WO2019048373A1

WO2019048373A1 - Method for preparation of a novel eri-molecular sieve

Info

Publication number: WO2019048373A1
Application number: PCT/EP2018/073599
Authority: WO
Inventors: Cristian-Renato BORUNTEA; Peter N. R. VENNESTRØM; Lars Fahl LUNDEGAARD; Avelino Corma CANÓS
Original assignee: Haldor Topsoe AS; Universidad Politecnica de Valencia
Current assignee: Topsoe AS; Universidad Politecnica de Valencia
Priority date: 2017-09-07
Filing date: 2018-09-03
Publication date: 2019-03-14
Anticipated expiration: 2020-03-07
Also published as: ES2703220A1

Abstract

A method for the preparation of a molecular sieve product with the ERI framework type by use of cyclohexane-1,4-bis(trialkylammonium) dication as an organic structure directing agent (OSDA).

Description

Title: Method for preparation of a novel ERI-molecular sieve

The present invention relates to a method for the preparation of a novel molecular sieve with the ERI framework type.

In particular, the invention is a method for the preparation of a crystalline molecular sieve material belonging to the ERI framework family essentially without intergrowth of OFF, with a high silica-to-alumina ratio and a tabular to prismatic crystal morphology.

Zeolites are crystalline microporous materials formed by corner-sharing T0₄ tetrahedra (T = Si, Al, P, Ge, B, Ti, Sn, etc.), interconnected by oxygen atoms to form pores and cavities of uniform size and shape precisely defined by their crystal structure. Zeolites are also denoted "molecular sieves" because the pores and cavities are of similar size as small molecules. This class of materials has important commercial applications as absorbents, ion-exchangers and catalysts.

Zeolite molecular sieves are classified by the International Zeolite Association (IZA) according to the rules of the lUPAC Commission on Molecular Sieve Nomenclature. Once the topology of a new framework is established, a three letter code is assigned. This code defines the atomic structure of the framework, from which a distinct X-ray diffraction patterns can be described.

The term framework type or framework topology as used herein, refers to the unique atomic structure of a specific molecular sieve, named by a three letter code devised by the International Zeolite Association [Atlas of Zeolite Framework Types, 6th revised edition, 2007, Ch. Baerlocher, L.B. McCusker and D.H. Olson, ISBN: 978-0-444-53064- 6]. Erionite (ERI) is a naturally occurring aluminosilicate zeolite [Staples, L.W. and Gard, J.A., Mineral. Mag., 32, 261 -281 (1959)] with a Si/AI ratio around 3. It is often found as an intergrowth with OFF [Schlenker, J.L., Pluth, J.J. and Smith, J.V., Acta Crystallogr., B33, 3265-3268 (1977)]. Several ways of preparing ERI by synthetic methods have been disclosed.

US Patent 2,950,952 discloses preparation of molecular sieve type T, which has been shown to be an intergrowth of ERI and OFF [J.M. Bennet et al., Nature, 1967, 214, 1005-1006. US Patent 3,699,139 discloses synthesis of ERI/OFF using trimethylben- zylammonium. US Patent 4,086,186 discloses synthesis of ZSM-34, which is also an intergrowth of ERI and OFF. US Patent 4,503,023 discloses synthesis of LZ-220, which is a slightly more siliceous form of molecular sieve type T and also an intergrowth. The use of DABCO(I) and DABCO(II) has also been reported to give intergrowths of ERI and OFF [M. L. Ocelli et al., Zeolites, 1987, 7, 265-271 ].

As illustrated by the above references, preparation of ERI typically leads to intergrowths with OFF. These intergrowths cannot be considered pure ERI topologies and leads to different channel systems and distribution of cages within the zeolite materials compared to pure ERI, which all-together will influence the properties of this class of materials.

Only a few publications relate to the synthesis of ERI essentially free of OFF intergrowths. US Patent 7,344,694 reports the preparation of UZM-12, which is proposed to have a Si/AI ratio above 5.5 (= Si02/AI203 > 1 1 ). Practically carrying out the invention to achieve silica-to-alumina (Si02/AI203) ratios higher than 12.6 were not given in the examples. Furthermore, UZM-12 is prepared using a density-mismatch approach where nanocrystalline material with crystallites of 15 to 50 nm with a spheroidal to "rice- grain" crystal morphologies can be obtained. Especially nanocrystallites are difficult to separate from the crystallization liquor.

