Catalyst compositions comprising small size molecular sieves crystals deposited on a porous material

Abstract

Catalyst compositions comprising an inorganic porous material with pore diameters of at least 2 nm and of crystals of molecular sieve, characterized in that the crystals of molecular sieve have an average diameter, measured by scanning electron microscopy, not bigger than 50 nm, and in that the catalyst composition presents a concentration of acid sites ranges from 50 to 1200 mol/g measured by TPD NH3 adsorption; and the XRD pattern of said catalyst composition is the same as the X ray diffraction pattern of said inorganic porous material.

Claims

1. A process of preparation of a catalyst composition comprising: a) providing an inorganic porous material; b) optionally calcinating the inorganic porous material at temperature from 400 C. to 1200 C.; c) providing a solution containing at least one charge surface modifying agent selected from the group consisting of inorganic surface modifying agents, ionic or non-ionic surfactants, water soluble anionic polymers, and water soluble cationic polymers; d) putting in contact the solution of step c) and the inorganic porous material to obtain a modified inorganic porous material modified with a charge surface modifying agent; e) providing a solution containing precursors for a molecular sieve; f) preparing the molecular sieves by: i) maturating, during a period of time from of no more than 100 h, the solution of step e), the maturating process being followed by dynamic light scattering (DLS) and stopped when crystals of molecular sieve have a maximum size of 50 nm, and subjecting the modified inorganic porous material to a contact with the maturated solution to deposit molecular sieve crystals on the surface of the modified inorganic porous material obtained at step d); and/or ii) putting in contact the modified inorganic porous material obtained at step d) with the solution of step e) and maturating during a period of time of no more than 100 h the obtained mixture until the acidity of the catalyst composition measured by TPD ammonia has increased by at least 10% compared with the acidity of the inorganic porous material; g) separating solid from liquid if any of the mixture obtained after step f); and h) calcinating the solid obtained at step g) to form the catalyst composition, wherein the catalyst composition comprises: an inorganic porous material with pore diameters of at least 2 nm and crystals of molecular sieve; wherein the crystals of molecular sieve have an average diameter not bigger than 50 nm measured using Scanning Electron Microscopy, wherein the crystals of molecular sieve comprise a zeolite selected from the group consisting of MOR, FAU, EMM, MWW, BETA, ZSM-21, ZSM-42, AEI, CHA, ERI, LEV, OFF, ZSM-34, AFI, AEL, LTL, MFI (ZSM-5, silicalite, TS-1), MEL (ZSM-11, silicalite-2, TS-2), MTT (ZSM-23, EU-13, ISI-4, KZ-1), MFS (ZSM-57), HEU (Clinoptilolite), FER (ZSM-35, Ferrierite, FU-9, ISI-6, NU-23, Sr-D), TON (ZSM-22, Theta-1, ISI-1, KZ-2 and NU-10), LTL (L), MAZ (mazzite, Omega, ZSM-4) and mixtures thereof; wherein the catalyst composition has a concentration of acid sites ranging from 50 to 1200 mol/g measured by Temperature-Programmed Desorption of ammonia, TPD NH3; and wherein an X-ray diffraction pattern of the catalyst composition is the same as an X-ray diffraction pattern of the inorganic porous material.

2. The process according to claim 1, further characterized in that the steps e) to g) are repeated at least two times prior to performing step h).

3. The process according to claim 2, wherein the maturation of the solution is conducted for at least 30 min and at most 100 h each time.

4. The process according to claim 3, wherein the steps e) to g) are performed once and maturation of the solution is conducted for at most 50 h.

