Process for the production of boronaaronate molecular sieve using ethylenediamine and quinoline or isoquinoline

Molecular sieve abstract

A new crystalline borosilicate molecular sieve, boronaaronate, having a composition in terms of mole ratios of oxides: wherein M is a cation of valence n, y is between 2 and about 700 and z is between 0 and about 200 and having a characteristic X-ray diffraction pattern. The boronaaronate is prepared by reacting under crystallization conditions, in substantial absence of a metal hydroxide, an aqueous mixture containing an oxide of silicon, an oxide of boron, ethylenediamine, and an organic material comprised of a heterocyclic nitrogen-containing aromatic compound or an aliphatic alcohol. Boronaaronate is useful in hydrocarbon conversion processes.

Molecular sieve claims

What is claimed is:

1. A method for preparing a crystalline molecular sieve composition having in terms of mole ratios of oxides:

wherein M is a cation of valence n, y is between 2 and about 700 and z is between 0 and about 200 and having the X-ray diffraction pattern substantially as shown in Table I which method comprises reacting under crystallization conditions an aqueous mixture containing an oxide of boron, ethylenediamine, an oxide of silicon, and an organic material selected from the group consisting of quinoline and isoquinoline in the substantial absence of alkali or alkaline earth metal ions wherein the mole ratio of said material to silica is between about 0.2 and about 3.0 the mole ratio of silica to oxide of boron is between about 5 and about 150 and the mole ratio of water to silica is between about 15 and about 80.

2. The method of claim 1 wherein the crystallizing mixture is maintained at about 100.degree. C. to about 200.degree. C. for about 2 to about 20 days.

3. The method of claim 2 wherein the crystallizing mixture is maintained at about 120.degree. C. to about 180.degree. C. for about 3 to about 14 days.

4. The method of claim 1 wherein the molecular sieve is incorporated within a suitable matrix material.

5. The method of claim 4 wherein the matrix material comprises silica, silica-alumina, or alumina.

6. The method of claim 1 wherein the mole ratio of said organic material to silica is between about 0.3 and about 2.0 the mole ratio of silica to oxide of boron is between about 15 and about 50 and the mole ratio of water to silica is between about 20 and about 40.

7. The method of claim 1 wherein said organic material is quinoline.

8. The method of claim 1 wherein said organic material is isoquinoline.

Molecular sieve description

This invention relates to a crystalline borosilicate molecular sieve having a crystalline topology similar to ferrierite aluminosilicate. The crystalline borosilicate molecular sieve is prepared by reacting under crystallization conditions, in substantial absence of a metal hydroxide, an aqueous mixture containing an oxide of silicon, an oxide of boron, ethylenediamine, and a heterocyclic nitrogen-containing aromatic compound or an aliphatic alcohol.

Some zeolitic materials, both natural and synthetic, are known to have catalytic capabilities for many hydrocarbon processes. Zeolitic materials typically are ordered porous crystalline aluminosilicates having a definite structure with cavities interconnected by channels. The cavities and channels throughout the crystalline material generally are uniform in size which sometimes permits selective separation of hydrocarbons. Consequently, these materials, in many instances, are known in the art as "molecular sieves" and are used, in addition to selective adsorptive processes, for certain catalytic properties. The catalytic properties of these materials are affected to some extent by the size of the molecules which selectively penetrate the crystal structure, presumably to contact active catalytic sites within the ordered structure of these materials.

Generally, the term "molecular sieve" includes a wide variety of both natural and synthetic positive-ioncontaining crystalline zeolite materials. They generally are characterized as crystalline aluminosilicates which comprise networks of SiO.sub.4 and AlO.sub.4 tetrahedra in which silicon and aluminum atoms are cross-linked by sharing of oxygen atoms. Negative framework charge resulting from substitution of an aluminum atom for a silicon atom is balanced by positive ions, for example, alkali-metal or alkaline-earth-metal cations, ammonium ions, or hydrogen ions.

Molecular sieves characterized as "ferrierite" by chemical composition and X-ray spectrum are known as naturally occurring materials and as synthesized materials. A ferrierite sieve is characterized as a crystalline aluminosilicate typically having a silica/alumina molar ratio of 2 to 40 and having a distinctive X-ray pattern.

