WO2010097224A2

WO2010097224A2 - Process for the preparation of hybrid zeolite or zeolite-like materials

Info

Publication number: WO2010097224A2
Application number: PCT/EP2010/001177
Authority: WO
Inventors: Karen Thrane HØJHOLT; Kresten Egeblad; Claus Hviid Christensen; Stig Helveg; Bo Anders Laursen; Michael Brorson
Original assignee: Haldor Topsøe A/S
Priority date: 2009-02-27
Filing date: 2010-02-25
Publication date: 2010-09-02
Also published as: WO2010097108A1; WO2010097224A3

Abstract

A process for the preparation of hybrid zeolite or zeolite-like materials comprising the steps of : - providing a solution or suspension or solid material containing nanoparticles comprising at least one metal, - providing a synthesis gel or a synthesis gel precursor of a zeolite or zeolite-like material, - mixing the synthesis gel or the synthesis gel precursor of the zeolite or zeolite-like material with the solution or suspension or solid material containing nanoparticles comprising at least one metal, to form a mixture, - converting the mixture under zeolite or zeolite-like synthesis conditions to hybrid zeolite or zeolite-material encapsulating nanoparticles comprising at least one metal.

Description

Title: Process for the Preparation of Hybrid Zeolite or Zeolite-like Materials

The invention relates to a process for the preparation of a hybrid zeolite or hybrid zeolite-like material. In particular, the invention concerns preparation of hybrid zeolite or zeolite-like material in which metal nanoparticles are encapsulated by the hybrid zeolite or zeolite-like material.

Incorporation of metal nanoparticles in host materials can improve the physical properties of the host material in many ways. This is known for host materials such as glasses, where application of metal nanoparticles improves the optical performance necessary for certain optical devices .

Materials based on noble metals dispersed on support materials of high surface area are useful in many fields, for instance catalysis. However they are generally not stable at high temperatures due to the increased mobility of the meteal particles, and there have been many attempts to prepare such materials that are stable during for instance sintering, which occurs at high temperatures. The reduced stability at high temperature leads to a corresponding reduction in for instance catalytic activity after high temperature treatment.

Gold clusters are known to have catalytic properties for reactions such as the water gas shift reaction, CO Ia

oxidation and NO reduction and as a result much effort has been devoted to the preparation of zeolites and mesoporous materials incorporated with metal clusters and nanoparticles, with the hope that the microporouos channels in the zeolite crystals limits the migration of gold and

the size of the resultant clusters. However, the preparation of gold clusters or nanoparticles in these materials is not feasible compared to the corresponding silver or copper loaded materials due to, amongst others, the formation of metal (gold) nanoparticles both outside and inside the pores and channels of the zeolite.

US patent application no. 20080206562 discloses the preparation of thiol-capped gold nanoparticles which are ligand exchanged, washed, precipitated and dissolved in water to form an aqueous gold nanoparticle solution. This solution is mixed with ethanol and ammonium hydroxide followed by addition of tetraethoxysilane . After stirring and centrifugation gold-silica core shell colloidal particles are obtained. The mixture is calcined to obtain ligand-free gold nanoparticles in hollow porous spheres of silicate .

The product obtained consists of mesoporous silicate particles with each silicate particle encapsulating one metal particle. However the gold nanoparticles are enclosed in hollow porous spheres of silicate and are thus not immobilised. This is a disadvantage because the migration and thus sintring of the nanoparticles is not prevented by the porosity of the silicate spheres.

EP patent application no. 0149343 discloses a process for preparing zeolite-coated substrates useful in forming fluidized beds of magnetically stabilised particles having a larger size preferably in the micron range. The substrate is magnetisable and can be for instance iron or magnetite and in the coating process it is ensured that a zeolite layer is formed on the surface of the magnetisable substrate only, eg by tumbling. The zeolite coating provides amongst others strength or a particular form and there is not indication that sintring of the metal particles may be a problem. Furthermore this product appears to be amorphous in form, which can be problematic to handle in practise.

US patent application no.2009/0048094 discloses the preparation of a catalyst comprising noble metal nanoparticles contained in a zeolite cage directly synthesized by combining the zeolite synthesis reagents with a salt of the meal particle. Finally the cage size can be reduced. A drawback of this process is that the nanoparticle is synthesized under zeolite synthesis conditions. Furthermore the disclosed process is only suitable for zeolite materials having cages.

Wang et al. in Microporous and Mesoporous Materials, Elsevier Science Publishing, New York, US, vol. 110, no. 2-

3. 4 March 2008, pages 451 to 460, disclose the formation of Pd nanoparticles in surfactant mesoporous silica composites such as MCM-41 and MCM-48 by one-pot synthesis.

These materials are amorphous and not as stable thermally as crystalline zeolites. The pores are mesoporous in size, thus allowing entrance and exit of particles of different sizes, including the Pd nanoparticles.

US patent application no. 20080072705 discloses the preparation of an iron oxide mesostructural matrix. A solution of iron oxide nanoparticles in water is added to a suspension containing zeolitic nanocrystals, then mixed, dried and calcined to obtain iron oxide nanoparticles entrapped in an aluminosilicate matrix with organised mesoporosity .

The product obtained consists of a mesoporous amorphous material encapsulating metals or zeolite crystals.

Arnal et al. (Angew. Chem. Int. Ed. 2006, 45, 8224-8227) disclose a process for the preparation of high temperature sinter stable catalysts consisting of gold particles encapsulated by a mesoporous Zrθ2 shell. Preparation of these catalysts is complicated, requiring several steps whereby colloidal gold particles are synthesised, covered with a dense silica layer, thereafter covered by a thin layer of zirconia particles and finally silica and loose gold particles are leached out. Sinter stable catalysts are obtained.

Mekkawy et al. (Egypt. J. Sol., Vol. 25, No. 1, 2002 pages 115-123) disclose electrochemical properties of gold catalysts encapsulated within host material NaY zeolite (microporous) or inside a zeolite like structure such as FSM-16 (mesoporous) . The zeolite is first synthesized and partially dehydrated. Subsequent mixing, evacuating and temperature increase leads to vaporisation and migration of AUCI₃ to interact with water molecules in the zeolite pores or channels. This process requires several steps and has the additional disadvantage that the size of the zeolite pores determine the size of the molecules which can migrate into the zeolite. Hashimoto et al. J. Phys . Chem. C, Vol. 112, No. 39, 2008) disclose a process whereby gold nanoparticle-doped zeolite L crystals are prepared by laser ablation and crystallisation inclusion. Stable gold nanoparticles are formed in a zeolite synthesis gel using laser ablation.

Crystallisation encapsulation allowed the formation of gold nanoparticles having a size exceeding the pore openings of the zeolite crystals, while maintaining the crystal structure as a whole. Gold nanoparticles of 20-50 nm in diameter embedded in the zeolite crystals are seen and it is stated that gold nanoparticles of 40 nm are detected.

The procedure proposed by Hashimoto et al. implies that the gold nanoparticles prepared by laser ablation are primarily 40-80 nm in size, which is generally too big for gold catalysis.