5. The process according to claim 1, further comprising, after step h), performing one or more of the following steps: introducing phosphorous on to the catalyst composition by impregnation of the catalyst composition by a solution containing phosphorous, said step being optionally followed by further steps of calcinations and/or steaming; adding at least one metal to the catalyst composition by impregnation of the catalyst composition by a solution containing the at least one metal, wherein the at least on metal is selected from the group consisting of: B, Cr, Co, Ga, Fe, Li, Mg, Ca, Mn, La, Ti, Mo, W, Ni, Ag, Sn or Zn, Pt, Pd, Ru, Re, Os, Au, and combinations thereof; adding at least one binder selected from the group consisting of: silica, silica alumina, metal silicates, metal oxides and/or metals, amorphous alumophophate or silica alumophosphates, gels including mixtures of silica and metal oxides, and combinations thereof, by spray drying or extrusion; shaping of the catalyst composition by extrusion.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1 presents the DRX patterns of the porous material prepared according to example 1.

(2) FIG. 2 presents NMR .sup.13C spectra of the catalyst composition according to example 1.

(3) FIG. 3 presents the measures of pyridine adsorption of the catalyst compositions prepared according to example 1

(4) FIG. 4 presents the catalytic tests of the solids prepared according to example 1

(5) FIG. 5 presents the DRX patterns of the materials prepared according to example 4.

(6) FIG. 6 presents the SEM micrographs of the materials prepared according to example 4 after three impregnations of the molecular sieve precursor on the porous material (sample 3 impregnations).

(7) FIG. 7 presents the acidic sites quantification measured using pyridine adsorption according to example 4.

(8) FIG. 8 presents the catalytic tests of the solids prepared according to example 1, 3 and 4

(9) FIG. 9 presents the detailed selectivity of the catalytic tests of the solids prepared according to example 4

(10) FIG. 10 correlation of the number of acidic sites measured via pyridine adsorption as function of the crystallization time

(11) FIG. 11 size of crystal of molecular sieve in solution after various tests measured via Dynamic Light Scattering (DLS)

(12) FIG. 12 Conversion of TiPBz as function of the number of Bronsted acidic sites measure by pyridine adsorption. The conversion was measured after 2 min on stream and after 180 min on stream (the catalyst slightly deactivated after 180 min on stream). On the right site of the graph the conversion of TiPBz is presented for the Siralox 300 without deposition of the crystal of molecular sieve. On the left side of the graph the conversion for nanosized commercial crystals of ZSM-5 are presented.

(13) FIG. 13 .sup.27Al MAS NMR spectra according to example 7 of the starting solution, the aged solution after 12 h, the matrix on which the siralox 30 is deposited, the matrix being deposited three times with the solution containing the nano size crystal of molecular sieve (3 nanocasted composite). The spectra C144 composite related to the preparation according to example 2 with a maturation time of 144 h. The letter t stands for synthesis time.

EXAMPLES

Example 1 (According to Invention)Preparation of the Catalyst Composition with a Precursor Solution being Maturated Before being Impregnated on Modified Porous Material

(14) A catalyst composition with a porous material being Siralox TH 30 (Sasol, Al2O3/SiO270/30 wt %) on which crystals of ZSM-5 molecular sieves are dispersed was prepared according to the following procedure.

(15) The solution containing the precursor of molecular sieve (ZSM-5 precursor solution4.5(TPA).sub.2O: 25SiO.sub.2: 0.25Al.sub.2O.sub.3: 430H.sub.2O: Si/Al=50) was prepared by mixing TPAOH (tetrapropylazanium hydroxide; CAS [66082-78-8]), H.sub.2O, Aluminium sulphate [10043-01-3], and TEOS (tetraethoxysilane; CAS [9044-80-8]). The ingredients were added gradually according to mention order and hydrolyzed at room temperature (RT) for 1 h with vigorous stirring and then closed and stirred for another 3 h. Prior to its use on the porous material, this solution was maturated at 100 C. for various maturation: 12 h, 36 h, 48 h, 72 h, 96 h, 120 h, 144 h, 168 h, 192 h.

