WO2020201756A1

WO2020201756A1 - Molecular sieve and preparation method

Info

Publication number: WO2020201756A1
Application number: PCT/GB2020/050877
Authority: WO
Inventors: Alessandro TURRINA; Paul Anthony Wright; Abigail E. WATTS
Original assignee: Johnson Matthey PLC
Current assignee: Johnson Matthey PLC
Priority date: 2019-04-04
Filing date: 2020-04-02
Publication date: 2020-10-08
Anticipated expiration: 2021-10-04
Also published as: GB201904794D0

Abstract

Molecular sieve materials having a new framework structure; STA-28, are described. Silicoaluminophosphate (SAPO)-STA-28, Aluminophosphate (AlPO)-STA-28 and metal substituted STA-28 molecular sieves are further disclosed. The invention also relates to methods of preparation of STA-28 molecular sieve materials, catalysts and articles comprising the STA-28 molecular sieve materials, uses of the STA-28 molecular sieve materials as catalysts and in the treatment of exhaust gases. The use of 1,10-phenanthroline and derivatives thereof as a structure directing agent in the preparation of STA-28 are also described.

Description

MOLECULAR SIEVE AND PREPARATION METHOD

Field of the Invention

The present invention relates to molecular sieve materials having a new framework structure; STA-28. As-made silicoaluminophosphate (SAPO)-STA-28 was produced using 1,10-phenanthroline and derivatives thereof as structure directing agents. A calcined product formed from SAPO-STA-28 is also disclosed. Aluminophosphate (AlPO)-STA-28 and metal substituted STA-28 molecular sieves are also disclosed. The invention also relates to methods of preparation of the STA-28 molecular sieve materials, catalysts and articles comprising the STA-28 molecular sieve materials, uses of the STA-28 molecular sieve materials as catalysts and in methods of treating exhaust gases, and use of 1,10- phenanthroline and derivatives thereof as a structure directing agent in the preparation of a molecular sieve, particularly in the synthesis of STA-28.

Background

Molecular sieves are a class of crystalline materials with defined arrangements of cavities, channels and/or pores. The molecular sieve framework or topology is characteristic of the specific type of molecular sieve. A framework type or topological type is unique and is provided with a unique three letter code by the IZA (International Zeolite Association), which maintains a full listing of framework types at http://www.iza-structure.org/data- bases/. Framework types or topological types can usually be identified by their X-ray diffraction pattern.

Molecular sieves may be formed of an aluminophosphate (A1PO). In general, aliovalent substitutions of A1 and P in such aluminophosphate (A1PO) materials are possible:

substitution of A1 with a metal cation provides metalloaluminophosphates (MAPOs) and substitution of P with Si gives a silicoaluminophosphate (SAPO). Metal

silicoaluminophosphates (MSAPOs) can be formed with metals and silica. Isovalent substitutions are also possible. For example, the framework type (topological type) CHA gets its designation from the natural mineral chabazite. Synthetic versions of the CHA topological type have been described, such as SSZ-13 (US 4,544,538). SSZ-13 has a silica: alumina compositional ratio that differs from that of the natural mineral. SAPO-34 (Lok et ah, 1984, J. Am. Chem. Soc., 106, 6092) is another example of a CHA topological type. Since this has a framework composition consisting of SiCk, AIO2 and PO2 tetrahedra, it is a SAPO and not an aluminosilicate.

Chabazite, SSZ-13 and SAPO-34 all have the same framework structure (topological type) but have different compositions. The compositional differences have a profound influence on properties and therefore affect utility in industrial applications.

Molecular sieves are commercially important, and many have several industrial applications particularly in catalysis and as adsorbents.

Zeolites are a kind of of molecular sieve. Zeolites have traditionally been considered as crystalline or quasi-crystalline aluminosilicates having repeating TO4 tetrahedral units.

The tetrahedrally-coordinated atoms T are usually A1 and Si, though examples with P, B, Fe and Ga are also known. The tetrahedral units are connected to form the framework. Various synthetic zeolites are known. In AlPOs - with A1:P of 1 : 1 - a zeolite-like framework structure is found in which each A1 is bonded to four phosphate tetrahedra. On the other hand, SAPOs typically have a three-dimensional microporous crystalline framework of P0²⁺, AIO² and S1O2 tetrahedral units.

Most A1 cations in an aluminophosphate have four-fold coordination, though it is also possible for them to bind additional ligands such as water, fluoride or hydroxide ions if these are present in the reaction mixture. Where a positively-charged structure directing agent is used, negatively charged ligands can act to balance the positive charge from the structure directing agent. Heating the framework to remove the structure directing agent molecules also removes the additional ligands. Since an aluminophosphate (AIPO4) framework is inherently neutral, the incorporation of silicon into the AIPO4 framework by substitution generates an overall negative charge. As with aluminosilicate zeolites, this can be used to generate acid sites. The number and location of silicon atoms incorporated into an AIPO4 framework can thus be used to tailor the catalytic properties of a given SAPO.

Most of the framework types described by the IZA require an organic template or structure directing agent to facilitate their synthesis. With some exceptions, the structure directing agent is incorporated into the molecular sieve framework during the synthesis process and must be removed, usually by a heat treatment stage, before the cavities, channels and/or pores can be made available and accessible to other molecules.

The structure directing agents are typically complex organic molecules which guide or direct the shape and pattern of the framework. Examples of known organic structure directing agents are aliphatic amines and alkylammonium cations. The structure directing agent can be considered a mold, and the molecular sieve (e.g. zeolite crystal) structure forms around the mold. The structure directing agent can then be removed, and the spaces they previously occupied remain as cavities, channels, and/or pores. For this reason, structure directing agents were historically called“templates”.

Typical synthetic methods for preparing molecular seives involves the hydrothermal precipitation of solid crystals from a reaction mixture comprising the framework components (e.g. a source of silicon and a source of aluminum), a source of hydroxide (e.g. NaOH), and a structure directing agent. Precipitation timescales vary according to various factors including crystallization temperature), but normally takes from several hours to several days to complete. The precipitate is separated from the mother liquor containing unused reactants and structure directing agent.

A large number of examples of molecular sieves exist in the art, such as SAPO STA-6 synthesized using quinolinium-derived molecules (R. Garcia et ah, J. Mater. Chem., 2001, 11, 1421-1427), a crystallised IM-8 solid of metallophosphate type and having particular X-ray diffraction pattern and chemical composition in its as-made form (US 2004/0258600 Al), ITQ-32 substantially free of fluoride ions in its as-made form (US 2014/0163228 Al), and - more recently - STA-20 (US 2017/0312743 Al).

It is desirable to develop new molecular seives having different framework types, compositional makeup and/or properties, especially catalytic properties. Unexpected developments in the catalytic activity of structurally modified molecular seives can be used in a variety of applications.

Preferred embodiments of the present invention seek to overcome one or more of the above disadvantages of the prior art. Preferred embodiments of the present invention seek to provide molecular sieves having improved and/or different framework types,

compositional makeup and/or properties, especially new molecular sieves capable of providing new, improved and/or different activity.

Summary of Invention

The inventors have surprisingly discovered that the aromatic diamine 1,10-phenanthroline, can be used as a structure directing agent in the synthesis of a molecular sieve. Derivatives of 1,10-phenanthroline have also been found to be useful as the structure directing agent. The inventors have discovered that a novel framework is produced using these structure directing agents, and that the structure directing agents can be removed by calcination.

This is despite 1,10-phenanthroline being known for its strong complexation properties (H. Ferreira, K. G. von Eschwege, J. Conradie, Electrochimica Acta 2016, 216, 339-346), particularly in tr is- 1,10-phenanthroline complexes of divalent transition metals. Bis and tris( 1,10-phenanthroline) complexes have been incorporated into zeolite supercages during post-synthetic processing (K. K. Bania and R. C. Deka, J. Phys. Chem. C, 2012, 116, 14295-14310; K. K. Bania and R. C. Deka, J. Phys. Chem. C, 2011, 115, 9601-9607; S. L. Hailu et al., RSC Adv., 2015, 5, 88636-88645; H. Mei et al., Appl. Catal. Gen., 2014, 475, 40-47; A. Nezamzadeh-Ejhieh and E. Shahriari, J. Ind. Eng. Chem., 2014, 20, 2719-2726; Y. Umemura et al., J. Radioanal. Nucl. Chem., 1994, 186, 213-226; M. T. Carter et al., J. Am. Chem. Soc., 1989, 111, 8901-8911), but this is believed to be the first report of the use of a phenanthroline as a structure directing agent or template in molecular sieve synthesis. The novel framework produced is called STA-28.

The structure of the as-made SAPO using 1,10-phenanthroline as structure directing agent has been solved using single-crystal X-ray diffraction, and Rietveld refinement used to derive the structure of related A1PO, MAPO and MSAPO materials. These framework materials have been found to have unusual and interesting properties. For example, the experimental work conducted by the inventors indicates the presence of an unexpected binding interaction between the structure directing agent to Al³⁺ cations at a specific crystallographic site in the framework. It is thought that these properties could be exploited in various applications including catalytic reactions. Especially, the inventors note that the frameworks according to the present invention display an unusual channel system and relatively large pore size compared to known frameworks. An interesting interaction has also been found to arise from the octahedral coordination (4 framework oxygen atoms and 2 nitrogen atoms from the 1,10-phenanthroline molecule) of one specific set of T atoms - i.e. Al, Fe, Mn, Sc, Mg etc. as described herein - in the as-made material.

Thus, the present invention provides a novel aluminophosphate framework STA-28 obtained using 1,10-phenanthroline-based structure directing agents, a method for producing the novel framework, and use of these molecules as structure directing agents in the formation of molecular frameworks. The structure directing agents can be removed by methods such as calcination, and thus provide a microporous tetrahedrally-coordinated framework. The inventors have found that the synthetic route can be generalised to make use of other complexing phenanthroline species, and to incorporate metal cations into the framework.

Accordingly, a first aspect of the invention provides a molecular sieve STA-28 having a characteristic X-ray powder diffraction pattern comprising at least the 2-theta positions shown in the following Table 1 : Table 1

wherein vs is very strong; s is strong; m is medium; and w is weak, and wherein the molecular sieve is free or substantially free of structure directing agent.

As noted, in the first aspect the molecular sieve is free, or substantially free, of structure directing agent. In general, it is a molecular sieve in which the as-made material has been subjected to a process for removing structure directing agent, such as calcination.

Preferably, the molecular sieve of the first aspect is free of structure directing agent.

Preferably, the characteristic X-ray powder diffraction pattern of the molecular sieve of the first aspect further comprises the 2-theta positions shown in the following Table la or in the following Table lb:

Table la

Table lb

and w is as defined above. More preferably, the characteristic X-ray powder diffraction pattern further comprises a 2- theta position at 26.0 (w), 26.2 (w), 25.7 (w) or 26.4 (w) ± 0.3 degrees, wherein w is as defined above.

The molecular sieve of the first aspect may be described by the following general formula (Si_wAl_xM_yP_z)0₂, wherein w is a mole fraction of Si and has a value of from 0.0 to 0.2, x is a mole fraction of A1 and has a value of from 0.4 to 0.6, y is a mole fraction of an intra- framework metal M and has a value of from 0.0 to 0.24, and z is a mole fraction of P and has a value of from 0.2 to 0.5, and wherein w+x+y+z=l . Intra-framework metals M are described in further detail below. According to a second aspect of the invention, there is provided a molecular sieve STA-28 having, in its as-made form including structure directing agent, a characteristic X-ray powder diffraction pattern comprising 2-theta positions as shown in the following Table 2:

Table 2

wherein vs is very strong; s is strong; m is mec ium; and w is weak. Preferably, the characteristic X-ray powder diffraction pattern of the as-made molecular sieve of the second aspect further comprises the 2-theta positions shown in the following Table 2a:

Table 2a

wherein s, m and w are as defined above.

The molecular sieve of the first or second aspect may be an aluminophosphate, a silicoaluminophosphate, a metal silicoaluminophosphate or a metal aluminophosphate. Of these, a silicoaluminophosphate and a metal aluminophosphate are particularly exemplified and accordingly preferred herein. The molecular sieve of the first or second aspect may comprise, in addition to aluminium, at least one further intra-framework metal M selected from at least one of the metals of Groups IIIA, IB, IIB, VA, VIA, VIIA, VIIIA of the Periodic Table, and combinations thereof. Particularly preferred are embodiments in which the at least one further intra- framework metal M is selected from the group consisting of Fe, Mn, Mg, Co, Zn and Sc. In some preferred embodiments, up to 40wt% of the aluminium may be replaced with the at least one further intra-framework metal M.

