MeAPO-18 Membranes with Lamellar Crystal Morphology and Their Preparation

Abstract

The invention relates to a method for preparing a MeAPO-18 supported membrane comprising a MeAPO-18 crystal layer on a porous support, wherein the obtained MeAPO-18 supported membrane as a lamellar crystal morphology. The invention is also directed to the said membranes and to their use.

Claims

1.-18. (canceled)

19. A method for preparing a MeAPO-18 supported membrane comprising a MeAPO-18 crystal layer on a porous support, said method comprising: a) providing a porous support; b) providing MeAPO-18 crystal seeds with a lamellar crystal morphology; c) seeding the porous support of step a) with the MeAPO-18 crystal seeds of step b), in order to obtain a seeded porous support; d) providing a growing mixture containing a texture influencing agent (TIA), an organic templating agent (TEMP), at least a reactive inorganic source of MeO.sub.2 insoluble in the TIA, reactive sources of Al.sub.2O.sub.3 and P.sub.2O.sub.5, said growing mixture having a composition expressed in terms of molar oxide ratios of: TEMP/Al.sub.2O.sub.3=0.3-5/1.0, P.sub.2O.sub.5/AI.sub.2O.sub.3=0.5-2/1.0, TIA/AI.sub.2O.sub.3=3-30/1.0, MeO.sub.2/AI.sub.2O.sub.3=0.005-2.0/1.0, optionally H2O/Al.sub.2O.sub.3=5 to 100/1.0 e) contacting the seeded porous support of step c) with the growing mixture of step d) at a synthesis temperature ranging from 373 K to 623 K for about 2 to 200 hours, in order to have a MeAPO-18 supported membrane growing; f) removing the organic templating agent; wherein Me is a metal selected from the group consisting of silicon, germanium, magnesium, zinc, iron, cobalt, nickel, manganese, chromium and mixtures thereof; wherein TIA is selected from acetone, 1,2-propanediol, 1,3-propanediol, methanol, ethanol, propanol, isopropanol, butanol, and ethylene glycol or any mixture thereof.

20. The method according to claim 19 wherein the MeAPO-18 crystal seeds have an average size from 0.01 to 500 m.

21. The method according to claim 19 wherein the molar oxide ratios of the growing mixture H.sub.2O/Al.sub.2O.sub.3 ranges from 12/1.0 to 60/1.0.

22. The method according to claim 19, characterised in that the texture influencing agent (TIA) is selected from ethanol and/or ethylene glycol.

23. The method according to claim 19 wherein the organic templating agent (TEMP) is a tetraethylammonium compound selected from the group of tetraethylammonium hydroxide (TEAOH), tetraethylammonium phosphate, tetraethylammonium fluoride, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium acetate.

24. The method according to claim 19 wherein (b) comprises the preparation of the MeAPO-18 crystal seeds with a lamellar crystal morphology, and comprises: i) forming a reaction mixture containing a texture influencing agent (TIA), an organic templating agent (TEMP), at least a reactive inorganic source of MeO.sub.2 insoluble in the TIA, reactive sources of AI.sub.2O.sub.3 and P.sub.2O.sub.5, said reaction mixture having a composition expressed in terms of molar oxide ratios of: TEMP/AI.sub.2O.sub.3=0.3-5/1.0, P.sub.2O.sub.5/AI.sub.2O.sub.3=0.5-2/1.0, TIA/AI.sub.2O.sub.3=3-30/1.0, MeO.sub.2/AI.sub.2O.sub.3=0.005-2.0/1.0, optionally H.sub.2O/Al.sub.2O.sub.3=5 to 100/1.0 ii) crystallising the above reaction mixture thus formed until MeAPO-18 crystals seeds are formed; iii) recovering a solid reaction product, iv) optionally washing the solid reaction product recovered in step iii) with water; v) optionally drying the solid reaction product of step iii), or of step iv) if a step iv) is performed; and vi) recovering MeAPO-18 crystal seeds wherein the MeAPO-18 crystal seeds with lamellar crystal morphology are SAPO-18 crystals.

25. The method according to claim 19 wherein Me is a metal selected from silicon, magnesium, cobalt, germanium and mixture thereof.

26. The method according to claim 19 wherein the growing mixture and the reaction mixture have the same composition.

27. The method according to claim 19 wherein (b) comprises providing MeAPO-18 crystal seeds with a lamellar crystal morphology having an empirical chemical composition on an anhydrous basis, after synthesis and calcination, expressed by the formula:
H.sub.xMe.sub.yAl.sub.zP.sub.kO.sub.2 wherein, y+z+k=1 and xy x has a value ranging from 0 to 0.4; y has a value ranging from 0.0008 to 0.4; z has a value ranging from 0.25 to 0.67; k has a value ranging from 0.2 to 0.67; wherein the x, y, z, and k are determined with ASTM UOP961 revised in 2012 wherein more than 50 wt % of the crystals as based on the total weight of the MeAPO-18 crystal seeds have a lamellar crystal morphology in which the width (W) and the thickness (T) are such as W/T is 10.

28. The method according to claim 19 wherein the MeAPO-18 crystal seeds comprise more than 80 wt % as based on the total weight of MeAPO-18 crystal seeds, of crystals being SAPO-18.

29. The method according to claim 19 wherein the porous support: a. is selected from silica, alpha-alumina, gamma-alumina, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, iron, bronze and stainless steel, glass, and carbon; and/or b. is selected from disks, tubes and any shape incorporating multiples channels.