Recently, another ERI molecular sieve designated SSZ-98 was reported in US Patent 9,409,786, 9,416,017 and US patent application 2016/0001273. This material is also essentially free of OFF intergrowth. SSZ-98 is claimed to have a Si02/AI203 ratio between 15 and 50 with a rod-like or plate crystal morphology and it is prepared using N,N'-dimethyl-1 ,4-diazobicy- clo[2.2.2]octane dication as a structure directing agent. Later patent applications also claim Ν,Ν-dimethylpiperidinium cations, 1 ,3-dicclohex- ylimidizalium cations and their combination in US Patent applications 2017/0088432, 2017/0073240 and 2016/0375428 respectively. It is commonly acknowledged in the art that the hydrothermal stability of aluminosilicate molecular sieves become higher when the Si02/AI203 molar ratio is increased. Consequently, there is a need to increase the Si02/AI203 molar ratios of the known ERI molecular sieve materials, in particular for applications where hydrothermal stability is an issue. Furthermore, it is also commonly acknowledged in the art that the crystal mor- phology has a large impact on the performance of the molecular sieve in catalytic applications. A description of the behavior of different crystal morphologies in zeolite catalysis can be found in [S. Teketel, L. F. Lundegaard, W. Skistad, S. M. Chavan, U. Ols- bye, K. P. Lillerud, P. Beato, S. Svelle, J. Catal. 2015, 327, 22-32]. Thus, there is also a need to prepare materials with specific morphologies for specific catalytic applica- tions.

To distinguish different crystal morphologies a parameter (r_c I r_a) is defined, which describes the ratio between the different dimensions along (r_c) and orthogonal (r_a) to the unique c-axis of the prepared crystallites e.g. determined by electron microscopy meth- ods (for hexagonal crystals the unique c-axis is parallel to the six-fold symmetry axis). Crystallite morphologies will be described using the words plate, tabular, prismatic, needle and rod-like. The relationship between these descriptions and r_c I r_a values is defined in the Table below

It is thus a general object of this invention, to provide an ERI-crystalline molecular sieve essentially free of OFF intergrowths, high Si02/AI203 molar ratios and crystal morphologies different to what is already known.

We have found that the use of a cyclohexane-1 ,4-bis(trialkylammonium) dication as an organic structure directing agent (OSDA) results in the successful achievement of pure ERI with high silica-to-alumina ratios of up to 100 and with crystal morphologies different to that of SSZ-98.

Pursuant to the above finding, the present invention provides a method for the prepara- tion of a molecular sieve product with the ERI framework type comprising the steps of i) preparing a synthesis mixture comprising at least one source of silica and at least one source of alumina, or a combined source of both silica and alumina, a source of alkali or earth alkali (A), at least one OSDA being a cyclohexane-1 ,4-bis(trialkylammo- nium) dication, and water in molar ratios of:

ii) subjecting the mixture to conditions capable of crystallizing the molecular sieve; and iii) separating the molecular sieve product to obtain the as-synthesized molecular sieve. The source of silica can comprise silica, fumed silica, silicic acid, amorphous or crystalline silicates, colloidal silica, tetraalkyl orthosilicates and mixtures thereof.

The source of alumina can comprise alumina, boehmite, aluminates and mixtures thereof.

A combined source of silica and alumina can be co-precipitated amorphous silica-alumina, kaolin, mesoporous materials, crystalline microporous aluminosilicates and mixtures thereof. In an embodiment of the invention, the molecular sieve product has in the as-synthesized and anhydrous state a composition with the molar ratios given in the table:

Component Broad range Preferred range

Si02 / AI203 8-100 10-60

OSDA / Si02 0.01 -0.6 0.02-0.2

A / Si02 0.01 -0.6 0.02-0.2

The OSDA is is a cyclohexane-1 ,4-bis(trialkylammonium)dication having the structures (R = alkyl group) as shown below.

Preferably, the OSDA is selected from the group consisting of cyclohexane-1 ,4-bis(tri- methylammonium), cyclohexane-1 ,4-bis(triethylammonium), cyclohexane-1 ,4-bis(ethyl- dimethylammonium), cyclohexane-1 ,4-bis(diethylmethylammonium). Presently, the most preferred OSDA is cyclohexane-1 ,4-bis(trimethylammonium).

