Patent Application
20170157598
The present invention relates to a method for preparing hierarchical materials combining both micro- and mesoporosity and involving a recoverable and recyclable mesopore templating agent in mild aqueous conditions.
Zeolites are important catalytic materials in petroleum refining industry and petrochemistry, thanks to their microporous structure, strong acidity and hydrothermal stability. However, the presence of micropores (diameter <2 nm), which allows both a high surface area and shape selectivity, may limit their unique catalytic properties to small reactant molecules, due to steric constraints. One of the major issues in the development of new zeolite catalysts is to ensure a better accessibility of the zeolite's active sites for the reactant and/or product molecules, in order to maximize the catalyst effectiveness.
The industrially developed method consists in creating mesoporosity in zeolites via a ‘destructive’ (structure breaking) approach such as dealumination using steaming or leaching techniques. From a cost perspective, these techniques are attractive, which explains why they are largely used today in industry. However, the introduction of mesopores by these ways presents two major drawbacks:
To alleviate the above mentioned issues, several routes have been developed:
However, the effective application in industry of hierarchically porous materials obtained following the above mentionned routes is still highly limited because of their high cost, which is partially related to the high cost of the organic template also called Structure Directing Agent (SDA). In order to remove this SDA, the material generally needs to be calcined at a high temperature, which decomposes the structuring agent into small components that may be extracted from the pores. Calcination may produce negative effects such as deterioration of the structure of the material and salting-out of effluents that may cause environmental problems and/or high energy consumption.
The present invention relates to a process for manufacturing hierarchically porous materials combining both micro- and mesoporosity, the controlled mesoporosity being obtained by using an organic structuring agent recoverable and recyclable under mild aqueous conditions, thus alleviating:
The use of organic SDA that can be disassembled within the zeolite pore space to allow removal of their fragments for possible use again by reassembly and thus avoid high temperature combustion was first reported by the group of M. E. Davis in 2003 [Nature 425, 385-388] in the field of microporous zeolite materials.
WO 2012/070067 A2 discloses the use of a templating agent for preparing a MWW type zeolite by mixing together, in the absence of any organic structure directing agent or crystalline MWW type zeolie seeds, a predetermined quantity of a compound containing silicon dioxide, a compound containing metal oxide, water and a pH modifier to obtain an aqueous amorphous metallosilicate gel followed by a step of hydrothermally treating said gel in the presence of an organic templating agent to provide a crystalline MWW zeolite. This document discloses the templating agent like N,N,N-trimethyl-l-adamantammonium hydroxide or trimethyl ammonium bromide. Such templating agent presents the ability to form micelles, they however do not present the ability to disable by changing one parameter like the temperature or the pH. The templating agent is then necessarily removed by calcination. All the examples presented in this document clearly indicate that the solid prepared has to be calcined.
WO 2007/130395 A2 discloses the preparation of zeolites with uniform intracrystal textural pores between 1 and 10 nm. An alumina source and a silica source are reacted in the presence of a silane modified polymer as a porogen and the reaction product is calcined to form the zeolite. In particular this document discloses the use of polymer modified silane. In such polymer modified silane, the polymer is covalently linked to the silicon. This polymer modified silane is then used as structure directing agent. The silicon of the polymer modified silane is incorporated in the zeolite formed and can only be removed via calcination.
Minkee Choi et al. in Nature Materials, vol. 5 no 9, pages 718-723 discloses the use amphiphilic organosilane surfactant in the preparation of zeolites. The amphiphilic organosilane surfactants present functional groups to enhance the interaction with growing crystals more precisely the amphiphilic organosilane surfactants present a hydrolysable methoxysilyl moiety, a zeolite structure-directing group such as a quaternary ammonium and a hydrophobic alkyl chain moiety. The organosilane strongly interact with the growing crystal domains through the formation of covalent bonds with other SiO2 and Al2O3 sources using the methoxysilyl moiety.
In 2008, the group of C. Gérardin was the first one to propose an ecologically minded design for preparing ordered mesoporous materials: the method is based on the use of new colloidal structuring agents obtained by the nonconvalent reversible assembly of hydrophilic polymers in water during the synthesis of silica; an important property of these polymers is their capacity to form induced micellar aggregates either by addition of another component, or by a physico-chemical stimulus such as a variation of pH, ionic strength, or temperature; the use of an opposite stimulus to recover the structuring agents circumvents the classical calcination treatment at high temperature. The concept was demonstrated by mesostructured silica preparation at room temperature using reversible pH-responsive micellar assemblies of water-soluble double hydrophilic block copolymers (DHBCs) [N. Baccile et al., Angew. Chem. Int. Ed., 2008, 47, 8433-8437; WO2009/081000].
The extension of this concept to the use of thermosensitive DHBC as SDA for the formation of mesoporous silica can be found in [J. Reboul et al., Polymer Preprints, 2011, 52(2), 717].
