TW201714669A - Porous substrate - Google Patents

Abstract

The present invention provides a method of producing a substrate comprising a porous network. The method comprises forming a substrate precursor containing an array of template particles; and removing the template particles from the substrate precursor using a solvent at a temperature below room temperature to yield the substrate. The present invention also provides a method of producing a substrate comprising a first porous network and a second porous network, the two porous networks being interconnected. The method comprises: forming a substrate precursor containing an array of first template particles and an array of second template particles; selectively removing the first template particles from the substrate precursor to form the first porous network; and subsequently removing the second template particles from the substrate precursor to form the second porous network.

Description

Porous substrate Field of invention

The present invention relates to a porous substrate, for example, a porous substrate useful as a heterogeneous catalyst; a method of producing such a porous substrate; and the use of such a porous substrate.

Background of the invention

It is known to use a substrate having an interconnected pore network as a heterogeneous catalyst for chemical reactions. The porous substrate is formed around a template particle array using sol-gel condensation of the substrate material and subsequent removal of the template particles. The template particles are typically removed from the substrate by high temperature solvation (e.g., refluxing with a solvent at 100 ° C) or by calcination. The remaining pores after removal of the template particles can be treated to provide functional sites that can subsequently act on the catalytic chemical reaction.

The use of crosslinked polystyrene beads as a template particle system produces a substrate having a network of large pores (with pore sizes greater than 50 nm and typically about 200-500 nm).

Using a surfactant or a ternary block copolymer, such as poloxamers as a template particle system to produce medium pores A substrate of a network (with a pore size between 2 and 50 nm).

As with substrates having a uniform range of pore sizes, it is also known to provide substrates having a porous network with pore sizes of different sizes.

Substrates of interconnected networks with large pores and medium pores are known which are considered to provide easier accessibility of the reactants to access the functionalized mesoporous network. The substrates are formed using two different arrays of template particles, such as a polystyrene bead array (forming the large pores) and an array of liquid crystal surfactant particles (forming the medium pores). The template particles are simultaneously removed by calcination, leaving an interconnected network of large pores and medium pores.

It is known to use sulfonic acids in yttrium oxide substrates to functionalize large pores with medium pores to form macroporous/mesoporous heterogeneous acid catalysts, demonstrating the effectiveness of transesterification reactions and thus potential applications for biofuel synthesis. (Dhainaut et al , Green Chem. , 2010, 12, 296-303).

Macroporous-mesoporous alumina substrates are also known (Dacquin et al , J. Am. Chem. Soc . 2009, 131 , 12896-12897).

Also described is a macroporous-mesoporous cerium oxide substrate carrying palladium nanoparticles for selective oxidation of alcohol to form commercially important cinnamaldehyde (Partlett et al. , ACS Catal. 2013, 3 , 2122-2129 ).

Such known substrates have a single, uniform functionality and thus can catalyze a single step reaction.

Multiple-step reactions, such as cascade reactions, can be catalyzed using a plurality of substrates having different functionalities, or using a single substrate having dual or multiple-functionality. Dual/multiple-functional substrates can be removed by removing the template It is prepared by performing more than one functionalization treatment on the remaining pores after the granules. Two or more functional sites resulting from the multi-functionalization process are uniformly distributed throughout the porous network, i.e., within the substrate, different functional sites are not spatially isolated.

The use of multiple homogeneous functional substrates hinders the chemical process because all of the reaction products are accessible to all available functionalities and therefore do not selectively direct the transition. By dual/multiple-functional substrates, the yield of the final desired product is often poor because there is little control over the interaction of the starting product with the intermediate and various functional sites.

There is still a need for a single heterogeneous catalyst substrate that can catalyze a multi-step reaction and produce an acceptable yield of the desired product.

Summary of invention

In a first aspect, the present invention provides a method of making a substrate comprising a porous network, the method comprising: forming a substrate precursor comprising an array of template particles; and using one below room temperature The solvent of the temperature removes the template particles from the substrate precursor to form the substrate.

The first aspect of the invention allows for the removal of template particles at sub-ambient temperatures, unlike known methods that require high temperature solvation or calcination. Such a method represents the possibility of selectively removing template particles in the case of providing multiple arrays of different template particles as described in the second aspect of the invention discussed below. The high temperature method of template particle removal previously used is too intense and does not allow selective template shifting. except.

Optional features of the invention will now be listed. These may be used alone or in any combination with any aspect of the invention.

The solvent temperature used to remove the template particles can be at or below 0 °C (eg, at or below -5 °C or -7 °C).

In some embodiments, the template particles are formed from a polymer. The polymer can be an uncrosslinked polymer, such as an uncrosslinked hydrophobic polymer or crosslinkable. The template particles may be formed of polystyrene (PS), polylactic acid (PLA) or poly(methyl methacrylate) (PMMA), which may be uncrosslinked or crosslinked.

Polystyrene beads used as template particles in conventional methods are generally crosslinked and require precision preparation. Conversely, uncrosslinked polymers, such as uncrosslinked polystyrene, can be used in the present invention and this preparation does not need to be controlled so precisely.

The solvent used to remove the polystyrene template particles may be an aromatic solvent such as benzene, xylene, mesitylene or toluene. Toluene is preferred in terms of cost and toxicity. The solvent used to remove the PLA template particles may be an organic solvent such as tetrahydrofuran (THF), a chlorinated organic solvent or acetonitrile. The solvent used to remove the PMMA template particles may be an organic solvent such as methyl isobutyl ketone, methyl acetate or THF, or a binary solvent mixture such as acetonitrile/alcohol (such as methanol, ethanol or propanol).

The substrate and substrate precursor may be formed from alumina, yttria, metal oxides such as zirconia, titania or yttria or mixed metal oxides. Conventional methods can be used to form the substrate precursor. For example, the template particle array can be prefabricated and using sol-gel synthesis or coprecipitation The substrate material is formed around the array of template particles.

In some embodiments, the method further comprises forming a functional site on the surface of the substrate within the porous network. The functional site can be formed by chemical adsorption (covalent, ionic, hydrogen), electrostatic physisorption, or ligand exchange using various chemical species. For example, chemisorption or electrostatic physical adsorption of metal-containing nanoparticles, covalent/ionic/hydrogen bonding of organic acid/base species, covalent bonding of aliphatic or aromatic hydrocarbons, formation of metal complexes An organic ligand species exchanged with a ligand or a gas, vapor or liquid phase deposited oxide such as alumina, yttria or zirconia via a precursor (such as an alkoxide, halide or hydroxide precursor) Addition layer deposition can be used to functionalize the surface within the porous network.

Once functionalized, the substrate can be used as a heterogeneous catalyst for a wide variety of toxic reactions.

In a second aspect, the present invention provides a method of making a substrate comprising a first porous network and a second porous network, the two porous networks being interconnected, the method comprising: forming a a first template particle array and a substrate precursor of a second template particle array; selectively removing the first template particles from the substrate precursor to form the first porous network; The substrate precursor subsequently removes the second template particles to form the second porous network.