The OSDA cation is associated with anions, which typically can be hydroxide, chloride, bromide, iodide etc. as long as they are not detrimental to the formation of the molecular sieve. In an embodiment, the as-synthesized form of the molecular sieve has a powder X-ray diffraction pattern collected in Bragg-Brentano geometry with a variable divergence slit using Cu K-alpha radiation essentially as shown in the following Table:

2-Theta (°) d-spacing (A) Relative peak area

7,80 11,32 M

9,82 9,00 W

11,92 7,42 w

13,53 6,54 w

14,26 6,21 w

15,64 5,66 M

16,75 5,29 M

18,07 4,91 w

19,57 4,53 M

19,71 4,50 S 20,74 4,28 S-VS

21,59 4,11 VS

23,55 3,77 VS

23,87* 3,73 W-M

23,97* 3,71 W-M

23,98* 3,71 S-VS

24,31 3,66 W

25,24 3,53 VS

26,47 3,36 W

27,26 3,27 S

27,54* 3,24 W-M

27,62* 3,23 W-M

28,40 3,14 W

28,75 3,10 M

29,04 3,07 W

29,75 3,00 W

29,84 2,99 W

^*Peak intensities and letter assignment is uncertain because of significant peak overlap where the relative areas of the observed peaks in the 2-Theta range are shown according to: W = weak: 0-20%; M = medium: 20-40%; S = strong: 40-60% and VS = very strong: 60-100%. 2-Theta values are ± 0.20°

The organic OSDA cation still retained in the as-synthesized molecular sieve product is in most cases, unless used in the as-synthesized form, removed by thermal treatment in the presence of oxygen. The temperature of the thermal treatment should be suffi- cient to remove the organic molecules either by evaporation, decomposition, combustion or a combination thereof. Typically, a temperature between 150 and 750°C for a period of time sufficient to remove the organic molecule(s) is applied. A person skilled in the art will readily be able to determine a minimum temperature and time for this heat treatment. Other methods to remove the organic material(s) retained in the as-synthe- sized molecular sieve include extraction, vacuum-calcination, photolysis or ozone-treatment.

In an embodiment, the calcined form of the molecular sieve product has a powder X- ray diffraction pattern collected in Bragg-Brentano geometry with a variable divergence slit using Cu K-alpha radiation essentially as shown in the following Table: 2-Theta (°) d-spacing (A) Relative peak area

7,81 11,31 M

9,79 9,03 w

11,79 7,50 w

13,55 6,53 s

14,16 6,25 w

15,66 5,65 w

16,75 5,29 w

18,00 4,92 w

19,40 4,57 w

19,65 4,51 W-M

20,77 4,27 s-vs

21,61 4,11 M-S

23,59 3,77 M-S

23,74* 3,74 W-M

23,72* 3,75 W-M

23,95* 3,71 S-VS

24,33 3,65 W

25,01 3,56 VS

26,45 3,37 W

27,30 3,26 VS

27,44* 3,25 W-M

27,41* 3,25 W-M

28,44 3,14 M

28,55 3,12 S-VS

29,07 3,07 W

29,67 3,01 W

29,83 2,99 W

The novel molecular sieve with the ERI framework type having a mole ratio of silica to alumina from about 8 to about 100 and a crystal morphology, defined by the ratio between the dimensions r_c along and r_a orthogonal to the unique c-axis, between 0.5 and 2.0.

The crystal morphology of the novel ERI-molecular sieve with an r_c/r_a ratio of between 0.5 and 2 has a prismatic to tabular crystal morphology as shown in Figure 2 and 4 in the examples below, which is different to rod-like or plate crystal morphology of the known ERI-molecular sieve SSZ-98.

In a further embodiment, the silica-to-alumina mole ratio of the novel ERI molecular sieve is between 8 and 100, preferably between 10 and 60.

Other tetravalent elements can also be introduced into the synthesis mixture. Such elements include tin, zirconium, titanium, hafnium, germanium and combinations thereof. Trivalent elements can also be included into the synthesis mixture either together with aluminium or without the presence of aluminium. Such trivalent elements include boron, iron, indium, gallium and combinations thereof. Both tetravalent and trivalent elements may be added in the form of metals, salts, oxides, sulphides and combinations thereof. Thus, in a further embodiment, at least a part of the aluminum in the alumina-source and/or silicon in the silica-source in the synthesis mixture is substituted by one or more elements selected from tin, zirconium, titanium, hafnium, germanium, boron, iron, indium and gallium. Transition metals may be included in the synthesis mixture either as simple salts or as complexes that protects the transition metal from precipitation under the caustic conditions dictated by the synthesis mixture. Especially, polyamine complexes are useful for protecting transition metal ions of copper and iron during preparation and can also act to direct the synthesis towards specific molecular sieves (see for example the use of polyamines in combination with copper ions in US Patent application 2016271596). In such a way, transition metal ions can be introduced into the interior of the molecular sieve already during crystallization.

