to this mixture cetyltrimethylammonium bromide (CTAB) was added in order to obtain a mass ratio CTAB/FER1 equal to 0.5. The same treatment was performed at 130° C. for 3 days and led to the sample FER1/NaOH-0.05-130-3-CTAB.
0.83 grams of FER1 (NaKFER, Si/Al=9.2) were used as the parent zeolite, which were treated in 0.25 mol/L of NaOH solution (25 mL, solid/solution=0.0334 g/mL) under the conditions of example 1, to this mixture cetyltrimethylammonium bromide (CTAB) was added in order to obtain a mass ratio CTAB/FER1 equal to 0.5. The same treatment was performed at 130° C. for 3 days and led to the sample FER1/NaOH-0.25-130-3-CTAB.
0.83 grams of FER1 (NaKFER, Si/Al=9.2) were used as the parent zeolite, which were treated in 0.50 mol/L of NaOH solution (25 mL, solid/solution=0.0334 g/mL) under the conditions of example 1, to this mixture cetyltrimethylammonium bromide (CTAB) was added in order to obtain a mass ratio CTAB/FER1 equal to 0.5. The same treatment was performed at 130° C. for 3 days and led to the sample FER1/NaOH-0.50-130-3-CTAB.
Catalytic Performances: Oligomerization of Pentenes:
The performances of the catalysts FER2 (parent zeolite—example 0) and DeFER1-1.25-130/3 (desilicated FER—example 1) were evaluated in oligomerization of a model feed consisting in a mixture of n-heptane (nC7) and 1-pentene (105=).
The FER samples (parent and desilicated) were pressed into wafers, crushed and sieved to obtain particles with diameters of 150-250 μm. Catalytic reactions were conducted down-flow in a tubular fixed-bed down-flow reactor (6 mm internal diameter) loaded with 1 g of catalyst.
The catalyst was supported by a porous disk (60 μm) and the dead volume was filled with quartz particles of 200-400 μm in size. The catalyst temperature was monitored with a thermocouple placed inside the bed. The catalyst, previously activated in flowing air (100 mL/min at 550° C. for 8 h) was loaded into the reactor and dehydrated at 180° C. for three hours in flowing air.
Pure n-heptane was then fed to the system using a HPLC pump (Gilson) until the operating pressure (50 barg) was achieved. The n-heptane flow was then shifted to the reagent feedstock, consisting of a 50/50 mixture of pent-1-ene and n-heptane (both from Sigma-Aldrich, 99% purity, WHSV: 0.5-2 h-1).
Reactor pressure was regulated using an Equilibar back-pressure regulator.
The catalytic tests were performed under the following operating conditions:
50 barg/WHSV(Weight Hourly Space Velocity) varying from 0.5 to 2 h−1/Temperature varying from 150 up to 200° C.
Analysis of the products is performed by using an on-line gas chromatography (Agilent 6850, using a capillary column DB 2887 (100% Diméthylpolysiloxane, 10 m, 0.53 mm, 3 μm).
The performances of parent zeolite (catalyst FER2) and of alkalinetreated sample (catalyst H-DeFER1-1.25-130/3 example 1) are presented in
By applying the desilication treatment to parent zeolite (DeFER1-1.25-130/3), the pentene conversion stabilizes at around 85% wt after 15 hours of stabilization period, while in the meantime, the formation of heavier oligomers becomes more favorable. The introduction of the mesoporosity within the FER structure, even if occluded, allows a better diffusion of the heavy molecules, and so the formation of higher amount of larger oligomers.
The pentene conversion and oligomers distribution for parent FER zeolite (FER2) and the modified FER (H-DeFER1-1.25-130/3) are as follows: with parent FER zeolite (FER2), the pentene conversion decreases from 90% (at 10 h of time on stream) down to 76% after 47 hours of TOS, while it remains stable at 86% from 15 h to 47 h of TOS in the case of the modified FER (H-DeFER1-1.25-130/3).
Selectivities vary as follows:
| Number | Date | Country | Kind |
|---|---|---|---|
| 15290179.9 | Jul 2015 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2016/065764 | 7/5/2016 | WO | 00 |