By selectively removing the first template particles, it is possible to selectively functionalize the pores within the first network without affecting the second Porosity within a porous network. This represents a previously unknown catalyst architecture option.

In some embodiments, the first and second template particles have different chemical and/or physical properties.

For example, in some embodiments, the first and second template particles can have different sizes. For example, the first template particle can be larger than the second template particle, for example, such that the first porous network comprises large pores and the second porous network comprises medium pores.

The large pores preferably have a size of from 50 nm to 10 μm as measured by mercury porosimetry or electron microscopy. The medium pore preferably has a size of 2-50 nm and more preferably 2.5-14 nm, which is determined by physical adsorption of nitrogen and analysis of the corresponding isotherm by the BJH method.

In some embodiments, the first and second template particles have different thermal stability. In some embodiments, the first and second template particles have different polarities. In some embodiments, the first and second template particles have different photochemistry.

These chemical/physical differences can be used to aid in the selective removal of the first template particles.

In some embodiments, the invention comprises the use of a solvent at a temperature below room temperature (e.g., at or below 0 °C) to selectively remove the first template particles. The solvent temperature used to remove the first template particles can be at or below -5 °C (eg, at or below -7 °C).

In some embodiments, the first template particles are formed from a polymer. The polymer can be an uncrosslinked polymer, such as an uncrosslinked hydrophobic polymer or crosslinkable. The template particles may be polystyrene (PS), polylactic acid (PLA) Or poly(methyl methacrylate) (PMMA) is formed, which may be uncrosslinked or crosslinked.

The solvent used to remove the polystyrene template particles may be an aromatic solvent such as benzene, xylene, mesitylene or toluene. Toluene is preferred in terms of cost and toxicity. The solvent used to remove the PLA template particles may be an organic solvent such as tetrahydrofuran (THF), a chlorinated organic solvent or acetonitrile. The solvent used to remove the PMMA template particles may be an organic solvent such as methyl isobutyl ketone, methyl acetate or THF, or a binary solvent mixture such as acetonitrile/alcohol (such as methanol, ethanol or propanol).

In some embodiments, the second template particles are formed from a surfactant. The surfactant may be a nonionic surfactant or may be a cationic surfactant such as cetyltrimethylammonium bromide (CTAB) or a derivative thereof (with different length alkyl groups and/or different Center ion). In some embodiments, the second template particles are formed from a non-ionic block copolymer, such as a poloxamer polymer (such as Pluronic P123). In some embodiments, the second template particles are formed from a carboxylic acid.

In some embodiments, the method includes subsequently removing the second template particles using thermal processing (such as furnace or microwave irradiation), chemical extraction (optionally under thermal, microwave or ultrasonic conditions), chemistry Decomposition (such as the use of concentrated mineral acids, such as concentrated sulfuric acid) or UV / visible light irradiation.

In some embodiments, the method comprises subsequently removing the second by using solvation at a reflux temperature, such as a solvent at a temperature above room temperature (eg, at or above 50 ° C or at or above 70 ° C) Template particles. The solvent may be a polar solvent such as an alcohol, such as a C1-C6 alcohol, It is methanol, ethanol, isopropanol, butanol, pentanol or hexanol. Non-polar solvents such as toluene or xylene or supercritical fluids such as carbon dioxide or water can also be used.

In some embodiments, the method comprises forming a first functional site on a surface of the substrate within the first porous network and/or forming a second surface on the surface of the substrate within the second porous network Functional site.

The surface within the first and/or second porous network may be physically or chemically adsorbed (covalent, ionic, hydrogen bonded) or surface within the first/second porous network The ligand of the hydroxyl group is exchanged for functionalization. For example, chemisorption or electrostatic physical adsorption of metal-containing nanoparticles, covalent/ionic/hydrogen bonding of organic acid/base species, covalent bonding of aliphatic or aromatic hydrocarbons, formation of metal complexes An organic ligand species exchanged with a ligand or a gas, vapor or liquid phase deposited oxide such as alumina, yttria or zirconia via a precursor (such as an alkoxide, halide or hydroxide precursor) An additive layer deposition can be used to functionalize the surface within the porous network. In a preferred embodiment, the surface within the first porous network is functionalized by covalent bonding.

The first and/or second functional sites may comprise a catalytic metal (such as platinum (Pt) or palladium (Pd)), a fluorescent label, an acidic group, a basic group, a hydrophilic group or a hydrophobic group. group. The first/second functional site may comprise an enzyme or dye when the pores within the first and/or second porous network are large pores.

In a preferred embodiment, the first and second functional sites are different from each other and the functionality of the first and second functional sites are different from each other.

In some embodiments, the method includes forming a first functional site on the surface of the first porous network prior to subsequent removal of the second template particle from the substrate precursor. In this way, the first porous network will be functionalized while the second porous network is unaffected.

In such specific embodiments, the first functional site is preferably covalently linked and, preferably, decomposed only at elevated temperatures (e.g., above -250 °C). Therefore they are not affected during the removal of the second template.

In some embodiments, the method includes forming a second functional site on the surface of the second porous network after the second template particle is subsequently removed from the substrate precursor.

Accordingly, some specific examples provide a method of fabricating a substrate comprising a first porous network having a first functional site and a second porous network having a second functional site, The two porous networks are interconnected, the method comprising: forming a substrate precursor comprising a first template particle array and a second template particle array; selectively removing the first template particles from the substrate precursor Forming the first porous network; forming the first functional site on the surface of the first porous network; subsequently removing the second template particles from the substrate precursor to form the second a porous network; and forming the second functional site on the surface of the second porous network.

In some embodiments, the first functional site is selected to block pores of the first porous network from being used to form the second functional site The reagents are subsequently functionalized.

For example, the first functional site can occupy all of the available surface hydroxyl groups within the first porous network such that it is less susceptible to further functionalization, is difficult to access, or the first functional site can be selected to The reagent used to form the second functional site is rejected.

For example, the first functional site can comprise a hydrophobic functionality that forms a strong covalent bond with a hydroxyl group on the surface of the first porous network and which also rejects an aqueous reagent, such as subsequently used in the first The two porous network forms an aqueous metal (e.g., Pt) salt solution of catalytic metal (e.g., Pt) particles.

The hydrophobic functionality at the first functional site may comprise an alkyl chain, such as an alkyl chain containing 6 or more carbon atoms, such as an octyl chain or an aryl group, such as a phenyl group. In these embodiments, the method can include forming the first functional site on the surface of the first porous network by hydrolysis of an alkyl decane precursor.

Catalytic platinum sites can be introduced using aqueous platinum salt solutions such as aqueous H ₂ PtCl ₆ . Chemical or photochemical reduction can be performed to induce formation of metal nanoparticles at the second functional site, wherein the reduction can be carried out at a low temperature (e.g., 25-100 ° C).

