MXPA00012790A - Molecular sieve adsorbent for gas purification and preparation thereof - Google Patents

Abstract

A molecular sieve adsorbent for the purification of gas streams containing water vapor and carbon dioxide. The adsorbent is a combination of sodium form of a low-silica faujasite, having a residual content of potassium ions less than about 8.0 percent (equiv.), a low content of crystalline and amorphous admixtures and crystal sizes generally within the range of 1-4&mgr;m, and a binder. A process for the adsorbent preparation which comprises specific parameters of low silica faujasite synthesis, sodium-potassium ion exchange, blending and granulation.

Description

MOLECULAR SIEVE ADSORBENT FOR PURIFICATION OF GAS AND PREPARATION OF THE SAME Technical Field 5 The present invention relates to a novel adsorbent for removing water and carbon dioxide from gases, and more particularly, an adsorbent for the purification of air, nitrogen, hydrogen and natural gas streams. The invention is also a method of preparing the adsorbent.

Art Background Carbon dioxide is an undesired impurity in many commercial gas applications because of its ability to freeze and form hydrates with moisture at low temperatures. The formation of solids or solid particles? they do the processing, operation, transportation of the gas quite difficult or even impossible. For example, cryogenic units stop air separation to produce oxygen and nitrogen demand virtually complete removal of dioxide? carbon dioxide (1 ppm or less) and steam (126002) * s-3g _-- a sa. '~ ... t, j __, ____. _.; t.i., _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ of water in the air before separation. Refineries establish similar requirements on the amount of carbon dioxide and moisture present in gas flows contaminated by hydrogen. Similar requirements are set in ammonia plants for nitrogen purity, and gas processing plants on the content of carbon dioxide and natural gas dew point before the recovery of ethane and helium and / or before the liquefaction of the natural gas. Also, petrochemical plants have to eliminate carbon dioxide and water in monomers: ethylene, propylene, butadiene, etc. To prevent the poisoning of the polymerization catalysts and the deterioration of the properties of the polymer.

The adsorption of carbon dioxide and water vapor is the most common method of removal of these compounds from gas streams, due to their high performance and relatively low capital and operating costs. Two adsorption techniques are commonly used in commercial gas manufacturing: temperature swing adsorption (TSA) and pressure swing adsorption (PSA). The efficiency of both adsorption techniques is determined by the properties of the adsorbent. The high adsorption of carbon dioxide is the most important property of the adsorbent, especially at very low partial pressures.

Various types of C02 adsorbents have been created to meet the needs of the industry. Because general working adsorbents, such as alumina, silica gel and activated carbon, do not have a substantial adsorption capacity for carbon dioxide, more complex adsorbents have been prepared.

The U.S. Patent No. 3,865,924, Gidaspow, describes an adsorbent for carbon dioxide, which constitutes a mechanical mixture of activated alumina and alkali metal carbonates. The U.S. Patent No. 4,433,981, Slaugh, describes an adsorbent prepared by the impregnation of alumina with an alkaline earth or alkaline metal oxide or salt that can be decomposed by calcination. The U.S. Patent No. 4,493,715, Hogan, describes an adsorbent for the removal of carbon dioxide from olefins comprising oxides of alkali metals, hydroxides, nitrates, acetates, etc. placed on an activated alumina.

All adsorbents employ chemisorption reversible chemical reactions to bind carbon dioxide to metal carbonates or bicarbonates. The main disadvantage of these adsorbents is the low operational reliability and the short life time 5 due to the tendency to agglutinate the active components. Secondly, the time before water penetration in most adsorbents is shorter than the time before the penetration of carbon dioxide. This results in the need to use additional beds of desiccants.

It is also impossible to use adsorbents that contain base in PSA-type units, because these form compounds with C02 that do not regenerate under reduced pressure.

A newer process for gas dehydration and technology in the recovery of carbon dioxide using molecular sieves, synthetic zeolites and natural It is known that synthetic zeolite types A and X are effective adsorbents of C02 and water. For example, U.S. Pat. Nos. 3,981,698, Leppard, 4,039,620, Netteland, 4,711,645, Kumar, 4,986,835, One, 5,156,657, Ravi, suggest the use of molecular sieves standard 5A, 1 OA and 13X as dioxide adsorbents ^ "aja, * -B» -i carbon These molecular sieves adsorb the C0, through physical adsorption and can be regenerated at ambient temperatures, however, they do not have sufficient adsorption capacity for carbon dioxide. In this way, such adsorbents can not provide extensive gas purification, demand an increase in the volume of charge and often require the use of supplementary beds or adsorbents to decrease the concentration of carbon dioxide and water before the introduction into the bed of zeolite. .