However, the work achieved by Gérardin et al. on thermosensitive DHBC as structuring agents is limited to the preparation of amorphous mesoporous materials under acidic conditions due to the nature of the (PEO) micelles corona. Such synthesis conditions are far from those required for the synthesis of crystallized zeolitic structures, as a strong basic solution (pH above 10, more preferably above 12) is used to favor the reorganization of the aluminosilicate species around the structuring agent. The interactions between the thermosensitive DHBC and the silice are of the nature of hydrogen bond under acidic condition and they cannot be transposed under basic conditions. However for the preparation of crystalline materials can only be performed under basic solution.
The present invention discloses the synthesis of mesoporized micropore-containing crystalline material including silicates and aluminosilicates by involving a mesopore templating agent, which is recoverable and recyclable under mild conditions in water.
For the first time, it has been demonstrated among others that:
Given the wide field of applications concerned by the use of hierarchically porous zeolites overcoming diffusional limitations, such as hydrocracking, oligomerization, FCC, and others, the present invention might play a crucial role for industrial implementation of hierarchically porous zeolites by alleviating:
For that aim, the instant invention discloses a method for preparing mesoporous microporous crystalline material involving at least one mesopore-templating agent, said method comprising the following steps:
The parent material of step (a) is preferably a microporous crystalline aluminosilicate.
Alternatively, the parent material of step (a) is chosen among
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, . . . ). The crystal structure of a crystalline silicate as determined by X-Ray diffraction is defined by the specific order in which a network of tetrahedral units are linked together. The size of the crystalline silicate pore openings is determined by the number of tetrahedral units, or, alternatively, oxygen atoms, required for forming the pores and the nature of the cations that are present in the pores. They possess a unique combination of the following properties: high internal surface area; uniform pores with one or more discrete sizes; ion exchangeability; good thermal stability; and ability to adsorb organic compounds. The Atlas of Zeolite Framework Types (C Baerlocher, L B McCusker, D H Olson, 6th ed. Elsevier, Amsterdam, 2007) in conjunction with the web-based version (http://www.iza-structure.org/databases/”) is a compendium of topological and structural details about crystalline silicate frameworks, including the types of ring structures present in the zeolite and the dimensions of the channels defined by each ring type.
Various commercial zeolite products may be used, or it is possible to use zeolites that have been synthesized by a known method disclosed in e.g. “Verified Synthesis of Zeolitic Materials” (2nd Revised Edition 2001 Elsevier) published by the above IZA.
According to an embodiment, the dealuminated crystalline silicate is advantageously such as about 10% by weight of the aluminium is removed. Such dealumination is advantageously made by a steaming optionally followed by a leaching.
In a preferred embodiment, suitable zeolites for use in the process described herein comprise a topology selected from the group comprising BEA, MFI, FAU, MEL, FER, MOR and MWW.
In a specific embodiment, the preferred parent crystalline silicate is a crystalline aluminosilicate having the FAU topology. A particularly preferred zeolite is a Y zeolite in protonated form having the FAU structure and a bulk Si/Al ratio greater than or equal to 12, preferably of 15. Such a zeolite Y may be obtained, for example, by applying to a parent Y at least one dealumination treatment, in particular, a partial dealumination treatment, for example with at least one acid and/or water vapour. Most particularly, these treatments correspond to those described in patent U.S. Pat. No. 5,601,798.
Exemplary commercially available zeolites suitable for use in the present invention described herein include, but are not limited to Y zeolite (FAU topology).
As a micropore-templating agent, it is possible to use alkaline metal ions, quaternary ammonium salts, organic ammonium salts. Tetraalkylammonium such as tetramethylammonium, tetraethylammonium, tetrapropylammonium, etc., may be preferably employed.
Said mesopore-templating agent can be either an ionic molecule or a polymer bearing at least one ionic function, rendered amphiphilic upon the effect of the variation of a physico-chemical parameter (pH, temperature, ionic strength).
The mesopore-templating agent according to the invention contains a thermosensitive oligomeric or polymeric chain, which is preferably made of the following constituting parts:
In a preferred embodiment, the selected organic polymer chain is a statistical copolymer of PEO (poly(ethyleneoxide)) and PPO (poly(propyleneoxide)), the relative proportion of EO (ethylene oxide) and PO (propylene oxide) units in the polymer chain being of key importance as it determines the LCST (Lower Critical Solution Temperature) of the organic polymer chain.
In a preferred embodiment, the mesopore-templating agent is selected among statistical copolymers of PEO (poly(ethylene oxide)) and PPO (poly(propylene oxide)) functionnalized by a quaternary ammonium salt, such as quaternized Jeffamines® (obtained from Hunstman International), the molecular size of which varying from 140 to 5000 g/mol and the ethylene oxide/propylene oxide molar ratio of which varing from 0.01 to 5, more preferably from 0.1 to 1, most preferably from 0.1 to 0.5, said Jeffamines® being quaternized on their primary amine.
The Jeffamine® can be selected among Jeffamine® M600 and Jeffamine® M2005.