30. The method according to claim 19 wherein: (e) is repeated at least one time, and/or the MeAPO-18 supported membrane is selected from a crystalline silicoaluminophosphate-18 (SAPO-18) membrane.

31. The method according to claim 19 wherein the removing of the organic template agent in (f) comprises: calcination in a thermostatic oven, or calcination in a microwave oven, or plasma treatment.

32. A MeAPO-18 supported membrane comprising a MeAPO-18 crystal layer on a porous support characterised in that more than 50 wt % of the crystals as based on the total weight of the MeAPO-18 crystals have a lamellar crystal morphology in which the width (W) and the thickness (T) are such as W/T is 10.

33. A MeAPO-18 supported membrane according to claim 32 characterized in that the MeAPO-18 crystal layer is a crystalline silicoaluminophosphate-18 (SAPO-18) membrane.

34. A MeAPO-18 supported membrane according to claim 32, comprising a MeAPO-18 crystal layer on a porous support, characterised in that the MeAPO-18 crystals have a lamellar crystal morphology and an empirical chemical composition on an anhydrous basis, after synthesis and calcination, expressed by the formula:
H.sub.xMe.sub.yAl.sub.zP.sub.kO.sub.2 wherein, y+z+k=1 and xy x has a value ranging from 0 to 0.4; y has a value ranging from 0.0008 to 0.4; z has a value ranging from 0.25 to 0.67; k has a value ranging from 0.2 to 0.67; wherein the x, y, z, and k are determined with ASTM UOP961 revised in 2012.

35. The MeAPO-18 supported membrane according to claim 32 wherein the MeAPO-18 crystal layer has a thickness of at most 5 m.

36. The use of a MeAPO-18 supported membrane according to claim 32: ain a method for separating gas mixtures or gas-liquid mixtures or liquid mixtures and/or bas membrane reactor in a process in order to extract a specific co-product from a reaction zone.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0131] For the purpose of the invention the following definitions are given: The term MeAPO-18 refers aluminosilicate or zeotype with a chemical composition and crystallographic structure similar to a SAPO-18 but with silicon being replaced by Me which is a metal selected from the group consisting of silicon, germanium, magnesium, zinc, iron, cobalt, nickel, manganese, chromium.

[0132] The terms templating agent or template refer to species added to the synthesis media (herein in the growing mixture and in the reaction mixture) to aid in and/or guide the polymerization and the organization of the building blocks that form the crystal frameworks.

[0133] The terms plate crystal morphology or lamellar crystal morphology relate to crystals having the shape of a simple polygon comprised in a square wherein the square's width is named W.

[0134] The terms comprising, comprises and comprised of as used herein are synonymous with including, includes or containing, contains, and are inclusive or open-ended and do not exclude additional, non-recited members, elements or method steps. The terms comprising, comprises and comprised of also include the term consisting of.

[0135] The recitation of numerical ranges by endpoints includes all integer numbers and, where appropriate, fractions subsumed within that range (e.g. 1 to 5 can include 1, 2, 3, 4 when referring to, for example, a number of elements, and can also include 1.5, 2, 2.75 and 3.80, when referring to, for example, measurements). The recitation of endpoints also includes the recited endpoint values themselves (e.g. from 1.0 to 5.0 includes both 1.0 and 5.0). Any numerical range recited herein is intended to include all sub-ranges subsumed therein.

[0136] The particular features, structures, characteristics or embodiments may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments.

Method to Produce the MeAPO-18 Supported Membrane

[0137] The invention provides a method for preparing a MeAPO-18 supported membrane comprising a MeAPO-18 crystal layer on a porous support, said method comprising the steps of: [0138] a) providing a porous support; [0139] b) providing MeAPO-18 crystal seeds with a lamellar crystal morphology; [0140] c) seeding the porous support of step a) with the MeAPO-18 crystal seeds of step b), in order to obtain a seeded porous support: [0141] d) providing a growing mixture containing a texture influencing agent (TIA), an organic templating agent (TEMP), at least a reactive inorganic source of MeO.sub.2 insoluble in the TIA, reactive sources of Al.sub.2O.sub.3 and P.sub.2O.sub.5, said growing mixture having a composition expressed in terms of molar oxide ratios of: [0142] TEMP/Al.sub.2O.sub.3=0.3-5/1.0, [0143] P.sub.2O.sub.5/Al.sub.2O.sub.3=0.5-2/1.0, [0144] TIA/Al.sub.2O.sub.3=3-30/1.0, [0145] MeO.sub.2/Al.sub.2O.sub.3=0.005-2.0/1.0, [0146] optionally H2O/Al.sub.2O.sub.3=5 to 100/1.0 preferably 12/1.0 to 60/1.0 more preferably 15/1.0 to 30/1.0 the most preferred 17/1.0 [0147] e) contacting the seeded porous support of step c) with the growing mixture of step d) at a synthesis temperature ranging from 373 K to 623 K for about 2 to 200 hours, in order to have a MeAPO-18 supported membrane growing; [0148] f) removing the organic templating agent.

[0149] In a preferred embodiment, the MeAPO-18 supported membrane produced by the method of the invention is selected from a crystalline silicoaluminophosphate-18 (SAPO-18) membrane. In a preferred embodiment, the step e) defines a synthesis cycle and is repeated at least one time in order to perform at least two synthesis cycles, preferably at least two times, more preferably at least three times and even more preferably at least four times.