To increase the adsorption capacity of carbon dioxide, various adsorbents have been proposed based on various forms of cation exchange of type X molecular sieve and other crystalline structures. Thus, U.S. Pat. No. 3,885,927, Sherman, describes a cationic form of zeolite type X barium in which 90-95 of the Na + ions are replaced by Ba + ions. The U.S. Patent No. 4,477,267, Reiss, uses an adsorbent for the purification of hydrogen containing CaX-zeolite. For the removal of carbon dioxide, U.S. Pat. No. 4,775,396, Rastelli, describes the use of zinc, rare alkaline metals, a proton and ammonium cation of exchanged forms of synthetic faujasite having a silica: alumina ratio in a broad range of 2-100. The U.S. Patent 5,587,003, Bulow, describes the use of a synthetic or natural clinoptilolite, which contains as cation that can exchange the ions of the 5 metals of groups 1A, 2A, 3A, 3B, the lanthanide group and mixtures of these.

All these molecular sieve adsorbents are characterized by the capacity of dioxide adsorption carbon that extends at high and moderate partial pressures of the mixture to be adsorbed. However, its ability to adsorb at low partial pressure of CO; (< 5 torr) and at ambient temperatures is not sufficient to provide the purity of the gas that is requires. In addition, due to the short relative time before the penetration of C02, the water capacity of these adsorbents seems to be only 10-15 percent of the potential. This decreases the performance of the adsorbent in such applications as the units of pre-puri fi cation of air by PSA and TSA where adsorption of carbon dioxide inlet is very low. Using the adsorbents mentioned above in such applications requires cooling the gas to a temperature below about 5 ° C. to its times, this results in a substantial increase in the - > , j-htüfc-teto- »< j < -8 ~. : _ «< -, -. . - • * *.-.- "< _ • _.. 1__i ¿i- ^ capital and operating costs The U.S. patent No. 5,531,808, Eye, describes an adsorbent for the adsorption of carbon dioxide comprising a type X zeolite having a ratio of aluminum to aluminum in the range of 1.0-1.15. The X-type zeclite adsorbent type contains ions from Group A, Group 2A, Group 3A, Group 3B, the lanthanide series, and ezcl of these. It does not teach any critical quantitative relationship between the various cations in the crystal structure of type X zeolite that is necessary to provide high levels of carbon dioxide adsorption capacity at low partial pressures and at ambient temperatures. It also does not describe preferred limits for crystal sizes and crystal purity. It also does not describe the limits of adsorbent macroporosity necessary to provide the appropriate kinetics and dynamics of carbon dioxide adsorption.

A process -) to prepare faujasite with low silica content (LSF) with a ratio of silica / alumina -2.0 is described in Khul 'Crystallization of Lo - Silica Faujasite "Zeolites, vol 7 p 451 (J 987). describes that both sodium and potassium cations must be present to obtain faujasite crystals with relatively low silica content.The described crystallization processes comprise the preparation of an aqueous solution of sodium aluminate with the addition of potassium hydroxides and sodium, the agitation of the solution with sodium silicate, the aging of the gelled mixture, and the filtration and washing of the chiral product: Khul also describes specific reagent ratios, temperatures and retention times, which are required for the crystallization of the product, however, it does not specify the range of crystallization parameters that provide the defined size of the faujasite crystals and a final product with a low content of crystals of the mixture of different types. Khul also does not describe sodium-potassium ion exchange procedures to obtain LSF with low residual potassium ion content.

Several patents disclose molecular sieve adsorbents having improved adsorption capacities, specifically for the removal of carbon dioxide from gas mixtures. For example, U.S. Pat. No. 2,882,224, Milton, describes a variety of crystalline aluminosilicates useful for adsorption to C02. The U.S. patent No. 3,078,639, Milton, describes a type X zeolite useful for the adsorption of carbon dioxide from a gas stream. British Patents Nos. 1,508,928, Mobil Oil- and 1,051,621 ,. Furting et al. Describe faujasite-type zeolites having an alumina ratio of 1.8 to 2.2.

While these products have been useful in the adsorption of carbon dioxide and water from gas streams, it is important to provide improved adsorbents. In addition, even though it has been discovered that faujasites with low silica content are useful in the adsorption of carbon dioxide and water from gas streams, the new low-silica content fajausites with improved adsorption capacities do not exhibit the limitations of the old products would be beneficial.

Accordingly, an aspect of the invention is important to provide an adsorbent for carbon dioxide and water vapor with enhanced adsorption capacity.