According to another aspect, the invention discloses a mesopore templating agent comprising an organic cationic product having (i) a molecular weight comprised between 250 and 3000 g/mol, (ii) an optionally branched hydrocarbon chain containing from 12 to 150 carbon atoms and from 5 to 45 oxygen atoms which are inserted within the hydrocarbon chain and wherein each oxygen is bound with two distinct carbon atoms to obtain ether bonds,(iii) a terminal quaternary ammonium moiety —({[N(R4)(R5)](R6)n}—H)+, wherein R4 and R5 are each selected among C1-C10 alkyl, R6 is —(CH2)m— with m=1 to 10 and n is 1, 2 or 3, preferably 1.
The mesopore templating agents according to the invention have the general structure {(R1—O—(R2—O—)a—(R3)b—[N(R4)(R5)(R6)]n—H)}+, X−; wherein (a) and (b) are each independently comprised between 0 and 75 and the sum of (a) and (b) is not above 75, and wherein R1, R2, R3, R4, R5, R6 are each independently chosen among C1-C6 alkyl, and X− is an anion, preferably chosen among Cl, Br and OH.
More preferably, R1 is methyl, R2, R3, are each ethyl, propyl or isopropyl, R4, R5, R6 are each independently chosen among C1-C3 alkyl, preferably C1 alkyl.
X— is advantageously an anion chosen among F, Cl, Br, I, OH, PF6, H2PO3, NO3, HSO4, BF4, R7—COO wherein R7 is C1-C3 alkyl, and wherein X— is preferably Cl, Br or OH.
Examples of suitable mesopore templating agents according to the invention include quaternized commercial or non commercial Jeffamine® such as Jeffamine® M600 and Jeffamine® M2005.
According to a first preferred embodiment, the mesopore templating agent according to the invention has the general structure [R1—O—(R2—O—)a—(R3)b—N(R4)(R5)(R6)]+, X−; wherein:
The quaternary ammonium group of the mesopore templating agent is quaternized, preferably with chloride, bromide or hydroxide.
The hydrodynamic diameter of the unimers can range from 0.1 to 5 nm at room temperature in the solution of step (a) and the micellar aggregates can have a hydrodynamic diameter of 10 nm to 2 μm at a temperature ranging from 40 to 90° C. respectively.
As regards the obtention of a mesoporous microporous crystalline silicate or aluminosilicate, the solution of step (a) is basic. The base used in step a) is a strong base and/or a weak base. Preferably the base is an alkali hydroxide, alkaline earth hydroxide, tetraalkylammonium hydroxide, sodium carbonate, potassium carbonate, ammonium carbonate, sodium citrate, potassium citrate, ammonium citrate, NH4OH.
According to another embodiment, the base of step (a) is NaOH, NH4OH or preferably tetramethylammonium hydroxide.
The concentration of the base ranges from 0.001 to 2M, more preferably from 0.01M to 2M, even more preferably from 0.5 to 1M.
The mesopore-templating agent/Si molar ratio in step (a) may range from 0.01 to 0.5, preferably from 0.041 to 0.3, more preferably from 0.08 to 0.18, in particular from 0.08 to 0.165.
In step (b), the mixture as prepared in step (a) can be submitted to mild hydrothermal conditions i.e.:
As regards the step (c), the treatment of step (b) is stopped by cooling down or quenching the system. Optionally, a neutralization may also be performed by contacting the system as obtained in step (b) with any type of acid-containing solution. The acid may be an inorganic or an organic acid, for example, sulfuric, phosphoric, citric, acetic, maleic, pyruvic, levulinic, 2-ketogulonic, keto-gluconic, thioglycolic, 4-acetylbutyric, 1,3-acetonedicarboxylic, 3-oxo propanoic, 4-oxo butanoic, 2,3-diformyl succinic, 5-oxo pentanoic, 4-oxo pentanoic, glycolic, oxamic, glyoxylic acid, EDTA (ethylenediaminetetraacetic acid), nitrilotriacetic acid, N-methylaminodiacetic acid, iminodiacetic acid, diglycolic acid, malic acid, gluconic acid, acetylacetone, tartaric acid, aconitic acid, suberic acid, tricarballylic acid, malonic acid, succinic acid and glycolic acid, formic acid, propionic acid, butyric acid, valeric acid, caproic acid, enantic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, benzoic acid, salicylic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, phtalic acid, isophtalic acid, lactic acid or a mixture of those, in particular, under industrial conditions, on a large amount of material. The neutralization step may likewise be performed in presence of water. This neutralization is advantageously carried out at room temperature under magnetic or mechanical stirring.
The acid-containing solution comprises at least one acid, for example, at a concentration ranging from 0.005 to 2M.
The purpose of the neutralization is to stop the process and to prevent the undesired destruction of the material that can result in extensive loss of crystalline structure of the zeolite, loss of microporosity and induce a decrease in the intrinsic activity of the material.