It will be understood that the molecular sieve of the first aspect may be a molecular sieve of the second aspect treated (e.g. by calcination) to remove structure directing agent. A molecular sieve of the first aspect should have no or substantially no structure directing agent remaining in its pores as described above while a molecular sieve of the second aspect, by contrast, comprises the structure directing agent(s).

Preferably, a molecular sieve of the second aspect contains one or more structure directing agents chosen from 1,10-phenanthroline optionally substituted by C₁-C₃ alkyl at one, two or three of the 4, 5, 6, or 7 positions. Most preferably, any C₁-C₃ alkyl groups are methyl groups. Particularly mentioned are embodiments in which the structure directing agent is selected from the group consisting of 1,10-phenanthroline; 4-methyl- 1,10-phenanthroline; 5-methyl-l,10-phenanthroline; 4,7-dimethyl-l,10-phenanthroline; and 5,6-dimethyl-l,10- phenanthroline. According to a third aspect of the invention, there is provided a molecular sieve STA-28 which has a framework type based on the following information on the unit cell of any one of the following (i) to (xi):

(i) a silicoaluminophosphate comprising 1,10-phenanthroline as structure directing agent:

(ii) a silicoaluminophosphate comprising 4-methyl- 1,10-phenanthroline as structure directing agent:

(iii) a silicoaluminophosphate comprising 5-methyl-l,10-phenanthroline as structure directing agent:

(iv) a silicoaluminophosphate comprising 4, 7-dimethyl- 1,10-phenanthroline as structure directing agent:

(v) a silicoaluminophosphate comprising 5, 6-dimethyl- 1,10-phenanthroline as structure directing agent:

(vi) a metal aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.05 Fe/P:

(vii) an iron aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.1 Fe/P:

(viii) an iron aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.16 Fe/P:

(ix) an iron aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.2 Fe/P:

It will be appreciated that each of the a, b , c and b values may preferably be within a range of ± 0.3 such as ±0.1 of the indicated value. For the avoidance of doubt, the ratios Fe/P shown above are molar ratios as the skilled person will recognise.

The molecular sieve of the third aspect may preferably be a molecular sieve of the second aspect. It will be understood that a molecular sieve of the first aspect may be obtainable by treatment (e.g. calcination) of a molecular sieve of the third aspect to remove structure directing agent.

According to a fourth aspect of the invention, there is provided a molecular sieve having an X-ray diffraction pattern as shown in any one of Figures lc, 5, 8 or 10. The molecular sieve of the fourth aspect may preferably be a molecular sieve of any of the first, second or third aspects. A molecular sieve of the first aspect may, in appropriate circumstances, be obtainable by removal of structure directing agent from a molecular sieve of the fourth aspect. Such removal may be effected by, for example, calcination.

In a fifth aspect, the present invention discloses a molecular sieve prepared by calcination of a molecular sieve of any of the first to fourth aspects. The calcination is used to remove some or all of any structure directing agent that may be present.

According to a sixth aspect of the invention, there is provided a catalyst comprising the molecular sieve of any one of the first to fifth aspects.

According to a seventh aspect of the invention, there is provided an article for treating exhaust gas comprising the catalyst of the sixth aspect, the article optionally comprising a structure on and/or within which the catalyst is disposed.

Articles and catalysts comprising a molecular sieve according to any one or more of the first to fifth aspects are contemplated.

According to an eighth aspect of the invention, there is provided a method of synthesizing a molecular sieve comprising the steps of: a. forming a reaction mixture comprising (i) at least one source of alumina;

(ii) at least one source of phosphorus; (iii) at least one source of silica and/or at least one source of a metal M; (iv) one or more structure directing agents; and (v) at least one solvent; b. heating the reaction mixture to form molecular sieve crystals comprising the one or more structure directing agents; c. recovering the product of step b from the reaction mixture; d. optionally drying the recovered product; and/or e. optionally calcining or chemically treating the recovered product to remove the one or more structure directing agents from the molecular sieve crystals; wherein the one or more structure directing agents is chosen from a 1,10-phenanthroline or a derivative thereof.

The method of the eighth aspect typically produces a molecular sieve which comprises STA-28.

In general, the preferences described herein in respect of the molecular sieves of each of the first to fifth aspects - especially in respect of the nature of the structure directing agent - are also applicable to the method of the eighth aspect.

In the method of the eighth aspect, it is preferred that the formation of a reaction mixture in step a. includes addition of a pH modifier. The pH modifier is typically an alkyl ammonium hydroxide. Particularly preferably, the pH modifier is tetrabutylammonium hydroxide (TBAOH).

Preferably, the at least one source of alumina comprises aluminium alkoxide, such as aluminium isopropoxide, aluminium phosphate, aluminium hydroxide, sodium aluminate, pseudobehemite, hydrated alumina, organoalumina, colloidal alumina, or a mixture thereof.

Preferably, the at least one source of phosphorus comprises phosphoric acid, organic phosphate such as triethyl phosphate, aluminophosphate, or a mixture thereof. In some embodiments, the reaction mixture comprises at least one source of silica and the at least one source of silica preferably comprises a silicon alkoxide, colloidal silica, silica gel, a silicate such as fumed silica, a tetraalkyl orthosilicate, an aqueous colloidal suspension of silica, or a mixture thereof.

In some embodiments, the reaction mixture comprises at least one source of metal M. The metal M preferably provides at least one of of the metals of Groups IIIA, IB, IIB, VA,

VIA, VIIA, VIIIA of the Periodic Table, and combinations thereof. The metal M corresponds with the intra-framework metal M described above in respect of the earlier aspects. Those preferences apply to this aspect also.

Preferably, the at least one solvent is aqueous. Most preferably, the solvent comprises water.

Typically, the heating of step b. is carried out at a heating temperature of between about 100°C and 220°C for a period of about 0.1 to 10 days. Preferably, the heating temperature is between about 150°C and 200°C, and more preferably between about 170°C and 190°C. Further preferably for any of the heating temperatures, the period is about 2 to 8 days.

In some embodiments, the method comprises step e. In such embodiments, it is preferred that step e. comprises calcining. In such cases, step e. is typically carried out at a calcining temperature of between about 300°C to 700°C, and more preferably between about 550°C to 600°C.

In some embodiments, the reaction mixture may further comprise from about 0.1 to about 10% w/w of seed crystals, the seed crystals comprising a molecular sieve according to any one of the first to fifth aspects. Seed crystals may permit quicker growth of a molecular sieve according to the method of the eighth aspect.

In general, the method of the eighth aspect preferably produces a molecular sieve according to any one of the first to fifth aspects. In turn, such molecular sieve produced by the method of the eighth aspect may be comprised in a catalyst of the sixth aspect or an article of the seventh aspect. Also provided herein is a method of preparing a molecular sieve comprising providing as- made STA-28 including one or more structure directing agents; and calcining or chemically treating the STA-28 to remove the one or more structure directing agents. Preferably, providing as-made STA-28 is carried out according to steps a to c and optional step d as described above. Preferably, the method comprises calcination and more preferably calcination in accordance with step e. described above.

According to a ninth aspect of the invention, there is provided a reaction mixture for preparing a molecular sieve, the mixture comprising (a) at least one source of alumina; (b) at least one source of phosphorus; (c) at least one source of silica and/or at least one source of a metal M; (d) one or more structure directing agents; and (e) at least one solvent, wherein the one or more structure directing agents comprises 1,10-phenanthroline or a derivative thereof.

In general, it is intended that the reaction mixture is suitable for use in the methods of the eighth aspect. Accordingly, the relevant preferences described for the eighth aspect herein also apply to the mixture of the ninth aspect.

According to a tenth aspect, the present invention provides the use of a molecular sieve of any of the first to fifth aspects, or a catalyst according to the sixth aspect, or an article of the seventh aspect, or a molecular sieve produced by a method of the eighth aspect, or a molecular sieve formed from or derived from a reaction mixture of the ninth aspect, as a catalyst. Accordingly, all the appropriate preferences described for each of the first to ninth aspects apply to the tenth aspect.

According to an eleventh aspect, the present invention provides a method for treating an exhaust gas comprising contacting a combustion exhaust gas with a molecular sieve of any of the first to fifth aspects, or a catalyst of the sixth aspect, or an article of the seventh aspect, or a molecular sieve formed from the method of the eighth aspect, or a molecular sieve formed from or derived from the reaction mixture of the ninth aspect. In general, in the method of the eleventh aspect, at least one exhaust gas is selectively reduced or oxidized. Accordingly, all the appropriate preferences described for each of the first to tenth aspects apply to the eleventh aspect.

Further aspects of the invention provide the use of a 1,10-phenanthroline or a derivative thereof as a structure directing agent in the synthesis of a molecular sieve, and provide a molecular sieve having the structure of STA-28. Accordingly, all the appropriate preferences described for each of the first to eleventh aspects apply. In particular, a molecular sieve having the structure of STA-28 may be a molecular sieve according to any of the first to fifth aspects, or prepared by a method according to the eighth aspect, or formed from a reaction mixture according to the ninth aspect.

It will be appreciated herein that the molecular sieves described or produced or comprised according to the various aspects contain STA-28.

In general in the invention, it is preferred that a structure directing agent other than one based on 1,10-phenanthrolines as described herein is not used to prepare the STA-28 materials. Accordingly, in order to prepare a substantially pure product, it is preferred if the structure directing agent consists of one or more of the 1,10-phenanthrolines or derivatives thereof or a mixture thereof as described herein. Of course, if mixtures are desired, the inclusion of other structure directing agents may be suitable.

It will be appreciated that features described in relation to one aspect of the invention may be equally applicable in another aspect of the invention. Certain of those are set out explicitly above by way of example and not limitation. Some features may not be applicable to, and may be excluded from, particular aspects of the invention, though this will be clear from context.

Description of the Drawings

Embodiments of the present invention will now be described, by way of example, and not in any limitative sense, with reference to the accompanying drawings, of which:

Figure 1 shows (a), (b) scanning electron microscope (SEM) images of as-made STA-28 obtained with 0.05 Si/Al in the starting gel; (c) powder X-ray diffraction pattern of the as- made STA-28 obtained with 0.05 Si/Al in the starting gel. The x-axis denotes 20 (degrees) in the range of from 5 to 40. It can be determined from (a) and (b) that the crystals have a block morphology with an average diameter of approximately 30 pm. Scale bars are 5pm

(a) and 10 pm (b). 1,10-phenanthroline was the structure directing agent.

Figure 2 shows Rietveld refinement of as-made, hydrated STA-28 on the space group 1 2_/a. a = 13.9916(5) A; b = 25.4790(9) A; c = 14.4450(5) A; b =95.9949(30) °; R_wp = 8.15%. Crosses show the experimental data points; the overlying line represents simulated data. These are indicated at (i) and (ii). The black tick marks (iii) underneath the crosses/line (i), (ii) show predicted peak positions. The bottom line (iv) represents a difference profile i.e. the difference between actual and predicted data points. The x-axis shows angle at 20 in degrees; the y-axis shows intensity in arbitrary units (a.u.).

Figure 3 is a schematic representation of the octahedral A1 unit within STA-28. The spheres represent atoms and the rods represent covalent bonds. Hydrogen atoms are not shown. The dashed lines represent non-covalent bonds, predicted to be coordinate bonds. The coordinate bonds link a 1,10-phenanthroline molecule (on the right of the figure) to the framework on the left. The central A1 atom is bonded to two N atoms from

phenanthroline and four framework O atoms. Each of the four framework O atoms are further bonded to Si or metal atoms M as discussed elsewhere herein. Although Figure 3 has been described as referring to an octahedral A1 unit, the skilled person will understand that the central atom described as being A1 could be a different framework metal M as described elsewhere herein, such as Fe, Mn, Sc, Mg, and so on.