A conventional ferrierite sieve is produced by crystallizing a basic mixture of sodium aluminate and an oxide of silicon without the use of an organic template compound. Such ferrierites are described in D. W. Breck "Zeolite Molecular Sieves," John Wiley & Sons, 1974 incorporated by reference herein. U.S. Pat. No. 4000248 discloses a method of producing a ferrierite molecular sieve using N-methyl pyridinium hydroxide as an organic template compound in the crystallization of the sieve. U.S. Pat. Nos. 4016245 4107195 and 4046859 disclose the formation of a ferrierite-like material using an organic template derived from ethylenediamine, pyrrolidine or butanediamine, or organometallic 2-(hydroxyalkyl)- trialkylaluminum compounds.

U.S. Pat. No. 4251499 discloses the preparation of synthetic ferrierite in the presence of piperidine or an alkyl-substituted piperidine. The reference specifically states that when other heterocyclic compounds such as pyridine are used "either no ferrierite at all is formed, or the ferrierite obtained is highly contaminated with other zeolitic and/or amorphous material." U.S. Pat. No. 4377502 discloses the use of oxygen-containing organic templates such as ethers and hydroxy amines in the preparation of aluminosilicate ferrierite molecular sieves.

Boron is not considered a replacement for aluminum or silicon in a zeolitic composition. Although over a hundred aluminosilicate zeolites are listed by Breck, the text states that "actual incorporation of boron in a zeolite structure has not been achieved." However, a new crystalline borosilicate molecular sieve AMS-1B was disclosed in U.S. Pat. Nos. 4268420 and 4269813 incorporated by reference herein. According to these patents AMS-1B can be synthesized by crystallizing a source of an oxide of silicon, an oxide of boron, an oxide of sodium, and an organic template compound such as a tetra-n-propylammonium salt. In order to form a catalytically-active species of AMS-1B, sodium ion typically is removed by one or more exchanges with ammonium ion followed by calcination. Other methods to produce borosilicate molecular sieves include formation of a borosilicate using ethylenediamine with sodium hydroxide disclosed in British patent application No. 2024790. Despite discoveries of borosilicates with crystalline structures, the formation of crstalline borosilicates remains unpredictable. The reaction mechanisms whereby reaction gels are converted into crystalline borosilicates are not sufficiently well known to suggest to one skilled in the art the reaction compositions and formulation techniques which could reasonably be expected to yield a crystalline borosilicate with an X-ray diffraction pattern similar to that of ferrierite.

The material of this invention is referred to as "boronaaronate", a crystalline borosilicate molecular sieve having a characteristic structure as shown by its X-ray diffraction pattern and composition. Although the X-ray diffraction pattern of the boronaaronate of this invention shows similarities to that of ferrierite aluminosilicate zeolite, which indicates a similar crystalline topology, there are substantive differences between the respective patterns which reflect incorporation of boron into the crystalline framework of the boronaaronate molecular sieve. For example, it is known that the boron-oxygen bond length is shorter than either the silicon-oxygen or aluminum-oxygen length. Thus, a contraction of the crystalline unit cell is expected in a molecular sieve in which boron is incorporated into the framework. Such effect on the unit cell is observed by shifts of lines in the X-ray diffraction pattern of a borosilicate as compared to an aluminosilicate. However, the crystalline boronaaronate of this invention is prepared in substantial absence of aluminum and consequently there may be very little aluminum present in the boronaaronate of this invention. The structure of boronaaronate is distinct from the structures of known crystalline borosilicates.

The object of this invention is to provide a crystalline borosilicate-type material, boronaaronate, having a crystalline topology similar to the topology of ferrierite. Another object of this invention is a method of producing boronaaronate, said method comprising reacting an oxide of silicon, an oxide of boron, ethylenediamine, a heterocyclic nitrogen-containing aromatic compound or an aliphatic alcohol, and water under crystallization conditions. A further object of this invention is a method of hydrocarbon conversion using the boronaaronate described in this invention.