Method to Produce the MeAPO-18 Crystal Seeds

[0150] In a preferred embodiment, the step b) comprises the preparation of said MeAPO-18 crystal seeds with a lamellar crystal morphology, comprising the step of: [0151] i) forming a reaction mixture containing a texture influencing agent (TIA), an organic templating agent (TEMP), at least a reactive inorganic source of MeO.sub.2 insoluble in the TIA, reactive sources of Al.sub.2O.sub.3 and P.sub.2O.sub.5, said reaction mixture having a composition expressed in terms of molar oxide ratios of: [0152] TEMP/Al.sub.2O.sub.3=0.3-5/1.0, [0153] P.sub.2O.sub.5/Al.sub.2O.sub.3=0.5-2/1.0, [0154] TIA/Al.sub.2O.sub.3=3-30/1.0, [0155] MeO.sub.2/Al.sub.2O.sub.3=0.005-2.0/1.0, [0156] optionally H.sub.2O/Al.sub.2O.sub.3=5 to 100/1.0 preferably 12/1.0 to 60/1.0 more preferably 15/1.0 to 30/1.0 the most preferred 17/1.0 [0157] ii) crystallising the above reaction mixture thus formed until MeAPO-18 crystals seeds are formed; [0158] iii) recovering a solid reaction product, [0159] iv) optionally washing solid reaction product recovered in step iii) with water; [0160] v) optionally drying the solid reaction product of step iii), or of step iv) if a step iv) is performed; and [0161] vi) recovering MeAPO-18 crystal seeds wherein the MeAPO-18 crystal seeds with lamellar crystal morphology and are preferably selected from SAPO-18 crystals or AlPO-18 crystals.

[0162] In an embodiment, the MeAPO-18 crystal seeds are not calcined before being deposited on the support.

[0163] In a preferred embodiment, the step b-ii) to crystallise the MeAPO-18 crystal seeds is conducted at a temperature ranging from 373 K to 623 K, preferably from 393 K to 523 K, more preferably from 423 K to 473 K.

[0164] Heating up to the crystallisation temperature is preferably carried out for a period of time ranging from about 0.5 to 16 hours, preferably from 1 to 12 hours, more preferably from 2 to 9 hours. The temperature may be increased stepwise or continuously. Continuous heating is preferred. The reaction mixture may be kept static or agitated by means of tumbling or stirring the reaction vessel during hydrothermal treatment. With preference, the reaction mixture is stirred. The temperature is then maintained at the crystallisation temperature for a period of time ranging from 2 to 200 hours. Heat and agitation are applied for a period of time effective to form a crystalline product. In a preferred embodiment, the reaction mixture is kept at the crystallisation temperature for a period of from 16 to 96 hours.

The Porous Support

[0165] The porous support is a body capable of supporting the MeAPO-18 membrane. The porous support may be of any shape, including disks, tubes or a shape incorporating multiples channels. In an embodiment, the support is in the shape of a tube. In an embodiment, the support has two sides (e.g. the inside and the outside of a tube). Preferably, the support is seeded on only one side.

[0166] The support is made of a metal or an inorganic material. Preferably, the porous support of the invention is selected from silica, alpha-alumina, gamma-alumina, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, iron, bronze and stainless steel, glass, and carbon, preferably the porous support is alpha-alumina, more preferably the porous support is tubular alpha-alumina.

[0167] Advantageously, the porosity of the porous support is ranging from 5 nm to 2000, preferably from 5 nm to 1300 nm, more preferably from 5 nm to 400 nm, and most preferably from 5 nm to 100 nm.

[0168] Preferably the porous support is cleaned prior to being seeded. The support may be cleaned by being boiled in purified water. After being cleaning with water, the support may then be dried.

The Gel Composition

[0169] The membranes of the invention are prepared by secondary seeded growth with a growing mixture preferably comprising an aluminophosphate gel or a silicoaluminophosphate gel. The growing mixture used in the invention to prepare the membrane from the MeAPO-18 crystal seeds may be the same that the reaction mixture used to prepare said MeAPO-18 crystal seeds or can be slightly different. The following considerations apply to both the growing mixture of step d) and the reaction mixture used in step b-i) to prepare the MeAPO-18 crystal seeds.

[0170] The preferred composition may vary depending on the crystallised temperature and time. The growing/reaction mixture is prepared by mixing sources of aluminium, phosphorus, oxygen and optionally metal (preferably being silicon) in the presence of a templating agent and a texture influencing agent.

[0171] The growing/reaction mixture contains an organic templating agent (TEMP). The organic templating agent can be any template used in the art in the synthesis of conventional zeolitic aluminosilicates and microporous aluminophosphates.

[0172] In general, these compounds contain elements of Group VA of the Periodic Table of Elements, particularly nitrogen, phosphorus, arsenic and antimony, preferably N or P and most preferably N, which compounds also contain at least one alkyl or aryl group having from 1 to 8 carbon atoms. Particularly preferred nitrogen-containing compounds for use as templating agents are the amines and quaternary ammonium compounds, the latter being represented generally by the formula R.sub.4N.sup.+ wherein each R is an alkyl or aryl group containing from 1 to 8 carbon atoms. Polymeric quaternary ammonium salts such as [(C.sub.14H.sub.32N.sub.2)(OH).sub.2]x wherein x has a value of at least 2 are also suitably employed. Both mono-, di and tri-amines are advantageously utilised, either alone or in combination with a quaternary ammonium compound or other templating compounds.