Figure 4 is a representative image showing the channels and voids giving three- dimensional pore space that the acquired data shows make up STA-28. The spheres represent atoms and the rods represent covalent bonds. Hydrogen atoms are not shown. The right-hand image (a) represents four unit cells of the framework. The central image

(b) is an expended portion of (a) as indicated by the arrow, showing a large central void surrounded by twelve atoms. These twelve atoms share atoms with four smaller voids. These four smaller voids have two different shapes (one surrounded by 8 atoms (top left and bottom right) and one surrounded by 10 atoms (top and bottom middle voids)). The 10-atom void adjoins a further 8-atom void (top right and bottom left). The rightmost image (c) is an expanded portion of (a) which is a different portion to that shown in (b). Here, the largest void is shown (central) and it shares atoms with two smaller voids each defined by 8 atoms (b) and (c) also indicate the superimposition of the different unit cells, showing the arrangement of channels through the crystals.

Figure 5 shows powder X-ray diffraction patterns for STA-28 (0.05 Si/Al) as-made (ii) and calcined (i). In each, the x-axis shows angle in 20 (degrees) which ranges from 5 to 40.

Figure 6 is a representative image showing how the secondary bonding units (SBUs) are arranged within STA-28 and how they connect to make up the‘rods’ . Specifically, (a) shows the two types of SBUs found within the STA-28 framework, and (b) and (c) showhow the d4R and t-lau units are linked down the z and x axes, respectively (d) depicts how a 12R opening along z is connected to a 12R opening along x. This gives rise to the 3-dimensional connectivity observed for STA-28.

Figure 7 is a schematic diagram showing the framework structure of calcined STA-28.

The x and y coordinates are indicated on the left. Bonds are represented by rods and atoms are represented by spheres.

Figure 8 shows powder X-ray diffraction patterns for as-made STA-28 prepared using a variety of structure directing agents. Slight shifts in the peaks indicate that the unit cell changes slightly. From upper to lower, the patterns represent STA-28 containing: (i) 5,6- dimethyl-l,10-phenanthroline as structure directing agent; (ii) 4,7-dimethyl-l,10- phenanthroline as structure directing agent; (iii) 5-methyl-l,10-phenanthroline as structure directing agent; (iv) 4-m ethyl- 1,1-phenanthroline as structure directing agent; and (v) 1,10- phenanthroline as structure directing agent. The x-axis represents angle 2Q (degrees) and ranges from 5 to 40.

Figure 9 shows N2 adsorption (open squares) and desorption (closed squares) isotherms taken on calcined STA-28 at 77K. The data indicates the calcined material is microporous. Figure 10 shows powder X-ray diffraction patterns for simulated (lower) and experimental (upper) calcined STA-28. These STA-28 materials were prepared using 1, 10- phenanthroline as SDA. The peaks are at similar positions. The x-axis is 2 theta (degrees). The inventors consider this further supports the experimentally-derived structure of STA- 28 described herein.

Detailed Description

Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

As used in this specification and the appended claims, the singular forms“a”,“an” and “the” include plural forms unless context clearly dictates otherwise. Thus, for example, reference to“a structure directing agent” includes mixtures of two or more structure directing agents, and the like.

The word“comprise” and“include” and variants thereof refer to the inclusion of a stated feature or step or group of features or steps but not the exclusion of any other feature or step or group of features or steps.

The term“about” means approximately and refers to a range that is optionally ± 25%, preferably ±10% and most preferably ±1% of the value with which the term is associated.

The term“calcine” or“calcination” has the usual meaning in the art, which includes heating the material in air or oxygen or an oxygen containing gas atmosphere. This definition is consistent with the IUPAC definition of calcination (IUPAC, Compendium of Chemical Terminology, 2^nd ed. (the“Gold Book”), compiled by A. D. McNaught and A. Wilkinson, Blackwell Scientific Publications, Oxford (1997), XML online corrected version: http://goldbook.iupac.org (2006) created by M. Nic et ak). Calcination is performed to decompose a metal salt and promote the exchange of metal ions within the material and also to adhere the material to a substrate. The temperatures used in calcination depend upon the components in the material to be calcined, but are generally between about 400-900°C for 1-24 hours. In some cases, calcination can be performed up to a temperature of about 1200°C. In general, in the present methods, calcinations are performed at temperatures from about 400-700°C for about 1-8 hours, preferably from about 400-650°C for about 1-4 hours.

The term“substantially similar” when used to describe a comparison of a diffraction pattern, means that the locations of one or more peaks, in degrees 2-theta (2Q), and the intensity of those peaks can vary based on experimental variability due to the

instrumentation used, the conditions under which the diffraction pattern was obtained, and impurities that may be present in a sample. Corresponding remarks apply to“substantially free”. For example, a molecular sieve herein which is“substantially free” of structure directing agent will in general be expected to have, relative to the amount of structure directing agent present in the as-made material, less than 10wt% of structure directing agent remaining, typically less than 5wt% and preferably less than lwt%.

When a range, or ranges, for various numerical values are provided, in one embodiment the range or ranges include the values unless specifically provided otherwise.

The term“gel” will be familiar to those skilled in the art. In general, a gel is a solid or semi-solid material in which the disperse medium forms a network of linked molecules through the dispersion medium. The network is typically, but not exclusively, loosely bound, and commonly a gel is described as being rigid or fixed or jelly-like.

“Cx-Cy” where x and y are integers refers to the number of carbon atoms in the hydrocarbon chain. For example, C1-C3 alkyl means an alkyl group having between 1 and 3 carbon atoms in the chain. It encompasses each of methyl, ethyl and propyl. It is not intended to limit the arrangement of atoms and so the hydrocarbon can be linear or branched or cyclic as appropriate.

The term“as-made” is used herein with reference to certain molecular sieves to describe the solid molecular sieve obtained as it is synthesised (as-prepared) and before other possible post-synthesis processes have been carried out (such as calcination or exchange or removal of structure directing agent). For example, when considering the methods proposed herein, it describes the solids obtained after the production of crystals, and recovery of crystals which may include washing.

Various headings are used herein for readability only: the descriptions therein are intended to be combinable.

General Remarks

The present invention provides a new family of crystalline molecular sieves with a new framework type, referred to herein as STA-28. The framework type of STA-28, which has not yet been given a Framework Type Code by the International Zeolite Association, is based on either of the characteristic X-ray powder diffraction pattern of the calcined material or that of the as-made material, discussed elsewhere herein.

The molecular sieve of the invention can be free (or substantially free) of, or contain one or more types of, structure directing agent. The as-made material contains structure directing agents (the nature of structure directing agents suitable for preparing STA-28 are discussed elsewhere). The as-made material may undergo calcination or chemical treatment to remove structure directing agents present in the as-made material to leave a molecular sieve which is preferably free or substantially free of structure directing agent. Partial removal of the structure directing agent is also contemplated.

The molecular sieve of the invention can be a silicoaluminophosphate (SAPO), an aluminophosphate (A1PO), a metal silicoaluminophosphate (MSAPO) or a metal aluminophosphate (MAPO). Preferably the molecular sieve is a SAPO or a MAPO, most preferably a SAPO.

In general, as-made STA-28 SAPO material using 1,10-phenanthroline as structure directing agent has been found to have the space group h_/a and in that context may have the chemical formula CiiHsAUNiOioPsSi. Thus, it will be understood that as-made STA-28 materials containing different structure directing agents and/or including different intra- framework metals M may have a slightly different chemical formula. Thus, the framework material by itself (e.g. when calcined to remove structure directing agent) may have a unit cell having the formula AUCkoPsSi. Slight deviations from this formula, up to about ±5mol%, may be expected. As-Made STA-28

In general, as-made STA-28 can have at least one property selected from the group consisting of: a characteristic powder X-ray diffraction pattern substantially as shown in Figure 1(c), 5 or 8(i) to (v); and a characteristic powder X-ray diffraction pattern comprising 2Q positions as indicated in Table 2: Table 2

wherein vs is very strong; s is strong; m is mec ium; and w is weak.

The characteristic powder X-ray diffraction pattern can further comprise at least one, preferably more than three and most preferably all, 2Q positions as shown in Table 2a: Table 2a

wherein s, m and w are as defined above.

The as-made STA-28 material may additionally or alternatively have a framework type based on the following information on the unit cell of any one of the following (i) to (xi): (i) a silicoaluminophosphate comprising 1,10-phenanthroline as structure directing agent:

(vi) a metal aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.05 Fe/P.

(vii) an iron aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.1 Fe/P

(viii) an iron aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.16 Fe/P

(ix) an iron aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.2 Fe/P

The as-made STA-28 crystalline products can have a visual appearance as shown in e.g. Figures 1(a) and (b) under a scanning electron microscope. Here, individual SAPO crystals are identifiable, separated by gaps where no STA-28 exists, see especially Figure 1(b). The crystals have a spheroidal appearance. Some evidence of twinning is observable in e.g. Figure 1(a). The particle size is relatively uniform. The particles in these images have a diameter of approximately 25-30 microns. Although the present images show broadly spheroidal particles or crystals, the invention is not limited to crystals having such shapes. Other crystal shapes and sizes are within the scope of this description. Figure 1(c) shows the powder X-ray diffraction pattern of particles produced according to the procedure used for those of Figure 1(a) and (b). Thus, it can be inferred that the crystalline structure of the frameworks are both based on the STA-28 framework. Other Si/Al ratios provided powder X-ray diffraction patterns with similar peak positions.

Without wishing to be bound by theory, the inventors believe that the structure directing agents of the present invention are bound to the aluminophosphate framework at a particular crystallographic site in a zeotype framework. In particular, the inventors believe that the structure directing agents in the as-made material are bound via O-Al-N linkages (the N being provided by the 1,10-phenanthroline or derivative thereof described above). Although it is unusual to find Al-N bonds in octahedrally arranged A1 in AlPOs, it is noted that the literature describes at least one other example (J. L. Jorda et ak, Microporous Mesoporous Mater., 2003, 65, 43-57). In support of this theory, the inventors have observed octahedrally coordinated A1 sited in ²⁷ A1 solid state NMR spectrum (not shown). Additionally, an alternative arrangement of N atoms in the phenanthroline molecule has been found to be unsuitable for use as a structure directing agent in the syntheses described herein.

In more detail, a dehydrated SAPO comprising structure directing agent may have the following unit cell information:

TABLE A

This experimental data suggests that the unit cell parameters differ slightly according to the choice of structure directing agent.

A dehydrated FeAPO containing 1,10-phenanthroline as structure directing agent may have the following unit cell information:

TABLE B:

This experimental data suggests that the unit cell parameters show small variations based on the change in molar ratio Fe/P. In general, the above tables A and B suggest that the unit cell parameters a to c of the

STA-28 molecular sieves synthesized differ by a maximum of about 0.44Ά from the value of that of the SAPO, and typically the difference is smaller.

The as-made SAPO STA-28 material (i.e. containing 1,10-phenanthroline as structure directing agent) was solved using single-crystal X-ray diffraction. Rietveld refinement has been used to determine the structure of the other materials, see also Figure 2. The inventors consider that one specific set of T atoms i.e. Al, Fe, Mn, Sc, Mg etc. as described herein has an octahedral coordination of four framework oxygen atoms and two nitrogen atoms from the phenanthroline in the as-made material. This is represented schematically in Figure 3. The dashed lines represent the expected coordination of the nitrogen atoms of the 1,10-phenanthroline molecule to an A1 site as described. The other bonds from the central A1 represent framework bonds to other TO4 tetrahedra (where T can be e.g. Si or P). Other 1,10-phenanthroline derivatives are expected to display a similar coordinating activity. Similarly, where MAPO or MSAPO frameworks are prepared, the A1 may be a metal M. Upon calcination or chemical treatment, it is believed that the bonds represented by the dashed lines in Figure 3 are broken.

Removal of the structure directing agent can be achieved by calcination or chemical treatment. This leads to a calcined STA-28 or to a chemically-treated STA-28: that is, STA-28 which is free or substantially free of structure directing agent. The process of removal of the structure directing agent is commonly referred to in the art as“activating” the as-made molecular sieve. [This expression is not intended to imply any lack of activity of the as-made STA-28 in this description.]

In general, the structure of as-made and calcined/chemically-treated STA-28 materials can be determined using X-ray diffraction patterns. Preferably, single-crystal X-ray diffraction is used. Suitable X-ray diffractometers will be known to the skilled person, but may include e.g. a Rigaku XtaLAB P200 diffractometer with monochomated Cu Kou radiation. A substantial amount of information can be found using powder X-ray diffraction.

Suitable X-ray diffractometers will be known to the skilled person, but may include e.g. a Panalytical Empyrean automated fitted with a copper anode (x-ray wavelength 1.5406 A) equipped with a primary monochromator and X‘Celerator detector. Data can be obtained using Bragg-Brentano flat-plate geometry.