(16) The porous material used was commercial Siralox TH 30 a silica alumina oxide from Sasol in spray-dried form (40-60 m) with a Al.sub.2O.sub.3: SiO.sub.2 ratio of 70:30. Prior to use, it was calcinated at 600 C. during 2 h. This calcination did not change the amorphous DRX signature of the Siralox 30 (see FIG. 1).

(17) The size of the crystal of molecular sieves formed was measured via Dynamic Light Scattering (DLS) after 12 h of maturation at 100 C. The results are shown on FIG. 11. The measure was reproduced for the same sample three times (runs 1, 2 and 3). It appears that the size of the crystal measured is lower than 10 nm.

(18) The 2.95 g of the calcined at 600 C. Siralox TH 30 was then impregnated with a 10 ml of 0.5 wt % solution of PDDA (Poly (diallyldimethylammonium chloride)). The mixture was stirred on a shaker at the speed of 175 rpm for 2 h at RT. Then the excess water was removed by evaporation overnight (on top of a 150 C. oven). The resulted solid was further dried at 100 C. for 15 min prior to be used in the synthesis. Then, the PDDA-impregnated Siralox TH 30 is added into the aged precursor solution (from 12 h to 192 h) and crystallization is carried out at 100 C. for 48 h (2 days). During this step, the precursors of the zeolite crystals in suspension in the solution are attracted and attached on the surface of the PDDA-impregnated Siralox TH 30.

(19) The corresponding samples after the different crystallization times were separated from the solution by filtration followed by drying at 100 C. and calcination at 550 C. for 4 h to remove the template.

(20) TABLE-US-00001 TABLE 1 Synthesis of ZSM-5/Siralox TH 30 (600 C.) composite Molar ZSM-5 precursor solution = A + B + C + D composition A B C D E Reagents TPAOH 1M TEOS Aluminium H.sub.2O Siralox TH sulphate 30 (600 C.) Source of Alfa Aesar Aldrich Aldrich Distilled water SASOL reagents % purity 20% 98% 98% 30% SiO.sub.2/ 70% Al.sub.2O.sub.3 Molecular weight 203 208 666 18 (g/mol) Theoretical 15.252 8.858 0.2834 0.6984 0.5 weight (g) Measured weight 15.263 8.862 0.283 0.712 0.5 (g) 1. TPAOH, H.sub.2O, Aluminium sulphate, and TEOS was added successively and hydrolyzed at RT for 1 h in an open bottle (50 mL) under vigorous stirring to facilitate hydrolysis. It was then closed and stirred for another 3 h at RT. 2. After that, the synthesis solution was transferred into a 125 mL Nalgene PP bottle and maturating was performed at 100 C. for 12 h, 24 h, 36 h, 48 h, 72 h, 96 h, 120 h, 144 h, 168 h, 192 h respectively. 3. After maturating, Siralox 30 (600 C.) which has been treated with PDDA was added into the synthesis solution and the mixture was stirred on a shaker at the speed of 125 rpm for 2 h at RT. 4. The crystallization was performed at 100 C. for 2 days. 5. After synthesis, the ZSM-5/Siralox 30 (600 C.) was treated under ultrasonic radiation for 3 min to disperse loosely attached crystals; washed under vacuum filtration until pH 8-9, dried at 100 C. followed by a calcinations at 550oC for 4 h. Aging: 12 h, 36 h, 48, 72 h, 96 h, 120 h, 144 h, 168 h, 192 h at 100 C. ZSM-5 precursor Transparent solution solution appearance: The samples are hereinafter identified as 12 h, 36 h, 48 h, 72 h, 96 h, 120 h, 144 h, 168 h, 192 h.