SUMMARY OF THE INVENTION

Boronaaronate, a crystalline borosilicate having a crystalline topology similar to the topology of ferrierite, has been discovered having the following composition in terms of mole ratios of oxides:

wherein M is at least one cation with the valence of n, y is between about 2 and about 700 or more, preferably between about 5 and about 150 and z is between 0 and about 200 preferably between 0 and 120 having an X-ray diffraction pattern substantially as shown in Table I.

This novel molecular sieve is prepared by a method which comprises reacting under crystallization conditions, an aqueous mixture containing an oxide of boron, a heterocyclic nitrogen-containing aromatic compound or an aliphatic alcohol, ethylenediamine, and an oxide of silicon. The crystalline boronaaronates of this invention are particularly useful in hydrocarbon conversion processes.

DESCRIPTION OF THE INVENTION

The boronaaronate of this invention is a new crystalline borosilicate molecular sieve material having the following composition in terms of mole ratios of oxides:

wherein M is at least one cation of valence n, y is between about 2 and about 700 or more, preferably between about 5 and about 150 and z is between 0 and about 200 preferably between 0 and 120 having a low alumina content and having an X-ray diffraction pattern substantially as shown in Table I. M is preferably hydrogen.

Boronaaronate preparations of this invention showing particular catalytic properties have a silica/boria mole ratio of about 15 to about 50.

Another aspect of this invention relates to a method of producing a crystalline boronaaronate by reacting an oxide of boron, an oxide of silicon, ethylenediamine, a heterocyclic aromatic compound or an aliphatic alcohol, and water under crystallization conditions. The crystalline boronaaronates of this invention are useful in hydrocarbon conversion processes and are particularly suitable for isomerization of alkylaromatics such as xylenes.

Examples of oxides of boron are H.sub.3 BO.sub.3 B.sub.2 O.sub.3 and H.sub.3 B.sub.3 O.sub.6. Examples of oxides of silicon are silicic acid, sodium silicate, tetraalkyl silicates, and "LUDOX" materials (stabilized polymers of silicic acid [40% solids] manufactured by E. I. du Pont de Nemours & Co.) which include Ludox HS-40 (sodium stabilized) and Ludox AS-40 (ammonia stabilized). Another example is Nalco 2327 an ammonia stabilized colloidal silica [40% solids] manufactured by Nalco Chemical Company.

In addition to ethylenediamine, other organic materials used in this invention include materials such as heterocyclic nitrogen-containing aromatic compounds and aliphatic alcohols or combinations thereof. Typically, suitable nitrogen-containing heterocyclic aromatic compounds contain about 4 to about 9 carbon atoms and at least one nitrogen atom in an aromatic nucleus together with their aryl- and alkyl-substituted derivatives. Examples of the aromatic compounds useful in this invention include pyridine, quinoline, isoquinoline, and pyrrole. Suitable pyridine compounds include pyridine and aryl- or alkyl-substituted pyridines. Pyridine, quinoline, and isoquinoline are the preferred heterocyclic compounds in this invention. Aliphatic alcohols useful in this invention include mono and polyhydroxy alcohols and mixtures of said alcohols. Examples of suitable alcohols include C.sub.1 -C.sub.10 alkyl alcohols such as ethanol, propanol, isopropyl alcohol, and butanol or mixtures thereof. Examples of suitable alkylene glycols include ethylene glycol and propylene glycol. Preferred alcohols include ethanol, propanol, and isopropyl alcohol. Ethylene glycol is the preferred glycol. Substitution of other organic compounds such as alkylammonium compounds for the alcohols or aromatic compounds in this invention results in amorphous products or products with distinctly different X-ray diffraction patterns, e.g., AMS-1B crystalline borosilicate molecular sieve.

Preferably, the boronaaronate of this invention is prepared in the substantial absence of alkali or alkaline earth metals or ions; i.e., no alkali or alkaline earth metals or compounds are added during the preparation of the boronaaronate. Although alkali or alkaline earth ions can be present as impurities in the starting materials, it is advantageous that the starting reagents contain as little alkali metal ion contaminant as practicable. When sodium hydroxide was used instead of ethylenediamine in the process of this invention, an amorphous product resulted. Because ethylenediamine is used as the base, the crystalline borosilicate of this invention requires no ion-exchange procedure before formulation into a catalytic composition. However, if an alkali metal cation is desired, it can be placed in the boronaaronate by ion exchange after it is formed.