In other embodiments, the step of forming the first functional site comprises introducing a hydrophilic species (such as a macropolyol or an alcohol/carboxylic acid functionalized organodecane species). In these embodiments, the step of forming the second functional site comprises introducing a hydrophobic species (such as an encapsulated metal (e.g., Pt) nanoparticle). The hydrophilic group at the first functional site repels the Pt nanoparticle to specifically enter the second porous network. Can introduce additional hydrophilic species (such as waterborne metals) (such as Pd) salt solution) to selectively enter large pores (too large to enter the medium pores and to be repelled by hydrophobic Pt nanoparticles from medium pores). In some embodiments, the first porous network is different in pore size from the second porous network, and the functional sites can be selected such that they are too large to form within the smaller pores. For example, the first functional site can comprise a giant hydrophobic or hydrophilic group having a size that is too large to enter a medium pore (eg, within the second porous network) that is capable of entering large pores ( For example, within the first porous network.) The first functional site may further comprise a catalytic metal and may be formed from pre-formed metal-containing particles that are too large to enter the medium-sized pores, such as Pd-containing nanoparticles.

A particularly preferred embodiment provides a method of making a substrate comprising a first porous network having catalytic palladium sites and a second porous network having catalytic platinum sites, The first porous network comprises large pores and the second porous network comprises medium pores, the two porous networks being interconnected, the method comprising: forming an array comprising a first template particle and a second template particle array a substrate precursor; selectively removing the first template particles from the substrate precursor to form the first porous network comprising large pores; forming a hydrophobic functional on the surface of the first porous network a site; subsequently removing the second template particles from the substrate precursor to form the second porous network comprising medium pores; and introducing an aqueous platinum salt solution on the surface of the second porous network Catalytic platinum sites; A catalytic palladium site is introduced within the first porous network.

The catalytic palladium site can be introduced using pre-formed Pd nanoparticle. This allows their dimensions to be controlled such that the dimensions are larger than the medium pore size and then the medium pores cannot be physically fitted. Suitable preformed nanoparticles are oleylamine encapsulated Pd nanoparticles which may have a scale of 5-50 nm. The encapsulant imparts hydrophobic properties to the nanoparticles. Unstabilized Pd nanoparticles can also be used.

The catalytic platinum site can be introduced using an aqueous platinum salt solution, such as aqueous H ₂ PtCl ₆ . Metal reduction at low temperatures (e.g., 25-100 ° C) can be performed to induce formation of metal nanoparticles.

Further preferred embodiments provide a method of making a substrate comprising a first porous network having catalytic palladium sites and a second porous network having catalytic platinum sites, The first porous network comprises large pores and the second porous network comprises medium pores, the two porous networks being interconnected, the method comprising: forming an array comprising a first template particle and a second template particle array a substrate precursor; selectively removing the first template particles from the substrate precursor to form the first porous network comprising large pores; forming hydrophilicity on the surface of the first porous network a functional site; the second template particle is subsequently removed from the substrate precursor to form the second porous network comprising a medium pore; the hydrophobic platinum nanoparticle is used on the surface of the second porous network Introducing a catalytic platinum site; A catalytic platinum site is introduced into the first porous network using an aqueous platinum salt solution.

The hydrophilic functional sites of the first porous network can be introduced using macropolyol or alcohol/carboxylic acid functionalized organodecane species. In these specific examples, the step of forming the second functional site comprises introducing hydrophobically encapsulated Pt nanoparticle. The hydrophilic group at the first functional site repels the Pt nanoparticle to specifically enter the second porous network. An aqueous Pd salt solution is then introduced to selectively enter the large pores (too large to enter the medium pores and to be repelled by the hydrophobic Pt nanoparticles from the medium pores).

In other preferred embodiments, the first functional site comprises an enzyme and the second functional site comprises a catalytic metal (such as Pt/Pd), an acidic group or a basic group.

In other preferred embodiments, the first functional site comprises a first fluorescent label and the second functional site comprises a second fluorescent label.

In other preferred embodiments, the first functional site comprises an acidic or basic functionality and the second functional site comprises a catalytic metal.

In other preferred embodiments, the first functional site comprises a catalytic metal and the second functional site comprises an acidic or basic functionality.

In other preferred embodiments, the first functional site comprises an acidic functionality and the second functional site comprises a basic functionality.

In other preferred embodiments, the first functional site comprises a basic functionality and the second functional site comprises an acidic functionality.

The acidic functionality can be a silic acid function that can be introduced by using a thiolated organodecane precursor that can be subsequently oxidized to a sulfonic acid.

The acidic functionality can be a Lewis acid functionality that can be introduced by using a metal alkoxide precursor that can be subsequently oxidized to a metal oxide such as ZrO ₂ or TiO ₂ .

The acidic functionality can be a carboxylic acid functionality which can be introduced by using an organodecane having a carboxylic acid group or an organic decane precursor having a nitrile group capable of being converted to a carboxylic acid group via acid or base hydrolysis.

The basic functionality can be amine functionality by using an organodecane having an amine functional group or an organic decane precursor having a nitrile group capable of conversion to an amine group via, for example, LiAlH ₄ - reduction. Come to introduce.

Enzyme functionality can be introduced by using an organodecane having a carboxylic acid group or an amine functional group followed by hydrogen bonding or covalent bonding to the organodecane carboxylic acid or amine functional group.

In some embodiments, the substrate and substrate precursor are formed from aluminum oxide, cerium oxide, a metal oxide such as zirconia, titania or cerium oxide or a mixed metal oxide. Conventional methods can be used to form the substrate precursor. For example, the template particle array can be preformed and the substrate material formed around the template particle array using sol-gel synthesis.

In a third aspect, the present invention provides a method of making a substrate comprising a first porous network having a first functional site and a second porous having a second functional site a network, the first porous network comprising large pores and the second porous network comprising medium pores, the two porous networks being interconnected, the method comprising: forming an array comprising a first template particle and a second template a substrate precursor of the particle array; Removing the first template particles from the second template particles from the substrate precursor to form the first porous network comprising large pores and the second porous network comprising medium pores; Forming the first functional site on the surface of the porous network; and subsequently forming the second functional site on the surface of the second porous network.

The surface within the first and/or second porous network may be physically or chemically adsorbed (covalent, ionic, hydrogen bonded) or surface within the first/second porous network The ligand of the hydroxyl group is exchanged for functionalization. For example, chemisorption or electrostatic physical adsorption of metal-containing nanoparticles, covalent/ionic/hydrogen bonding of organic acid/base species, covalent bonding of aliphatic or aromatic hydrocarbons, formation of metal complexes An organic ligand species exchanged with a ligand or a gas, vapor or liquid phase deposited oxide such as alumina, yttria or zirconia via a precursor (such as an alkoxide, halide or hydroxide precursor) Addition layer deposition can be used to functionalize the surface within the porous network. In a preferred embodiment, the surface within the first porous network is functionalized by covalent bonding.