(21) TABLE-US-00002 TABLE 2 Quantification of the crystals of molecular sieves deposited on the porous materials after various crystallization times (Zeolite/Siralox TH 30 (600 C.) composite after Na.sup.+ exchange (TG data)). Crystallization time, t/h Weight loss, W/% Wt % active phase 0 1.457 12 1.876 4.2 24 2.172 7.2 36 2.261 8.0 48 2.300 8.4 60 2.347 8.9 72 2.458 10.0 96 2.987 15.3 120 2.500 16.8 144 3.297 18.4 168 3.630 21.7 192 3.474 20.2

(22) TABLE-US-00003 TABLE 3 BET surface area of the catalyst composition Samples S.sub.BET/m.sup.2g.sup.1 S.sub.EXT/m.sup.2g.sup.1 V.sub.mic/cm.sup.3g.sup.1 V.sub.meso/cm.sup.3g.sup.1 Siralox 30 322 227 0.00 1.00 (600 C.) 12 h 317 232 0.03 1.20 144 h 397 316 0.04 1.22 168 h 414 320 0.04 1.22 192 h 419 316 0.05 1.20

(23) TABLE-US-00004 TABLE 4 TPD NH3 of the catalyst composition Samples TPD NH3/mol/g % Siralox 30 (600 C.) 297 100 72 h 402 135 144 h 487 167

(24) The XRD spectra do not evidence any crystals of molecular sieve. However those crystals are evidenced by indirect techniques, in particular by surface area measurements. An increase of the surface area is evidenced whereas there is only a very little increase of the microporous volume (from 0.03 to 0.05 cm.sup.3 g.sup.1). Such an increase of the surface area is an evidence of presence of small size crystal on the porous material. It can therefore be concluded that the crystals are too small to be detected via XRD. The detection limit of the crystal size by XRD being of 50 nm, the crystals of molecular sieves are smaller than 50 nm. The NMR .sup.13C spectra show that the signature of the template is similar to a signature of the template inside ZSM-5 crystal. There is therefore deposition of crystals of ZSM-5 on the porous support.

(25) Both the Bronsted and Lewis concentration of acidic site was measured using pyridine adsorption at 150 C. The results obtained are displayed on FIG. 10. It appears that the number of both Bronsted and Lewis acidic site significantly increases with the crystallization i.e. with the quantity of crystal of molecular sieve deposited on siralox 30. Bronsted acidic site concentration of up to 20 mol/g was obtained with a crystallization time of 144 h.

Example 2 (According to Invention)Catalytic Tests of Materials Prepared According to Example 1

(26) Catalytic tests of cracking of the TiPBz were performed on the catalyst composition prepared (see FIG. 4). It appears that the catalyst compositions prepared with a longer crystallisation time (more than 36 h) have a higher activity than the initial Siralox TH 30 (600 C.). Without willing to be bound to any theory, it is interpreted that the catalysts with longer crystallisation time have more acid sites and more developed surface area (table 3-4). This higher acidity originates from the small crystals of molecular sieve deposited on the surface of the Siralox TH 30. The catalyst compositions prepared by deposition of the crystal of molecular crystals on Siralox TH 30 present a higher conversion than the Siralox TH 30.

Example 3 (Comparative) Preparation of the Catalyst Composition with a Precursor Solution being Maturated Followed by Drying and Calcinations. No Contact with the Porous Material

(27) Molecular sieve precursor solution was prepared by mixing TPAOH (tetrapropylazanium hydroxide; CAS [66082-78-8]), H.sub.2O, Aluminium sulphate, and TEOS (tetraethoxysilane; CAS [9044-80-8]). The ingredients were added successively according to mentioned order and hydrolyzed at RT for 3 h with vigorous stirring. Prior to its use, this solution was maturated at 100 C. for 12 h. Dynamic Light Scattering (DLS) shows that particles smaller than 10 nm with a narrow particle size distribution are present in the seed solution aged for 12 h at 100 C. The catalyst composition was prepared by evaporating of the solution followed by at 100 C. and calcinations at 550 C. for 4 h. The sample is hereinafter identified as Dried Seed.

Example 4 (According to Invention)Preparation of the Catalyst Composition with a Precursor Solution being Maturated Before being Impregnated on Modified Porous Material with One or More than One Impregnations

(28) A series of catalyst compositions with a porous material being Siralox TH 30 (Sasol) on which crystal of molecular sieves are dispersed by repeating the deposition step.