The synthesis mixture can also contain inexpensive pore-filling agents that can help in the preparation of more siliceous products. Such pore filling agents can be crown- ethers (for example 18-crown-6), simple amines (for example trimethyl- and triethyl- amine) and other uncharged molecules. Crystallization of the synthesis mixture to form the novel molecular sieve is performed at elevated temperatures until the molecular sieve is formed. Hydrothermal crystallization is usually conducted in a manner to generate an autogenous pressure at temperatures from 100-200°C in an autoclave and for periods of time between two hours and 20 days. The synthesis mixture can be subjected to stirring during the crystallization.

Once the crystallization has completed the resulting solid molecular sieve product is separated from the remaining liquid synthesis mixture by conventional separation techniques such as decantation, (vacuum-)filtration or centrifugation. The recovered solids are then typically rinsed with water and dried using conventional methods (e.g. heating to 75-150°C under atmospheric pressure, vacuum drying or freeze-drying etc.) to obtain the 'as-synthesized' molecular sieve. The 'as-synthesized' product refers herein to the molecular sieve after crystallization and prior to removal of the structure directing agent(s) or other organic additives.

Usually it is desirable to remove the remaining alkali or earth alkali ions (e.g. Na⁺) from the molecular sieve essentially free of occluded organic molecules by ion-exchange or other known methods, lon-exchange with ammonium and/or hydrogen are well recognized methods to obtain the NhU-form or H-form of the molecular sieve. Desired metal ions may also be included in the ion-exchange procedure or carried out separately. The NhU-form of the material may also be converted to the H-form by simple heat treatment in a similar manner as described above.

In certain cases, it may also be desirable to alter the chemical composition of the ob- tained molecular sieve, such as altering the silica-to-alumina molar ratio. Without being bound by any order of the post-synthetic treatments, acid leaching (inorganic and organic using complexing agents such as EDTA etc. can be used), steam-treatment, de- silication and combinations thereof or other methods of demetallation can be useful in this case.

To promote specific catalytic applications certain metals can be introduced into the novel molecular sieve to obtain a metal-substituted, metal-impregnated or metal-exchanged molecular sieve. Metal ions may be introduced by ion-exchange, impregnation, solid-state procedures and other known techniques. Metals can be introduced to yield essentially atomically dispersed metal ions or be introduced to yield small clusters or nanoparticles with either ionic or metallic character. Alternatively, metals can simply be precipitated on the surface and in the pores of the molecular sieve. In the case where nanoparticles are preferred, consecutive treatment in e.g. a reductive atmos- phere can be useful. In other cases, it may also be desirable to calcine the material after introduction of metals or metal ions.

Thus, in another embodiment, the method according to the invention comprises the further step of introducing copper and/or iron on or into the molecular sieve product.

The molecular sieve according to the invention is particularly useful in heterogeneous catalytic conversion reactions, such as when the molecular sieve catalyzes the reaction of molecules in the gas phase or liquid phase. It can also be formulated for other commercially important non-catalytic applications such as separation of gases. The molecular sieve provided by the invention and from any of the preparation steps described above can be formed into a variety of physical shapes useful for specific applications. For example, the molecular sieve can be used in the powder form or shaped into pellets, extrudates or moulded monolithic forms, e.g. as full body corrugated substrate containing the molecular sieve. In shaping the molecular sieve, it will typically be useful to apply additional organic or inorganic components. For catalytic applications it is particularly useful to apply a combination with alumina, silica, titania, ceria, zirconia, various spinel structures or other oxides or combinations thereof. It may also be formulated with other active compounds such as active metals or other molecular sieves etc.

The molecular sieve can also be employed coated onto or introduced into a substrate that improves contact area, diffusion, fluid and flow characteristics of the gas stream. The substrate can be a metal substrate, an extruded substrate or a corrugated substrate, the latter being made of ceramic paper. The substrate can be designed as a flow-through or a wall-flow design. In the latter case, the gas flows through the walls of the substrate, and in this way, it can also contribute with an additional filtering effect. The molecular sieve is typically present on or in the substrate in amounts between 10 and 600 g/L, preferably 100 and 300 g/L, as calculated by the weight of the molecular sieve per volume of the total catalyst article. The molecular sieve is coated on or into the substrate using known wash-coating techniques. In this approach the molecular sieve powder is suspended in a liquid media together with binder(s) and stabilizer(s). The wash coat can then be applied onto the surfaces and walls of the substrate. The wash coat optionally also contains binders based on T1O2, S1O2, AI2O3, ZrC>2, CeC>2 and combinations thereof.