A reduction of the particle sizes by an order of magnitude is needed for an efficient use of costly noble metals such as Au in catalytic applications. However, a reduction of the particle size enhances the tendency for sintering due to the increase in surface free energy. Furthermore, this procedure is not feasible in practise due to the laser ablation.

It is thus an objective of the invention to provide a process for the preparation of a hybrid zeolite or zeolite- like material which is suitable for size selective catalysis . It is furthermore an objective of the invention to provide a process for the preparation of a hybrid zeolite or zeolite-like material which is stable towards sintering.

Yet another objective of the invention is to provide a process for the preparation of hybrid zeolite or zeolite- like-nanoparticle materials containing ultra-small metal nanoparticles, in which the nanoparticles are stabilized by being dispersed throughout and within the crystals of the zeolite or zeolite-like material.

The invention therefore relates to a process for the preparation of hybrid zeolite or zeolite-like materials comprising the steps of: - providing a solution or suspension or solid material containing nanoparticles comprising at least one metal

- providing a synthesis gel or a synthesis gel precursor of a zeolite or zeolite-like material

- mixing the synthesis gel or the synthesis gel precursor of the zeolite or zeolite-like material with the solution or suspension or solid material containing nanoparticles comprising at least one metal, to form a mixture

- converting the mixture under zeolite or zeolite-like synthesis conditions to hybrid zeolite or zeolite-material encapsulating nanoparticles comprising at least one metal, the hybrid zeolite or hybrid zeolite-like material consisting of individual single crystals having at least one X-Ray Powder Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees determined by the zeolite type, and the encapsulated nanoparticles comprising at least one metal being immobilised in the zeolite framework. Furthermore the invention concerns hybrid zeolite or zeolite-like material comprising one or more nanoparticles encapsulated within each individual single crystal of a microporous zeolite or zeolite-like material consisting of individual single crystals having at least one X-Ray Powder Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees determined by the zeolite type, the encapsulated nanoparticles comprising at least one metal being immobilised in the zeolite framework of the zeolite or zeolite-like material.

The process of the invention does not require the use of laser ablation.

A particular advantage of the process of the invention is that it allows tuning of the nanoparticle size in a completely independent step prior to zeolite synthesis.

By the term "hybrid zeolite material" is meant a conventional microporous zeolite material that has physical and chemical properties which have been modified by encapsulation of nanoparticles within the pore system of the single zeolite crystals. Zeolite materials are known as aluminosilicate molecular sieves and different zeolite structures suitable for application in the process of the invention are ZSM-5, MEL (ZSM-Il), MTW (ZSM-12), Y (faujasite) and BEA (zeolite beta) . Zeolite materials may be dealuminated to modify the properties.

By the term "hybrid zeolite-like material" is meant a conventional microporous zeolite-like material that has physical and chemical properties which have been modified by encapsulation of nanoparticles within the pore system of the single zeolite crystals. Examples of zeolite-like materials are non-silicon comprising materials such as aluminium phosphate (AlPO₄) molecular sieves, known as AlPO' s.

By the term "zeolite type" is meant a zeolite or a zeolite- like material.

The product of the process of the invention is thus a hybrid zeolite or zeolite-like material with one or more nanoparticles encapsulated within each individual single crystal of the zeolite or the zeolite-like material.

The hybrid zeolite or hybrid zeolite-like material consists of individual single crystals having at least one X-Ray Powder Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees determined by the zeolite type, and the encapsulated nanoparticles comprise at least one metal immobilised in the zeolite framework of the zeolite or zeolite-like material.

By zeolite framework is meant a crystalline network consisting of channels and/or cages in the micropore range.

It is advantageous that the metal nanoparticle is immobilised in the zeolite framework because the nanoparticles are only accessible through the framework channels which therefore can act as molecular sieves excluding certain molecules by e.g. their size. The small dimensions of the framework channels makes it difficult for nanoparticles to sinter via these.

The hybrid zeolite or hybrid zeolite-like materials of the invention are crystalline and not amorphous and this is an advantage because of their ease in handling e.g. when centrifuging. Furthermore use of these materials is advantageous due to stability of the supporting zeolite phase/matrix in many applications.

The hybrid zeolite or hybrid zeolite-like materials of the invention are useful as catalytic material for chemical reactions .

In an embodiment of the invention the hybrid zeolite or zeolite-like material encapsulates at least two nanoparticles within each individual single crystal of the zeolite or the zeolite-like material.

In a further embodiment of the invention the hybrid zeolite or zeolite-like material encapsulates a plurality of nanoparticles within each individual single crystal of the zeolite or the zeolite-like material.

In an embodiment of the invention the suspension containing nanoparticles comprising at least one metal is a colloidal solution obtained by dispersing nanoparticles of the at least one metal in a fluid. The colloidal solution is also referred to as a colloid.

In an embodiment of the invention the suspension containing nanoparticles comprising at least one metal is a colloidal 10

suspension obtained by dispersing nanoparticles of the at least one metal in a fluid.

In an embodiment of the invention the nanoparticles comprise at least one non-metal and the non-metal may be selected from the group consisting of boron, carbon, nitrogen, oxygen, sulphur, phosphorous and mixtures thereof. Preferably, the non-metal is selected from the group consisting of carbon, nitrogen, sulphur and mixtures thereof.

In an embodiment of the invention the nanoparticles comprise at least one metal and the metal is selected from the group consisting of Group IB, HB, IVB, VIIB, VIII and mixtures thereof. Preferably, the metal is selected from the group consisting of titanium, osmium, iridium, platinum, ruthenium, palladium, rhodium, rhenium, copper, nickel, cobalt, silver, gold, cadmium and mixtures thereof. More preferably, the metal is selected from the group consisting of gold, platinum, cadmium, titanium, copper and mixtures thereof, and most preferably the metal is gold or platinum.

In an embodiment of the invention the synthesis gel or the synthesis gel precursor of the zeolite or zeolite-like material comprises compounds of elements selected from the group consisting of aluminum, silicon, phosphorous, nitrogen, carbon and mixtures thereof.

In an embodiment of the invention the aluminum compound of the synthesis gel or the synthesis gel precursor is selected from the group consisting of sodium aluminate 11

(NaAlO₂), aluminum isopropoxide (Al [OCH (CH₂) 2] ₃) and aluminum nitrate nonahydrate (Al (NO₃) ₃"9H₂O) . The aluminium compound is useful in the preparation of both the hybrid zeolite material and the hybrid zeolite-like material.

In an embodiment of the invention the silicon compound of the synthesis gel or the synthesis gel precursor is selected from the group consisting of silica, silicates and mixtures thereof. Preferably, the silicon compound is selected from the group consisting of silica gel, tetraethyl orthosilicate, sodium silicate and mixtures thereof. The silicon compound is useful in the preparation of the hybrid zeolite material.

In an embodiment of the invention the phosphorous compound is selected from the group consisting of phosphoric acid, phosphate salts and mixtures thereof. By the term "phosphate salts" is meant salts of phosphates, monohydrogen phosphates and dihydrogen phosphates. The phosphorous compound is useful in the preparation of the hybrid zeolite-like material.