In step (d), the mesoporous microporous crystalline material can be recovered by filtration optionally followed by washing treatment.
In step (d) the mesoporous microporous crystalline material is preferably recovered according to the following procedure: (d1) filtration, (d2) optionally washing, in sequential or continuous mode, of the mesoporous microporous crystalline material so as to extract the mesopore-templating agent at least in part, with a washing solution, (d3) drying, and (d4) optionally calcination.
The washing step can be conducted using water or a solution containing nitric acid, ammoniac or ammonium nitrate, or methanol either pure or in mixture with another solvent, a filtration step allowing to extract a part of the mesopore templating agent(s) and a washing step allowing to extract another part of the mesopore-templating agent(s).
The washing solution is preferably (i) demineralized water or (ii) a water solution containing nitric acid, ammonia or ammonium nitrate, or (iii) pure methanol
The filtration step is preferably performed at a temperature below the LCST, which allows releasing at least 20% of the mesoporosity of the final material, and preferably at least 25% of the final material.
The additional washing step is preferably performed with water at a temperature below the LCST, wherein more than 70% of the mesoporosity of the material is released, preferably at least 75%.
More preferably, the washing step is performed using an aqueous solution containing an acid, preferably nitric acid, allowing to release up to 90% of the mesoporosity of the material. The concentration of the acid ranges from 0.001 to 0.2M, preferably from 0.01 to 0.15M, more preferably from 0.05 to 0.012M.
In step (d) the mesoporous microporous crystalline material can be recovered by filtration and the filtrate can be recovered and recycled as a basic aqueous solution at step (a) in a further mesoporization processing after being adjusted to a basic pH required for synthesis, and optionally after the mesopore templating agent concentration is adjusted to the required level, said mesoporization processing being repeated at least one more time.
The method according to the present invention, when applied to microporous crystalline silicates or aluminosilicates, can lead to the synthesis of mesoporous microporous crystalline material having the following characteristics:
In another specific embodiment, the hierarchical micro- and mesoporous crystalline material of the present invention can be formulated into a catalyst by combination with other materials that provide additional hardness or catalytic activity to the finished catalyst product. Materials which can be blended with the hierarchical material can be various inert or catalytically active materials or various binder materials. These materials include compositions such as kaolin and/or other clays, various forms of rare earth metals, phosphates, alumina or alumina sol, titania, zorconia, quartz, silica or silica sol and mixtures thereof. The catalyst may be formulated into pellets, spheres, extruded into other shapes pr formed into spray-dried particles. The amount of hierarchical material which is contained in the final catalyst product ranges from 10 to 90 weight percent of the total catalyst preferably 20 to 80 weight percent of the total catalyst.
The catalyst will contain an effective amount of an active phase comprising at least one hydrogenating/dehydrogenating component selected from the group VIB elements and the non-precious elements of group VIII of the periodic table, used alone or in a mixture, said catalyst being a sulphide phase catalyst.
Preferably, the group VIB elements of the periodic table are selected from the group formed by tungsten and molybdenum, used alone or in a mixture. According to a preferred embodiment, the hydrogenating/dehydrogenating element selected from the group formed by the group VIB elements of the periodic table is molybdenum. According to another preferred embodiment, the hydrogenating/dehydrogenating element selected from the group formed by the group VIB elements of the periodic table is tungsten.
Preferably, the non-precious elements of group VIII of the periodic table are selected from the group formed by cobalt and nickel, used alone or in a mixture. According to a preferred embodiment, the hydrogenating/dehydrogenating element selected from the group formed by non-precious group VIII elements is cobalt. According to another preferred embodiment, the hydrogenating/dehydrogenating element selected from the group formed by non-precious group VIII elements is nickel.
Preferably, said catalyst comprises at least one metal of group VIB in combination with at least one non-precious metal of group VIII, the non-precious group VIII elements being selected from the group formed by cobalt and nickel, used alone or in a mixture, and the group VIB elements being selected from the group formed by tungsten and molybdenum, used alone or in a mixture.
Advantageously, the following combinations of metals are used: nickel-molybdenum, cobalt-molybdenum, nickel-tungsten, cobalt-tungsten, the preferred combinations being: nickel-molybdenum, cobalt-molybdenum, cobalt-tungsten, nickel-tungsten and even more advantageously nickel-molybdenum and nickel-tungsten.
In the case where the catalyst comprises at least one metal of group VIB in combination with at least one non-precious metal of group VIII, the content of metal of group VIB, in oxide equivalent, is advantageously between 5 and 40 wt. % relative to the total weight of said catalyst, preferably between 10 and 35 wt. % and very preferably between 15 and 30 wt. % and the content of non-precious metal of group VIII, in oxide equivalent, is advantageously between 0.5 and 10 wt. % relative to the total weight of said catalyst, preferably between 1 and 8 wt. % and very preferably between 1.5 and 6 wt. %.