Suitable software can be used to analyse the resulting patterns using methods known to the skilled person. For example, the CryAlisPro (Rigaku Oxford Diffraction) software can be used.

The relative intensities, 100 I/Io, where Io is the intensity of the strongest peak or line, and d, the interplanar spacing in Angstroms (A) corresponding to the recorded lines, can be calculated by the usual methods. The X-ray diffraction pattern of Table 2 is characteristic of all species of the as-made STA-28 family compositions. The X-ray diffraction pattern of Table 1 is characteristic of all species of calcined STA-28 family compositions. Minor variations in the diffraction patters of the as-made and calcined materials in the tables or figures can also result from variations in the structure directing agent used in the preparation and from variations in the Si, A1 and P molar ratios from sample to sample. Notwithstanding these minor perturbations, the basic crystal structures for the as-made condition and the calcined condition remain substantially unchanged. Similar variations can also be found in the X-ray diffraction patterns of various as-made STA-28 materials.

As will be understood by those skilled in the art, the determination of the parameter 2-theta (2Q) is subject to both human and mechanical error, which in combination can impose an uncertainty of about ±0.3 degrees on each reported value of 2-theta. This uncertainty is, of course, also manifested in the reported values of the d-spacings, which are calculated from the 2-theta values. This imprecision is general throughout the art and is not sufficient to preclude the differentiation of the present crystalline materials from each other and from the compositions of the prior art. In some of the x-ray patterns reported, the relative intensities to the d-spacings are indicated by the notations vs, s, m, and w which represent very strong, strong, medium, and weak, respectively. In terms of 100 I/Io - which is the same as 100 x I/Io - the designations in this application are defined as w < 20; 20 < m < 40; 40 < s < 65 and 65 < vs. Where the intensity is at or near the endpoint of a range, the intensity may be characterised as in either of the ranges. However, due to variations in intensity of the lines, as known in the art, one or more of the lines may have an intensity that is in a different (usually adjacent) range.

STA-28 After Structure Directing Agent Removal

Calcined or chemically-treated STA-28 can have at least one property selected from the group consisting of: a characteristic powder X-ray diffraction pattern substantially as shown in Figure 5(i) or 10; and a characteristic powder X-ray diffraction pattern comprising at least the 2-theta positions shown in the following Table 1 :

Table 1

Preferably, the characteristic X-ray powder diffraction pattern of the calcined or chemically treated STA-28 further comprises the 2-theta positions shown in the following Table la or in the following Table lb:

Table la

Table lb

and w is as defined above.

Preferably, the characteristic X-ray powder diffraction pattern of the calcined or chemically treated STA-28 further comprises a 2-theta position at 26.0 (w), 26.2 (w), 25.7 (w) or 26.4 (w) ± 0.3 degrees, wherein w is as defined above.

As for the as-made material, the calcined or chemically treated molecular sieve is an aluminophosphate, a silicoaluminophosphate, a metal silicoaluminophosphate or a metal aluminophosphate, and preferably a silicoaluminophosphate or a metal aluminophosphate.

The calcined or chemically treated molecular sieve may be described by the following general formula (Si_wAl_xM_yP_z)0₂, wherein w is a mole fraction of Si and has a value of from 0.0 to 0.2, x is a mole fraction of A1 and has a value of from 0.4 to 0.6; y is a mole fraction of an intra-framework metal M and has a value of from 0.0 to 0.24, and z is a mole fraction of P and has a value of from 0.2 to 0.5, and wherein w+x+y+z=l.

The inventors find that STA-28 remains crystalline upon removal of structure directing agent (see e.g. Figure 5, in which the as-made material is the lower pattern, denoted (ii), and the calcined material is the upper pattern, denoted (i), and also Figure 10 (upper)). The STA-28 materials have been found to be microporous following removal of structure directing agent (see e.g. Figure 9).

Structure Directing Agents

In the present invention, suitable structure directing agents for preparing STA-28 materials comprise a 1 , 10-phenanthroline or a derivative thereof. 1 , 10-phenanthroline has the following structure:

Formula 1

The term“derivative of 1,10-phenanthroline” as used herein means a 1,10-phenanthroline molecule which contains one or more substituent groups.

The one or more substituent groups are generally short-chain alkyl groups, and specifically Ci -₃ alkyl groups. While different substituent groups may have different numbers of C atoms, at least one, and most preferably each, of the one or more substituent groups is Ci alkyl (i.e. methyl). The one or more substituent groups of the 1,10-phenanthroline derivatives herein are located on the aromatic rings i.e. a C-H group of the aromatic phenanthroline rings is replaced with a C-substituent group. The 1,10-phenanthroline derivatives described herein preferably have one or more substituents on the 3, 4, 5, 6, 7 and/or 8 positions, preferably one or more substituents at the 4, 5, 6 and/or 7 positions.

Preferably, the 1,10-phenanthroline derivatives described herein have up to three, more preferably one or two, substituent groups. Accordingly, it is most preferable that 1, 10-phenanthroline derivative of the present invention has one or two substituent groups chosen from Ci-alkyl and which are located at the 4, 5, 6 and/or 7 positions of the aromatic ring.

Where the 1,10-phenanthroline derivative has two substituent groups, the combination of the two positions are preferably chosen from 4 and 7, or 5 and 6. Particularly suitable 1,10-phenanthroline derivatives for use as structure directing agents in the present invention are 4-methyl- 1,10-phenanthroline (A), 5-methyl-l, 10-phenanthroline (B), 4, 7-dimethyl-l, 10-phenanthroline (C) and 5, 6-dimethyl-l, 10-phenanthroline (D). The structures of these specific molecules (A-D) are shown below.

A B c D

X-ray diffraction patterns of STA-28 materials produced using 1,10-phenanthroline and the four above-depicted derivatives (A-D) are shown in Figure 8.

The STA-28 molecular sieve (e.g. SAPO, A1PO and MAPO) can contain any one of the above structure directing agents i.e. 1,10-phenanthroline or a derivative thereof, or a mixture of the above-described structure directing agents. Preferably, only one kind of structure directing agent is used in the invention. In order to minimize the possibility that molecular sieves other than STA-28 might form, and when mixtures are not wanted, it may be advantageous to avoid using a structure directing agent other than a 1,10-phenanthroline or derivative thereof as described herein.

Also provided in this disclosure is a use of 1,10-phenanthroline or a derivative thereof as structure directing agents in the synthesis of a molecular sieve. The 1,10-phenanthroline or derivative thereof is as described above.

Preferably, the molecular sieve that is produced contains a framework of the invention (i.e. a STA-28). It follows that it is also preferable that the synthesis is carried out according to the methods of the invention. Also preferably, the 1,10-phenanthroline-based molecules are used in a reaction mixture according to the invention, such that further preferably the use results in the formation of a molecular sieve according to the present invention (STA- 28) and consequently downstream products as proposed herein.

Further Embodiments

STA-28 in either its as-made or calcined form can comprise at least one different metal M within the framework, where the at least one different metal M is selected from at least one of the metals of Groups IIIA, IB, IIB, VA, VIA, VIIA, VIIIA of the Periodic Table, and combinations thereof. (By“different metal”, we refer to a metal M which is not Al.) Preferably, the at least one metal M is selected from the group consisting of cerium, chromium, nickel, cobalt, iron, magnesium, manganese, molybdenum, palladium, platinum, rhodium, titanium, tungsten, vanadium, scandium, copper and zinc. Most preferably, the framework of MAPO STA-28 includes one or more metals M chosen from the group consisting of scandium (Sc), iron (Fe), manganese (Mn), zinc (Zn), cobalt (Co) and magnesium (Mg), such as the group consisting of Sc, Fe, Mn and Mg. Such metals are also referred to herein as“intra-framework” metals and denoted“M”.

Substantially preferably, only one intra-framework metal M is used.

Without wishing to be bound by theory, the inventors believe that the framework metals M replace Al atoms and not P atoms. It is thought, based on the Rietvald analyses carried out to date, that it is predominantly the octahedral A1 sites that are replaced; however, it is not intended to exclude the possibility that smaller metal atoms, such as Mg, could replace some tetrahedral A1 atoms in certain embodiments.

Where the framework contains an intra-framework metal M in addition to Al, the relative molar ratios of these elements will be adjusted accordingly in the chemical formula of the framework. In general, the one or more intra-framework metals M may replace in total up to 40wt% of the Al atoms, preferably up to about 30wt%, more preferably up to 20wt%. In some embodiments, the one or more different framework metals M may replace at least lwt%, preferably at least 2wt% and more preferably at least 5wt% of the Al atoms. In some embodiments, the one or more different framework metals M may replace between about 1 and 30wt%, preferably between about 1 and 20wt% and more preferably between about 2 and 20wt% of the Al atoms.

Framework Structure

From all the characterization studies carried out on the present materials, though without wishing to be bound by theory or limit the invention, the inventors believe that the following is an adequate description of STA-28 (see also Figures 4, 6 and 7). With reference to Figures 4, 6 and 7, it can be seen that the structure of STA-28 is believed to contain channels with distorted 12R openings along the x and z axes, which have centres at heights of ¼ & ¾ , and 0 & ½ , respectively. In the as-made form, the 1,10-phenanthroline templates are understood to be stacked within these channels and have a distance between the centre of the rings of 3.376 A. The 1,10-phenanthroline molecules are thought to be framework bound, resulting in two types of Al sites - octahedral and tetrahedral. The 12R openings have 3 -dimensional connectivity by infinite d4R and t-lau chains in the x and z directions. These infinite chains are themselves believed to be linked together down they axis by another set of t-lau. In total, the inventors have identified two d4R sites (along x and z) and three t-lau sites, of which two are associated with d4R along x and z, respectively, and the other‘bridging’ t-lau along they axis. This bridging t-lau shares faces with 2 d4Rs and the two other t-lau’s. A 12R in the z-plane is linked to a 12R in the x-plane through 6R openings of t-lau. In the inventors’ view, STA-28 can therefore be described as having two secondary building units (SBUs) which are D4R and t-lau. A pore opening/window has an approximate size of 8.18 x 10.32 A (by length x cross-sectional diameter) and 9.45 ^c 10.89 A (by two diagonal lengths).

Accordingly, the inventors currently theorize that the STA-28 framework shares some similarities with the framework topologies SAO and -ITV. MgAPO STA-1 (SAO) has 12R channels connected by lau , aww and sti subunits. They consider the germanosilicate ITQ-37 (-ITV) is somewhat more closely related to STA-28. The large channels (which have 10R openings when viewed along [110]) found within ITQ-37 are connected by lau and d4R building units. It has one unique lau unit and, as with STA-28, ITQ-37 has two unique d4Rs. Notably, the -ITV framework is not fully connected as a d4R terminated by a hydroxyl (so not linked to the rest of the framework) faces a cavity. It is speculated that a silicate analogue of STA-28 could be thought of as a fully connected‘-ITV’ framework, whereby an A1 atom can bind to the 1,10-phenanthroline template thus filling that cavity.

A germanosilicate could also be favoured due to the preference of Ge to occupy d4R sites.

STA-28 has a framework density (defined as the number of T-atoms per 1000 A³) of 15.6. This makes it slightly denser than comparable framework structures; MgAPO STA-1 and ITQ-37 which have framework densities of 14.2 and 10.3 T/1000 A³, respectively.

Therefore, the inventors believe - and have demonstrated - that the synthetic route described herin can be generalised to make use of other complexing phenanthroline species as described herein, and to incorporate metal cations into the framework as described herein e.g. in the formation of MAPOs.

Preparation Methods

Also provided herein is a method of manufacturing a molecular sieve of the invention. The methods preferably prepare STA-28 in substantially pure form [while mixtures of STA-28 and optionally other molecular sieves are not excluded in the invention, it is believed that substantially pure STA-28 will in general be the more common goal].

The general method of preparing STA-28 involves a. forming a reaction mixture comprising (i) at least one source of alumina; (ii) at least one source of phosphorus; (iii) at least one source of silica and/or at least one source of a metal M; (iv) one or more structure directing agents; and (v) at least one solvent; b. heating the reaction mixture to form molecular sieve crystals comprising the one or more structure directing agents; c. recovering the product of step b from the reaction mixture; d. optionally drying the recovered product; and/or e. optionally calcining or chemically treating the recovered product to remove the one or more structure directing agents from the molecular sieve crystals; wherein the one or more structure directing agents is chosen from a 1,10-phenanthroline or a derivative thereof. The preferences for the structure directing agents correspond with those set out elsewhere and will not be repeated now.