The molecular sieve can also be applied as one or more layers on the substrate in combination with other catalytic functionalities or other zeolite catalysts. One specific combination is a layer with an oxidation catalyst containing for example platinum or palladium or combinations thereof. The molecular sieve can be additionally applied in limited zones along the gas-flow-direction of the substrate.

The molecular sieve according to the invention can be used in the catalytic conversion of oxides of nitrogen, typically in the presence of oxygen. In particular, the molecular sieve can be used in the selective catalytic reduction (SCR) of oxides of nitrogen with a reductant such as ammonia and precursors thereof, including urea, or hydrocarbons. For this type of application, the molecular sieve will typically be loaded with a transition metal such as copper or iron or combinations thereof, using any of the procedures described above, in an amount sufficient to catalyse the specific reaction. In certain aspects of the invention a certain amount of alkali or earth alkali can be beneficial. See for example a description of alkali and earth alkali effects on copper promoted CHA in [F. Gao, Y. Wang, N. M. Washton, M. Kollar, J. Szanyi, C. H. F. Peden, ACS Catal. 2015, 5, 6780-6791 ]. In other aspects, it may be preferred to use the molecular sieve essentially free of alkali or earth alkali.

The ERI molecular sieve according to the invention can advantageously be used as catalyst in the reduction of nitrogen oxides in the exhaust coming from a vehicular (i.e. mobile) internal combustion engine. In this application the exhaust system can comprise one or more of the following components: a diesel oxidation catalyst (DOC), a diesel particulate filter (DPF), a selective catalytic reduction catalyst (SCR) and/or an ammonia slip catalyst (ASC). Such a system typically also contains means for metering the reduct- ant as well as the possibility to meter hydrocarbons into the exhaust system upstream the SCR and DOC, respectively.

Preferably, the SCR catalyst comprises the ERI molecular sieve of the invention. The SCR catalyst may also contain other active components such as other molecular sieves. When the SCR catalyst is located in such an exhaust system it is exposed to high temperatures either from the engine or during thermal regeneration of one or more of the components in the system.

In the exhaust system as described above, the SCR catalyst, comprising the ERI molecular sieve, can be located between the DPF and the ASC components. Another possibility is to arrange the SCR catalyst up-stream of the DOC, where some tolerance to unburnt hydrocarbons is required. The SCR functionality may also be included in the DPF or combined with the ASC into a single component with a dual function.

The ERI molecular sieve according to the invention can also be part of an ammonia slip catalyst (ASC). The ASC catalyst is used in combination with the SCR article, and its function is to remove excess amount of ammonia, or a precursor thereof, that is needed in the SCR stage to remove high amounts of nitrogen oxides from the exhaust gas.

ASC-type catalysts are bifunctional catalysts. The first function is oxidation of ammonia with oxygen, which produces NOx, and the second function is NH3-SCR, in which NOx and residual amounts of ammonia react to nitrogen.

Hence, ASC catalysts consist of a combination of a component active for the oxidation of ammonia by oxygen and a component active for NH3-SCR. The most commonly applied components for the oxidation of ammonia by oxygen are based on metals like Pt, Pd, Rh, Ir, Ru, but transition metal oxides or a combination of metal oxides, for example oxides Ce, Ti, V, Cr, Mn, Fe, Co, Nb, Mo, Ta, W can also be used for this purpose. When such materials are combined with metal-loaded form of the molecular sieve of the invention having SCR activity, an ammonia slip catalyst is obtained.

Ammonia slip catalysts based on the molecular sieve of the invention may also contain auxiliary materials, for example, and not limited to binders, support materials for the noble metal components, such as AI203, ΤΊ02, Si02. Such combinations can have different forms, such as a mixture of the ammonia oxidation component with the SCR-active form of the molecular sieve of the invention, reactors or catalyst items in series (See examples US patent 4,188,364).