In an embodiment of the invention the carbon compound of the synthesis gel or the synthesis gel precursor may be combined with the nitrogen compound as a quaternary ammonium compound with four alkyl groups attached to a central nitrogen atom. The alkyl group is selected from the group consisting of ethyl and propyl.

In an embodiment of the invention the zeolite or zeolite- like synthesis conditions include heating of the mixture from room temperature to a final temperature maximum of 12

200⁰C and maintaining this final temperature for a predetermined time period. It is important to reach a final temperature maximum of 200°C in order to ensure crystallisation of the zeolite or zeolite-like material.

In a further embodiment of the invention the zeolite or zeolite-like synthesis conditions include a predetermined time period of 1-10 days and a final temperature of 100- 220⁰C. The length of time chosen is dependent on the length of time required to ensure crystallisation of the zeolite or zeolite-like material and a final temperature of 220⁰C is suitable for many zeolites or zeolite-like materials, whereby crystallisation is ensured. However, some zeolite or zeolite-like materials require a higher temperature than 220⁰C and more than 10 days for crystallisation.

In an embodiment of the invention the solid material containing nanoparticles is a ceramic i.e. an inorganic, non-metallic material. This includes for instance an oxide of silicon, aluminium, phosphorous, titanium, galium or mixtures thereof, or the solid material is carbon.

When the solid material is carbon this includes carbon nanotubes and particulate carbon such as active carbon. Preferably, the solid material is an oxide of silicon, aluminium, phosphorous or titanium or mixtures thereof. Most preferably, the solid material is silica, alumina, titania or mixtures thereof.

In an embodiment of the invention the solid material containing nanoparticles comprising at least one metal is obtained by impregnation of the at least one metal on the 13

solid material followed by reduction with a reducing gas. Preferably, the solid material is impregnated with nanoparticles comprising platinum. A most preferable embodiment of the invention is silica impregnated with platinum.

In an embodiment of the invention the reducing gas is hydrogen.

In an embodiment of the invention the solution containing nanoparticles comprising at least one metal is a colloid obtained by reducing a solution of the at least one metal with a reducing agent. In a preferable embodiment of the invention the colloid is a salt of the metal and the reducing agent is sodium citrate. Most preferably, the metal is gold.

In an embodiment of the invention the colloid or the solution containing nanoparticles comprising at least one metal is cooled, mixed with a polymeric compound, optionally centrifuged and thereafter mixed with a synthesis gel for preparing an oxide of silicon, aluminium, phosphorous, titanium, gallium or mixtures thereof, to provide, under synthesis conditions, a solid material containing nanoparticles comprising at least one metal coated with said oxide.

The addition of a polymeric compound is useful for improving the adhesion between the metal particles and the zeolite or zeolite-like material. Complete adsorption of the polymeric compound on the metal surface is important for adhesion. Polymeric compounds having surfactant 14

properties are suitable, for instance a polymeric compound such as polyvinylpyrrolidone can be used.

In an embodiment of the invention the hybrid zeolite or zeolite-like material prepared by the process of the invention is useful as catalytic material in the water gas shift reaction, alcohol oxidation and CO and NO oxidation reactions .

Fig. 1 illustrates the synthetic approach for preparation of hybrid zeolite or zeolite-like materials. Figs. 2a and 2b show respectively scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of a hybrid material consisting of Au nanoparticles embedded in silicalite-1 crystals.

Fig. 3 shows a tomogram of the hybrid material in figs. 2a and 2b.

Fig. 4 shows TEM images of nanocrystals before and after calcination. Fig. 5 shows a TEM image of gold nanoparticles in ZSM-5 zeolite.

Fig. 6 shows a TEM image of a single zeolite crystal. Fig. 7 shows a section through the tomogram of the TEM image of Fig. 6. Fig. 8 shows the presence of platinum nanoparticles within the single zeolite crystal.

Fig. 9 shows the X-Ray Powder Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees of gold (diagram B) and of a hybrid zeolite material of the invention (diagram A) .

The product of the process of the invention is a hybrid zeolite or zeolite-like material with nanoparticles 15

encapsulated within the individual crystals of the zeolite or the zeolite-like material, the hybrid zeolite or hybrid zeolite-like material consisting of individual single crystals having at least one X-Ray Powder Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees determined by the zeolite type, the encapsulated nanoparticles comprising at least one metal being immobilised in the zeolite framework of the zeolite or zeolite-like material.

Using the inventive process, the physical and chemical properties of a conventional microporous zeolite or zeolite-like material can be modified by encapsulation of nanoparticles within the pore system of the individual zeolite crystals. The nanoparticles comprise metals having specific chemical properties. The resulting properties of the hybrid zeolite or hybrid zeolite-like material are a combination of the chemical properties of the encapsulated nanoparticles and the molecular sieve properties of the zeolite or zeolite-like material.

By the term "individual crystal" is meant a single crystal. By the term "hybrid material" is meant a material which is a combination of a zeolite or a zeolite-like material with a nanoparticle or nanocluster.

The process of the invention is advantageous as it is based on synthesis of the zeolite or zeolite-like material around the individual nanoparticles, resulting in hybrid zeolite or zeolite-like material having individual crystals with regular channels whose aperture diameters are in the micropore range of less than 2 nm and thus simultaneously having encapsulated nanoparticles which are also 16

immobilised, having desirable chemical properties within the crystal.

Carrying out the synthesis of the hybrid zeolite or zeolite-like material simultaneously with encapsulation of the nanoparticles allows prior preparation of the nanoparticles . This is advantageous because nanoparticles having specific desirable qualities such as catalytic properties, can be prepared prior to encapsulation. The zeolite or zeolite-like material having the pore size required for allowing entrance of molecules with a specific size to be catalytically reacted can be chosen. Combining the chosen zeolite or zeolite-like synthesis gel or synthesis gel precursor with the nanoparticles to form a mixture and synthesising hybrid zeolite or zeolite-like material under synthesis conditions for the zeolite or zeolite-like material results in a hybrid zeolite or zeolite-like material that has been tailored to catalyse a specific reaction with some specific reactants. The hybrid zeolite or zeolite-like material obtained is therefore size-selective and at the same time has the catalytic properties required.

The hybrid zeolite or zeolite-like material prepared by the process of the invention is thus suitable as catalytic material.

The requirements regarding metal nanoparticle size for catalysis differs from reaction to reaction. However, by the process of the invention nanoparticles comprising at least one metal can be prepared with a size less than 30 17

nm, thus rendering the nanoparticles particularly suitable for catalysis.

In the process of the invention when the solution containing nanoparticles comprising at least one metal is a colloid, then the nanoparticle size obtained can be as low as 8 nm. The nanoparticles encapsulated in an oxide have a size of 8-15 nm before encapsulation and immobilisation in the zeolite or zeolite-like material.