[0173] Representative templating agents include tetramethylammonium, tetraethylammonium, tetrapropylammonium or tetrabutylammonium cations; di-n-propylamine, tripropylamine, triethylamine; diethylamine, triethanolamine; piperidine; morpholine; cyclohexylamine; 2-methylpyridine; N,N-dimethylbenzylamine; N,N-diethylethanolamine; dicyclohexylamine; N,N-dimethylethanolamine; choline; N1N-dimethylpiperazine; 1,4-diazabicyclo(2,2,2)octane; N-methyldiethanolamine, N-methylethanolamine; N-methylpiperidine; 3-methylpiperidine; N-methylcyclohexylamine; 3-methylpyridine; 4-methylpyridine; quinuclidine; N1N-dimethyl-1,4-diazabicyclo(2,2,2)octane ion; di-n-butylamine, neopentylamine; di-n-pentylamine; isopropylamine; t-butylamine; ethylenediamine; pyrrolidine; and 2-imidazolidone.

[0174] Advantageously organic templating agent is selected among tetraethylammonium hydroxide (TEAOH), diisopropylethylamine (DPEA), tetraethylammonium salts, cyclopentylamine, aminomethyl cyclohexane, piperidine, triethylamine, diethylamine, cyclohexylamine, triethyl hydroxyethylamine, morpholine, dipropylamine, pyridine, isopropylamine di-n-propylamine, tetra-n-butylammonium hydroxide, diisopropylamine, di-n-propylamine, n-butylethylamine, di-n-butylamine, and di-n-pentylamine and combinations thereof.

[0175] In an embodiment, the organic templating agent (TEMP) is a tetraethylammonium compound selected from the group of tetraethylammonium hydroxide (TEAOH), tetraethylammonium phosphate, tetraethylammonium fluoride, tetraethylammonium bromide, tetraethylammonium chloride, tetraethylammonium acetate, preferably the organic templating agent is tetraethylammonium hydroxide (TEAOH).

[0176] In an embodiment, the texture influencing agent (TIA) is selected from alcohols, ketones, aldehydes, diols and acids

[0177] The texture influencing agent (TIA) is a C.sub.1-C.sub.5 oxygenated hydrocarbon, preferably the TIA is selected from alcohols, ketones, aldehydes, diols and acids.

[0178] In an embodiment, the texture influencing agent is selected from Acetone, 1,2-propanediol, 1,3-propanediol, methanol, ethanol, propanol, isopropanol, butanol, and ethylene glycol; preferably the texture influencing agent is selected from alcohol or glycerol, and more preferably the texture influencing agent is ethanol and/or ethylene glycol.

[0179] The reactive source of Al.sub.2O.sub.3 can be any aluminium species capable of being dispersed or dissolved in an alcohol synthesis solution. In an embodiment, the source of alumina is an aluminium alkoxide such as aluminium isopropoxide or an aluminium hydroxide. Useful sources of alumina can also be one or more sources selected from hydrated alumina, organo-alumina, pseudo-boehmite, colloidal alumina, aluminium halides, aluminium carboxylates, aluminium sulphates and mixtures thereof.

[0180] In an embodiment, the reactive source of Al.sub.2O.sub.3 is organo-alumina, preferably the reactive source of Al.sub.2O.sub.3 is Al(OiPr).sub.3.

[0181] The reactive sources of P.sub.2O.sub.5 can be any phosphorous species capable of being dispersed or dissolved in an alcohol synthesis solution. Useful sources are one or more sources selected from: phosphoric acid, organic phosphates, crystalline and amorphous aluminophosphates and mixtures thereof. Useful organic phosphates are for example triethyl phosphate, tetraethylammonium phosphate.

[0182] In an embodiment, the reactive source of P.sub.2O.sub.5 is phosphoric acid.

[0183] The growing mixture and the reaction mixture are in the form of gels. The growing mixture and the reaction mixture have preferably the same composition but may have a different composition. The growing mixture and the reaction mixture can be prepared in accordance with the following compositions.

[0184] In the growing/reaction, the reactive inorganic source of MeO.sub.2, wherein Me is a metal selected from the group consisting of silicon, germanium, magnesium, zinc, iron, cobalt, nickel, manganese, chromium and mixtures thereof, preferably selected from silicon, magnesium, cobalt, germanium and mixture thereof; more preferably, Me is silicon. The MeO.sub.2 is to be selected to be insoluble in the texture influencing agent (TIA).

[0185] When MeO.sub.2 is SiO.sub.2, non-limiting examples of useful inorganic silicon source material non-soluble in alcohols include fumed silica, pyrogenic silica, precipitated silica and silica gel. These source materials are insoluble in the texture influencing agent (TIA) being an alcohol or a glycol.

[0186] In an embodiment of the invention, the growing/reaction mixture comprises MeO.sub.2 and the growing mixture has a composition expressed in terms of molar oxide ratios of TEMP/Al.sub.2O.sub.3=0.3-5/1.0; MeO.sub.2/Al.sub.2O.sub.3=0.005-2.0/1.0; P.sub.2O.sub.5/Al.sub.2O.sub.3=0.5-2/1.0; TIA/Al.sub.2O.sub.3=3-30/1.0; and optionally H.sub.2O/Al.sub.2O.sub.3=5-17/1.0.