In particular, the ammonia slip catalyst can be a washcoated layer of a mixture of the ammonia oxidation component with the SCR-active form of the ERI molecular sieve of the invention on a monolith, or a multi-layered arrangement washcoated on a monolith, in which the different layers contain different amounts of the ammonia oxidation compo- nent, or of the SCR-active form of the molecular sieve of the invention, or of any combination of the ammonia oxidation component and the SCR-active form of the molecular sieve of the invention (JP3436567, EP1992409).

In another configuration, the ammonia oxidation component or the SCR-active form of the ERI molecular sieve of the invention or any combination of the ammonia oxidation component and the SCR-active form of the molecular sieve of the invention is present in walls of a monolith. This configuration can further be combined with different combinations of washcoated layers. Another configuration of the ASC catalyst is a catalyst article with a gas inlet end and a gas outlet end, in which the outlet end contains an ammonia oxidation component and the SCR-active form of the molecular sieve of the invention. The inlet end of the catalyst article may then contain other functionalities. The ERI molecular sieve of the invention is useful as catalyst in the reduction of nitrogen oxides in the exhaust gas from a gas turbine using ammonia as a reductant. In this application, the catalyst may be arranged directly downstream from the gas turbine. It may also be exposed to large temperature fluctuations during gas turbine start-up and shutdown procedures. In certain applications, the molecular sieve catalyst is used in a gas turbine system with a single cycle operational mode without any heat recovery system down-stream of the turbine. When placed directly after the gas turbine the molecular sieve is able to with- stand exhaust gas temperatures up to 650°C with a gas composition containing water.

Further applications of the molecular sieve of the invention are in a gas turbine exhaust treatment system in combination with a heat recovery system such as a Heat Recovery System Generator (HRSG). In such a process design, the molecular sieve catalyst is arranged between the gas turbine and the HRSG. The molecular sieve can be also arranged in several locations inside the HRSG.

Still an application of the ERI molecular sieve according to invention is the employment as catalyst in combination with an oxidation catalyst for the abatement of hydrocarbons and carbon monoxide in exhaust gas.

The oxidation catalyst, typically composed of precious metals, such as Pt and Pd, can e.g. be arranged either up-stream or down-stream of the molecular sieve and both inside and outside of the HRSG. The oxidation functionality can also be combined with the molecular sieve catalyst into a single catalytic unit.

The oxidation functionality may be combined directly with the molecular sieve by using the molecular sieve as support for the precious metals. The precious metals can also be supported onto another support material and physically mixed with the molecular sieve.

The molecular sieve of the invention is capable of removing nitrous oxide. It can for example be arranged in combination with a nitric acid production loop in a primary, secondary or a tertiary abatement setup. In such an abatement process, the molecular sieve can be used to remove nitrous oxide as well as nitrogen oxides as separate cata- lytic articles or combined into a single catalytic article. The nitrogen oxide may be used to facilitate the removal of the nitrous oxide. Ammonia or lower hydrocarbons, including methane, may also be added as a reductant to further reduce nitrogen oxides and/or nitrous oxide. The ERI molecular sieve of the invention can also be used in the conversion of oxygenates into various hydrocarbons. The feedstock of oxygenates is typically lower alcohols and ethers containing one to four carbon atoms and/or combinations thereof. The oxygenates can also be carbonyl compounds such as aldehyde, ketones and carboxylic acids. Particularly suitable oxygenate compounds are methanol, dimethyl ether, and mixtures thereof. Such oxygenates can be converted into hydrocarbons in presence of the molecular sieve. In such a process the oxygenate feedstock is typically diluted and the temperature and space velocity is controlled to obtain the desired product range. A further use of the molecular sieve of the invention is as catalyst in the production of lower olefins, in particular olefins suitable for use in gasoline or as catalyst in the production of aromatic compounds.

In the above applications, the ERI molecular sieve is typically used in its acidic form and will be extruded with binder materials or shaped into pellets together with suitable matrix and binder materials as described above.

Other suitable active compounds such as metals and metal ions may also be included to change the selectivity towards the desired product range.

The ERI molecular sieve according to the invention can further be used in the partial oxidation of methane to methanol or other oxygenated compounds such as dimethyl ether. One example of a process for the direct conversion of methane into methanol at temperatures below 300°C in the gas phase is provided in W01 1046621 A1. In such a process, the molecular sieve of the invention is loaded with an amount of copper sufficient to carry out the conversion. Typically, the molecular sieve will be treated in an oxidizing atmosphere where-after methane is subsequently passed over the activated molecular sieve to directly form methanol. Subsequently, methanol can be extracted by suitable methods and the active sites regenerated by another oxidative treatment. Another example is disclosed in [K. Narsimhan, K. lyoki, K. Dinh, Y. Roman-Leshkov, ACS Cent. Sci. 2016, 2, 424-429] where an increase or a continuous production of methanol is achieved by addition of water to the reactant stream to continuously extract methanol without having to alter the conditions between oxidative treatments and methanol formation.