Preferences for each of steps a to e as set out herein can be combined.

Step a

STA-28 can be produced by generally forming a reaction mixture. The reaction mixture is produced by generally combining a source of aluminum, a source of silicon and/or metal M, a source of phosphorus and one or more structure directing agents. These components are included in a solvent, such as water. The framework forms as crystals from this reaction mixture, and the crystals or a portion thereof can be recovered from the reaction mixture using any suitable procedure.

Preferably, the reaction mixture comprises a source of silicon and/or metal M. In particularly exemplified and preferred embodiments, the reaction mixture comprises one of a source of silicon or a source of metal M. A number of aluminium compounds and their mixtures are suitable for use as the aluminium component (source of aluminium) in the present invention. A source of aluminium can comprise for example an aluminium alkoxide, such as aluminium isopropoxide, aluminium tri-ethoxide, aluminium tri-n-butoxide and aluminium tri- isobutoxide, an aluminium oxide, an aluminium phosphate, aluminium hydroxide, sodium aluminate, (pseudo)boehmite, hydrated alumina, organoalumina, aluminium hydroxy chloride, colloidal alumina, and mixtures thereof. Preferably, the aluminium component comprises a material selected from the group consisting of aluminium hydroxide, boehmite and pseudoboehmite, most preferably aluminium hydroxide.

A source of phosphorus can comprise, but is not limited to, orthophosphoric acid, phosphorus acid, phosphoric acid, organic phosphate such as triethyl phosphate and trimethylphosphate, aluminophosphate, and mixtures thereof. Preferred is a source of phosphorus comprising a material selected from the group consisting of phosphoric acid (such as the commercially available 85wt% phosphoric acid in water), and orthophosphoric acid. Alternatively, phosphorus oxides (P2O3, P2O4, P2O5 and POCI3) may be used, preferably after they are dissolved in a suitable solvent such as water. Most preferred is phosphoric acid.

A source of silica can comprise a number of silicon compounds and their mixtures. The silicon compounds include for example a silica sol, silica gel, tetraethyl silicate, tetramethyl silicate, silicon alkoxide, colloidal silica, silica gel, a silicate such as fumed silica, a tetraalkyl orthosilicate, or an aqueous colloidal suspension of silica, and mixtures thereof. Preferably the source of silica comprises a silicon component selected from the group consisting of silica sol, silica gel, colloidal silica, fumed silica, silicic acid, most preferably fumed silica.

A source of metal M generally corresponds with a source of metal M ion. The source of metal M can comprise any suitable metal M salt, for example metal halide, metal sulfate, metal oxide, metal oxalate, metal nitrate, metal carbonate and metal acetate. Metal halide can encompass metal fluoride, metal chloride, metal bromide and metal iodide. Preferred is metal acetate, metal sulfate, metal nitrate, metal carbonate or metal oxide, and particularly preferably metal acetate.

Typical metal salts are metal M (II) salts, but in some instances metal M (III) salts can be used e.g. iron (III) chloride and iron (III) nitrate.

The choice of metal M element(s) corresponds with the intra-framework metal M described elsewhere herein.

The solvent or solvents used for the reaction mixture are not especially limited. The skilled person will be able to make suitable choices. Examples include but are not limited to water and alcohols such as methanol, ethanol, n-propanol, iso-propanol, C4 alcohols, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, or mixtures thereof.

Preferably the solvent comprises water.

The solvent can be combined with the reaction mixture in any suitable manner and is not particularly limited. In some embodiments, a solvent may be mixed with the structure directing agent before it is added to the other components of the reaction mixture.

Preferably, the structure directing agent is completely mixable with, or soluble in, the solvent. pH modifier

A pH modifier can be used to adjust the pH of the reaction mixture used to prepare the molecular sieve of the present invention. Suitably, the pH modifier can comprise an alkyl ammonium hydroxide, also known as a quaternary ammonium hydroxide (R₁R₂R₃R₄OH). The alkyl ammonium hydroxide can be a simple quaternary molecule, where each of R_1-4 are the same, or it can be a more complex molecule, where not all of R_1-4 are the same (i.e. only one, two or three of Ri, R₂, R₃ and R₄ are the same). In the most complex cases, each of R_I-4 is different. Preferably, the quaternary ammonium hydroxide comprises one or more alkyl groups each containing from 1 to 8 carbon atoms. Preferably in the invention, all of RI-4 are the same. Preferably, the lower alkyl ammonium hydroxide is Ci-4 alkyl, and most preferably C4 alkyl. Specifically, the inventors have found that tetrabutylammonium hydroxide

(TBAOH) allowed for the synthesis of pure, or substantially pure STA-28, and although known to drive the formation of A1PO-5 (A. Turrina, R. Garcia, P. A. Cox, J. L. Casci and P. A. Wright, Chem. Mater., 2016, 28, 4998-5012), the inventors find it does not act as an structure directing agent in the present invention. Thus, TBAOH should be viewed as a particularly suitable pH modifier in all embodiments of the present method.

It is preferable that the pH value of the final reaction mixture or reaction gel is close to neutral. Preferably, it is in the range about 5.5 to about 8.5, preferably between 5.5 and 7.5, most preferably between 6 and 7. The pH can be adjusted by adding an appropriate amount of base to the reaction gel, such as the pH modifiers set out above.

Typical synthetic methods for as-made STA-28 include combining a source of

phosphorous, a source of aluminum, a source of silicon or a metal M, a structure directing agent which is 1,10-phenanthroline or a derivative thereof as described above in relation to other aspects of the invention, and a pH modifier as described below. The combination of these ingredients generally produces a gel.

Preferably, the general methods of the invention comprise combining the source of aluminum, source of phosphorous and source of silicon or metal M in a suitable solvent (e.g. water) to form a mixture, and stirring the mixture. To the stirred mixture, the structure directing agent and optional metal salt is added. Finally, the pH modifier - typically TBAOH - is added to form a reaction mixture. The reaction mixture is usually stirred continuously during the preparation procedure.

As will be understood from this description, the reaction mixture for SAPO STA-28 typically contains at least one source of aluminium, at least one source of phosphorus, at least one source of silicon, at least one structure directing agent and at least one pH modifier, all in one or more solvents. The synthesis method is not necessarily limited to SAPOs, but can be applied to synthesize other compositions of STA-28 such as MSAPOs and MAPOs in which the reaction mixture will contain a source of metal M or sources of metals M as described elsewhere herein, and may or may not contain a source of silicon.

In such cases, the reaction mixture may comprise a source of another metal M which is not A1 e.g. a source of Mg and/or Mn and/or Fe and/or Co and/or Zn and/or Sc.

Further preferences

It is preferable to use adequate mixing, blending, stirring or agitation to provide a substantially uniform or homogeneous composition throughout the mixture. The inventors consider that the use of a concentration or composition gradient should generally be minimised as far as possible if a substantially pure product is wanted, because a gradient is thought to increase the potential formation of different molecular sieve products from the same reaction mixture.

Generally, the reaction mixture forms a solution, a colloidal dispersion (colloidal sol), gel or paste. That is, the resulting reaction mixture following the mixing described above, takes one of the listed forms. Typically, a gel forms.

Preferably, for the reasons explained above, the resulting reaction mixture is homogeneous or substantially homogeneous. Stirring of the resulting reaction mixture e.g. gel, is generally carried out over a number of hours, such as more than 1 hour to 6 hours, preferably between 1 hour and 4 hours.

Preferably, a constant temperature is maintained during the preparation of the mixture. Cooling or heating may be needed to provide a constant temperature environment. A suitable temperature for preparation of the mixture can be in the range of 18-25 °C.

Typically, the mixture is prepared at atmospheric pressure.

Preferably, the components are mixed in the following order: combining source(s) of phosphate, source(s) of silica and/or metal M, source(s) of alumina in a solvent(s) followed by addition of structure directing agent and subsequently addition of pH modifier (e.g. TBAOH). The relative amounts of each component in the reaction mixture can be determined by the skilled person based on the information set out herein. For reference, some exemplary molar ratios of components are provided now.

Suitably, a molar ratio of P to A1 is at least about 0.5:1, preferably at least about 0.75: 1 and most preferably at least about 0.9:1. Suitably, the molar ratio is at most about 1:1. Most commonly, the molar ratio is between about 0.5:1 to 1:1, preferably about 0.75:1 to 1:1 and more preferably about 0.9:1 to 1:1.

Suitably, a molar ratio of P to M is at least about 1:1, preferably about 3 : 1 and most preferably about 5:1. Suitably, the molar ratio is at most about 100:1, preferably about 50:1, more preferably about 20: 1. Most commonly, the molar ratio is between about 1 : 1 to 100:1, preferably about 1:1 to 50:1, and more preferably about 5:1 to 20:1.

Suitably, a molar ratio of P to Si is at least about 2:1, preferably about 3 : 1 and more preferably about 5:1. Suitably, the molar ratio is at most about 100:1, preferably 50:1, and more preferably about 10:1. Most commonly, the molar ratio is between about 2: 1 to 100:1, preferably about 2:1 to 50:1, and more preferably about 5:1 to 10:1.

Suitably, a molar ratio of structure directing agent to A1 is at least about 0.05: 1, preferably about 0.07: 1 and most preferably about 0.1:1. Suitably, the molar ratio of structure directing agent to A1 is at most about 0.6:1, preferably at most about 0.5:1 and most preferably at most about 0.3:1. Most commonly, the molar ratio is between about 0.05 : 1 to 0.6:1, preferably about 0.05:1 to 0.3:1 and more preferably about 0.1:1 to 0.3:1.

Suitably, a molar ratio of structure directing agent to P is at least about 0.05: 1, preferably 0.07:1 and most preferably about 0.1:1. Suitably, the molar ratio is at most about 0.6:1, preferably about 0.5:1 and most preferably about 0.3:1. Most commonly, the molar ratio is between about 0.05:1 to 0.6:1, preferably about 0.05:1 to 0.3:1 and more preferably about 0.1:1 to 0.3:1.

Suitably, a molar ratio of structure directing agent to Si is at least about 1:1. Suitably, the molar ratio is at most about 15:1, preferably about 10:1 and most preferably about 2:1. Most commonly, the molar ratio is between about 1 : 1 to 15: 1, preferably about 1 : 1 to 10: 1, and more preferably about 1 : 1 to 2: 1.

Suitably, a molar ratio of structure directing agent to metal M is at least 1 : 1, preferably about 3 : 1 and more preferably about 5: 1. Suitably, the molar ratio is at most about 15:1, preferably 12: 1 and more preferably about 10: 1. Most commonly, the molar ratio is between about 1 : 1 to 15: 1, preferably about 1 : 1 to 10: 1, and more preferably about 5: 1 to 10: 1.

Suitably, a molar ratio of water to A1 is at least about 20: 1, preferably about 25: 1 and more preferably about 35: 1. Suitably, the molar ratio is at most about 100:1, preferably 75: 1 and more preferably about 45 : 1. Most commonly, the molar ratio is between about 20: 1 to 100: 1, preferably about 25:1 to 75: 1, and more preferably about 35: 1 to 45: 1.

Suitably, a molar ratio of water to P is at least about 20: 1, preferably about 25: 1 nad more preferably about 35:1. Suitably, the molar ratio is at most about 100: 1, preferably about 75 : 1 and more preferably about 45 : 1. Most commonly, the molar ratio is between about 20: 1 to 100: 1, preferably about 25: 1 to 75: 1, and more preferably about 35: 1 to 45: 1.

Suitably, a molar ratio of water to Si is at least about 80: 1, preferably about 100: 1 and more preferably about 200: 1. Suitably, the molar ratio is at most about 4000: 1, preferably about 2000: 1 and more preferably about 800: 1. Most commonly, the molar ratio is between about 80: 1 to 4000: 1, preferably about 100: 1 to 2000: 1, and more preferably about 200: 1 to 800: 1.

Suitably, a molar ratio of water to metal M is at least about 50: 1, preferably about 75: 1 and more preferably about 130: 1. Suitably, the molar ratio is at most about 4000: 1, preferably about 1500:1 and more preferably about 400: 1. Most commonly, the molar ratio is between about 50: 1 to 4000: 1, preferably about 75:1 to 1500: 1, and more preferably about 130: 1 to 400: 1.