[0187] In an embodiment, the growing/reaction mixture has a composition expressed in terms of molar oxide ratios of TEMP/Al.sub.2O.sub.3=0.5-2/1.0; MeO.sub.2/Al.sub.2O.sub.3=0.022-0.8/1.0; P.sub.2O.sub.5/Al.sub.2O.sub.3=0.8-1.2/1.0; TIA/Al.sub.2O.sub.3=6-20/1.0; and optionally H.sub.2O/Al.sub.2O.sub.3=5-17/1.0.

[0188] In another embodiment, the growing/reaction mixture has a composition expressed in terms of molar oxide ratios of TEMP/Al.sub.2O.sub.3=0.5-2/1.0; MeO.sub.2/Al.sub.2O.sub.3=0.022-0.7/1.0; P.sub.2O.sub.5/Al.sub.2O.sub.3=0.8-1.2/11.0; TIA/Al.sub.2O.sub.3=6-20/1.0; and optionally H.sub.2O/Al.sub.2O.sub.3=5-17/1.0.

[0189] In an advantageous embodiment, the growing/reaction mixture has a composition expressed in terms of molar oxide ratios of TEMP/Al.sub.2O.sub.3=0.7-2/1.0; MeO.sub.2/Al.sub.2O.sub.3=0.022-0.7/1.0; P.sub.2O.sub.5/Al.sub.2O.sub.3=0.8-1.2/1.0; TIA/Al.sub.2O.sub.3=6-20/1.0; and optionally H.sub.2O/Al.sub.2O.sub.3=5-17/1.0.

[0190] In a more advantageous embodiment, the growing/reaction mixture has a composition expressed in terms of molar oxide ratios of TEMP/Al.sub.2O.sub.3=0.7-2/1.0; MeO.sub.2/Al.sub.2O.sub.3=0.05-0.7/1.0; P.sub.2O.sub.5/Al.sub.2O.sub.3=0.8-1.2/1.0; TIA/Al.sub.2O.sub.3=6-20/1.0; and optionally H.sub.2O/Al.sub.2O.sub.3=5-17/1.0.

[0191] In a preferred embodiment, the growing/reaction mixture has a composition expressed in terms of molar oxide ratios of TEMP/Al.sub.2O.sub.3=0.7-1.1/1.0; MeO.sub.2/Al.sub.2O.sub.3=0.05-0.6/1.0; P.sub.2O.sub.5/Al.sub.2O.sub.3=0.8-1.2/1.0; TIA/Al.sub.2O.sub.3=6-20/1.0; and optionally H.sub.2O/Al.sub.2O.sub.3=5-17/11.0.

[0192] The low content of MeO.sub.2 (e.g. silicon) favours the formation of lamellar crystal morphology,

[0193] The person skilled in the art may adapt the ratio of Me to Al in order to favour the formation of MeAPO crystals over AlPO crystals or vice-versa. When the ratio of Me to Al is high enough the AlPO crystals are not formed. Preferably, Me is Si.

[0194] Optionally, the growing/reaction mixture is aged for 4 to 24 hours. Preferably the growing/reaction mixture is not aged.

The MeAPO-18 Crystal Seeds

[0195] In a preferred embodiment, step b) comprises providing MeAPO-18 crystal seeds with a lamellar crystal morphology having an empirical chemical composition on an anhydrous basis, after synthesis and calcination, expressed by the formula:

H.sub.xMe.sub.yAl.sub.zP.sub.kO.sub.2

wherein, y+z+k=1 and xy [0196] x has a value ranging from 0 to 0.4; [0197] y has a value ranging from 0.0008 to 0.4; [0198] z has a value ranging from 0.25 to 0.67; [0199] k has a value ranging from 0.2 to 0.67;
wherein more than 50 wt % of the crystals as based on the total weight of the MeAPO-18 crystal seeds have a lamellar crystal morphology in which the width (W) and the thickness (T) are such as W/T is 10, and preferably W/T is ranging from 10 to 100.

[0200] In a preferred embodiment, T is at most 0.15 m, preferably at most 0.10 m. With preference, T is ranging from 0.01 to 0.07 m, and preferably from 0.04 to 0.07.

[0201] In an embodiment, y has a value ranging from 0.005 to 0.18, z has a value ranging from 0.38 to 0.55 and k has a value ranging from 0.36 to 0.54.

[0202] In another embodiment, y has a value ranging from 0.005 to 0.16. z has a value ranging from 0.39 to 0.55 and k has a value ranging from 0.37 to 0.54.

[0203] In a further embodiment, y has a value ranging from 0.011 to 0.16, z has a value ranging from 0.39 to 0.55 and k has a value ranging from 0.37 to 0.54.

[0204] In a further embodiment, y has a value ranging from 0.011 to 0.14, z has a value ranging from 0.40 to 0.55 and k has a value ranging from 0.38 to 0.54.

[0205] In a preferred embodiment, more than 80% by weight of the MeAPO-18 crystals seeds as based on the total weight of the MeAPO-18 crystal seeds have the structure CHA or AEI or a mixture thereof, preferably more than 90 wt %.

[0206] With preference, the MeAPO-18 crystal seeds comprise more than 80 wt % as based on the total weight of MeAPO-18 crystal seeds, of crystals being selected from SAPO-18 crystals or AlPO-18 crystals; preferably more than 90 wt %.

[0207] In a preferred embodiment, the MeAPO-18 crystal seeds have an average size ranging from 5 nm to 5 m.

[0208] In an embodiment, the MeAPO-18 crystal seeds have an average size that is larger than the average pore size of the support.