In another embodiment, the catalyst will contain an effective amount of at least one Group VIII metal. Group VIII metals include platinum, palladium, rhodium, osmium, iridium, ruthenium, cobalt, nickel, and iron. Noble metals (platinum, palladium, rhodium, osmium, iridium, and ruthenium) are preferred. Most preferably, the Group VIII metal is platinum or palladium.
The amount of Group VIII metal present in the catalyst will usually be an amount of at least about 0.01 percent by weight to about 3.0 percent by weight (based on the weight of the molecular sieve).
The hydrogenating/dehydrogenating phase may be incorporated into the catalyst by methods known in the art, such as by ion exchange, impregnation or by physically intimately admixing with the molecular sieve.
The unique structure of the catalysts produced according to the invention will be useful to a variety of fields, and should address certain limitations associated with conventional zeolites. It may benefit to all catalytic applications encountering diffusional limitations, especially in applications using bulky molecules. Among others catalytic cracking, fluidized catalytic cracking, hydrogenation, hydrodesulfurization, hydrocracking, hydroisomerization, oligomerization, alkylation processes.
The following Examples illustrate the present invention without limiting its scope.
In these Examples, the following abbreviations are used:
The main characteristics of HY15 parent zeolite are gathered in the table below
To be stressed, the presence of disordered mesopores already present in the zeolite crystals.
A polymer group, called Jeffamine®, are statistic copolymers of PEO and PPO. Different types of functionnalization (mono-, di-, tri-primary amines) are proposed. All these polymers are cheap commercially available polymers.
The size of the PEO and PPO chain may vary as well as the relative proportion of the PEO/PPO ratio, leading to a large variety of commercially available Jeffamines®, the molecular size of which varying from 140 to 5000 g/mol. The relative proportion of EO and PO units in the polymer chain is of key importance as it determines the hydrophilic/hydrophobic balance as well as the LCST. Jeffamines® are thermosensitive copolymers.
The powder X-ray diffraction patterns were measured on a Bruker D8 Advance diffractometer (weighted mean CuKα radiation at λ=1.541838 Å) with a Bragg-Brentano geometry and equipped with a Bruker Lynx Eye detector. The data were recorded in the range 0.5-6° and 5-35° 2θ with an angular step size of 0.0197° and a counting time of 0.1 s per step.
The SEM observations were performed by using a Hitachi S4800 microscope with a resolution of 1 nm. The samples were first covered with platinum.
The TEM experiments were performed by using a JEOL 1200 EX II electron microscope operated at 100 kV with a resolution of 0.5 nm. The samples were prepared by dispersion in ethanol and deposition onto a carbon-coated copper grid. The observations of thin slices of 70 nm thickness were also obtained by ultramicrotomy of the sample embedded in a polymer resin (LR White) then deposited on a copper grid.
The N2 and Ar adsorption-desorption isotherms were measured at −196° C. on a Micromeritics TriStar 3000 instrument and an ASAP 2020 instrument. Prior to each measurement, the samples were outgassed in vacuum at 250° C. for at least 6 hours (for N2) and at least 12 hours (for Ar).
The apparent surface areas (SBET) were determined according to the BET model from the adsorption branches. The micro- and mesopore volumes (Vmic, Vmes) together with the micro- and mesopore surface areas (Smic, Smes) for nitrogen and argon were calculated using the αs-plot method, with the non porous silica Aerosil 200 as a reference adsorbent. The total pore volumes (Vtot) were evaluated from the amount adsorbed at a relative pressure of about 0.99 using the liquid nitrogen (or argon) density at 77K.
The Dynamic Light Scattering (DLS) measurements were performed with a Zetasizer Nano ZS apparatus from Malvern Instruments equipped with a helium-neon laser of 4 mW at 632.8 nm and a backscatter detector located at 173° to the incident beam. The temperature can be set from 5 to 90° C. with precision (+/−0.1° C.) using thermoelectric Peltier cells. The samples were filtered through nylon syringe filter 0.2 μm, directly into the quartz measurement cell (1 cm) previously dried. The cell is closed with a Teflon stopper and stabilized at the desired temperature for 2 minutes. Parameters such as the number of accumulations or the depth measurement in the vessel are automatically optimized by the device. This technique allows determining the size of objects in solution based on their Brownian motion by studying the distribution of a coherent monochromatic incident beam (laser). These objects may be nano particles or polymers in solution, assembled or not in the form of micelles or aggregates.
The quaternization of the primary amine of the Jeffamine® has been performed by reacting an excess of iodomethane CH3I according to the synthesis protocol of Cope et al. [A. C. Cope, JACS, 1960, 82, 4651-4655].