Typically, only one kind of compound is used as source material for each of Al, P, Si and metal M as appropriate. That is, where present, only one kind of Al-containing compound is typically used as source compound for Al; only one kind of P-containing compound is typically used as source compound for P; only one kind of Si-containing compound is typically used as source compound for Si; and only one kind of metal M-containing compound is typically used as source compound for metal M.

In particularly preferred embodiments of the reaction mixture - where present - the Al- containing compound is aluminium hydroxide; the P-containing compound is phosphoric acid; the Si-containing compound is fumed silica; and the M-containing compound is M- acetate. Preferably in such embodiments, the reaction mixture satisfies at least one, and typically all of the following applicable molar ratios: a molar ratio of P to Al is between about 0.5: 1 to 1 : 1; a molar ratio of P to metal M is between about 1 : 1 to 100: 1; a molar ratio of P to Si is between about 2: 1 to 100:1; a molar ratio of structure directing agent to Al is between about 0.05: 1 to 0.6: 1; a molar ratio of structure directing agent to P is between about 0.05: 1 to 0.6: 1; a molar ratio of structure directing agent to Si is between about 1 : 1 to 15 : 1 ; a molar ratio of structure directing agent to M is between about 1 : 1 to 15: 1; a molar ratio of water to Al is between about 20: 1 to 100: 1; a molar ratio of water to P is between about 20: 1 to 100: l;a molar ratio of water to Si is between about 80: 1 to 4000: 1 ; and a molar ratio of water to M is between about 50:1 to 4000: 1.

Typical, non-limiting gel ratios are set out below. In the following, R is 1,10- phenanthroline and R² is a phenanthroline derivative such as 4- or 5-methyl-l,10- phenanthroline; and M is a metal ion, suitably a divalent metal ion such as Mg²⁺, Zn²⁺,

Co²⁺ or Mn²⁺.

SAPO-STA-28: Al: 0.95 P: 0.05 Si: 40 H₂O: 0.1 R or R²: 0.61 TBAOH

FeAPO-STA-28: 0.8 Al: 1 P: 0.2 Fe :40 H₂0: 0.4 R: 0.61 TBAOH

MSAPO-STA-28: 0.9 Al: 0.95 P: 0.05 Si: 0.1 M :40 H₂O: 0.1 R: 0.61 TBAOH

For each, a typical synthesis would be conducted according to the conditions set out above, particularly the preferred conditions. The substantially homogenized resulting reaction mixture e.g. gel is then heated according to step b described elsewhere herein. Optionally, the reaction mixture is subjected to an aging procedure before being subjected to heating. The optional aging procedure may involve allowing the reaction mixture to stand at room temperature and pressure for a number of days. Aging can be carried out at a temperature of between e.g. room

temperature (which may be between about 20-30°C, such as 25°C) to 95°C.

In a specific embodiment, a preferred reaction mixture comprises (i) at least one source of alumina chosen from the group consisting of aluminium hydroxide, boehmite and pseudoboehmite; (ii) at least one source of phosphorus chosen from the group consisting of phosphoric acid and orthophosphoric acid; (iii) at least one source of silica chosen from the group consisting of silica sol, silica gel, colloidal silica, fumed silica, silicic acid or a metal salt chosen from the group consisting of metal acetate, metal sulfate, metal nitrate, metal carbonate or metal oxide; and (iv) one or more structure directing agents chosen from 1,10- phenanthroline optionally substituted by C1-C3 alkyl at one or two of the 4, 5, 6, or 7 positions; and a pH modifier which is an alkyl ammonium hydroxide such as TBAOH.

A more preferred reaction mixture comprises (i) at least one source of alumina which includes aluminium hydroxide; (ii) at least one source of phosphorus which includes phosphoric acid; (iii) at least one source of silica chosen which includes fumed silica, or a metal salt which includes metal acetate; (iv) one or more structure directing agents chosen from 1,10-phenanthroline optionally substituted by C1-C3 alkyl at one or two of the 4, 5, 6, or 7 positions; and a pH modifier which is an alkyl ammonium hydroxide such as TBAOH.

Other preferred combinations of components can be derived from the preferred options set out in the preparation methods section. For example, it is considered that a preferred source of e.g. alumina and/or phosphorus could be combined with a most preferred source of silica or metal salt, or a preferred source of silica or metal salt could be combined with a most oreferred source of alumina and/or phosphorus as described herein. Other

combinations of features are also contemplated. Step b

For the heating step, the reaction mixture resulting from step a, e.g. the gel, is typically transferred to a suitable heating apparatus, such as an autoclave (e.g. a Teflon-lined stainless steel autoclave), and heated (e.g. hydrothermally treated) at a desired temperature for a sufficient period of time for crystals to form.

Generally, heating is carried out at between at a temperature of between about 100-250°C, preferably between about 100-220°C, more preferably between about 150-220°C and most preferably between about 170-190°C.

Suitably, the heating is carried out for more than 0.1 days, preferably more than 1 day such as at least 2 days, to form crystals of a suitable size. There is no particular upper limit, though it is not usually necessary to heat for more than 10 days, such as 8 days or less. Thus, an appropriate time range is between about 0.1 to 10 days, and preferably 2 to 8 days.

In preferred embodiments, heating is carried out at 150-220°C e.g. 180°C for 2 to 8 days.

If the heating is carried out in an enclosed or sealed heating apparatus, the pressure within the heating apparatus may vary as the reaction proceeds. The extent to which the pressure will vary is related to both the size of the heating temperature and reaction volume and so the present invention is not particularly limited by the pressure change.

The heating can be carried out either in static conditions or under stirring. Thus, the extent of stirring is not particularly limiting in the present invention. In addition, the speed of stirring can be varied according to the requirements of the skilled person and may be limited by e.g. the nature or functionality of the heating apparatus. The skilled person will be able to select suitable stirring conditions (including no stirring i.e. static).

During the heating step (alternatively called the crystallization step), crystals of STA-28 can be allowed to nucleate spontaneously from the reaction mixture. Alternatively, previously-prepared STA-28 crystals (preferred) or crystals of another suitable material (less preferred) can be added prior to heating. Such added crystals are typically called “seed” crystals. The addition of seed crystals may advantageously decrease the time needed for crystallization to occur. A typical amount of seed crystals added to the reaction mixture is between e.g. 0.1 and 10wt% of the weight of A1 used. The size and shape of the seed crystals is not particularly limited.

Step c

Recovery of the crystalline product can be achieved using methods known to the skilled person and is not particularly limited in the invention.

For example, following heating step b, the products may be suspended in a liquid, preferably water. The crystal products can be separated from the mother liquor by any suitable means. For example, filtration may be used, and/or centrifugation. The skilled person will be able to determine suitable separation e.g. filtration or centrifugation protocols.

Preferably, sonication is carried out for a short time before separation of the products from the mother liquor. Typically, sonication may be performed for about 10-30 minutes.

Sonication is considered to separate crystalline from any amorphous solid. It has been found that any amorphous solid can be removed by decanting. After sonication and optional decanting, the separation (e.g. filtration or centrifugation) described above can be carried out.

The product is STA-28 containing the structure directing agents. Typically, the inventors find that the yield (on Al) is 50-70%, but this is not particularly limited in the invention.

The STA-28 zeolite crystals produced in accordance with this process can be uniform, with limited or substantially no twinning or multiple twinning or agglomeration. The mean crystallite size is not particularly limited but is typically of the order of microns. For example, the mean crystallite size may be between 0.1 and 100 microns, such as between 10 and 75 microns, more typically between 15 and 50 microns. In preferred embodiments, it has been found that the mean crystallite size is between 20-30 microns. The shape of the crystals is not particularly limited. It will be appreciated that for each of steps a to c, the foregoing sequence of processes, and the indicated periods of time and temperature values are exemplary and may be varied.

Optional step d

The resulting crystalline product can be dried. The skilled person will be able to identify suitable drying parameters, but for example drying may involve heating to between 60 to 120°C for 6 to 24 hours, such as 80 °C for 12 hours or 110°C for 16 hours. Drying may suitably be performed in air.

Optional step e

A STA-28 product which is free or substantially free of structure directing agent can be prepared by calcining or chemically treating an as-made STA-28 molecular sieve comprising one or more structure directing agents at a temperature and for a period of time sufficient to remove the structure directing agents.

Thus, the present disclosure encompasses a preparation method in which as-made STA-28 is calcined or chemically treated. Optionally, the method of preparing calcined or chemically treated STA-28 further comprises the steps of preparing the as-made STA-28 (i.e. steps a to c and optionally d described above).

Preferred herein is a calcination step.

Calcining can be carried out in any suitable vessel, for example a furnace such as a tube furnace. Generally, calcining occurs in the presence of an oxygen-containing gas, such as air, to oxidise the structure directing agents and effect their removal from the framework. Typically, for practical reasons, the gas used during the calcining process comprises an oxygen-containing gas throughout. The inventors have found that it is possible to use an inert gas, such as nitrogen, argon, neon, helium, carbon dioxide or the like, for part of the calcination process, typically the beginning of the calcination process. Without wishing to be bound by theory, the inventors believe the inert gas assists in disrupting the bonds or connections between the structure directing agent and the framework. However, in order to fully remove the structure directing agent, an oxygen-containing gas such as air must be used during at least a part of the calcining process in order to“bum off’ (oxidise) the remaining carbon-containing species.

An oxygen-containing gas can be pure oxygen, or oxygen as part of a stream of another gas, and includes air. In order to fully remove the structure directing agent molecules, it is necessary to provide sufficient oxygen to fully oxidise the species during calcination. The proportion of oxygen comprised in the gas is not particularly limited, though low oxygen amounts may require longer calcination times. Air has an advantageously lower cost.

Suitable calcination temperatures are 400 to 800°C, preferably 500 to 600°C. By way of example, 575°C may be used.

The calcination time will be partly determined by the heating rate. The final temperature may be e.g. Suitable heating rates may be between about 1 to 10°C/min, such as between about 3 to 7°C/min.

Reaction Mixtures

In a further aspect of the invention, provided are reaction mixtures for manufacturing a molecular sieve according to the first aspect (STA-28). Typically, these reaction mixtures are suitable for use in the methods of the invention. Preferably, STA-28 molecular sievees and catalysts containing them as described herein can be produced using reaction mixtures according to this aspect.

In general, the preferences expressed for the components and characteristics of the reaction mixture described for use in the methods of the invention are applicable to the reaction mixtures of this aspect.

Catalysts and Articles

Provided herein is a catalyst comprising the molecular sieve of the invention. The catalyst may take any suitable form and is not particularly limited in the present invention.

Although it is expected that the calcined STA-28 materials will likely be most suited for use in or as catalysts or adsorbents, it is not intended to exclude that the as-made STA-28 materials may show some useful catalytic or adsorbing properties and therefore also be suitable for use according to the second aspect of the invention. The STA-28 may be used as the active material alone, or it may be part of a composition, or a mixture with other active materials. In any of these applications, the STA-28 could be used either with or without a post-synthesis metal exchange.

Thus, in certain aspects of the invention, provided is a catalyst comprising STA-28 that is free or essentially free of any exchanged metal, particularly post-synthesis exchanged or impregnated metals.

STA-28 can comprise one or more catalytic metal ions exchanged or otherwise impregnated into the channels and/or cavities of the (e.g. zeolite) material. Examples of metals that can be post-(zeolite) synthesis exchanged or impregnated include transition metals, including copper, nickel, zinc, iron, tungsten, molybdenum, cobalt, titanium, zirconium, manganese, chromium, vanadium, niobium, as well as tin, bismuth, and antimony; noble metals including platinum group metals, such as ruthenium, rhodium, palladium, indium, platinum, and precious metals such as gold and silver; alkaline earth metals such as beryllium, magnesium, calcium, strontium, and barium; and rare earth metals such as lanthanum, cerium, praseodymium, neodymium, europium, terbium, erbium, ytterbium, and yttrium. Preferred transition metals for post-synthesis exchange are base metals, and preferred base metals include those selected from the group consisting of manganese, iron, cobalt, nickel, copper, noble metals including platinum group metals and mixtures thereof.