In some embodiments, the step of forming the first functional site comprises introducing a first functional species that is too large to enter the medium pore. For example, pre-formed catalytic metal (such as Pd) nanoparticles, enzymes or dyes or giant hydrophilic species such as polyalcohol or alcohol/carboxylic acid functionalized organodecane species or giant hydrophobic groups may be used, for example containing 6 An alkyl chain of more than one carbon atom, such as an octyl chain or an aromatic group, for example having a phenyl group having a size greater than the size of the medium pore size.

In some embodiments, the first functional site is selected to block subsequent functionalization of the pores of the first porous network by the reagents used to form the second functional site.

For example, the first functional site can occupy all of the available surface hydroxyl groups within the first porous network such that it is less susceptible to further functionalization, is difficult to access, or the first functional site can be selected to The reagent used to form the second functional site is rejected. In some embodiments, the step of forming the first functional site comprises introducing a hydrophobic species that is too large to enter the medium pore. In these specific examples, the step of forming the second functional site comprises introducing a hydrophilic species such as an aqueous metal (Pt) salt solution.

The hydrophobic species can bind to surface hydroxyl groups within the first porous network. The hydrophobic species blocks the formation of any second functional sites within the first porous network by binding to surface hydroxyl groups. The hydrophobic functionality at the first functional site may comprise an alkyl chain, such as an alkyl chain containing 6 or more carbon atoms, such as an octyl chain or an aromatic group, such as a phenyl group. In these embodiments, the method can include forming the first functional site on the surface of the first porous network by hydrolysis of an organodecane precursor.

The step of forming the second functional site comprises introducing an aqueous metal (e.g., Pt) salt solution into the second porous network. The hydrophobic group at the first functional site repels the aqueous solution and the metal salt specifically into the second porous network. Catalytic platinum sites can be introduced using aqueous platinum salt solutions such as aqueous H ₂ PtCl ₆ . Metal reduction at a low temperature (e.g., 25-100 ° C) is performed to induce formation of metal nanoparticles at the second functional site.

The catalytic metal sites can then be introduced into the first porous network using pre-formed Pd nanoparticles that are too large to enter the medium pores.

In other embodiments, the step of forming the first functional site comprises introducing a hydrophilic species (such as a macropolyol or an alcohol/carboxylic acid functionalized organodecane species) that is too large to enter the medium pore. In these embodiments, the step of forming the second functional site comprises introducing a hydrophobic species (such as an encapsulated metal (e.g., Pt) nanoparticle). The hydrophilic group at the first functional site repels the Pt nanoparticle to specifically enter the second porous network. Additional hydrophilic species (such as aqueous metal (e.g., Pd) salt solutions) can be introduced to selectively enter large pores (too large to enter the medium pores and to be repelled by hydrophobic Pt nanoparticles from the medium pores).

In other preferred embodiments, the first functional site comprises an enzyme and the second functional site comprises a catalytic metal (such as Pt/Pd), an acidic group or a basic group.

In other preferred embodiments, the first functional site comprises a first fluorescent label and the second functional site comprises a second fluorescent label.

In other preferred embodiments, the first functional site comprises an acidic or basic functionality and the second functional site comprises a catalytic metal.

In other preferred embodiments, the first functional site comprises a catalytic metal and the second functional site comprises an acidic or basic functionality.

In other preferred embodiments, the first functional site comprises an acidic functionality and the second functional site comprises a basic functionality.

In other preferred embodiments, the first functional site comprises a basic functionality and the second functional site comprises an acidic functionality.

The acidic functionality can be a silic acid function that can be introduced by using a thiolated organodecane precursor that can be subsequently oxidized to a sulfonic acid.

The acidic functionality can be a Lewis acid functionality that can be introduced by using a metal alkoxide precursor that can be subsequently oxidized to a metal oxide such as ZrO ₂ or TiO ₂ .

The acidic functionality can be a carboxylic acid functionality which can be introduced by using an organodecane having a carboxylic acid group or an organic decane precursor having a nitrile group capable of undergoing acid or base hydrolysis to convert to a carboxylic acid group.

The basic functionality can be amine functionality by using an organodecane having an amine functional group or an organic decane precursor having a nitrile group capable of conversion to an amine group via, for example, LiAlH ₄ - reduction. Come to introduce.

Enzyme functionality can be introduced by using an organodecane having a carboxylic acid group or an amine functional group followed by hydrogen bonding or covalent bonding to the organodecane carboxylic acid or amine functional group.

In some embodiments, the substrate and substrate precursor are formed from aluminum oxide, cerium oxide, a metal oxide such as zirconia, titania or cerium oxide or a mixed metal oxide. Conventional methods can be used to form the substrate precursor. For example, the template particle array can be preformed and the substrate material formed around the template particle array using sol-gel synthesis.

In a fourth aspect, the present invention provides a substrate comprising a first porous network having one of a first functional site and a second porous network having one of a second functional site, wherein The first and second functional sites are spatially separated/isolated and functionally and/or chemically distinct.

In a preferred embodiment, the pore system in the first porous network Greater than the pores within the second porous network. For example, the first porous network can comprise large pores and the second porous network can comprise medium pores.

In some embodiments, the first functional site comprises a catalytic metal (such as Pt/Pd), an enzyme, a dye, a fluorescent label, an acidic group, a basic group, a hydrophilic group, or a hydrophobic group.

In some embodiments, the second functional site comprises a catalytic metal (Pt/Pd), a fluorescent label, an acidic group, a basic group, a hydrophilic group, or a hydrophobic group.

In some embodiments, the first functional site comprises an enzyme and the second functional site comprises a catalytic metal (Pt/Pd), an acidic group, or a basic group. Such substrates can be used as biochemical catalysts to catalyze multiple-step reactions.

In some embodiments, the first functional site comprises a first fluorescent label and the second functional site comprises a second fluorescent label. Such substrates can be used as sensing devices for clinical applications (such as protein sensing devices) that are capable of resolving the presence of multiple analytes based on size, for example, enzymes such as bone marrow peroxidase (<5 nm) and C. - Reactive protein (> 5 nm).

In some embodiments, the first functional site comprises an acidic functional group and the second functional site comprises a catalytic metal. Such a substrate can be used as a catalyst for the conversion of glucose to sorbitol.

In some embodiments, the first functional site comprises Pd and the second functional site comprises Pt. Such substrates can be used as catalysts for the selective oxidation of alcohols to acids, such as cinnamyl alcohol to cinnamic acid (via cinnamaldehyde).

Cinnamic acid is an important spice and essential oil. Pd is highly selective Catalyzing the oxidation of cinnamyl alcohol to cinnamaldehyde, but promoting the decarbonylation of the resulting aldehyde product. Conversely, Pt prefers the undesired hydrogenation of cinnamyl alcohol (via activated surface hydrogen) to 3-phenylpropanal, but highly selective oxidation of cinnamaldehyde to the desired cinnamic acid product.