It is possible to vary the SiO.sub.2 /B.sub.2 O.sub.3 molar ratio in the final product in a range of about 2 to about 700 preferably about 4 to about 300 and most preferably about 5 to about 150 or more by varying the quantity of the boron-containing reactant in the reaction mixture. A molar excess of boria to silica typically is needed to produce a sieve with a particular boron content.

The molecular sieves of this invention typically have a high SiO.sub.2 /Al.sub.2 O.sub.3 ratio which can range to over 3000:1 typically from about 1000:1 to about 3000:1. The typical ratio for boronaaronate is much higher than SiO.sub.2 /Al.sub.2 O.sub.3 ratios found in the prior art synthetic ferrierite materials and is generally limited only by the availability of aluminum-free raw materials. Because of their high SiO.sub.2 /Al.sub.2 O.sub.3 ratios, boronaaronates are expected to have superior stability characteristics over the prior art ferrierites and to exhibit more hydrophobic surface selectivity.

In another aspect of this invention, molecular sieves with topologies similar to that of ferrierite but having lower aluminum content (higher SiO.sub.2 /Al.sub.2 O.sub.3 ratios) than prior art synthetic ferrierites can be prepared by controlling the amount of aluminum (relative to the amount of boron) present in the starting materials and mixture. Through careful control of the aluminum content in the starting mixture, ferrierite-like molecular sieves with silica/alumina mole ratios above 40 preferably above 100 and most preferably above 300 can be prepared by the process of this invention.

The material of the present invention is prepared by mixing in water (preferably distilled or deionized) ethylenediamine, a boron oxide source, and the alcohol or aromatic compound. The order of addition is typically not critical and a typical procedure is to dissolve ethylenediamine and boric acid in water and then add the alcohol or aromatic compound. Generally, the silicon oxide compound is added with intensive mixing. The resulting slurry is transferred to a closed crystallization vessel for a suitable time. After crystallization, the resulting crystalline product can be filtered, washed with water, dried, and calcined.

During preparation, acidic conditions should be avoided. Advantageously, the pH of the reaction system falls within the range of about 8 to about 12 and most preferably between about 9 and about 10.5. The pH is controlled by the concentration of ethylenediamine.

In a more detailed description of a typical preparation of this invention, suitable quantities of ethylenediamine and boric acid (H.sub.3 BO.sub.3) are dissolved in distilled or deionized water followed by addition of the aromatic compound or aliphatic alcohol. The resulting slurry is transferred to a closed crystallization vessel and reacted usually at a pressure at least the vapor pressure of water for a time sufficient to permit crystallization which usually is about 0.5 to about 100 days, typically is about 2 to about 20 days, and preferably is about 3 to about 14 days, at a temperature maintained below the decomposition temperature ranging from about 100.degree. to about 200.degree. C., preferably about 120.degree. to about 180.degree. C. The crystallizing material can be stirred or agitated as in a rocker bomb. Preferably, the crystallization temperature is maintained below the decomposition temperature of the alcohol or aromatic compound used in the preparation. Especially preferred conditions are crystallizing at about 165.degree. C. for about 2 to about 14 days. Samples of material can be removed during crystallization to check the degree of crystallization and determine the optimum crystallization time.

The crystalline material formed can be separated and recovered by well-known means such as filtration with washing. This material can be mildly dried for anywhere from a few hours to a few days at varying temperatures, typically about 25.degree. to 200.degree. C., to form a dry cake which can then be crushed to a powder or to small particles and extruded, pelletized, or made into forms suitable for its intended use. Typically, materials prepared after mild drying contain amounts of the alcohol or aromatic compound and water of hydration within the solid mass. A subsequent activation or calcination procedure is necessary, if it is desired to remove these material from the final product. Typically, mildly dried product is calcined at temperatures ranging from about 260.degree. to about 850.degree. C. and preferably from about 525.degree. to about 600.degree. C. Extreme calcination temperatures or prolonged crystallization times can prove detrimental to the crystal structure or may totally destroy it. Generally, there is no need to raise the calcination temperature beyond about 600.degree. C. in order to remove organic material from the originally formed crystalline material. Typically, the molecular sieve material is dried in a forced draft oven at about 145.degree.-250.degree. C. for about 16 hours, then calcined in air in a manner such that the temperature rise does not exceed 125.degree. C. per hour until a temperature of about 540.degree. C. is reached. Calcination at this temperature usually is continued for about 4 to 16 hours.