(29) ZSM-5 precursor solution was prepared by mixing TPAOH (tetrapropylazanium hydroxide; CAS [66082-78-8]), H.sub.2O, Aluminium sulphate, and TEOS (tetraethoxysilane; CAS [9044-80-8]). The ingredients were added successively according to mentioned order and hydrolyzed at RT for 3 h with vigorous stirring. Prior to its use, this solution was maturated at 100 C. for 12 h. Dynamic Light Scattering (DLS) shows that particles smaller than 10 nm with a narrow particle size distribution are present in the seed solution aged for 12 h at 100 C.

(30) The porous material used was commercial Siralox TH 30 a silica alumina oxide from Sasol with a Al.sub.2O.sub.3: SiO.sub.2 ratio of 70:30. Prior to use, it was calcinated at 600 C. during 2 h. This calcination did not change the amorphous XRD signature of the Siralox 30 (see FIG. 5).

(31) In order to obtain the PDDA-modified Siralox 30, 2.95 g of the calcined at 600 C. Siralox 30 was impregnated with a 10 ml of 0.5 wt % solution of PDDA (Poly (diallyldimethylammonium chloride)). The mixture was stirred on a shaker at the speed of 175 rpm for 2 h at RT. Then the excess water was removed by evaporation overnight (on top of a 150 C. oven). The resulted solid was further dried at 100 C. for 15 min prior to be used in the synthesis. The Siralox TH 30 once impregnated with PDDA was then impregnated with 1 g of ZSM-5 precursor solution added drop wise to 0.5 g of the impregnated Siralox 30. The mixture obtained was then dried overnight in open air and then at 100 C. for 2 h.

(32) Then, the impregnation of ZSM-5 precursor solution is repeated up to three times using the same procedure. Before characterisation, the solid was calcinated under air at 550 C. for 4 h.

(33) The solids hence prepared were characterized via DRX (see FIG. 5). The DRX patterns show that the solid conserves an amorphous pattern. Similarly the dried seed also have an amorphous DRX pattern.

(34) The SEM micrographs of the material prepared (see FIG. 6) demonstrate that the matrix of Siralox TH 30 is covered with seeds of an average diameter of about 10 nm. SEM investigation also shows a random shape and size of the aggregates obtained by drying of seed particles. The SEM micrograph in FIG. 6 illustrates that after three impregnations with ZSM-5 precursor solution, the surface of Siralox TH 30 (600 C.) matrix is covered by crystals of seeds.

(35) The adsorption of pyridine was also measured (see FIG. 7) demonstrating that the number of acidic sites increase with the number of impregnation. There is therefore an increase of the amount of active phase present.

(36) The samples are hereinafter identified as 1 impregnation or 3 impregnations

Example 5Catalytic Test of Materials Prepared According to Example 3

(37) Catalytic tests of cracking of the TiPBz were performed on the catalyst composition prepared (see FIG. 8). Even the material prepared by one impregnation of the Siralox TH 30 shows higher activity than the dried seeds (comparative example) and the Siralox TH 30 without impregnation. The material prepared according to example 1 shows also higher activity than the dried seeds (comparative example). The technical advantage of dispersing such seeds on a porous material is therefore higher activity and easy handling the seeds-containing materials. In addition, having the active sites dispersed on such matrix also allows an easier formulation of the material.

(38) The selectivity of the catalysts in TiPBz cracking is displayed on FIG. 9. With the catalyst impregnated three times (example 3), the selectivity toward benzene and cumene is higher relative to the sample prepared according to example 1. This means that different preparation procedure allows adjusting catalyst design toward selectivity to secondary cracking reaction.