A specific embodiment of the invention having Pd as the first functional site and Pt as the second functional site provides a catalyst design that ensures that cinnamyl alcohol is first oxidized by Pd prior to encountering the Pt site while allowing for the activation to form Cinnamaldehyde can be subsequently brought close to the Pt site to selectively produce cinnamic acid in a second oxidation step. Such targets are achievable through the spatial control of the Pd and Pt positions within the substrate.

In some embodiments, the first functional site comprises an acidic functionality and the second functional site comprises a basic functionality. Such substrates can be used as catalysts for the conversion of cellulose to hydroxymethylfurfural (HMF) or conversion of biomass oil to biodiesel to avoid subsequent poisoning of the base sites required to catalyze the oil component via transesterification.

In some embodiments, the substrate is formed from alumina, yttria, a metal oxide such as zirconia, titania or yttria or a mixed metal oxide.

Specific examples of the invention will now be exemplified with reference to the accompanying drawings: Figures 1A and 1B show transmission electron microscopy images of the substrate precursor before (Figure 1A) and after (Figure 1B) toluene extraction; Figure 2 shows the substrate in the Stacked nitrogen pore method isotherm before and after continuous extraction of the first template particles; Figure 3 shows the surface area as a function of the number of toluene extractions; Figure 4 shows the results of the thermogravimetric analysis; Figure 5 shows the nitrogen pore method isotherm of the substrate after octyl functionalization; Figure 6 shows the substrate in the Nitrogen pore isotherm and medium pore size analysis after extraction of the second template particles (P123); Figure 7 shows the pyrolysis weight of the substrate after P123 template particle extraction (C8 functionalization) and P123 template particle extraction Analysis; Figures 8A and 8B show water contact angle analysis of octyl-functionalized substrate after P123 template particle extraction (Figure 8A) and non-octyl-functionalized equivalent material (Figure 8B); Figures 9A and 9B show high resolution Scanning electron microscopy images showing Pt nanoparticles in the medium pores of the substrate; Figure 10 shows the particle size distribution of Pt nanoparticles; Figures 11A and 11B show high resolution of the substrate after introduction of Pd nanoparticles Scanning electron microscopy images; Figure 12 shows the particle size distribution of Pt nanoparticles and Pd nanoparticles in bimetallic substrates; Figure 13 shows energy dispersive X-ray spectra of medium porosity and large porosity regions. Figure 14A and 14B The cinnamyl alcohol conversion of the bimetallic substrate is shown; and Figure 15 shows the alignment of the bimetallic substrate and the conventional substrate in the conversion of cinnamyl alcohol and the manufacture of cinnamaldehyde and cinnamic acid.

experiment

A substrate precursor comprising an array of first template particles comprising uncrosslinked polystyrene bead template particles and a second template particle array comprising Pluronic P123 is formed.

The substrate precursor was synthesized by the methodology reported by Sen at al , Chemistry of Materials , 2004, 16, 2044-2054.

Styrene (105 cm ³ ) was washed five times with sodium hydroxide solution (0.1 M, 1:1 vol/vol), followed by washing five times with distilled water (1:1 vol/vol) to remove the polymerization inhibitor. At 80 deg.] C The washed organic phase was added to the denitrification of water (850cm ^3), followed by dropwise addition of an aqueous solution of potassium persulfate (0.24M, 50cm ³⁾ and shaken at 300rpm. The reaction was allowed to continue for 22 h, after which time the solution turned white due to the formation of polystyrene nanospheres. The solid product was recovered by centrifugation (8000 rpm, 1 h) and induced colloidal crystal alignment. The resulting highly ordered polystyrene colloidal nanosphere crystals were finally ground into a fine powder for use as the first template particles.

Pluronic P123 (2 g) was ultrasonically shaken to a homogenous gel at 40 ° C with hydrochloric acid acidified water (pH 2, 2 g).

6 g of uncrosslinked polystyrene particles were mixed and added at 100 rpm to carry out gel homogenization in a two minute time course. The gel was then dried under vacuum at 40 ° C to a solid powder. After 2 hours, the solid was exposed to room temperature in the atmosphere for 24 hours.

10 g of the substrate precursor was placed in 100 ml of toluene at -8 ° C and shaken at a high speed over 600 rpm for 1 minute to remove the first template particles. The solid was recovered by vacuum filtration and washed with cold toluene. Repeatedly The extraction was carried out four times to completely extract the polystyrene template particles.

1A and 1B show transmission electron microscope images of the substrate precursor before (Fig. 1A) and after (Fig. 1B) extraction of toluene. It can be seen that a first porous network comprising large pores having an average size of 400 nm was produced. The Pluronic 123 template particles remain intact within the substrate precursor. This was confirmed by nitrogen porosimetry, thermogravimetric analysis (TGA) and gel permeation chromatography (GPC).

The nitrogen porosimetry was performed on a Quantachrome Autosorb IQTPX porosimeter and analyzed using ASiQwin v3.01 software. Samples were degassed for 12 h at 150 °C prior to recording the N2 adsorption/desorption isotherm. The BET surface area is calculated as a relative pressure range of 0.02-0.2. The medium porosity property is calculated by applying the BJH method to the desorption isotherm at a relative pressure > 0.35 and matching the isotherms to the associated DFT core of the software combination. Thermogravimetric analysis (TGA) was carried out at 10 ° C min ^-1 in a N ₂ /O ₂ stream (80:20 v/v 20 cm ³ min ^-1 ) using a Stanton Redcroft STA 780 thermal analyzer.

Figure 2 shows the stacked nitrogen pore isotherm of the substrate before and after continuous extraction of the first template particles, showing large porosity (high relative pressure ~ 0.95, rapid volume increase) and no medium porosity (In the 0.3-0.9 relative pressure range, there is no increase in volume), ie no extraction to the second template particles (Pluronic P123).

Figure 3 shows the surface area as a function of the number of extractions, showing that due to the removal of the first template particles from the large pores, the surface area increases with extraction, increases to a maximum after four extractions, and since the first template particles are completely extracted and Subsequent extraction of the subsequent plateau value of the second template particle.

Figure 4 shows the results of the thermogravimetric analysis showing the first and second template particle levels remaining in the material after the first template particles are continuously extracted. The extraction of the first template particles increases with up to four extractions, while the second template particle level is unaffected.

Next, the large pores within the first porous network functionalize the first functional site with an octyl group by refluxing the organodecane precursor in a heptane solvent overnight or at room temperature with an organic decane. The precursor is wet immersed. In one embodiment, 2 g of the substrate precursor was stirred in 6 cm ^{3 of} triethoxy(octyl)decane for 3 minutes and recovered by vacuum filtration and then dried overnight at room temperature.