Furthermore, the hybrid zeolite or zeolite-like material obtained by the process of the invention has the advantage of being more stable towards sintering than for instance hybrid zeolite or zeolite-like materials prepared by impregnation of precursor compounds on already prepared zeolite or zeolite-like materials. Impregnation of already prepared zeolite or zeolite-like materials with nanoparticles leads to deposition of nanoparticles on the surface of the zeolite or zeolite-like material, and these nanoparticles are more exposed to sintering than nanoparticles located inside the micropores of the zeolite or zeolite-like material.

Zeolite materials are known as aluminosilicate molecular sieves and different zeolite structures suitable for application in the process of the invention are ZSM-5, MEL (ZSM-Il), MTW (ZSM-12), Y (faujasite) and BEA (zeolite beta) . Zeolite materials may be dealuminated to modify the properties.

In carrying out the process of the invention, a solution comprising at least one metal can be prepared, and 18

subsequently optionally the metal can be encapsulated by an oxide of for example silicon (SiO₂) forming a nanoparticle of a metal particle or a nanocluster surrounded by the oxide of silicon (metal/SiC>2 nanoparticle) .

Subsequently, a zeolite or zeolite-like material can be synthesized around the metal/SiO₂ nanoparticle with the SiO₂ participating in the synthesis of the hybrid zeolite or zeolite-like material. The presence of aluminium in the synthesis gel or the synthesis gel precursor leads to the formation of a hybrid zeolite material based on aluminium and silicon, while the absence of aluminium in the synthesis gel or the synthesis gel precursor leads to the formation of a hybrid zeolite material based on silicon only, for instance silicalite.

If encapsulation of the metal by an oxide of silicon is to be prepared prior to synthesis of the zeolite or zeolite- like material, then the synthetic approach can comprise the following:

1. preparing a metal nanoparticle colloid with suitable anchoring points for generation of a silica shell

2. followed by encapsulation of the metal nanoparticles in an amorphous silica matrix to form a silica- nanoparticle precursor

3. subjecting the silica-nanoparticle precursor to hydrothermal conditions in order for zeolite or zeolite-like crystallization to take place.

The oxide of silicon can be replaced by an oxide of aluminium, phosphorous, titanium, gallium, or mixtures thereof, including mixtures with oxides of silicon. 19

If encapsulation of the metal by an oxide of silicon is left out, then the solution containing nanoparticles comprising at least one metal is mixed directly with the synthesis gel or synthesis gel precursor of the zeolite or zeolite-like material and then the synthetic approach can comprise the following:

1. preparing a metal nanoparticle colloid and

2. mixing a synthesis gel or synthesis gel precursor of a zeolite or zeolite-like precursor with the metal nanoparticle colloid and

3. subjecting the metal nanoparticle colloid to hydrothermal conditions in order for zeolite or zeolite- like crystallization to take place.

Alternatively, a solution comprising at least one metal can be prepared, and subsequently impregnated on a solid material to provide a solid material containing nanoparticles comprising at least one metal. Subsequently a zeolite or zeolite-like material can be synthesized around the solid material.

By hydrothermal conditions is meant an autogenous pressure of steam at a temperature of max. 200⁰C. Furthermore often a template for controlling which type of zeolite is crystallised is added.

In the process of the invention hydrothermal conditions are required for preparation of the hybrid zeolite or zeolite- like material in combination with a maximum temperature of 200⁰C or 220⁰C, depending on which zeolite or zeolite-like 20

material is to be prepared. Preferable is a maximum temperature of 200⁰C.

The synthesis of the zeolite or zeolite-like material requires a synthesis gel which can include an organic template that assists in determining the zeolite or zeolite-like material to be obtained. The organic template is typically a quaternary ammonium salt such as tetrapropyl ammonium bromide (TPA-Br) and tetrapropyl ammonium hydroxide (TPAOH) .

The synthesis gel or the synthesis gel precursor of the zeolite or zeolite-like material is mixed in an autoclave with the solution or suspension or solid material containing nanoparticles comprising at least one metal, to form a mixture that is converted under zeolite or zeolite- like synthesis conditions to hybrid zeolite or zeolite- material encapsulating nanoparticles comprising at least one metal.

The zeolite or zeolite-like synthesis conditions are autoclaving under hydrothermal conditions at a maximum temperature of 200°C or 220°C, depending on which zeolite or zeolite-like material is to be prepared, during which the zeolite or zeolite-like material crystallises. Finally the obtained product is dried and calcined, for instance at 550°C for removal of the template.

The obtained product, a zeolite or zeolite-like material, is crystalline and microporous. 21

Fig. 1 illustrates an example of the synthetic approach of the process of the invention. First, a metal nanoparticle colloid with suitable anchoring points for generation of a silica shell is prepared. This is followed by encapsulation of the particles in an amorphous silica matrix. Finally, the silica-nanoparticle precursor is subjected to hydrothermal conditions in order for zeolite crystallization to take place.

The following examples illustrate the process of the invention.

In all the examples the hybrid zeolite or zeolite-like material obtained by the process of the invention had individual single crystals with at least one X-Ray Powder

Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees.

EXAMPLES

Example 1: Preparation of Au encapsulated in silicalite-1

A material consisting of approximately 1 nm sized Au nanoparticles embedded in silicalite-1 crystals is prepared. X-ray diffraction reveals that the material contains exclusively Au as well as MFI structured material.

Figs. 2a and 2b show scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the hybrid material consisting of Au nanoparticles embedded in silicalite-1 crystals. The SEM images reveal that the material is mainly composed of coffin-shaped crystals (Fig. 2a) with a minor fraction of intergrown coffin- shaped crystals and irregularly shaped crystals. The 22

former two crystal morphologies are commonly observed for MFI-structured zeolite materials. By far, the majority of the crystals, regardless of their morphology, are 1-2 μm long.

To obtain information about the internal structure, the coffin-shaped crystals were investigated by TEM. The mosaic TEM image (Fig. 2b) reveals an overall uniform contrast extending over the entire crystal superimposed by areas of darker and brighter contrast. The varying contrast is attributed to varying mass-thickness contrast and so that the darker areas correspond to Au particles and the brighter areas correspond to voids in the crystal. Gold particles imaged in plane view in the crystal are ca . 1 nm whereas those imaged in profile view at the crystal edges are significantly larger as well as more agglomerated. Concerning the Au particles in the crystal, it is not possible from the mosaic TEM image shown in Fig. 2b to determine whether the particles are located on the crystal surfaces oriented perpendicular to the electron beam or inside the zeolite crystal because the TEM image represents a two-dimensional projection of the specimen.

To uniquely determine the relative positions of the Au nanocrystals with respect to the zeolite crystal, three- dimensional imaging was pursued by means of bright field transmission electron tomography.

The reconstructed tomogram shows all the characteristic features observed in the TEM images except the smallest gold particles which are a result of the blurring effect caused by the weighted back projection algorithm. 23

From the tomogram sections shown in Figs. 3a and 3b it is clear that significant amounts of gold are observed inside the zeolite crystallite. Investigation of all tomogram sections shows that all of the gold particles shown in Fig. 2b (except those marked by circles) are encaged in the zeolite matrix.