It is a further aspect of the invention to provide an adsorbent for carbon dioxide useful for adsorption at ambient temperatures and low partial pressures.

It is still a further aspect of the invention to provide an adsorbent for carbon dioxide in a gas stream, which reduces capital expenditure and operation when it is used.

It is still a further aspect of the invention to provide an adsorbent for carbon dioxide and water vapor with improved kinetics and adsorption dynamics for both the Temperature Oscillation Adsorption processes and the Pressure Swing Adsorption processes, and an aggregate of the two processes.

It is still a further aspect of the invention to describe an adsorbent for carbon dioxide, which produces a gas stream containing less than one part per million carbon dioxide.

It is still a further aspect of the invention to provide a process for the production of a faujasite adsorbent with low silica content for carbon dioxide.

These and further aspects of the invention will become apparent from the foregoing description of a preferred embodiment of the invention.

Brief Description of the Invention The present invention is an adsorbent for carbon dioxide, and preferably water vapor, of gas streams where the adsorbent exhibits high adsorption capacity at low partial pressures and ambient temperatures. The adsorbent comprises a sodium form of a faujasite with low silica content, wherein the ratio of silica to alumina is from about 1.8: 1 to about 2.2: 1, about 2.0: 1 to about 2.1: 1 is preferred, and wherein the content of the potassium ions present in the faujasite with low content of silica constitutes less than about 8.0 percent, preferably less than about 2.5 percent, more preferably less than about 1.0 percent of the interchangeable cations (equivalents). Preferably, the volume of the macropores is in the range of from about 1,000 to about 10,000 A the radii are greater than about 0.4 cm 3 / g, preferably from about 0.4 to about 0.6 cm 3 / g and more preferably from about 0.4 to about 0.5 cm 3 / g.

The present invention also highlights a process for the production of the adsorbent product comprising the preparation of a sodium form of a faujasite with low silica content, where the faujasite with low silica content has a silica: alumina ratio of about 1.8: 1 to about 2.2: 1 and a residual content of potassium ions of less than about 8.0 percent (equivalent); the resulting product is mixed with a binder; to form the mixed product in a moldable article; and drying and calcining the article to produce the adsorbent product.

Brief Description of the Drawings Figure 1 shows the carbon dioxide adsorption isotherms for faujasites with low silica content that have percentages that differ from the residual potassium cations.

FIG. 2 compares the adsorption of carbon dioxide from various adsorbents including the present invention (Example 4) and other adsorbents, including a 5A molecular sieve (CaA-94.5 percent by weight). Ca +), the molecular sieve 1 OA (CaX), the molecular sieve 13X (NaX) and the Example 16 showing a faujasite of calcium with bromine contained in silica, with a content of potassium ion of 0.16 D cent.

Description of the invention It is known to use faujasites with low silica content for the adsorption of carbon dioxide and water vapor from gas streams. It is also known that the replacement of sodium cations by other metal ions of larger size causes an increase in the adsorption capacity of standard faujasites with the content of silica. For example, it is known that the calcic forms of a faujasite of zeolite type X q: 3 have a sice / alumina ratio larger than 2.3 1 is characterized by adsorption capacities plus gi ^. it is for carbon dioxide that the sodium forms of these same faujasites.

Conventionally, faujasite crystals with low silica content are produced having a sodium: potassium ratio of about 2 to 3: 8 to 7. It has surprisingly been found that by substituting sodium for all potassium ions in a substantial form, the capacity of Carbon dioxide adsorption of the fajausite with low silica content increases significantly by means of faujasite with low conferred in conventional silica with conventional ratios of sodium ions to potassium ions. It has also been surprisingly discovered that the few potassium ions that are present in the crystal structure of faujasite with low silica content and, respectively, the more sodium ions that are present, improve the adsorption capacity for carbon dioxide of the adsorbent that is produced.

Previously, Kuhl discovered that the crystallization of faujasite with low silica content is typically accompanied by the formation of faujasites with high silica content, zeolite type A, zeolite type P, sodalite and other crystalline and amorphous mixtures. It was also discovered that to create improved adsorption capacity by the adsorbent, the impurities that occur conventionally in faujasite with low silica content should be reduced as much as possible. Thus, it is preferable that the faujasite with low silica content used as an adsorbent contain at least about 90 percent, by weight, of the faujasites with low silica content, preferably less than about 95 percent, by weight, and more preferably of at least about 98 percent, by weight.

In addition, it has also been discovered that in order to increase the adsorption capacity of faujasites with low silica content, with high sodium content, at least about 80 percent, by weight, of the faujasite crystals with low silica content. they should have a crystal size within a range of about 1 to 4 μm, preferably 1 to 3 μm and more preferably 1 to 2 μm.