Figure 5 shows the nitrogen pore isotherm of the substrate after octyl functionalization, which is similar to that obtained prior to octyl functionalization and without moderate porosity from P123 template particle removal, shown in During the first porous network functionalization, the P123 template particles remain in the substrate. The surface area of 19 m ³ g ^-1 corresponds to the parent material.

Next, the P123 template particles were removed by refluxing 2 g of the substrate template in methanol (400 cm ³ ) overnight (18 hours).

Figure 6 shows the nitrogen pore isotherm of the substrate after extraction of the second template particles (P123) and shows an increase in surface area due to - removal via P123 - medium pore evacuation (up to 300 m ² g ^-1 The resulting increase in nitrogen uptake volume is seen by the shape of the type IV isotherm. Medium pore size analysis - using the BJH methodology (insertion) - reveals an average medium pore diameter of 3.5 nm.

Figure 7 shows the thermogravimetric analysis of the substrate prior to P123 template particle extraction (C8 functionalization) and P123 template particle extraction. Before extraction The material mass loss at ~190 °C was due to P123 burning and the extracted material did not have this feature, confirming the removal of P123 template particles.

Figures 8A and 8B show water contact angle analysis of an octyl-functionalized substrate after P123 template particle extraction (Figure 8A) and a non-octyl-functionalized equivalent material (Figure 8B), wherein the first and second template particles It has been extracted under the same conditions.

Contact angle measurements were made on a Kruss DSA100 drop shape analyzer equipped with a digital camera for continuous data collection. The shape of the water droplets was analyzed by DSA3 software after 10 seconds of settling.

The 137[deg.] high contact angle of the water droplets of the octyl-functionalized material indicates a hydrophobic material. Conversely, the unfunctionalized material that instantaneously draws the water droplets into the substrate indicates that the substrate does not exhibit hydrophobicity.

Next, the substrate (06.g) and 1% by weight of aqueous H ₂ PtCl ₆ (3 cm ³ , 0.01575 g of Pt, salt) were stirred in the dark. The platinum nanoparticles are selectively driven into the medium pores because the hydrophobic groups within the large pores repel the aqueous solution. The dry powder was obtained by gently heating the slurry at 50 ° C for 10 hours, followed by reducing the metal at low temperature (100 ° C) for one hour under H ₂ (10 cm ³ min ^-1 ) to leave 2.2 nm in the medium pores. Average diameter Pt particles. A Pt loading of 0.73 wt% was observed.

9A and 9B show high-resolution scanning transmission electron microscope images. In the dark field (Fig. 9A), Pt nano particles appear as bright spots, and in bright fields (Fig. 9B), Pt nano particles appear as black spots, showing the substrate. Pt nanoparticles within the medium pores.

High-resolution scanning transmission electron microscope (S) TEM image is The following records: FEI Tecnai F20 FEG TEM, operating at 200kV with Oxford Instruments X-Max SDD EDX detector (10nm diameter spot size) or JEOL 2100F FEG STEM, operating at 200keV with spherical aberration detector corrector (CEOS GmbH) and Bruker XFlash 5030 EDX. Figure 10 shows the particle size distribution of the Pt nanoparticles, showing that ~98% of the particles are smaller than the average medium pore size and are then capable of mating with the second pore network of the substrate.

Near-monodisperse palladium nanoparticles of 5.6 ± 0.8 nm diameter were prepared by Mazumder and Sun ( J. Am. Chem. Soc. 131, 4588-4589 (2009)) using readily available borane complexes. The particle aging time course is extended at 90 ° C to obtain larger nano particles. The synthesis was carried out under an argon atmosphere using standard Schlenk techniques. After venting the Pd(acac) ₂ (73 mg, Alfa Aesar) in a three-necked round bottom flask and backfilling argon (repeated three times), oleylamine (15 cm3, Acros 26 Organics, 80-90%) was added and allowed to stir while stirring. The flask was heated to 60 °C. Borane triethylamine (0.52 cm3, Aldrich, 97%) was added to convert the solution from pale yellow to light brown, followed by heating to 90 ° C in 15 minutes, during which time the solution turned black, indicating colloidal naphthalene The formation of rice grains. Heating was continued at 90 ° C for 90 minutes and then cooled to room temperature. Ethanol (Fisher Scientific, HPLC grade, about 30 cm ³ ) was added to the suspension to precipitate the nanoparticles, followed by extraction by centrifugation (8000 rpm, 20 minutes, 50 cm ³ plastic centrifuge tube, pre-washed with ethanol).

The resulting solid was redispersed in hexane (about 4 cm ³ , Fisher Scientific, reagent grade), the hexane volume was drained to about 2 cm ³ in flowing argon, and then precipitated by adding a minimum amount of ethanol, and by Centrifugation (6000 rpm, 10 minutes). Wash with about 2 cm ^{3 of} hexane and precipitate with ethanol, then centrifuge, and repeat the above two times to remove any excess oleylamine and other residual synthetic agents. Finally the solid was again dispersed and stored in hexane (30 ^cm3 ) until further use.

The Pd content of this nanoparticle solution was determined by ICP-OES to be 11.0 ± 0.12 mg (at 30 cm ³ ), indicating that about 43% of the initial Pd was present in the nanoparticles after purification.

The nanoparticle thus prepared was characterized by TEM by throwing a drop of nanoparticle solution onto a porous carbon-encapsulated copper grid (Agar Scientific) and draining. TEM images were performed using a JEOL 2100F FEG TEM with a Schottky field emission source and an Oxford INCAx-sight Si (Li) detector equipped with energy scattering spectroscopy. The acceleration voltage is 200kV. The particle size distribution was obtained by taking images of six different grid regions and measuring the diameter of 800 individual nanoparticles. There are no significant particle size changes in different areas of the grid.

Next, the substrate (0.3 g) was treated with a 6.5 cm ^{3 portion of} a preformed oleylamine-encapsulated palladium nanoparticle in 1 wt% heptane.

The size of the preformed nanoparticle is greater than the average medium pore size.

The resulting solid was stirred in the solution for 1 hour, and then the solvent was evaporated at room temperature to leave a dry powder.

Tests have shown that the catalytic Pd sites are contained within the large pores and the catalytic Pt sites are contained within the medium pores.

Figures 11A and 11B show high resolution scanning transmission electron microscopy images of the substrate after introduction of Pd nanoparticle. In bright field (Fig. 11A) with Dark field (Fig. 11B), larger Pd nanoparticles appear in the large pores of the substrate. It is also feasible that Pt is present in the medium pores because these deposits are deposited prior to Pd deposition. Due to the atomic-order contrast nature of the technique, it is possible to distinguish between Pd and Pt using a dark-field configuration, and Pt appears to be brighter than Pd (shown in Figure 11B).

Figure 12 shows the particle size distribution of Pt nanoparticles and Pd nanoparticles in a bimetallic substrate compared to an equivalent monometallic material. The display dimensions are not affected by the presence of two metals, the average size of the Pt particles being less than the average diameter of the second pore structure, and the size of the Pd nanoparticles being greater than the second pore structure.