To address if the zeolite-embedment indeed stabilizes the Au nanocrystals, TEM images of nanocrystals acquired before and after calcination in air at 550 ⁰C for 3 h (Fig. 4a-b) were recorded. Before calcination, the majority of the Au particles are generally 1 nm (Fig. 4a) . After calcination, however, the particles imaged in profile view at the edges of particle obtain a larger size and more round (Fig. 4b), whereas the majority of the particles imaged in plane view in the crystal remain unaltered in size, indicating that the Au particles embedded within the zeolite crystals have an enhanced stability towards sintering despite the smaller Au particles size. Thus, the present synthesis approach yields a hybrid Au-silicalite-1 material with an enhanced sintering stability of the metal nanoparticles .

The enhanced stabilization of the Au nanoparticles is further corroborated by a series of in situ transmission electron microscopy images (Fig. 4c) obtained during exposure of the hybrid material to an oxygen atmosphere at temperatures from 25 ⁰C to 500 ⁰C. At 25 ⁰C, the sample area contains Au particles of different sizes (Fig. 4c-e) . By heating to 300 ⁰C and further up to 500 °C, it is preferentially the larger Au particles that sinter, while 24

the smallest particles are stable. This is regarded as unexpected since the sintering rate of nanoparticles usually scales inversely with their size. Given the post mortem information in Fig. 4a-b, the in situ observation is fully consistent with the finding that particle embedment improves the stability towards sintering.

Hybrid Au-silicalite-1 material prepared according to the process of the invention has been shown to consist of 1 nm sized Au embedded in the silicalite-1 crystals.3- dimensional TEM tomography shows that some Au particles are embedded within and some are on the external surface of the zeolite crystals. Moreover, calcination experiments by both ex situ and in situ TEM indicate that the nanoparticles embedded in the zeolite crystals are highly stable towards sintering, whereas the particles located at the outer surface of the zeolite tend to sinter under similar conditions.

Example 2: Preparation of Au encapsulated in zeolite

Step 1: Preparation of Au encapsulated in SiO₂

Catalyst preparation: Millipore water (212.5 mL, 18.2 MWcm_2) was vigorously stirred under reflux and a HAuC14 solution (25 mL, 2.54 K 10_3m; Alfa-Aesar, 99.99%) was added. The resultant solution was stirred until boiling point was reached again. Then, a sodium citrate solution (12.5 mL, 10 itigmL_l; citric acid trisodium salt dehydrate, 99% purity from ACROS Organics) was added and the system was refluxed for 30 min. Finally, the resultant colloid was cooled to room temperature. 25

Next, a solution of polyvinylpyrrolidone (0.325 mL, 12.8 mgmL_l) , which was freshly prepared by dissolution in Millipore water with ultrasonication (30 min) , was added to a previously prepared, cold, colloidal gold solution (240 mL) . The resultant mixture was stirred for 24 h to allow complete adsorption of the polymer on the gold surface. After this time, the solution was centrifuged (10000 rpm; 50 min) and the supernatant was removed. The volume of the concentrated colloid was then adjusted to 6 mL by dilution with water. The colloid was vigorously stirred for 5 min. followed by addition of ethanol (18.90 mL) premixed with concentrated ammonia solution (0.84 mL, 28-30% NH3 in water) .

Immediately afterwards, a solution of tetraethylorthosilicate (1.19 mL) in ethanol (12.80 mL) was added. The reaction mixture was then stirred for an additional 12 h at room temperature. The resultant colloid was centrifuged (10000 rpm; 30 min) and washed twice with water and twice with absolute ethanol. In between washing and following centrifugation the solid was redispersed by ultrasonication.

Step 2: Synthesis of Au encapsulated in zeolite

(1) In a small Teflon beaker, 0.72g H₂O + 0.043g TPA-Br + 0.074g NH₄F was mixed and stirred until dissolved.

(2) 0.12g Au/SiO₂ (from step 1) was added to (1) and the mixture was stirred with Teflon spatula until a homogeneous mixture was obtained.

(3) Teflon beaker transferred to Teflon-lined autoclave along with approximately 10 ml water outside the beaker. 26

Autoclave heated in furnace using the following heating program: room temp -> 200⁰C. Final temperature maintained for 5d 18h.

(4) Solid product collected by filtration, washed with approximately 1 1 of deionised water and dried for 12h at 120⁰C.

Example 3 : Preparation of Pt encapsulated in zeolite

Step 1: Preparation of Pt impregnated on SiO₂ :

0,21g H₂PtCl₂ is dissolved in H₂O (total volume equal 3,6ml) and impregnated on 4g of silica gel (SiO₂) . The mixture was dried over night at room temperature (25⁰C) . The platinum was reduced in a flow of H₂ at 450⁰C for 2 hours.

Step 2: Synthesis of Pt encapsulated in zeolite:

0,256g NaOH is dissolved in 14,34g TPAOH (40 wt%) and impregnated on the Pt/SiO₂ compound. The mixture is dried over night at room temperature (25°C) .

The mixture is then transferred into a Teflon beaker inside an autoclave along with approximately 20ml water outside the beaker. The autoclave is then heated in a furnace using the following heating program: room temperature -> 18O⁰C and the final temperature is maintained for 5 days. Then cooling to room temperature (25°C) .

The solid product is collected by filtration, washed with 1 1 of deionised water and dried for 12 hours at 110⁰C. Finally, the product is calcined at 550⁰C for 5 hours. 27

Example 4 : TEM analysis of Au particles in ZSM-5

A sample containing gold particles in ZSM-5 zeolite prepared according to Example 2 was tested by TEM analysis to determine whether the gold particles were located on the surface of the zeolite crystals or whether they were encapsulated by ZSM-5.

Sample preparation: A sample was crushed and distributed in ethanol using ultrasound. A drop of the suspension was placed on a transmission electron microscopy (TEM) grid (Cu med lacey C) .

Experimental procedure: CM200 was used for the TEM photograph, while bright-field electron tomography was used elsewhere. Electron tomography was carried out on a single zeolite crystal with TEM depiction over tilt-angles from - 75 to 75° med 1° step. Reconstruction of the tomogram was made with Avizo.

Results :

Fig. 5 shows a TEM image of gold nanoparticles in ZSM-5 zeolite. The gold nanoparticles shown in profile on the borders of the zeolite indicate that some gold nanoparticles are present on the surface of the zeolite crystals .

A single zeolite crystal is studied using tomography in order to determine whether gold nanoparticles also are located within the zeolite crystal. 28

Fig. 6 shows a TEM image of the single zeolite crystal and five gold nanoparticles (a plurality of nanoparticles) are observed in and the single individual crystal.

Fig. 7 shows a section through the corresponding tomogram and one encapsulated, immobilised nanoparticle is observed and two nanoparticles are present on the surface of the single individual crystal. Figs. 6 and 7 both show the presence of gold nanoparticles within the single zeolite crystal.

Fig. 7 clearly shows three gold nanoparticles in the sample with two gold nanoparticles at the periphery of the sample and one gold nanoparticle of approximately 25 nm encapsulated centrally within the sample.