[0209] In another embodiment, the MeAPO-18 crystal seeds have an average size that is equal to or smaller than the average pore size of the support.

The Step c) of Seeding the Porous Support

[0210] In a preferred embodiment, the seeding is performed by rubbing one side of the porous support with dry, un-calcined MeAPO-18 crystal seed. When the porous support is a tube, the seeded side is the inside surface of the tube, for example by the means of a cotton-tipped swab.

[0211] In another embodiment, the seeding is performed by dip-coating. This method includes immersing dry support in a suspension of MeAPO-18 crystal seeds in hydroxypropyl cellulose. After a period of time of about 25 seconds, the soaked support is lifted up, dried at 373 K for 2 hours and calcined in air at 673 K for 4 hours.

[0212] In a further embodiment, the seeding is performed by the use of a seeded growing mixture wherein the seeds are added to the growing mixture; preferably the seeds are added to the growing mixture in a TIA suspension preferably prepared by sonication.

The Step e) of Growing the MeAPO-18 Layer on a Support

[0213] The synthesis temperature of step e) of growing the membrane and the crystallisation temperature of step b-ii) to crystallise the MeAPO-18 crystal seeds can be the same or different, preferably they are the same.

[0214] In a preferred embodiment, the step e) of growing of the membrane is conducted at a synthesis/crystallisation temperature ranging from 373 K to 623 K, preferably from 393 K to 523 K, more preferably ranging from 413 K to 463 K, even more preferably ranging from 423 K to 473 K and most preferably ranging from 433 K to 453 K.

[0215] Heating up to the synthesis temperature is preferably carried out for a period of time ranging from about 0.5 to 16 hours, preferably from 1 to 12 hours, more preferably from 2 to 9 hours. The temperature may be increased stepwise or continuously. Continuous heating is preferred.

[0216] In a preferred embodiment, the step e) of growing of the membrane is conducted for about 2 to 200 hours, preferably from 16 to 96 hours, more preferably for about 24 to 72 hours.

[0217] In a preferred embodiment, the steps c) of seeding and the step e) of growing the membrane are only performed once in order to obtain a MeAPO-18 crystal layer. The steps c) of seeding is not repeated, but the step e) of growing the membrane is repeated if multiple synthesis cycles are required.

The Step f) of Removing the Templating Agent

[0218] After the synthesis of the membrane is complete, the membrane is heated to remove the organic template material. After template removal, the membrane becomes a semi-permeable barrier that is capable of restricting the movement of molecules.

[0219] The step f) of removing the templating agent is preferably done: [0220] by calcination in a thermostatic oven, or [0221] by calcination in a microwave oven, or [0222] by plasma treatment.

[0223] In an embodiment, the step f) of removing the templating agent is done by calcination in a thermostatic oven by heating up to a calcination temperature ranging from 633 K to 773 K for 8 to 20 hours in the presence of 1 to 100 vol % of oxygen.

[0224] In another embodiment, the step f) of removing the templating agent is done by calcination in a microwave oven by heating up to a calcination temperature ranging from 473 K to 673 K for 8 to 20 hours.

[0225] In another embodiment, the step f) of removing the templating agent is done by a plasma treatment by heating up to a temperature ranging from 293 K to 473 K.

[0226] Advantageously, the step f) of calcination of the MeAPO-18 crystals supported membrane is performed at a calcination temperature ranging from 663 K to 683 K for 8 to 20 hours. The membrane is preferably heated in an O.sub.2 reduced atmosphere if calcining in thermostatic or microwave oven. An O.sub.2 reduced atmosphere is a gas atmosphere containing less than 50 vol % of O.sub.2 as beads on the total volume of the gas atmosphere.

[0227] With preference, a step of washing of the MeAPO-18 supported membrane obtained in step e) with water is performed before the step f) of calcinating the MeAPO-18 supported membrane.

[0228] In a preferred embodiment, an optional treatment step g) is performed after step f) in which the calcinated MeAPO-18 supported membrane is soaked in a saturated solution of beta-cyclodextrin in isopropanol at room temperature during at least 2 h or the calcinated MeAPO-18 supported membrane is soaked in an aqueous solution containing at least 2.5 wt % of beta-cyclodextrin at room temperature during at least 2 h; followed by a drying under air at room temperature for 4 h, followed by a drying under air for at least 12 h at a temperature ranging from 150 to 250 C. preferably at 200 C.

The MeAPO-18 Supported Membrane

[0229] The invention provides a MeAPO-18 supported membrane made by the method described above.

[0230] According to the invention, the MeAPO-18 supported membrane comprises a MeAPO-18 crystal layer on a porous support. The MeAPO-18 supported membrane of the invention is remarkable in that the MeAPO-18 crystals have a lamellar crystal morphology and an empirical chemical composition on an anhydrous basis, after synthesis and calcination, expressed by the formula:

H.sub.xMe.sub.yAl.sub.zP.sub.kO.sub.2

wherein, y+z+k=1 and xy [0231] x has a value ranging from 0 to 0.4; [0232] y has a value ranging from 0.0008 to 0.4; [0233] z has a value ranging from 0.25 to 0.67; [0234] k has a value ranging from 0.2 to 0.67;
wherein more than 50 wt % of the crystals as based on the total weight of the MeAPO-18 crystal seeds have a lamellar crystal morphology in which the width (W) and the thickness (T) are such as W/T is 10, preferably ranging from 10 to 100.