The ERI molecular sieve of the invention can be used to separate various gasses. Examples include the separation of carbon dioxide from natural gas and lower alcohols from higher alcohols. Typically, the practical application of the molecular sieve will be as part of a membrane for this type of separation.

The ERI molecular sieve of the invention can further be used in isomerization, cracking hydrocracking and other reactions for upgrading oil. The ERI molecular sieve of the invention may also be used as a hydrocarbon trap e.g. from cold-start emissions from various engines.

Furthermore, the molecular sieve can be used for the preparation of small amines such as methyl amine and dimethylamine by reaction of ammonia with methanol.

EXAMPLES

Example 1 : Synthesis of cvclohexane-1 ,4-bis(trimethylammonium hydroxide) OSDA A mixture of 30 mL formic acid (89.5 wt. % aqueous solution), 6.1 g NaHCC>3, 5 g trans- 1 ,4-diaminocyclohexane (98% purity powder) and 14 mL formaldehyde (37 wt. %aque- ous solution) was refluxed until no visible evolution of CO2 was noticed. The synthesis mixture was vacuum distillated after 50 mL HCI (2 mol/L aqueous solution) was added, followed by the addition of an excess of NaOH and extraction 3 times with chloroform. The chloroform portions were combined and 8 mL of methyl iodide (99 wt. %) was added followed by mixing overnight. The obtained solid was dissolved in water and ion exchange to hydroxide form, using an ion exchange resin.

Example 2: Synthesis of ERI

A mixture of 1.87 g cyclohexane-1 ,4-bis(trimethylammonium hydroxide)(12.7 wt. % aqueous solution), 1.7 g KOH (10 wt. % aqueous solution), 0.48 g distilled water and 0.94 g co-precipitated amorphous silica-alumina (Si02/AI203 = 12) was prepared. The mixture was heated in a closed Teflon lined autoclave at 135°C for 7 days and the solid product separated by filtration and washing with deionized water.By X-ray powder diffraction analysis, the as-synthesized product is seen to be phase-pure ERI.

Example 3: Synthesis of ERI

A mixture of 1.97 g cyclohexane-1 ,4-bis(trimethylammonium hydroxide)(12.7 wt. % aqueous solution), 1 .79 g KOH (10 wt. % aqueous solution), 0.46 g distilled water and 0.79 g FAU zeolite (Si02/AI203= 12) was prepared. The mixture was heated in a closed Teflon lined autoclave at 135°C for 7 days and the solid product separated by filtration and washing with deionized water.

The dried solid product had a Si02/AI203 ratio of 9.8 determined by ICP-AES analysis. By X-ray powder diffraction analysis, the as-synthesized product is seen to be phase- pure ERI. SEM analysis further reveals a tabular to prismatic crystal morphology.

Example 4: Synthesis of ERI

A mixture of 1.95 g cyclohexane-1 ,4-bis(trimethylammonium hydroxide)(12.7 wt. % aqueous solution), 1 .77 g KOH (10 wt. % aqueous solution), 0.5 g distilled water and 0.79 g co-precipitated amorphous silica-alumina (Si02/AI203 = 30) was prepared. The mixture was heated in a closed Teflon lined autoclave at 135°C for 7 days and the solid product separated by filtration and washing with deionized water.

By X-ray powder diffraction analysis, the as-synthesized product is seen to be phase- pure ERI. The measured diffractogram for the as-synthesized product is shown in Figure 1 . SEM analysis further reveals a tabular crystal morphology (see Figure 2).

Figure 1 XRPD of the as-prepared molecular sieve prepared in Example 4.

Figure 2 SEM micrograph of the as-prepared molecular sieve prepared in Example 4. Example 5: Synthesis of ERI

A mixture of 1.99 g cyclohexane-1 ,4-bis(trimethylammonium hydroxide)(12.7 wt. % aqueous solution), 1 .81 g KOH (10 wt. % aqueous solution), 0.45 g distilled water and 0.74 g FAU zeolite (Si02/AI203= 30) was prepared. The mixture was heated in a closed Teflon lined autoclave at 135°C for 7 days and the solid product separated by filtration and washing with deionized water.