A catalytically active material can be placed onto the boronaaronate structure by ion exchange, impregnation, a combination thereof, or other suitable contact means. The cation, M, in the crystalline boronaaronate is usually hydrogen ion, but can be other cations including metal ions and their amine complexes, alkylammonium ions, ammonium ions, and mixtures thereof by replacing the hydrogen ion, by ion exchange, with these cations. The cation has a valence, n, which can be 1 to 8 preferably 1 to 6 and most preferably 1 2 or 3. Preferred replacing cations are those which render the crystalline boronaaronate catalytically active, especially for hydrocarbon conversion. Typical catalytically active ions include metal ions of Groups IB, IIA, IIB, IIIA, and VIII, and of manganese, vanadium, chromium, uranium, and rare earth elements. Water soluble salts of catalytically active materials can be impregnated onto the crystalline boronaaronate of this invention. Such catalytically active materials include hydrogen, metals of Groups IB, IIA, IIIA, IVB, VIB, VIIB, and VIII, and rare earth elements.

Ion exchange and impregnation techniques are well known in the art. Typically, an aqueous solution of a cationic species is exchanged one or more times at about 25.degree. to about 100.degree. C. Impregnation of a catalytically active compound on the boronaaronate or on a composition comprising the crystalline boronaaronate suspended in and distributed throughout a matrix of a support material, such as a porous refractory inorganic oxide such as alumina, often results in a suitable catalytic composition. A combination of ion exchange and impregnation can be used. The presence of sodium ion in a composition usually is detrimental to catalytic activity. Catalyst compositions useful in xylene isomerization can be based on hydrogen form sieves or on that prepared by ion exchange with species such as nickelous nitrate or by impregnation with species such as ammonium molybdate.

The amount of additional catalytically active material placed on the boronaaronate can vary from less than 1 wt. % to about 30 wt. %, typically from about 0.05 to about 25 wt. %, depending on the intended use. The optimum amount can be determined by routine experimentation.

The crystalline boronaaronate useful in this invention can be incorporated as a pure material in a catalyst or adsorbent, or may be admixed with or incorporated within various binders or matrix materials depending upon the intended process use. The crystalline boronaaronate can be combined with active or inactive materials, synthetic or naturally-occurring zeolites, as well as inorganic or organic materials which would be useful for binding the boronaaronate. Well-known materials include silica, silica-alumina, alumina, alumina sols, hydrated aluminas, clays such as bentonite or kaoline, or other binders well known in the art. Typically, the boronaaronate is incorporated within a matrix material by blending with a sol of the matrix material and gelling the resulting mixture. Also, solid particles of the boronaaronate and matrix material can be physically admixed. Typically, such boronaaronate compositions can be pelletized or extruded into useful shapes. The crystalline boronaaronate content can vary from anywhere up to 100 wt. % of the total composition. Catalytic compositions can contain about 0.1 wt. % to about 100 wt. % crystalline boronaaronate and typically contain about 2 wt. % to about 65 wt. % of such material.

Catalytic compositions comprising the crystalline boronaaronate of this invention and a suitable matrix material can be formed by adding a finely-active metal compound to an aqueous sol or gel of the matrix material. The resulting mixture is thoroughly blended and gelled, typically by adding a material such as aqueous ammonia. The resulting gel can be dried and calcined to form a composition in which the crystalline boronaaronate and catalytically active metal compound are distributed throughout the matrix material.

The methods of catalyst formulation in a matrix which are described in U.S. Pat. Nos. 4268420 4269813 and European Published Application No. 68796 (all incorporated by reference herein) can be used to prepare catalytic formulations incorporating boronaaronate.