[0235] In a preferred embodiment, Me is selected from Si, Mg, Co, Ge, Zn, Fe, Ni and any mixture of thereof, preferably from Si, Mg, Co, Ge and any mixture thereof, more preferably Me is Si.

[0236] Preferably, the MeAPO-18 supported membrane is selected from a crystalline silicoaluminophosphate-18 (SAPO-18) membrane or a crystalline aluminophosphate-18 (AlPO-18) membrane.

[0237] In a preferred embodiment, T is at most 0.15 m, preferably at most 0.10 m. With preference, T is ranging from 0.01 to 0.07 m, and preferably from 0.04 to 0.07.

[0238] In an embodiment, y has a value ranging from 0.005 to 0.18, z has a value ranging from 0.38 to 0.55 and k has a value ranging from 0.36 to 0.54.

[0239] In another embodiment, y has a value ranging from 0.005 to 0.16, z has a value ranging from 0.39 to 0.55 and k has a value ranging from 0.37 to 0.54.

[0240] In a further embodiment, y has a value ranging from 0.011 to 0.16, z has a value ranging from 0.39 to 0.55 and k has a value ranging from 0.37 to 0.54.

[0241] In a further embodiment, y has a value ranging from 0.011 to 0.14, z has a value ranging from 0.40 to 0.55 and k has a value ranging from 0.38 to 0.54.

[0242] In a further embodiment, y has a value of 0, z has a value ranging from 0.40 to 0.55 and k has a value ranging from 0.38 to 0.54.

[0243] Preferably, the porous support is selected from silica, alpha-alumina, gamma-alumina, mullite, zirconia, titania, yttria, silicon nitride, silicon carbide, iron, bronze and stainless steel, glass, and carbon, preferably the porous support is alpha-alumina, more preferably the porous support is tubular alpha-alumina.

[0244] In a preferred embodiment, the MeAPO-18 crystal layer has a thickness of at most 5 m or of at most 4 m, preferably of at most 3 m, even more preferably at most 2 m, most preferably of at most 1.5 m and even most preferably of at most 1.0 m or of at most 0.9 m.

[0245] In a preferred embodiment, the average pore size of the membrane is 0.38 nm.

Inventive Uses of the MeAPO-18 Supported Membrane

[0246] MeAPO-18 membranes of the invention are useful in a variety of purification processes for both gas-gas and liquid-liquid separations and the mixture of thereof.

[0247] For example, the MeAPO-18 supported membrane can be used in a method for separating a first gas component from a mixture comprising at least a first gas component and a second gas component, wherein the method comprises the steps of: [0248] providing a MeAPO-18 supported membrane, the membrane having a feed and permeate side and being selectively permeable to the first gas component over the second gas component; [0249] applying a feed stream including the first and the second gas component to the feed side of the membrane; and [0250] providing a pressure drop sufficient for permeation of the first gas component through the membrane, thereby producing a permeate stream enriched from the first gas component from the permeate side of the membrane.

[0251] Preferably, the first gas component is carbon dioxide and the second gas component is methane.

[0252] MeAPO-18 supported membranes of the invention can be used as well in membrane reactors in extraction mode to extract a specific co-product from the reaction zone, hence boosting conversion and enhancing selectivity towards the desired product by avoiding competitive reactions.

Test Methods

[0253] The average pore size of the support and the pore size of the membrane are determined by permporometry as described in C. Z. Cao, J. Meijerink, H. W. Brinkman, A. J. Burggraff Journal of Membrane Science 83 (1993), 221 especially in the paragraph relating to permporometry.

[0254] The thickness of the MeAPO-18 crystal layer was determined by Scanning Electron Microscopy (SEM) and measuring the thickness of the MeAPO-18 crystal layer.

[0255] X-ray diffraction is used to determine the crystallographic structure of MeAPO-18 crystals. When only one phase was identified, it was assumed that a pure sample was obtained.

EXAMPLES

[0256] The following examples illustrate the invention.

Synthesis of MeAPOs Supported Membranes

[0257] A reaction mixture of TEAOH, aluminium iso-peroxide, ethanol, texture influencing agent (TIA), Aerosil (in the case of SAPOs) and phosphoric acid was prepared in Teflon vessels. This slurry was homogenised for 30 minutes each time after adding a further component. Then the Teflon vessel was inserted into a stainless autoclave. The autoclave was closed and kept at elevated temperatures. After cooling down to room temperature, a sample was taken, washed and dried. Separation of the solid and liquid phases after synthesis was performed by centrifugation. Separated solid was dried at 100 C. overnight. Proportions of the gel components and operating conditions are presented in Table 1. For all the preparations, the ratio of H.sub.2O/Al (iC.sub.3H.sub.7O).sub.3 was equal to 17.

[0258] The example E4 was analysed via scanning electronic microscopy (SEM) with a 15 000 magnification a power of the electronic beam of 2 kV under secondary electron imaging and with a working distance of 3 mm and under acquisition mode GB_HIGH. The average crystal size of the SAPO-18 was measured at 20 m. The other preparation methods (E1, E2, E3 and E5) showed a similar crystal size.

[0259] The resulted SAPOs powder has been used to seed the support of a ceramic membrane.

[0260] Porous ceramic tube with 5 nm mean surface pore size was used as support. The two ends were sealed with glaze. The external surface of the support was covered by Teflon tape upon cleaning and drying. The supports were seeded by rubbing the inside surface of the support using a pipe cleaner. In a typical synthesis, the composition of the membrane gel corresponds to the composition of the gel used in the preparation of the seeds (Table 1). After dry gel synthesis, the membranes were washed with deionised water thoroughly and dried. Template removal was carried out in a tubular furnace at 673 K for 10 h. The calcination heating and cooling rates were 1 K/min, respectively.