In a 500 ml vessel equipped with a cooler, 41.5 g (0.07 mol) of Jeffamine® M600 are dissolved in 300 ml of methanol in presence of 34 g (0.4 mol) of sodium bicarbonate. 30 g (0.21 mol) of iodomethane CH3I are added under stirring before heating under reflux during 72 hours away from light. After 24 hours, 30 g (0.21 mol) of additional iodomethane CH3I are added to the reaction medium. After complete cooling, the water traces are removed by adding anhydrous magnesium sulfate and the solution is filtered to remove the precipitated salts. The filtrate is evaporated at 80° C. under vacuum to obtain a visqueous ambarino yellow liquid, containing precipitated salts. A small amount of chloroform is added to dissolve the polymer and insoluble salts are removed by cold filtration. The solvent is then evaporated to recover the Jeffamine® iodide quaternized M600.
The yield of the quaternization is 95% for the iodide quaternized Jeffamine® M600.
20 g (0.026 mol) of iodide quaternized Jeffamine® from step (a) were dissolved in 200 ml of water. 20 ml of Amberlyst IRA400 resin (1.4 meq/ml) under chloride form were first washed with water before adding the solution of iodide quaternized Jeffamine®. The reactional medium is then heated up to 50° C. under stirring during 24 hours. After cooling down, the suspension is filtered and the filtrate is subsequently processed with a flowrate of 2 ml/min on a column loaded with 20 ml of Amberlyst IRA400 resin previously washed. The recovered solution is evaporated at 90° C. under vacuum to remove water. The remaining chloride quaternized Jeffamine® is then dissolved in absolute ethanol to remove any water traces by azeotropic evaporation under vacuum. The obtained chloride quaternized Jeffamine® is a white waxy solid.
The polymeric chain of Jeffamine® is thermosensitive. At low temperature, the quaternized Jeffamine® M600 is soluble under the form of unimer (˜1 nm) in solution. Starting from 50° C., the hydrophobicity of the polymer chain is high enough to generate a surfactant behavior so that unimers assemble to form small objects. With temperature increase, the chain becomes more and more hydrophobic and micelles turn into aggregates of around 50 nm from 50° C. up to 530 nm at 90° C. as determined by DLS. No precipitation is observed as micelles are stabilized by their positive charged corona. The micelles formation is reversible as by decreasing the temperature back below 50° C. the Jeffamine® unimers are completely dissociated in solution.
For the quaternized Jeffamine® M600, micelles are formed from 75° C. and the size of the micelles grows from 75° C. up to 90° C.
The recrystallization of the parent sample HY15 zeolite has been performed according to the synthesis protocol described by Ying. et al. [J. Y. Ying, US2007244347]: 1.67 g of the HY15 zeolite are mixed together at room temperature with 50 ml of a 0.09M TMAOH solution under vigourous stirring in a 120 ml autoclave. 0.83 g of CTAB are then added to the suspension maintained under stirring during 20 min. The mixture has a CTAB/Si molar ratio of 0.082. The autoclave is then hermetically closed and the reactional medium submitted to static hydrothermal conditions at 150° C. under autogeneous pressure during 20 hours. After quick cooling down of the autoclave in a water bath, the solid is recovered by filtration and washed using demineralized water until a neutral pH is reached. The solid is then dried overnight in an oven at 80° C. The whole solid porosity is recovered by complete calcination of the contained organic species (CTAB and TMAOH) in a tubular oven at 550° C. (1° C./min) during 8 hours under air (200 ml/h).
The characteristics of the parent zeolite Solid A as obtained are reported in Table 2.
adetermined by ATG between 150 and 900° C.;
bdetermined by XRD;
cdetermined by EDX;
dbetween 2 and 10 nm.
The recrystallization of zeolite HY15 in the presence of the CTAB is efficient to generate mesoporosity inside the zeolite, while preserving the initial crystal shape. The recrystallized materials possess a hierarchical structure with long range zeolite crystallinity and a high mesoscopic order of the mesopores located in the same crystals (
0.462 g (0.682 mmol) of chloride quaternized Jeffamine® M600 is dissolved under stirring at room temperature in 15 ml of 0.09M TMAOH solution during 10 min in a 20 ml autoclave.
0.5 g of HY15 are then added to the solution under stirring during 20 min. The amount of quaternized Jeffamine® M600 has been determined by keeping a N+/Si ratio of 0.082.
The autoclave is then hermetically closed and the reactional medium submitted to static hydrothermal conditions at 150° C. under autogeneous pressure during 20 hours. After quick cooling down of the autoclave in a water bath, the solid is recovered by filtration and washed using demineralized water until a neutral pH is reached. The solid is then dried overnight in an oven at 80° C. The solid porosity is recovered by washing or calcination of the contained organic matter in a tubular oven at 550° C. (1° C./min) during 8 hours under air (200 ml/h).
The characteristics of the Solid B are reported in Table 3.
In
The procedure is the same as in Example 3 (a).
The procedure is the same as in Example 3 (b) except that the reaction mixture was subjected to 120° C. instead of 150° C.
The characteristics of the Solid C are reported in Table 3.