Figure 13 shows the energy dispersive X-ray spectrum of the medium porosity and large porosity regions, further showing the exact location of the Pd and Pt nanoparticles. The strongest secondary porosity (medium porosity) region of bismuth (Si) and oxygen (O) also shows the existence of discrete Pt sites and no Pd, while the first porosity (large pores) block due to large voids Shows less yttrium oxide and oxygen levels and shows Pd level and no Pt.

The bifunctionalized substrate was used at 150 ° C, 5 bar O ₂ as a catalyst for the selective oxidation of cinnamyl alcohol to cinnamic acid.

The catalytic selective oxidation reaction was carried out in a 100 cm ³ Buchi small autoclave stirred batch reactor at 150 ° C on a 75 cm ³ scale. 12.5 mg of the catalyst was added to a reaction mixture containing 4.2 mmol of cinnamyl alcohol (0.562 g), an internal standard (trimethylbenzene, 0.1 cm ³ ), and a toluene solvent (75 cm ³ ) at 150 ° C under 5 bar of oxygen and stirred. The reaction was periodically sampled for off-line gas chromatography analysis via a Varian 3800 GC equipped with a CP-Sil5 CB column (15 m x 0.25 mm x 0.25 μm), 8400 autosampler. Conversion, selectivity and yield were calculated by calibrating to a reference compound and citing ±2%. The frequency of turnover in terms of cinnamyl alcohol conversion is quoted relative to the surface density of the PdO site (measured by XPS), and the frequency of turnover in terms of cinnamic acid production is relative to the surface density of PtO ₂ site (measured by XPS). The same is the respective active sites for selective oxidation of Pd nanoparticles and Pt nanoparticles.

The results show that the conversion rate is similar to that of the monometallic Pd or Pt catalyst prepared on the same substrate, but the yield of cinnamic acid is an order of magnitude higher than that achievable with a single metal catalyst.

The Pd catalytic site catalyzes the conversion to an aldehyde - the alcohol will achieve good exposure to the Pd catalyst due to the large pore size of the first porous network. The Pt catalyst site then inserts catalytic oxygen into the C-H of the aldehyde and forms an acid.

Figures 14A and 14B show that the cinnamyl alcohol conversion of the bimetallic substrate is similar to two single metallic substrates, Pd is within the large pores or Pt is within the medium pores (Figure 14A). The real benefit of the bimetallic system is evident in the cinnamic acid yield (Fig. 14B) - the desired product of continuous oxidation - which is evaluated as a bimetallic substrate that is 10 times more productive than either single metallic substrate.

Figure 15 also shows the combination of a bimetallic substrate (with spatially isolated Pd/Pt sites) of the present invention and a conventional single metal catalyst, as a physical mixture, and a conventional bimetallic substrate (with For co-localized, unisolated Pd/Pt sites), cinnamyl alcohol conversion and cinnamaldehyde versus cinnamic acid production.

By low alcohol oxidation rate, poor selectivity of cinnamaldehyde intermediates And/or very poor acid production, conventional substrates have proven to be ineffective, demonstrating that Pd or Pt cannot individually catalyze multiple-step, cascade reactions, or efficacies when isolated from discrete catalyst support particles.

Conversely, Pd and Pt, which are separated by nanometer space within a separate but interconnected pore network, allow control of the reaction sequence, and the cinnamyl alcohol entering the large pore can be oxidized to cinnamaldehyde by Pd, and the subsequent aldehyde diffuses into The medium pores are oxidized to cinnamic acid with Pt, giving an increase in the yield of cinnamic acid by an order of magnitude.

While the invention has been described in terms of the foregoing specific embodiments, various modifications and Accordingly, the specific examples of the invention described above are considered as illustrative and not limiting. Various changes may be made to the specific examples without departing from the spirit and scope of the invention.

All documents cited above are incorporated by reference.

Claims (63)