[0261] Each step of preparation of the crystal seeds and of preparation of the membrane lasted 72 hours in total.

[0262] In the below table: [0263] Eth means ethanol [0264] EG means ethylene glycol [0265] XRD means X-ray diffraction [0266] Aerosil 200 is a fumed silica supplied by Degussa

Membrane Synthesis.

[0267] SAPO-18 membranes were prepared according to the method of preparation E4 and deposited on the inner surface of the macroporous support of -Al2O3 obtained from the Fraunhofer Institut IKTS. The -Al2O3 tubes have a length of 62.5 mm, 10 mm of outer diameter, 7 mm of internal diameter and 5 nm average pore size. The support was washed with boiling de ionized water for 30 min and dried at 373 K for 18 h. After that, the inner surface of -alumina tubes was seeded by rubbing it with uncalcined SAPO-18 crystals. The synthesis gel was prepared using AI-isopropoxide as an Al-source, fumed SiO2 as a silica precursor, H.sub.3PO.sub.4 as a phosphorous source and TEAOH as a template. The final molar ratio was 1.0 Al.sub.2O.sub.3: 0.3 SiO.sub.2: 1.0 P.sub.2O.sub.5: 1.0 TEAOH: 17 H.sub.2O. The seeded supports were placed vertically in the autoclave filled with a synthesis gel. Hydrothermal treatment (heating in an autoclave under autogenous pressure) was carried out in the conventional oven at 433 K for 72 hours. The synthesised membranes were washed by DI water, soaked for 15 minutes and dried at 453 K under air for 18 h. The membranes were calcined in a temperature programmed furnace at 773 K under air for 8 hours with a heating ramp of 0.4 K/min and cooling ramp of 0.2 K/min. The calcined membranes were treated at 423 K under the vacuum for 18 h before the gas separations tests.

Membrane Testing.

[0268] Mixed gas separations were measured without a sweep gas at the pressure drop maintained at 1.5 barg. The module temperature is kept at 22 C. and the feed pressure was 2.5 bars. The feed had a composition of CO.sub.2/CH.sub.4 (vol %/vol %, 50/50). Retentate and permeate composition were measured by a gas chromatograph having a thermal conductivity detector. The flow rate of a CO.sub.2/CH.sub.4 mixture was 0.024 Nm.sup.3/h. The selectivity is the ratio of permeance CO.sub.2 to CH.sub.4. CO.sub.2 permeance is equal to 2.34*107 mol/m.sup.2*s*Pa, the selectivity CO.sub.2/CH.sub.4 is 29.3.

Post-Treatment of the Membrane

[0269] The as synthesised membrane of SAPO-18 was calcined in a temperature programmed furnace at 773 K for 8 hours with a heating ramp of 0.4 K/min and cooling ramp of 0.2 K/min. The calcined membrane was treated at 423 K under the vacuum for 18 h before the single gas separation test. Permeate composition was measured by a gas chromatograph having a thermal conductivity detector. The selectivity is the ratio of a single permeance of CO2 to CH4. Before the post-treatment CO.sub.2 single gas permeance is equal to 0.86*107 mol/m2*s*Pa, CH4 single gas permence is 0.16*107 mol/m2*s*Pa, the CO2/CH4 selectivity is 5.4.

[0270] After that, the membrane was treated by beta-cyclodextrin. To deposit beta-cyclodextrin in the membrane defects, this membrane was soaked in 0.5-5 wt % aqueous solutions of beta-cyclodextrin at room temperature for 5 min to 4 h. It was dried at room temperature for 4 h and stored at 473K for at least 12 h before the measurements. CO2 single gas permeance is equal to 0.43*107 mol/m2*s*Pa, CH4 single gas permence is 0.04*107 mol/m2*s*Pa, the CO2/CH4 selectivity is 9.8.

[0271] The post-treatment with beta-cyclodextrin allows improving the CO2/CH4 selectivity.

TABLE-US-00001 TABLE 1 Proportions of gel components and operating conditions for MeAPOs membranes Molar composition of the reaction Aerosil time, T, # mixture and of the growing mixture Al(iC.sub.3H.sub.7O).sub.3 200 H.sub.3PO.sub.4 TEAOH TIA h C. XRD E1 1TEAOH/0.3SiO.sub.2/1Al.sub.2O.sub.3/1P2O5/12Eth 23.14 1.25 13.14 23.31 33.25 72 160 SAPO-18 E2 1TEAOH/0.3SiO.sub.2/1Al.sub.2O.sub.3/1P2O5/12EG 31.86 1.41 17.54 32.10 57.49 72 180 SAPO-18 E3 1TEAOH/1Al.sub.2O.sub.3/1P2O5/12Eth 67.31 0.00 38.23 67.82 96.73 72 160 AlPO-18 E4 1TEAOH/0.1SiO.sub.2/1Al.sub.2O.sub.3/1P2O5/12Eth 32.80 0.47 18.69 33.04 47.13 72 160 SAPO-18 E5 1TEAOH/0.1SiO.sub.2/1Al.sub.2O.sub.3/1P2O5/12Eth 32.80 0.47 18.69 33.04 47.13 72 180 SAPO-18