Example 5 : TEM analysis of Pt particles in ZSM-5

A sample containing platinum particles in ZSM-5 zeolite prepared according to Example 3 was analyzed by TEM analysis using the procedure described in Example 3 to determine whether the platinum particles were located on the surface of the zeolite crystals or whether they were encapsulated by zeolite ZSM-5.

Fig. 8 shows the presence of platinum nanoparticles within the single zeolite crystal.

Example 6 : Preparation of Au encapsulated in zeolite

Step 1: gold colloid synthesis

0.404 g HAuCl₄- 3H₂O are dissolved in 20.0 ml deionised water in an Erlenmeyer flask. Simultaneous 60.0 ml 0.2 M 29

NaOH are mixed with 900 ml deionised water in an Erlenmeyer flask. Both solutions are magnetically stirred vigorously lOmin. Then 20 ml 0.203 M tetrakishydroxymethylphosphonium chloride solution and stirred another 2 min before adding the gold solution. After 30 min' s vigorous stirring the colloidal solution has reacted.

Step 2: silica covering of gold colloid and crystallisation to Silicalite-1

260 ml of the Au colloid (prepared in step 1) is stirred vigorously in an Erlenmeyer flask on a heating plate then 69.4 ml 1 mM 3-mercaptopropyltrimethoxysilane is added. After stirring 30 min 503 ml diluted water glass (0.16 wt% SiO₂) is added and stirred at 500 rpm for 24 h. Next the solution is drop wise added 1.10 L 99 % ethanol under continuous stirring. 1.00 ml 25 % NH₄OH is added. Finally 0.270 ml 98 % tetraethoxysilane is added 3 times a day until the total amount of silica has been added (9.82 ml) . After the last addition the solution is left stirring 16 h and the colloidal particles settled out by adding NaCl to make an over saturated solution.

After 16 h the colloid has precipitated and is recovered by filtration and washed in 2 L water. The product is dried at

120 ⁰C for 16h. 89.7 ml deionised water, 23.0 g 99 % ethanol, 0.110 g NaOH, and 2.91 g 40% tetrapropylammoniumhydroxide are magnetically stirred 10 min at 600 rpm. 0.755 g Au in silica are added and stirred 10 min. The suspension is transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 100 ⁰C for 72 h. The solid product is recovered and washed in deionised water by 30

centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h. The sample is calcined at 550 ⁰C for 3 h to remove the template molecules.

Example 7 : Preparation of Au encapsulated in zeolite Step 1: gold nanocluster colloid synthesis

0.062 g HAuCl₄ -3H₂O is dissolved in 4.4 mL THF in a round- bottomed flask, and cooled to 0 ⁰C. After 30 min. 0.156 ml of 3-mercaptopropyltrimethoxysilane is added. Next the stirring is reduced around 60 rpm. After 24 h the stirring is increased anew to 1200 rpm after which 60 mg NaBH₄ dissolved freshly in 1.5 ml ice-cold deionised water is quickly added. After 3 h of reaction time, the ice bath is removed and the solution allowed to heat to room temperature. After 60 h the precipitates (by-products) are removed by filtration over a cellulose filter. The solution is diluted to the final 10 g by adding THF.

Step 2: silica covering of gold nanocluster colloid and crystallisation to Silicalite-1.

20.0 ml of the gold colloid produced in step 1 is diluted to 420 ml by THF under vigorous stirring on a heating plate then 4.20 ml 25% NH₄OH are added. Next 0.312 ml 98% tetraethoxysilane are added 3 times a day until the total amount of silica has been added (11.9 ml) . After the last addition the solution is left stirring 16 h and the colloidal particles settled out by gravitation. 31

After 16 h the colloid has precipitated and is recovered by filtration and washed in 2 L water. The product is dried at 120 ⁰C for 16h. 240 ml deionised water, 61.4 g 99 % ethanol, 0.294 g NaOH, and 7.77 g 40 % tetrapropylammoniumhydroxide are magnetically stirred in an Erlenmeyer flask for 10 min at 600 rpm. 2.02 g Au in silica are added and stirred 10 min. The suspension is transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 100 ⁰C for 240 h. The solid product is recovered and washed in deionised water by centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h. The sample is calcined at 550 ⁰C for 3 h to remove the template molecules.

Example 8: Preparation of Pt encapsulated in zeolite

Step 1: Pt colloid synthesis

1.23 g K₂PtCl₄ are mixed with 3.23 g sodium acetate, 5.81 g dibenzylideneacetone, and 75.0 ml methanol in a round bottomed flask. The flask is fitted with a condenser and the solution is heated until refluxing on heating plate under vigorous stirring (keeping the solids suspended at all times) . After 72 h the platinum complex is recovered by filtration and washed in methanol. 0.320 g platinum complex is dissolved in 75.0 ml THF and transferred to an evacuated Schlenk flask fitted with a Schlenk funnel. The flask is evacuated and one bar CO atmosphere is applied. After reacting 20 min under vigorous stirring the flask is evacuated and a nitrogen atmosphere is introduced. 0.017 ml 3-mercaptopropyltrimethoxysilane is degassed in the funnel by nitrogen flow, then added and allowed to react for 16 h. 32

Step 2: Pt colloid in silica and crystallisation to Silicalite-1.

75.0 ml of the platinum colloid produced in step 1 is diluted to 431 ml by THF under vigorous stirring on a heating plate, then 0.200 ml 25% NH₄OH are added. Next 0.279 ml TEOS are added 3 times a day until the total amount of silica has been added (12.6ml) . After the last addition the solution is left stirring 16 h the colloid is diluted by 300 ml deionised water and washed in n-heptane by two phase extraction. The solid product is recovered by evaporation at 120 ⁰C for 16h. 89.7 ml deionised water, 23.0 g 99 % ethanol, 0.110 g NaOH, and 2.91 g 40 % tetrapropylammoniumhydroxide are magnetically stirred in an Erlenmeyer flask for 10 min at 600 rpm. 0.755 g Pt in silica are added and stirred 10 min. The suspension is transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 100 ⁰C for 240 h.

The solid product is recovered and washed in deionised water by centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h. The sample is calcined at 550 ⁰C for 3 h to remove the template molecules.

Example 9 : Preparation of Pd encapsulated in zeolite Step 1: Pd colloid synthesis

The colloid is prepared by dissolving 0.324 g Pd₂ (dibenzylidieneacetone) ₃ in 150 ml THF and transferring this to an evacuated Schlenk flask fitted with a Schlenk funnel. The flask is evacuated and one bar CO atmosphere is 33

applied. After reacting 20 min under vigorous stirring the flask is evacuated and a nitrogen atmosphere is introduced. 0.034 ml 95 % 3-mercaptopropyltrimethoxysilane is degassed in the funnel by nitrogen flow, then added and allowed to react for 16 h.

Step 2: Pd colloid in silica and crystallisation to Silicalite-1.