The transition metal can be present in an amount of about 0.1 to about 10 weight percent, for example about 0.1 to about 5 weight percent, about 0.1 to about 1.0 weight percent, about 2.5 to about 3.5 weight percent, and about 4.5 to about 5.5 weight percent, wherein the weight percent is relative to the total weight of the zeolite material, and the endpoints can be included. Particularly preferred exchanged metals include copper and iron, particularly when combined with calcium and/or cerium and particularly when the transition metals and the alkaline metals are present in a transition metal: alkaline metal molar ratio of about 15: 1 to about 1 : 1, for example about 10: 1 to about 2: 1, about 10: 1 to about 3 : 1, or about 6: 1 to about 4: 1, where the endpoints can be included. Metals incorporated post-synthesis can be added to the molecular sieve via any known technique such as ion exchange, impregnation, isomorphous substitution, etc. These exchanged metal cations are distinct from metals constituting the molecular framework of the zeolite, and thus metal exchanged zeolites are distinct from metal-substituted zeolites.

An article for treating exhaust gas comprising the molecular sieve of the present invention or catalyst comprising the molecular sieve of the present invention may be provided, the article optionally comprising a structure on and/or within which the molecular sieve or catalyst is disposed. Preferably, the molecular sieve for such applications is free or substantially free of structure directing agent i.e. it has been treated to remove structure directing agent e.g. by calcination or chemical treatment. The structure on and/or within the article is not particularly limited.

Thus, use of a molecular sieve of the invention, or as prepared from a method of the invention or obtained from a reaction mixture according to the invention, as a catalyst is also part of the present disclosure. Relevant methods and reaction mixtures are described elsewhere herein.

According to a still further aspect of the invention, provided is a method of treating an exhaust gas comprising contacting a combustion exhaust gas with a molecular sieve of the invention, a catalyst or article of the invention, a molecular sieve prepared according to a method of the invention, or a molecular sieve obtained from a reaction mixture of the invention. The treatment may comprise contacting any of these under conditions permitting the reduction and/or oxidation of at least one exhaust gas. The reduction and/or oxidation may be selective i.e. specific to a particular exhaust gas. The treatment may comprise contacting the combustion exhaust gas with one or more inventive materials, either alone or optionally in combination with another catalytic material. The exhaust gas referred to herein is a gas typically produced in the exhaust of an automobile such as a car, truck, lorry, motorcycle etc.

Examples

The following examples demonstrate, but do not limit, aspects of the present invention. STA-28 was prepared using 1,10-phenanthroline, 4-m ethyl- 1,10-phenanthroline,

5-methyl-l, 10-phenanthroline, 4,7-dimethyl-l, 10-phenanthroline, or

5,6-dimethyl-l,10-phenanthroline as structure directing agent. Tetrabutylammonium hydroxide (TBAOH) was used as a pH modifier.

Chemicals may be provided from any suitable source. In the following examples, aluminium hydroxide and orthophosphoric acid 85% was purchased from Alfa Aesar; silica fumed, powder 0.007pm, 1,10-phenanthroline, 4-m ethyl- 1,10-phenanthroline, 5- m ethyl- 1,10-phenanthroline, iron (II) acetate and magnesium acetate tetrahydrate from Aldrich; tetrabutylammonium hydroxide solution (TBAOH) 55 wt. % in ¾0, from Sachem.

Example 1 _ Synthesis of a SAPO having a STA-28 framework

A reaction gel having a molar composition of 1.0 Al: 0.95 P: 0.05 Si: 40 H2O: 0.10 1,10- phenanthroline: 0.61 TBAOH was prepared in 30 ml pressure vessels. The reagents used were, in order of addition: a) The required amount of phosphoric acid (H3PO4 85wt%, Alfa Aesar) was weighed into a Teflon cup of a 30 ml Parr reactor.

b) The required amount of de-mineralised water was added.

c) The required amount of aluminium hydroxide (Al(OH)3, Alfa Aesar) was added. d) The required amount of fumed silica (S1O2, Aldrich) was added.

e) 1,10-phenanthroline (Aldrich) was added.

f) Tetrabutylammonium hydroxide (55wt%, Sachem) was added.

After stirring the gel continuously at room temperature for 2 hours until homogeneous, the reaction vessel - which was a pressure vessel - was closed at atmospheric pressure and heated in an oven for 4 days at 180°C in static condition i.e. without stirring. At the end of the reaction time, the reaction vessel was cooled to room temperature. The contents of the reaction vessel were centrifuged to separate the solid product from the mother liquor, and the solid product washed with de-mineralised water. The resulting product was dried overnight at 110°C. The powder X-ray diffraction data appears in TABLE C. TABLE C

2 Theta d-spacing I/Ip x lOO

7.07 12.49 vs

7.24 12.20 s

10.89 8.12 w

11.61 7.62 w

12.11 7.30 s

12.22 7.24 m

12.31 7.18 w

13.91 6.36 m

14.87 5.95 w

16.79 5.28 m

18.63 4.76 w

18.88 4.70 w

19.45 4.56 m

22.57 3.94 m

22.93 3.88 w

23.34 3.81 w

23.85 3.73 w

24.12 3.69 w

24.79 3.59 s

25.25 3.52 m

25.60 3.48 m

26.71 3.33 m

27.10 3.29 w

27.22 3.27 w

27.81 3.21 w

29.65 3.01 w

32.89 2.72 w

33.89 2.64 w

46.80 1.94 w

Example 2 Activation of a SAPO having a STA-28 framework

The as-made (template containing) material of Example 1 was calcined in air in a tube furnace at 575 °C (heating rate of 5 °C min^-1), for 8 hours in air. The powder X-ray diffraction data appears in TABLE D.

TABLE D 2 Theta [°] d-spacing [A] I/Ip x 100

7.14 12.37 vs

11.56 7.65 w

12.40 7.14 w

14.31 6.18 w

17.04 5.20 w

18.28 4.85 w

19.02 4.66 w

23.29 3.82 w

25.00 3.56 w

26.01 3.42 w

26.52 3.36 w

Example 3 _ Synthesis of a FeAPO (a MAPO) having a STA-28 framework

A reaction gel having a molar composition of 1.0 Al: 0.80 P: 0.20 Fe: 40 H2O: 0.40 1,10-phenanthroline: 0.61 TBAOH was prepared in 30 ml pressure vessels following the same procedure described in Example 1. Iron (II) acetate, 95% (Aldrich) was used as iron source. The as-made FeAPO STA-28 sample was calcined as described in Example 2. The powder X-ray diffraction data of as-made and calcined samples appears in TABLE E and TABLE F respectively.

TABLE E

2 Theta °] d-spacing [A] I/Ip x 100

7.05 12.53 vs

7.22 12.24 s

10.83 8.16 w

11.61 7.61 w

12.11 7.31 s

12.20 7.25 s

12.30 7.19 w

13.91 6.36 m

14.90 5.94 w

16.67 5.31 m

18.61 4.76 w

18.87 4.70 m

19.41 4.57 m

22.56 3.94 m 2 Theta [°] d-spacing [A] I/Ip x 100

22.96 3.87 w

23.39 3.80 m

23.73 3.75 w

23.99 3.71 w

24.75 3.59 s

25.28 3.52 s

25.56 3.48 m

26.56 3.35 s

27.02 3.30 w

27.24 3.27 w

27.72 3.22 w

29.73 3.00 w

32.88 2.72 w

33.85 2.65 w

46.85 1.94 w

TABLE F

2 Theta [°] d-spacing [A] I/Ip x 100

7.19 12.28 vs

11.61 7.61 w

12.48 7.09 w

14.43 6.13 w

17.06 5.19 w

18.34 4.83 w

19.15 4.63 w

23.43 3.79 w

25.16 3.54 w

26.22 3.40 w

26.60 3.35 w

Example 4 _ Synthesis of a ScAPO (a MAPO) having a STA-28 framework

A reaction gel having a molar composition of 1.0 Al: 0.80 P : 0.20 Sc : 40 ELO : 0.40 1,10- phenanthroline : 0.61 TBAOH was prepared in 30 ml pressure vessels following the same procedure described in Example 1. Scandium (III) acetate hydrate, 99.9% (Alfa Aesar) was used as scandium source. The powder X-ray diffraction data of as-made and calcined samples appears in TABLE G and TABLE H respectively. TABLE G

2 Theta °] d-spacing [A] I/IO x 100

7.07 12.49 vs

7.22 12.23 s

10.81 8.18 w

11.63 7.60 w

12.11 7.30 m

12.20 7.25 m

12.31 7.18 w

13.91 6.36 m

14.90 5.94 w

16.63 5.33 w

18.61 4.76 w

18.86 4.70 w

19.38 4.58 w

22.54 3.94 m

22.94 3.87 w

23.37 3.80 w

23.67 3.76 w

23.93 3.72 w

24.73 3.60 m

25.25 3.52 m

25.49 3.49 m

26.49 3.36 m

26.96 3.30 w

27.18 3.28 w

27.64 3.22 w

29.68 3.01 w

32.87 2.72 w

33.78 2.65 w

46.77 1.94 w

TABLE H

2 Theta [°] d-spacing [A] I/Ip x 100

7.13 12.39

11.50 7.69

12.27 7.21

14.14 6.26

17.00 5.21

2 Theta [°] d-spacing [A] I/Io x 100

18.24 4.86

18.97 4.68

23.15 3.84

25.04 3.55

25.69 3.47

26.50 3.36

Example 5 _ Synthesis of a MSAPO having a STA-28 framework

Reaction gels having a molar composition of 0.90 Al: 0.95 P : 0.05 Si : 0.10 M²⁺ : 40 H2O : 0.20 1,10-phenanthroline : 0.61 TBAOH where M²⁺ = Mg²⁺, Zn²⁺, Co²⁺, Mn²⁺ were prepared in 30 ml pressure vessels following the same procedure described in Example 1. Magnesium (II) acetate tetrahydrate, 99% (Aldrich), Zinc (II) acetate dihydrate, 99% (Aldrich), Cobalt (II) acetate tetrahydrate, 98% (Alfa Aesar), Manganese (II) acetate tetrahydrate, 99% (Aldrich) were used as sources. The powder X-ray diffraction data of as- made and calcined MgAPO samples appears in TABLE J and TABLE K respectively. TABLE J

2 Theta °] d-spacing [A] I/IO x 100

7.10 12.44 vs

7.32 12.07 s

10.90 8.11 w

11.72 7.55 w

12.17 7.27 s

12.30 7.19 m

12.37 7.15 w

13.99 6.33 m

14.96 5.92 w

16.78 5.28 w

18.64 4.76 w

19.00 4.67 w

19.60 4.53 w

22.63 3.93 m

23.03 3.86 w

23.48 3.79 w

23.82 3.73 w

24.13 3.69 w 2 Theta [°] d-spacing [A] I/I0 x 100

24.75 3.59 m

25.34 3.51 m

25.77 3.45 m

26.60 3.35 m

27.03 3.30 w

27.43 3.25 w

27.92 3.19 w

29.91 2.99 w

32.84 2.72 w

34.03 2.63 w

46.90 1.94 w

TABLE K

2 Theta [°] d-spacing [A] I/Ip x 100

7.36 12.01 vs

11.61 7.61 w

12.66 6.99 w

14.55 6.08 w

17.06 5.19 w

18.17 4.88 w

19.45 4.56 w

23.72 3.75 w

25.66 3.47 w

26.39 3.37 w

26.76 3.33 w

Examples 6-12

Sol -gel ratios were as follows:

Example 6: 1 Al: 0.95 P: 0.05 Si: 0.1 4-methyl-l,10-phenanthroline: 0.61 TBAOH: 40 ¾0

Example 7: 1 Al: 0.95 P: 0.05 Si: 0.1 5-methyl-l,10-phenanthroline: 0.61 TBAOH: 40 ELO

Example 8: 0.95 Al: 1 P: 0.05 Fe: 0.1 1,10-phenanthroline: 0.61 TBAOH: 40 ¾0

Example 9: 0.9 Al: 1 P: 0.1 Fe: 0.2 1,10-phenanthroline: 0.61 TBAOH: 40 ¾0 Example 10: 0.84 Al: 1 P: 0.16 Fe: 0.3 1,10-phenanthroline: 0.61 TBAOH: 40 H₂0

Example 11 : 0.8 Al: 1 P: 0.2 Fe: 0.4 1,10-phenanthroline: 0.61 TBAOH: 40 H₂0

Example 12: 0.9 Al: 0.95 P: 0.05 Si: 0.05 Mg: 0.1 1,10-phenanthroline: 0.61 TBAOH: 40 H₂0 The gels were prepared by mixing H3PO4 (85%) with Si0₂ (if required) and Al(OH)3 in water and stirred at room temperature. Then phenanthroline template and metal acetate (if required) were added. TBAOH was used to reach a pH of 7.