A method of fabricating a substrate comprising a first porous network and a second porous network, the two porous networks being interconnected, the method comprising: forming an array comprising a first template particle and a substrate precursor of a second template particle array; selectively removing the first template particles from the substrate precursor to form the first porous network; and subsequently moving from the substrate precursor The second template particles are removed to form the second porous network. The method of claim 1, wherein the first and second template particles have different chemical and/or physical properties. The method of claim 2, wherein the first template particle system is larger than the second template particle, such that the first porous network comprises large pores and the second porous network comprises medium pores. The method of claim 2 or 3, wherein the first and second template particles have different thermal stability and/or different polarities and/or different photochemistry. The method of any one of claims 1 to 4, which comprises using a solvent at a temperature below room temperature to selectively remove the first template particles. The method of claim 5, wherein the solvent temperature for removing the first template particles is at or below 0 °C. The method of claim 5 or 6, wherein the first template particle is removed The solvent temperature is at or below -5 °C. The method of claim 7, wherein the solvent is an aromatic solvent. The method of claim 8, wherein the solvent is benzene, xylene, mesitylene or toluene. The method of any one of claims 1 to 9, wherein the first template particles are formed from a polymer. The method of claim 10, wherein the polymer is an uncrosslinked polymer. The method of claim 10 or 11, wherein the polymer is polystyrene (PS), polylactic acid (PLA) or poly(methyl methacrylate) (PMMA). The method of any one of claims 1 to 12, wherein the second template particles are formed from a surfactant, a nonionic block copolymer or a carboxylic acid. The method of any one of claims 1 to 13, the method comprising subsequently removing the second template particles using thermal processing, chemical extraction, chemical decomposition, or UV/visible illumination. The method of claim 14, the method comprising subsequently removing the second template particles by solvation using a polar solvent above room temperature. The method of claim 15, wherein the polar solvent is methanol, ethanol or isopropanol. The method of any one of claims 1 to 16, the method comprising forming a first functional site on the surface of the substrate within the first porous network and/or within the second porous network A second functional site is formed on the surface of the substrate. The method of claim 17, wherein the surface within the first porous network It is functionalized by covalent bonding. The method of claim 17 or 18, wherein the first and/or second functional sites comprise a catalytic metal, a fluorescent label, an acidic group, a basic group, a hydrophilic group or a hydrophobic group, an enzyme Or dye. The method of any one of clauses 17 to 19, wherein the functionality of the first and second functional sites are different from each other. The method of any one of clauses 17 to 20, the method comprising: forming the first functional group on the surface of the first porous network prior to subsequently removing the second template particle from the substrate precursor Site. The method of any one of clauses 17 to 21, the method comprising, after subsequently removing the second template particles from the substrate precursor, forming a second functional group on the surface of the second porous network point. The method of any one of clauses 17 to 22, wherein the first functional site is selected to block the pores of the first porous network from being subsequently functionalized along with the second functional site. The method of any one of clauses 17 to 23, wherein the first functional site has hydrophobic or hydrophilic functionality. The method of claim 24, wherein the first functional site has a hydrophobic functional group and comprises an alkyl group or an aromatic group. The method of any one of clauses 17 to 25, wherein the first functional site has hydrophobic functionality and the formation of a second functional site on the surface of the substrate within the second porous network comprises introduction An aqueous solution of a metal salt. The method of any one of clauses 17 to 24, wherein the first functional site Has hydrophilic functionality and comprises an alcohol group or an alcohol/carboxylic acid functionalized organodecane species. The method of claim 27, wherein forming the second functional site on the surface of the substrate within the second porous network comprises introducing hydrophobic metal nanoparticles. The method of any one of claims 1 to 28, the method for producing the first porous network having a first functional site and the second porous network having a second functional site The substrate, the two porous networks are interconnected, the method comprising: forming the substrate precursor comprising the first template particle array and the second template particle array; selectively removing from the substrate precursor The first template particles to form the first porous network; forming the first functional site on the surface of the first porous network; subsequently removing the second template particles from the substrate precursor, Forming the second porous network; and forming the second functional site on the surface of the second porous network. The method of any one of claims 1 to 26, wherein the method is for producing the first porous network having a catalytic palladium site and the second porous network having a catalytic platinum site. The substrate, the first porous network comprising large pores and the second porous network comprising medium pores, the two porous networks being interconnected, the method comprising: Forming the substrate precursor comprising the first template particle array and the second template particle array; selectively removing the first template particles from the substrate precursor to form the first porous comprising large pores a hydrophobic network forming a hydrophobic functional site on the surface of the first porous network; subsequently removing the second template particle from the substrate precursor to form the second porous network comprising a medium pore; A catalytic platinum site is introduced on the surface of the second porous network using an aqueous platinum salt solution; and a catalytic palladium site is subsequently introduced within the first porous network. The method of claim 30, wherein the catalytic palladium site is introduced using pre-formed palladium nanoparticles. The method of any one of claims 1 to 24, the method for producing a first porous network comprising one of catalytic palladium sites and a second porous network having one of catalytic platinum sites a substrate, the first porous network comprising large pores and the second porous network comprising medium pores, the two porous networks being interconnected, the method comprising: forming an array comprising a first template particle and a first a substrate precursor of the two template particle array; selectively removing the first template particles from the substrate precursor to form the first porous network comprising large pores; in the first porous network Hydrophilic functional sites Pointing; subsequently removing the second template particles from the substrate precursor to form the second porous network comprising medium pores; and using hydrophobic platinum nanoparticles on the surface of the second porous network Introduction of a catalytic platinum site; and introduction of a catalytic platinum site within the first porous network using an aqueous platinum salt solution. A method of making a substrate comprising a porous network, the method comprising: forming a substrate precursor comprising an array of template particles; and using a solvent at a temperature below room temperature from the substrate precursor The template particles are removed to form the substrate. The method of claim 33, wherein the temperature of the solvent used to remove the template particles is at or below 0 °C. The method of claim 33 or 34, wherein the temperature of the solvent used to remove the template particles is at or below -5 °C. The method of claim 35, wherein the solvent is an aromatic solvent. The method of claim 36, wherein the solvent is benzene, xylene, mesitylene or toluene. The method of any one of claims 33 to 37, wherein the template particles are formed from a polymer. The method of claim 38, wherein the polymer is an uncrosslinked polymer. The method of claim 38 or 39, wherein the polymer is polystyrene (PS), polylactic acid (PLA) or poly(methyl methacrylate) (PMMA). The method of any one of claims 33 to 40, which comprises forming a functional site on the surface of the substrate within the porous network. A method of making a substrate comprising a first porous network having one of a first functional site and a second porous network having a second functional site, the first porous network comprising a large pore and the second porous network comprising medium pores, the two porous networks being interconnected, the method comprising: forming a substrate precursor comprising a first template particle array and a second template particle array; The substrate precursor removes the first template particles and the second template particles to form the first porous network comprising large pores and the second porous network comprising medium pores; The first functional site is formed on the surface of the network; and the second functional site is subsequently formed on the surface of the second porous network. The method of claim 42, wherein the step of forming the first functional site comprises introducing a first functional species that is too large to enter the mesoporous pore. The method of claim 43, wherein the first functional species is a catalytic metal, an enzyme, a dye, a hydrophobic species, or a hydrophilic species. The method of any one of claims 42 to 44, wherein the step of forming the first functional site comprises introducing a hydrophobic species that is too large to fit into the medium pore and the step of forming the second functional site comprises introducing water gold Is a salt solution into the second porous network. The method of claim 45, the method comprising introducing a metal nanoparticle that is too large to fit into the medium pore. The method of any one of claims 42 to 44, wherein the step of forming the first functional site comprises introducing a hydrophilic species that is too large to fit into the medium pore and the step of forming the second functional site comprises introducing Hydrophobic metal nanoparticles are incorporated into the second porous network. The method of claim 47, the method comprising introducing an aqueous metal salt solution into the hydrophilic large pores. A substrate comprising a first porous network having one of a first functional site and a second porous network having a second functional site, wherein the first and second functional sites are Spatially separated/isolated and functionally and/or chemically distinct. The substrate of claim 49, wherein the pore system within the first porous network is larger than the pores within the second porous network. The substrate of claim 50, wherein the first porous network comprises large pores and the second porous network comprises medium pores. The substrate of any one of claims 49 to 51, wherein the first functional site comprises a catalytic metal, an enzyme, a dye, a fluorescent label, an acidic group, a basic group, a hydrophobic group or a hydrophilic Group. The substrate of any one of claims 49 to 52, wherein the second functional site comprises a catalytic metal, a fluorescent label, an acidic group, a basic group, a hydrophobic group or a hydrophilic group. The substrate of any one of claims 49 to 53, wherein the first functional site An enzyme is included and the second functional site comprises a catalytic metal, an acidic group, or a basic group. The substrate of any one of claims 49 to 54, wherein the first functional site comprises a first fluorescent label and the second functional site comprises a second fluorescent label. The substrate of any one of claims 49 to 55, wherein the first functional site comprises an acidic functional group and the second functional site comprises a catalytic metal. The substrate of any one of claims 49 to 51, wherein the first functional site comprises catalytic Pd nanoparticle and the second functional site comprises catalytic Pt nanoparticle. Use of a substrate according to any one of claims 49 to 57 as a catalyst or as a sensing device. A use of a substrate as claimed in claim 58 for the selective aerobic oxidation of an alcohol to an acid. A use of the substrate of claim 59 for the selective oxidation of cinnamyl alcohol to cinnamic acid. A method substantially as herein described with reference to the accompanying drawings. A substrate substantially as in any of the specific examples described herein with reference to the accompanying drawings. A use of a substrate substantially as herein described with reference to the accompanying drawings.