75.0 ml of the palladium colloid produced in step 1 is diluted to 431 ml by THF under vigorous stirring on a heating plate, then 0.200 ml 25% NH₄OH are added. Next 0.279 ml TEOS are added 3 times a day until the total amount of silica has been added (12.6ml) . After the last addition the solution is left stirring 16 h the colloid is diluted by 300 ml deionised water and washed in n-heptane by two phase extraction. The solid product is recovered by evaporation at 120 ⁰C for 16h. 89.7 ml deionised water, 23.0 g 99 % ethanol, 0.110 g NaOH, and 2.91 g 40 % tetrapropylammoniumhydroxide are magnetically stirred in an Erlenmeyer flask for 10 min at 600 rpm. 0.755 g Pd in silica are added and stirred 10 min. The suspension is transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 100 ⁰C for 240 h. The solid product is recovered and washed in deionised water by centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h. The sample is calcined at 550 ⁰C for 3 h to remove the template molecules.

Example 10: Preparation of rutile TiO₂ encapsulated in zeolite

Step 1: Rutile TiO₂ colloid synthesis 34

57.93 ml TiCl₄, cooled on ice for 16 h, are stirred at 500 rpm on a heating plate in an Erlenmeyer flask. 350 ml deionised water cooled on ice for 2 h is added drop wise to the TiCl₄. After addition of all the water the liquid is transferred to a funnel from which it is added drop wise to 14.53 ml 90 % Lactic acid in 335.47 ml deionised water under stirring. The final mixture is heated to 70 ⁰C for 72h. The solid product is recovered by filtration and washed in water and ethanol, then dried at 120 ⁰C for 16h.

Step 2: Rutile TiO₂ in ZSM-5 (zeolite hybrid material)

Dissolve 7.80 ml 40 % tetrapropylammonium hydroxide, and 0.935 g NaOH in 50ml deionised water. Dissolve 1.10 g anhydrous NaAlO₂ in 12 ml deionised water. Mix 0.45g rutile TiO₂ nanoparticles produced in step 1 into 49.0 g 98 % tetraethoxysilane for 20 min at 600 rpm. Add the alkaline ammonium and aluminium solution to the nanoparticle suspension under stirring for 2 h. Transfer the suspension to a 150 ml Teflon autoclave; seal and heat this to 180 ⁰C for 72 h. The solid product is recovered and washed in deionised water by filtration on a cellulose filter. The product, a zeolite hybrid material, is dried at 120 ⁰C for 16h. The sample is calcined at 550 ⁰C for 3 h to remove the template molecules.

Example 11: Preparation of anatase TiO₂ encapsulated in zeolite Step 1: anatase TiO₂ colloid synthesis 35

413 ml 15 % TiOSO₄ solution is added drop wise to 14.53 ml 90 % Lactic acid in 330 ml deionised water under stirring. The final mixture is heated to 70 ⁰C for 5 days. The solid product is recovered by centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h.

Step 2: anatase TiO₂ in ZSM-5 (zeolite hybrid material)

Dissolve 7.80 ml 40 % tetrapropylammonium hydroxide, and 0.935 g NaOH in 50ml deionised water. Dissolve 1.10 g anhydrous NaAlO₂ in 12 ml deionised water. Mix 0.45g anatase TiO₂ nanoparticles produced in step 1 into 49.0 g 98 % tetraethoxysilane for 20 min at 600 rpm. Add the alkaline ammonium and aluminium solution to the nanoparticle suspension under stirring for 2 h. Transfer the suspension to a 150 ml Teflon autoclave; seal and heat this to 180 ⁰C for 72 h. The solid product is recovered and washed in deionised water by filtration on a cellulose filter. The product, a zeolite hybrid material, is dried at 120 ⁰C for 16h. The sample is calcined at 550 ⁰C for 3 h to remove the template molecules.

Example 12 : Preparation of CdS encapsulated in zeolite Step 1: synthesis of CdS covered in silica colloid

92.O g Triton XlOO (polyoxyethylene (10) octylphenyl ether) is mixed with 48.1g 1-butanol, and 212g cyclohexane to make a clear emulsifier solution. A H of this is mixed with 0.678g Cd (NO₃) ₂* 4H₂O in 11.0 g deionised water to make a clear emulsion. Another H of the emulsifier solution is mixed with 0.341 ml 40-48 % (NH₄)₂S solution in 11.0 g deionised water to make a clear yellow solution. The Cd 36

emulsion is degassed in a Schlenk funnel fitted on an evacuated Schlenk flask by sparking the solution with nitrogen for 5 min. The Cd emulsion is stirred at 900 rpm while the sulphide emulsion is degassed in the funnel.

The two emulsions are mixed under nitrogen for 2 h. The rest of the emulsifier solution is mixed with 22.0 g 25 % NH₄OH to make a clear solution which is degassed prior to adding it to the CdS emulsion. Then 0.315 ml 98 % tetraethoxysilane are added and stirred 72 h. Next 1.07 ml tetraethoxysilane are added and stirred 24 h, this is repeated 4 times. 54.57 ml tetraethoxysilane are then added and stirred 24 h. The emulsion is ruptured by adding 200 ml acetone and leaving the solid to precipitate for 16 h. The solid is recovered by filtration and washed in 1 L 1:1 water/ethanol mixture, then 0.5 L water. The solid is dried overnight at room temperature under Al-foil.

Step 2: template free synthesis of CdS in ZSM-5 (zeolite hybrid material)

0.261 g NaOH, 1.00 g CdS in silica produced in step 1, and 11.75 ml deionised water are mixed 10 min on a heating plate at 500 rpm. 0.217 g Al₂ (SO₄) 3 ^• 8H₂O are dissolved in 11.75 ml deionised water. The aluminium source is added to the CdS suspension and stirred another 10 min. The suspension is then transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 180 ⁰C for 5 days. The solid product is recovered centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The solid is dried overnight at room temperature under Al-foil. 37

Example 13 : Preparation of Cu encapsulated in zeolite

Step 1: synthesis of Cu covered in silica colloid.

200 g Triton XlOO is mixed with 50.O g 1-pentanol, and 1937 g cyclohexane to make a clear emulsifier solution. Half of this is mixed with 0.825 g CuCl₂- 2H₂O in 21.75 ml deionised water and stirred until clear emulsion is obtained. The other half of the emulsifier solution is mixed with 0.332 g NaBH₄ solution in 21.75 ml deionised water to make a clear solution. The NaBH₄ emulsion is degassed in a Schlenk funnel fitted on an evacuated Schlenk flask by sparking the solution with nitrogen for 5 min. The NaBH₄ emulsion is stirred at 900 rpm while the Cu emulsion is degassed in the funnel. The two emulsions are mixed under nitrogen for 2 h. Next the solution is added 51.33 ml 98 % tetraethoxysilane and stirred 24h. 4 ml 0.2 M NaOH are added next after which the solution is heated to 50 ⁰C over night. 100 ml 0.2 M NaOH are added to secure condensation of the silica after 3 h the emulsion is ruptured by adding 1 L acetone. After another 3 h the solid may be recovered by filtration on a cellulose filter. Drying this product at 120 ⁰C overnight yields a CuO₂ product.

Step 2: crystallisation of Cu in silica to Silicalite-1.