The final gels were stirred continuously at room temperature during the preparation procedure until homogeneous for at least 2 hours, prior to be transferred to a teflon-lined stainless-steel autoclave and heated at 180 °C for between 2 and 7 days. The resultant products were suspended in water and sonicated to force separation of crystalline from amorphous solid, which was removed by decanting. Then, the crystalline materials were dried in air at 80°C for 12 hours.

Detemplation was performed in a tube furnace at 575°C (heating rate of 5°C min ¹), for 8 hours in air.

TABLE L shows unit cell parameters of the samples.

TABLE L Unit cell parameters of as-made STA-28 samples

Example sample space unit cell (A) Volume (A³) b (°)

group

1 STA-28 I 2/a a = 13.9916(5) b 5121.4(4) 95.9949(30)

=25.4790(9) c =

14.4450(5)^[a]

6 STA-28 I 2/a a = 13.9168(16) b

=25.6501(29) c =

14.4538(15)^[b]

7 STA-28 I 2/a a = 14.1887(8) b

=25.4482(13) c =

14.4083(7)^[c]

8 STA-28 I 2/a a = 14.0088(18) b

=25.4386(32) c =

14.4543(17)^[d]

9 STA-28 I 2/a a = 14.0149(7)*

=25.4385(12) c =

14.465 l(6)^[e]

10 STA-28 I 2/a a = 14.0341(7) b

=25.4432(12) c =

14.4790(6)^ra

11 STA-28 I 2/a a = 14.0510(6) *

=25.4639(11) c =

14.4908(5)^[g]

[a] Prepared using 1,10-phenanthroline.

[b] Prepared using 4-methyl- 1,10-phenanthroline.

[c] Prepared using 5-methyl-l,10-phenanthroline.

[d] Prepared using 1,10-phenanthroline and 0.05 Fe/P.

[e] Prepared using 1,10-phenanthroline and 0.1 Fe/P.

[f] Prepared using 1,10-phenanthroline and 0.16 Fe/P.

[g] Prepared using 1,10-phenanthroline and 0.2 Fe/P.

TABLE X: A summary of the gel compositions and conditions used in various STA-28 syntheses

(a) x = 0.05 to 0.20, y =0.2 to 0.6. Characterization Methods

(1) Powder X-ray diffraction

Rietveld refinement of the structures of selected as-made, hydrated STA-28 materials was carried out using the GSAS suite of programs and the EXPGUI graphical interface (A. C. Larson and R. B. Von Dreele, Los Alamos Natl. Lab. Rep. LAUR). The crystal structure of STA-28, synthesised using 1, 10-phenanthroline and solved by single-crystal X-ray diffraction was used as the starting model for the refinements. The instrumental background was fitted automatically by using a Chebyschev function. The peak profiles were modelled using a Pseudo-Voigt function (type 2) (C. J. Howard, J. Appl. Crystallogr., 1982, 15, 615-620 and P. Thompson, D. E. Cox and J. B. Hastings, J. Appl. Crystallogr., 1987, 20, 79-83).

For Rietveld refinement of powder X-ray diffraction data from as-made STA-28 using 4- methyl- and 5-methyl-l, 10 phenanthrolines, the same starting modelling obtained from single-crystal X-ray diffraction structure solution was used. For 4,7-dimethyl and 5,6- dimethyl-l, 10-phenanthrolines, a similar method was used except the background was fitted using a Cosine-Fourier function and the peak profile modelled using a Pseudo- Voight function (type 3) (A. C. Larson and R. B. Von Dreele, Los Alamos Natl. Lab. Rep. LAUR).

In the case of MAPO STA-28, the refinement process is the same as described earlier, with the added step of determining the M (Fe, Mg, Mn or Sc) occupancy and location within the framework.

(2) Single crystal X-ray diffraction

A colourless prism crystal of CiiHsALlNriChoPsSi having approximate dimensions of 0.030 x 0.030 x 0.030 mm was mounted in a loop. All measurements were made on a Rigaku

XtaLAB P200 diffractometer using graphite monochromated Cu Kai radiation.

The data was collected at a temperature of -148 + 1°C to a maximum 2Q value of 150.7°. The data obtained was collected and processed using CrysAlisPro (Rigaku Oxford

Diffraction) ( CrysAlisPro : Data Collection and Processing Software , Rigaku Corporation, Tokyo 196-8666, Japan, 2015). The data was also corrected for Lorentz and polarization effects. The structure was solved by direct methods (G. M. Sheldrick, Acta Crystallogr. A, 2014, A70, C1437) and expanded using Fourier techniques.

All calculations were performed using the Crystal Structure ( CrystalStructure 4.2: Crystal Structure Analysis Package, Rigaku Corporation, Tokyo 196-8666, Japan, 2000) crystallographic software package except for refinement, which was performed using SHELXL Version 2017/1 (G. M. Sheldrick, Acta Crystallogr. A, 2008, A64, 112-122).

It will be appreciated by persons skilled in the art that the above embodiments have been described by way of example only, and not in any limitative sense, and that various alterations and modifications are possible without departure from the scope of the invention as defined by the appended claims. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Particularly, the features disclosed in the foregoing description or in the appended claims or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

For the avoidance of doubt, any theoretical explanations provided herein are for the purposes of improving the understanding of the reader. The inventors do not wish to be bound by any of these theoretical explanations. Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject-matter.

Claims

Claims:

1. A molecular sieve STA-28 having a characteristic X-ray powder diffraction pattern comprising at least the 2-theta positions shown in the following Table 1 :

Table 1

wherein vs is very strong; s is strong; m is mec ium; and w is weak, and wherein the molecular sieve is free or substantially free of structure directing agent.

2. A molecular sieve according to claim 1, wherein the characteristic X-ray powder diffraction pattern further comprises the 2-theta positions shown in the following Table la or in the following Table lb: Table la

Table lb

and w is as defined in claim 1.

3. A molecular sieve according to claim 1 or claim 2, wherein the characteristic X- ray powder diffraction pattern further comprises a 2-theta position at 26.0 (w), 26.2 (w), 25.7 (w) or 26.4 (w) ± 0.3 degrees, wherein w is as defined in claim 1.

4. A molecular sieve according to any one of claims 1 to 3, wherein the molecular sieve is an aluminophosphate, a silicoaluminophosphate, a metal silicoaluminophosphate or a metal aluminophosphate.

5. A molecular sieve according to any one of claims 1 to 4, having a formula (Si_wAl_xM_yP_z)0₂, wherein w is a mole fraction of Si and has a value of from 0.0 to 0.2, x is a mole fraction of A1 and has a value of from 0.4 to 0.6; y is a mole fraction of intra- framework metal M and has a value of from 0.0 to 0.24, and z is a mole fraction of P and has a value of from 0.2 to 0.5, and wherein w+x+y+z=l.

6. A molecular sieve STA-28 having, in its as-made form including structure directing agent, a characteristic X-ray powder diffraction pattern comprising 2-theta positions as shown in the following Table 2:

Table 2

wherein vs is very strong; s is strong; m is mec ium; and w is weak.

7. A molecular sieve according to claim 6, wherein the characteristic X-ray powder diffraction pattern further comprises the 2-theta positions shown in the following Table 2a:

Table 2a

wherein s, m and w are as defined in claim 6.

8. A molecular sieve according to any one of claims 6 to 7, wherein the molecular sieve is an aluminophosphate, a silicoaluminophosphate, a metal silicoaluminophosphate or a metal aluminophosphate.

9. A molecular sieve according to any one of claims 6 to 8, which contains one or more structure directing agents chosen from 1,10-phenanthroline optionally substituted by C1-C3 alkyl at one, two or three of the 4, 5, 6, or 7 positions.

10. A molecular sieve according to claim 9, wherein any C1-C3 alkyl groups are methyl groups.

11. A molecular sieve according to any one of claims 9 to 10, wherein the structure directing agent is selected from the group consisting of 1,10-phenanthroline; 4-methyl- 1,10-phenanthroline; 5-methyl-l,10-phenanthroline; 4,7-dimethyl-l,10-phenanthroline; and 5,6-dimethyl-l, 10-phenanthroline.

12. A molecular sieve according to any one of claims 1 to 11, wherein the molecular sieve comprises, in addition to aluminium, at least one further intra-framework metal M selected from at least one of the metals of Groups IIIA, IB, IIB, VA, VIA, VIIA, VIIIA of the Periodic Table, and combinations thereof.

13. A molecular sieve according to claim 12, wherein the at least one further intra- framework metal M is selected from the group consisting of Fe, Mn, Mg, Co, Zn and Sc.

14. A molecular sieve according to any one of claims 12 to 13, wherein up to 40wt% of the aluminium is replaced with the at least one further intra-framework metal M.

15. A molecular sieve STA-28 which has a unit cell of any one of the following (i) to

(xi):

(viii) an iron aluminophosphate comprising 1,10-phenanthroline as structure directing agent and 0.

16 Fe/P:

16. A catalyst comprising the molecular sieve of any one of claims 1 to 15.

17. An article for treating exhaust gas comprising the catalyst of claim 16, the article optionally comprising a structure on and/or within which the catalyst is disposed.

18. A method of synthesizing a molecular sieve comprising the steps of: a. forming a reaction mixture comprising (i) at least one source of alumina;

19. A method according to claim 18, wherein the structure directing agent is chosen from 1,10-phenanthroline optionally substituted by C1-C3 alkyl at one, two or three of the 4, 5, 6, or 7 positions.

20. A method according to claim 19, wherein any C1-C3 alkyl groups are methyl groups.

21. A method according to any one of claims 18 to 20, wherein the structure directing agent is selected from the group consisting of 1,10-phenanthroline; 4-m ethyl- 1,10- phenanthroline; 5-methyl-l,10-phenanthroline; 4,7-dimethyl-l,10-phenanthroline; and 5,6- dimethyl-1, 10-phenanthroline.

22. A method according to any one of claims 18 to 21, wherein the formation of a reaction mixture in step a. includes addition of a pH modifier, which is optionally an alkyl ammonium hydroxide.

23. A method according to any one of claims 18 to 22, wherein the at least one source of alumina comprises aluminium alkoxide, such as aluminium isopropoxide, aluminium phosphate, aluminium hydroxide, sodium aluminate, pseudobehemite, hydrated alumina, organoalumina, colloidal alumina, or a mixture thereof; and/or wherein the at least one source of phosphorus comprises phosphoric acid, organic phosphate such as triethyl phosphate, aluminophosphate, or a mixture thereof; and/or wherein the reaction mixture comprises at least one source of silica and the at least one source of silica comprises a silicon alkoxide, colloidal silica, silica gel, a silicate such as fumed silica, a tetraalkyl orthosilicate, an aqueous colloidal suspension of silica, or a mixture thereof; and/or wherein the reaction mixture comprises at least one source of metal M, and wherein metal M is selected from at least one of the metals of Groups IIIA, IB, IIB, VA, VIA, VIIA, VIIIA of the Periodic Table, and combinations thereof; and/or the at least one solvent is water.

24. A method according to any one of claims 18 to 23, wherein the heating of step b. is carried out at a heating temperature of between about 100°C and 220°C for a period of about 0.1 to 10 days.

25. A method according to any one of claims 18 to 24, wherein the method comprises step e.

26. A method according to claim 25, wherein step e. includes calcining and the calcining is carried out at a calcining temperature of between about 300°C to 700°C.

27. A method according to any one of claims 18 to 26, wherein the reaction mixture further comprises from about 0.1 to about 10% w/w of seed crystals, the seed crystals comprising a molecular sieve according to any one of claims 1 to 18.

28. A method according to any one of claims 18 to 27, which produces the molecular sieve according to any one of claims 1 to 18.

29. Use of a molecular sieve according to any one of claims 1 to 15, or a catalyst according to claim 16, or an article according to claim 17, or a molecular sieve produced by a method according to any one of claims 18 to 28.

30. A method for treating an exhaust gas comprising contacting a combustion exhaust gas with a molecular sieve according to any one of claims 1 to 15, or a catalyst according to claim 16, or an article according to claim 17, or a molecular sieve produced by a method according to any one of claims 18 to 28, to selectively reduce and/or oxidise at least one exhaust gas.

31. Use of a 1, 10-phenanthroline or a derivative thereof as a structure directing agent in the synthesis of a molecular sieve.