(39) The impact of the quantity of acidic Bronsted sites on the conversion of TiPBZ is displayed on FIG. 12. It appears that when the concentration of Bronsted site increases, the conversion of TiPBZ increases. There is therefore an advantage in using the catalyst composition prepared according to the example compared with pure Siralox 30. When pure MFI-90 (ZSM-5) is used, the number of Bronsted acidity sites is significantly higher, but the conversion decreases. This is due to the low accessibility of the acidity sites when pure MFI-90 is used. The composition according to the invention therefore allows increasing the conversion of bulky molecules like TiPBZ.

Example 6 (According to Invention)on Extruded Body Treatment

(40) Preparation of the catalyst composition with a precursor solution being maturated before being impregnated on modified porous material.

(41) A catalyst composition with a porous material being extruded 1.5 mm cylinders Siralox 30 (Sasol, Al2O3/SiO2-70/30 wt %) on which crystals of ZSM-5 molecular sieves are dispersed was prepared according to the procedure described in example 1 using 144 h maturation time. The sample on which the ZSM-5 is impregnated has the suffixC144. 5 g of sample was used for synthesis and the amount of the reagent was adjusted proportionally to the amount of the support. The surface area and the acidic sites measured on the catalyst composition obtained are summarized in table 5.

(42) TABLE-US-00005 TABLE 5 Extruded Siralox 30 impregnated with crystals of ZSM-5 molecular sieve. Acid sites, SBET, Vmicro, TPD NH3, cm3/g cm3/g mol/g Siralox 30, 1.5 mm cylinders 284 0.001 414 Siralox 30, 1.5 mm cylinders -C144 375 0.029 505

(43) It appears that the impregnation of crystal of ZSM-5 according the invention allows increasing the surface area of the already shaped catalyst.

Example 7Characterization of the Various Catalysts by .SUP.27.Al MAS NMR

(44) The catalyst compositions were also characterized via .sup.27Al MAS NMR. Indeed .sup.27Al MAS NMR allows determining the coordination and the local structure of aluminium species in zeolites since each .sup.27Al site can be readily resolved based on their distinctly different chemical shifts (). FIG. 13 shows the .sup.27Al MAS NMR spectra of the composites and its precursors. The .sup.27Al NMR spectrum of the starting solution shows a signal of 51.3 ppm characteristic peak of tetrahedrally coordinated aluminium (Al.sup.IV) in which the aluminium atoms are integrated within the siliceous tetrahedral lattice with four fold coordination. After 12 h aging at 100 C., some octahedrally coordinated aluminium (Al.sup.VI) is also present in the aged precursor as indicated by the peak with chemical shift ca.0.7 ppm.

(45) The .sup.27Al NMR spectrum of the parent matrix (Siralox 30; 600 C.) shows signals at 6.6 and 63.4 ppm which are attributed to octahedrally and tetrahedrally coordinated Al atoms, respectively. The .sup.27Al NMR spectra of the catalyst compositions (C144 and 3 nanocasted composite) exhibit some differences compared to the spectrum of the parent matrix; the signal of the tetrahedrally coordinated aluminium is shifted to higher field.

(46) The nanocasted composites shows a broad low-intensity Al.sup.IV peak at =53.4 ppm, which evolves with the crystallization time (i.e. 6 days or 144 h), shifting toward =55.4; the latter peaks present an outline sharper than the former peak, thus indicating a more defined coordination of Al atom into zeolite lattice, which is a consequence of the crystallite growth in C144 composite.

(47) The crystals of molecular sieves deposited on the siralox matrix cannot be evidenced by XRD. They are indeed too small to being detected via XRD. However they can be evidence via .sup.27Al NMR as the Al.sup.IV peak at =53.4 ppm demonstrates the presence of tetrahedrally coordinated aluminium Al characteristic of crystallized molecular sieve.

(48) The increase of surface area, the absence of XRD signature and the presence of tetrahedrally coordinated aluminium demonstrate that very small crystal of molecular sieve are deposited on the surface of the siralox matrix.