The dried solid product had a Si02/AI203 ratio of 22.0 determined by ICP-AES analysis. By X-ray powder diffraction analysis, the as-synthesized product is seen to be phase-pure ERI. The measured diffractogram for the as-synthesized product is shown in Figure 3. SEM analysis further reveals a prismatic crystal morphology (see Figure 4).

Figure 3 XRPD of the as-prepared molecular sieve prepared in Example 5. Figure 4 SEM micrograph of the as-prepared molecular sieve prepared in Example 5.

Calcination of the dried as-prepared molecular sieve was carried out at 550°C for 3h. Afterwards the calcined product was ion-exchanged with NH4⁺. The measured X-ray diffractogram for the calcined product is shown in Figure 5. Furthermore, N2-physisorp- tion revealed a multipoint BET surface area of 559 m2/g and a micropore volume of 0.19 cm3/g, clearly indicating the microporous nature of the prepared material.

Figure 5 XRPD of the calcined molecular sieve prepared in Example 5.

Claims

1 . A method for the preparation of a molecular sieve product with the ERI framework type comprising the steps of i) preparing a synthesis mixture comprising at least one source of silica and at least one source of alumina, or a combined source of both silica and alumina, a source of alkali or earth alkali (A), at least one OSDA being a cyclohexane-1 ,4-bis(trialkylammo- nium) cation, and water in molar ratios of:

ii) subjecting the mixture to conditions capable of crystallizing the molecular sieve; and iii) separating the molecular sieve product to obtain the as-synthesized molecular sieve.

2. The method of claim 1 , wherein molecular sieve product has in the as-synthe- sized and anhydrous state a composition with the molar ratios given in the following Table:

Component Broad range Preferred range

Si02 / AI203 8-100 10-60

OSDA / Si02 0.01 -0.6 0.02-0.2

A / Si02 0.01 -0.6 0.02-0.2 where the OSDA is is a cyclohexane-1 ,4-bis(trialkylammonium) dication and A is an alkali or earth alkali cation.

3. The method of claim 1 or 2, wherein the cyclohexane-1 ,4-bis(trialkylammonium) dication is selected from the group consisting of cyclohexane-1 ,4-bis(trimethylammo- nium), cyclohexane-1 ,4-bis(triethylammonium), cyclohexane-1 ,4-bis(ethyldime- thylammonium), cyclohexane-1 ,4-bis(diethylmethylammonium). 4. The method of claim 1 or 2, wherein the cyclohexane-1 ,4-bis(trialkylammonium) dication is cyclohexane-1 ,

4-bis(trimethylammonium).

5. The method of any one of claims 1 to 4, wherein the as-synthesized form of the molecular sieve has a powder X-ray diffraction pattern collected in Bragg-Brentano geometry with a variable divergence slit using Cu K-alpha radiation essentially as shown in the following Table:

^*Peak intensities and letter assignment is uncertain because of significant peak overlap where the relative areas of the observed peaks in the 2-Theta range are shown according to: W = weak: 0-20%; M = medium: 20-40%; S = strong: 40-60% and VS = very strong: 60-100%.2-Theta values are ± 0.20°.

6. The method of any one of claims 1 to 5 comprising the further step of calcining the molecular sieve product and wherein the calcined form of the molecular sieve product has a powder X-ray diffraction pattern collected in Bragg-Brentano geometry with a variable divergence slit using Cu K-alpha radiation essentially as shown in the following Table:

*Peak intensities and letter assignment is uncertain because of significant peak overlap where the relative areas of the observed peaks in the 2-Theta range are shown according to: W = weak: 0-20%; M = medium: 20-40%; S = strong: 40-60% and VS = very strong: 60-100%. 2-Theta values are ± 0.20°.

7. The method of any one of claims 1 to 6, wherein the silica-to-alumina mole ratio of the molecular sieve is between 8 and 100.

8. The method of any one of claims 1 to 6, wherein the silica-to-alumina mole ratio of the molecular sieve is between 10 and 60.

9. The method of any one of claims 1 to 8, wherein at least a part of the aluminum in the alumina-source and/or silicon in the silica-source in the synthesis mixture is substituted by one or more elements selected from tin, zirconium, titanium, hafnium, germanium, boron, iron, indium and gallium.

10. The method of any one of claims 1 to 9, comprising the further step of introducing copper and/or iron on or into the molecular sieve product.