As for Solid B, the same conclusions can be drawn: conservation of the structure of the parent zeolite Y; formation of a homogeneous vermicular mesoporous phase in the solid; mesopores have a narrow distribution centered around 5.5 nm; microporosity and mesoporosity are intimately connected suggesting an excellent interconnectivity between the two pore systems and bringing the proof of the true hierarchical porosity of the recrystallized zeolite crystals.
The procedure is the same as in Example 3 (a).
The procedure is the same as in Example 3 (b) except that the reaction mixture was subjected to 100° C. instead of 150° C.
The characteristics of the Solid D are reported in Table 3.
As for Solid B and C, the same conclusions can be drawn: conservation of the structure of the parent zeolite Y; formation of a homogeneous vermicular mesoporous phase in the solid; mesopores have a narrow distribution centered around 5.5 nm; microporosity and mesoporosity are intimately connected suggesting an excellent interconnectivity between the two pore systems and bringing the proof of the true hierarchical porosity of the recrystallized zeolite crystals.
0.924 g (1.36 mmol) of chloride quaternized Jeffamine® M600 is dissolved under stirring at room temperature in 15 ml of 0.09M TMAOH solution during 10 min in a 20 ml autoclave. 0.5 g of HY15 zeolite are then added to the solution under stirring during 20 min. The amount of quaternized Jeffamine® M600 has been determined by keeping a N+/Si ratio of 0.164.
The procedure is the same as in Example 4 (b).
The characteristics of the Solid E are reported in Table 3.
As for Solid B, C and D, the same conclusions can be drawn: conservation of the structure of the parent zeolite Y; formation of a homogeneous vermicular mesoporous phase in the solid; conservation of the Y zeolitic structure; mesopores have a narrow distribution centered around 5.5 nm; microporosity and mesoporosity are intimately connected suggesting an excellent interconnectivity between the two pore systems and bringing the proof of the true hierarchical porosity of the recrystallized zeolite crystals.
0.74 g (0.682 mmol) of chloride quaternized Jeffamine® M1000 is dissolved under stirring at room temperature in 15 ml of 0.09M TMAOH solution during 10 min in a 20 ml autoclave. 0.5 g of HY15 zeolite are then added to the solution under stirring during 20 min. The amount of quaternized Jeffamine® M1000 has been determined by keeping a N+/Si ratio of 0.082.
The autoclave is then hermetically closed and the reactional medium submitted to static hydrothermal conditions at 150° C. under autogeneous pressure during 20 hours. After quick cooling down of the autoclave in a water bath, the solid is recovered by filtration and washed using demineralized water until a neutral pH is reached. The solid is then dried overnight in an oven at 80° C. The solid porosity is recovered by washing or calcination of the organic matter contained in a tubular oven at 550° C. (1° C./min) during 8 hours under air (200 ml/h).
The characteristics of the Solid F are reported in Table 3. The use of chloride quaternized Jeffamine® M1000 does not allow to create a mesostructure in the HY15 zeolite: the N2 isotherms of solid F present the same trend as the one of the parent HY15, indicating a similar pore size distribution. The Jeffamine® M1000 having a high hydrophilic/hydrophobic balance, its corresponding LCST is not fitting with the recrystallization conditions used.
1.42 g (0.682 mmol) of chloride quaternized Jeffamine® M2005 is dissolved under stirring at room temperature in 15 ml of 0.09M TMAOH solution during 10 min in a 20 ml autoclave. 0.5 g of HY15 zeolite are then added to the solution under stirring during 20 min. The amount of quaternized Jeffamine® M2005 has been determined by keeping a N+/Si ratio of 0.082.
The procedure is the same as in Example 5 (b).
The characteristics of the Solid G are reported in Table 3.
Here again, the formation of a true hierarchical porosity of the recrystallized zeolite crystals is confirmed having the following characteristics: conservation of the structure of the parent zeolite Y; formation of a homogeneous vermicular mesoporous phase in the solid; the distribution of mesopores is this time larger than for Solid B with two main contributions centered respectively around 8 and 15 nm; microporosity and mesoporosity are intimately connected. It is also the proof that even by using recyclable structuring agents, it is possible to tune the size of the mesopores of the mesostructure by an accurate choice of the structuring agent.
0.924 g (1.36 mmol) of chloride quaternized Jeffamine® M600 is dissolved under stirring at room temperature in 15 ml of 0.09M TMAOH solution during 10 min in a 20 ml autoclave. 0.5 g of HY15 zeolite are then added to the solution under stirring during 20 min. The amount of chloride quaternized Jeffamine® M600 has been determined by keeping a N+/Si ratio of 0.164.
The autoclave is then hermetically closed and the reactional medium submitted to static hydrothermal conditions at 120° C. under autogeneous pressure during 20 hours. After quick cooling down of the autoclave in a water bath, different routes have been investigated:
adetermined by ATG between 150 and 900° C.
bdetermined by EDX
cdiameter of main pores
afiltration without washing;
bdetermined by ATG between 150 and 900° C.;
cdetermined by elemental analysis;
ddetermined by EDX;
emesopores <10 nm;
After recrystallization of the zeolite, during the cooling down of the solution, micelles of chloride quaternized Jeffamine® M600 disassemble within the mesopores of the material.