89.7 ml deionised water, 23.0 g 99 % ethanol, 0.11 g NaOH, and 2.91 g 40 % tetrapropylammoniumhydroxide are magnetically stirred in an Erlenmeyer flask for 10 min at 600 rpm. 0.755 g Cu in silica produced in step 1 are added and stirred 10 min. The suspension is transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 100 ⁰C for 240 h. The solid product is recovered and washed in 38

deionised water by centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h. The sample is calcined at 550 ⁰C for 3 h to remove the template molecules and reduce any malachite to copper oxide.

Example 14 : Preparation of Cu encapsulated in zeolite

Step 1: As example 13, step 1.

Step 2: template free synthesis of Cu in ZSM-5.

0.261 g NaOH, 1.00 g Cu in silica (step 1), and 11.75 ml deionised water are mixed 10 min on a heating plate at 500 rpm. 0.217 g Al₂ (SO₄) ₃ • 8H₂O are dissolved in 11.75 ml deionised water. The aluminium source is added to the Cu suspension produced in step 1 and stirred another 10 min. The suspension is then transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 180 ⁰C for 5 days. The solid product is recovered centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h.

Example 15 : Preparation of Co/Pt alloy encapsulated in zeolite Step 1: synthesis of solid Co/Pt alloy in silica.

200 mL of 12.9 mM NaBH₄ and 0.409 mM citric acid in deionised water is degassed in a Schlenk funnel under nitrogen prior to introduction into an evacuated Schlenk flask. This solution is stirred under nitrogen at 600 rpm. Next 52.5μL of 0.8 M CoCl₂ in deionised water and 45 μL 0.4 M H₂PtCl₆ also in deionised water are degassed in a Schlenk funnel and simultaneously added to the Schlenk flask. After 39

1 min 800 ml of ethanol solution containing 15.6 μL of 95 '^■ 3-mercaptopropyltrimethoxysilane and 169 μL of 98 % tetraethoxysilane are degassed and added to the mixture. 169 μL of tetraethoxysilane are added three times a day until 1.10 ml has been added. After stirring another 16 h the solid product is recovered by centrifugation at 9000 rpm for 12 min this cycle is repeated 5 times. The product is dried at 120 ⁰C for 16h.

Step 2: crystallisation of Co/Pt alloy in silica to silicalite-1.

29.7 ml deionised water, 7.62 g 99 % ethanol, 0.0364 g NaOH, and 0.964 g 40 % tetrapropylammoniumhydroxide are magnetically stirred in an Erlenmeyer flask for 10 min at 600 rpm. 0.250 g Co-Pt-alloy in silica are added and stirred 10 min. The suspension is transferred to a 150 ml Teflon lined autoclave, sealed, and heated to 100 °C for 240 h.

Example 16; XRPD analysis of Au encapsulated in zeolite:

A hybrid zeolite material of the invention was prepared according to example 2, and before calcination of the organic template, an X-Ray Powder Diffraction (XRPD) reflection pattern was recorded of the hybrid zeolite material of Au encapsulated in MFI zeolite. Fig. 9 shows the XRPD pattern of gold alone (diagram B) and of the hybrid zeolite material of the invention (diagram A) . Diagram A is a reference pattern for bulk Au and is indicated by vertical bars. 40

Peaks are observed for bulk Au at 2Θ values of approx. 38, 45 and 65 degrees. These values are all above 30 degrees. The most intense peaks for the hybrid zeolite material are observed at 2Θ values of approx. 21 to 22 degrees.

Claims

41CLAIMS

1. Process for the preparation of hybrid zeolite or zeolite-like materials comprising the steps of: - providing a solution or suspension or solid material containing nanoparticles comprising at least one metal

- converting the mixture under zeolite or zeolite-like synthesis conditions to hybrid zeolite or zeolite-material encapsulating nanoparticles comprising at least one metal, the hybrid zeolite or hybrid zeolite-like material consisting of individual single crystals having at least one X-Ray Powder Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees determined by the zeolite type, and the encapsulated nanoparticles comprising at least one metal being immobilised in the zeolite framework of the zeolite or zeolite-like material.

2. Process according to claim 1, wherein the nanoparticles comprise at least one non-metal.

3. Process according to claim 1 or 2, wherein the metal is selected from the group consisting of Group IB, HB, IVB, VIIB, VIII and mixtures thereof, and the non- metal is selected from the group consisting of boron, carbon, nitrogen, oxygen, sulphur, phosphorous and mixtures thereof. 42

4. Process according to anyone of claims 1, 2 or 3, wherein the metal is selected from the group consisting of titanium, osmium, iridium, platinum, ruthenium, palladium, rhodium, rhenium, copper, nickel, cobalt, silver, gold, cadmium and mixtures thereof.

5. Process according to anyone of claims 1 to 4, wherein the synthesis gel or the synthesis gel precursor comprises compounds of elements selected from the group consisting of aluminum, silicon, phosphorous, nitrogen, carbon and mixtures thereof.

6. Process according to anyone of claims 1 to 5, wherein the aluminum compound is chosen from the group consisting of sodium aluminate, aluminum isopropoxide and aluminum nitrate nonahydrate, the silicon compound is selected from the group consisting of silica gel and silicates and mixtures thereof and the phosphorous compound is selected from the group consisting of phosphoric acid and phosphate salts and mixtures thereof.

7. Process according to anyone of claims 1 to 6, wherein the zeolite or zeolite-like synthesis conditions include heating of the mixture from room temperature to a final temperature maximum of 200°C and maintaining this final temperature for a predetermined time period.

8. Process according to claim 7, wherein the predetermined time period and the final temperature are chosen to ensure crystallisation of the hybrid zeolite or zeolite-like material. 43

9. Process according to anyone of claims 1 to 8, wherein the solid material is an oxide of silicon, aluminium, phosphorous, titanium, galium or mixtures thereof, or the solid material is carbon.

10. Process according to anyone of claims 1 to 9, wherein the solid material containing nanoparticles comprising at least one metal is obtained by impregnation of the at least one metal on the solid material followed by reduction with a reducing gas.

11. Process according to anyone of claims 1 to 10, wherein the at least one metal is platinum.

12. Process according to anyone of claims 1 to 11, wherein the solution containing nanoparticles comprising at least one metal is a colloid obtained by reducing a solution of the at least one metal with a reducing agent.

13. Process according to claims 9 or 12, wherein the solution containing nanoparticles comprising at least one metal is cooled, mixed with a polymeric compound, optionally centrifuged and thereafter mixed with a synthesis gel for preparing an oxide selected from the group consisting of oxides of silicon, aluminium, phosphorous, titanium, gallium or mixtures thereof, to provide a solid material containing nanoparticles comprising at least one metal coated with said oxide.

14. Process according to anyone of claims 1 to 13, wherein the at least one metal is gold. 44

15. Hybrid zeolite or zeolite-like material comprising one or more nanoparticles encapsulated within each individual single crystal of a microporous zeolite or zeolite-like material consisting of individual single crystals having at least one X-Ray Powder Diffraction (XRPD) reflection in the 2Θ range 8-30 degrees determined by the zeolite type, and the encapsulated nanoparticles comprising at least one metal being immobilised in the zeolite framework of the zeolite or zeolite-like material.