The boronaaronates prepared according to this invention are useful as catalysts for various hydrocarbon conversion processes and are suitable for chemical adsorption. As used herein, the term hydrocarbon conversion means any changing or altering of the carbon bonding or structure of an organic compound containing at least carbon and hydrogen atoms. Included in hydrocarbon conversion processes are isomerization, oligomerization, polymerization, dehydration, dehydrogenation, alkylation, dealkylation, aromatization, hydrocracking, dewaxing, and the like. Some of the hydrocarbon conversion processes for which the boronaaronate appears to have useful catalytic properties are fluidized catalytic cracking; hydrocracking; isomerization of normal paraffins and naphthenes; reforming of naphthas and gasoline-boiling-range feedstocks; isomerization of alkylaromatics, such as xylenes; disproportionation of aromatics, such as toluene, to form mixtures of other more valuable products including benzene, xylene, and other higher methyl-substituted benzenes, hydrotreating, alkylation, including (a) alkylation of benzenes with ethylene, ethanol, or another ethyl carbonation precursor to yield ethylbenzene, (b) alkylation of benzene or toluene with methanol or another methanol or carbonation precursor to yield xylene, especially p-xylene, or pseudocumene, (c) alkylation of benzene with propylene and (d) alkylation of C.sub.3 to C.sub.5 paraffins with C.sub.5 to C.sub.3 olefins, hydrodealkylation; hydrodesulfurization; and hydrodenitrogenation. They are particularly suitable for the isomerization of alkylaromatics, such as xylenes, and for the conversion of ethylbenzene. Boronaaronate catalysts can be used to convert alcohols, such as methanol, to hydrocarbon products, such as aromatics or olefins.

Operating conditions for hydrocarbon conversion broadly comprise a temperature of about 95.degree. to about 540.degree. C., a hydrogen-to-hydrocarbon mole ratio of about 0 to about 20 a weight hourly space velocity (WHSV) of about 0.01 weight unit of feed per hour per weight unit of catalyst (hr.sup.-1) to about 90 hr.sup.-1 and a pressure of about 0.1 atmosphere to about 100 atmospheres.

The boronaaronates prepared by this invention are especially suitable for hydrocarbon isomerization and disproportionation. They are especially useful for liquid- or vapor-phase isomerization of xylenes. In a preferred process, a boronaaronate-based catalyst converts a hydrocarbon stream containing C.sub.8 aromatics by isomerization of xylenes and concurrent conversion of ethylbenzene by hydrodealkylation and disproportionation mechanisms. Advantageously, the conditions for isomerization of xylenes and conversion of ethylbenzene comprise a temperature of about 250.degree. to about 480.degree. C., a hydrogen-to-hydrocarbon mole ratio of about 1 to about 12 a WHSV of about 1 hr.sup.-1 to about 20 hr.sup.-1 and a pressure of about 10 psig to about 500 psig. The preferred conditions for the isomerization of xylenes comprise a temperature of about 315.degree. to about 455.degree. C., a hydrogen-to-hydrocarbon mole ratio of about 2 to about 8 a WHSV of about 1 hr.sup.-` to about 10 hr.sup.-1 and a pressure of about 100 psig to about 300 psig. The choice of catalytically active metals to be placed on the crystalline boronaaronate can be selected from any of those well known in the art. When used as a catalyst in isomerization processes with suitable catalytically-active materials placed on boronaaronate, good selectivities for production of desired isomers are obtained.

When boronaaronate is used as a hydrocracking catalyst, hydrocracking charge stocks can pass over the catalyst at temperatures anywhere from about 260.degree. to about 455.degree. C. or higher using known mole ratios of hydrocarbon to hydrogen and varying pressures anywhere from a few up to many thousands of pounds per square inch or higher. The weight hourly space velocity and other process parameters can be varied consistent with the well-known teachings of the art.

Boronaaronate is also suitable as a reforming catalyst to be used with the appropriate hydrogenation components at well-known reforming conditions including temperatures ranging from about 260.degree. to 565.degree. C. or more, pressures anywhere from a few up to 300 psig to 1000 psig, and weight hourly space velocities and hydrogen-to-hydrocarbon mole ratios consistent with those well known in the art.

The boronaaronates of this invention can also be used as adsorbents to selectively absorb specific isomers or hydrocarbons, in general, from a liquid or vapor stream. For example, selective absorption of branched chain hydrocarbons from cyclic hydrocarbons is possible.