A single filtration at room temperature without washing (Solid Hi) allows extracting 30% of the structuring agent present in the recrystallized zeolite.
A washing by water at room temperature allows to extract 30% additional structuring agent (Solid Hii), bringing to 60% the total amount of extracted quaternized M600 Jeffamine® from the material. 73% of the mesoporous volume is then recovered in mild conditions without calcining the material. The temperature of the water used during the washing does not seem to have a strong impact on the amount of organic material extracted (Table 5).
The use of an acid solution (Solid Hv) improves furthermore the extraction by exchanging TMA+ cations with H+: by 90% of the mesoporous volume by 15% of the microporous volume become accessible.
The results obtained with methanol as washing solvent (Solid Hviii) are better than those obtained using NH4OH (Solid Hvi) or NH4NO3 (Solid Hvii) containing solution, but remain not so good as with HNO3 solution (Solid Hv).
The results obtained here clearly show the feasibility of the extraction of the structuring agents from the porosity of the mesoporized zeolites.
The same recrystallization protocol as for Solid H was used (Example 9).
After cooling down in an ice bath, the suspension is filtered at room temperature and the solid is rinsed with 3 ml of demineralized water. The solid is dried at 80° C. (Recrist.1).
The filtrate is recovered and before being reused in further recrystallization experiences, the pH of the filtrate is adjusted to 13, corresponding to the pH of the initial recrystallization solution before the hydrothermal treatment by adding drops of TMAOH (25% solution). The parent zeolite HY15 is then added and the system is stirred during 20 minutes followed by the hydrothermal treatment at 120° C. After cooling down and filtration at room temperature, the second solid is recovered (Recrist.2). The recycling/recrystallization protocol is repeated two more times using the same solution of quaternized Jeffamine® M600. Two additional recrystallized zeolite samples are obtained (Recrist.3/ Recrist.4).
The recrystallization yields are high comprised between 92 and 94%.
The characteristics of the recrystallized zeolites are gathered Table 6 and
adetermined by ATG between 150 and 900° C.;
bdetermined by elemental analysis;
cdetermined by EDX;
dmesopores <10 nm
0.421 g (0.682 mmol) of Jeffamine M600 is dissolved under stirring at room temperature in 15 ml of 0.09M TMAOH solution during 10 min in a 20 ml autoclave.
0.5 g of HY15 are then added to the solution under stirring during 20 min. The amount of Jeffamine M600 has been determined by keeping a NH2/Si ratio of 0.082.
The autoclave is then hermetically closed and the reactional medium submitted to static hydrothermal conditions at 150° C. under autogeneous pressure during 20 hours. After quick cooling down of the autoclave in a water bath, the solid is recovered by filtration and washed using demineralized water until a neutral pH is reached. The solid is then dried overnight in an oven at 80° C. The solid porosity is recovered by washing or calcination of the contained organic matter in a tubular oven at 550° C. (1° C./min) during 8 hours under air (200 ml/h).
The characteristics of the Solid I are reported in Table 7.
adetermined by ATG between 150 and 900° C.
bdetermined by EDX
cdiameter of main pores
In solid I, large-angles XRD clearly exhibits a sharp decrease of the cristallinity compared to the parent HY15 zeolite and compared to solid B, whereas a large peak between 15 to 30° 2θ assigned to an amorphous aluminosilica phase is present (
Using small-angles XRD (
Those results are consistent with the textural properties of solid I as measured by N2 adsorption and desorption isotherms (
All these results indicate that a controlled mesoporization is not possible with not quaternized Jeffamine M600 in the considered synthesis conditions (high alkaline medium). A large part of the zeolite structure is destroyed, together with the formation of large mespores and macropores in the material.
1.67 g of the HY15 zeolite are mixed together at room temperature with 50 ml of a 0.09M TMAOH solution under vigourous stirring in a 120 ml autoclave.
0.83 g of CTAB are then added to the suspension maintained under stirring during 20 min. The mixture has a CTAB/Si molar ratio of 0.082.
The autoclave is then hermetically closed and the reactional medium submitted to static hydrothermal conditions at 150° C. under autogeneous pressure during 20 hours. After quick cooling down of the autoclave in a water bath, the solid is recovered by filtration at 25° C. and washed using demineralized water until a neutral pH is reached. The solid is then dried overnight in an oven at 80° C. (solid J).
By calcining solid J in a tubular oven at 550° C. (1° C./min) during 8 hours under air (200 ml/h), solid A is then recovered.
CTAB is a surfactant conserving its amphiphilic properties whatever the temperature or pH conditions are. The N2-physisorption measurements (
| Number | Date | Country | Kind |
|---|---|---|---|
| 14290200.6 | Jul 2014 | EP | regional |
| 15161176.1 | Mar 2015 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/065174 | 7/3/2015 | WO | 00 |