It has also been found that the volume of macropores of a size with radii of from about 1,000 to 10,000 angstroms should be larger than about 0.4 crnVg, preferably from about 0.4 to about 0.6 cm3 / g and more preferably from about 0.4 to approximately O .5 cm3 / g If these criteria are met for faujasites with low silica content, with high sodium content, the adsorption capacity of the adsorbent is improved under dynamic conditions. Without using these preferred embodiments for faujasites with low silica content, high sodium content, the adsorption of carbon dioxide in a flow on an adsorbent molecular sieve is limited by mass transfer within the granules of the adsorbent. In this way, a large macropore volume is required to provide rapid diffusion of the carbon dioxide molecules from the outer surface of the adsorbent granules to the outer surface of the crystals. Whereas, the small size of the zeolite crystals decreases the resistance to surface diffusion within microcrystals.

In addition, the improvement in adsorption capacity of the carbon dioxide of the adsorbent of the present invention also increases the water adsorption capacity of the adsorbent above 40-50 percent by means of conventional carbon dioxide adsorbents.

In general, faujasites with ba or silica content, with high sodium content, are prepared by preparing an aqueous solution of sodium aluminate, sodium silicate, and sodium and potassium hydroxide from those ratios that are expressed as mixtures of oxides within The following ranges: S i 02: A1203 1.9-2.2 (Na20 + K20): S i 02 3.0-3.4 H20: (Na20 + K20) 15.5-17.5 Na20: (Na20 + K20) 0.72-0.78 The reaction mixture should be maintained at a temperature of about 85 ° to 95 ° C by means of the 2-10 hour reaction process. Additionally, to provide the reduced distribution of faujasite microcpstals with low silica content so that their sizes are within the range of about 1 to 4 μm, preferably 1 to 3 μm and more preferably 1 to 2 μm, submicrometic powders fine of montmori 1 loni ta, such as Rym®Kill 10 MB, with particle size of 0.4-0.8 μm in an amount of 0.6-1.5 percent, by weight should be introduced under intensive agitation in the reaction mixture after approximately 15 to 30 minutes. The composition is subsequently stirred for at least about 2 hours and maintained at a temperature of about 85 ° to 95 ° during stirring. The crystals produced are filtered out of the reaction solution. The crystals obtained from this reaction are subsequently washed with deionized water to maintain the pH of the crystals in a range of about 10.5 to about 11.

Once the crystals are obtained, the potassium ion content of the faujasites with low silica content should be reduced to levels of less than about 8 percent, preferably less than 2.5 percent, more preferably about 1.0 percent.

There are several methodologies that can be used to produce this type of faujasite with low silica content, with high sodium content. For example, a powder exchange can be carried out on a band filter with one to three steps of feeding sodium chloride solution. The concentration of j ~ fc¿3: »Sodium chloride solution should be increased at each stage so that the equivalent ratio of sodium in the potassium solution in the zeolite reaches 1.5 during the first stage, 2.2 during the second stage, and 3.0 during the third stage.

In an alternative method, faujasite beads with low silica content, calcined sodium / potassium may be intercalated in an ionic form in a column with a sodium chloride solution (10-15 per cent by weight) or preferably with sodium chloride plus a solution of sodium hydroxide (7-10 percent NaCl + 3-5 percent NaOH), by weight, at a temperature of approximately 60 ° to 85 ° C. In any process, the product exchanged by ionic action is washed with de-ionized water to remove excess sodium ion. Both processes produce adsorbents with a potassium content of less than about 8.0 percent, preferably less than about 2.5 percent, and more preferably, less than about ".0 percent (equivalent).

The powder of r: faujasite wave with low silica content, with the resulting sodium content, is then mixed with a binder to produce a final adsorbent product. The binder can be chosen from mineral or synthetic materials, such as clays ~ (kaolinite, bentonite, montmorillonite, attapulgite or other clay materials), silica, alumina, alumina hydrate (pseudoboehmite), alumina trihydrate, aluminosilicates, cements or other materials. The binder comprises about 15-40 weight percent of the final adsorbent. The mixture is then kneaded with 18-35 percent, by weight, of water to form a paste which is subsequently added to form moldable articles in conventional ways.

In a preferred embodiment certain peptizers and / or pore forming ingredients are added with the molecular sieve product and / or with the binder in an amount of about 0.5 to about 2.0 percent of the final adsorbent product by weight to produce the volume of macropore. extended that is required. Such additives typically include mineral acids, surfactants and plasticizers such as, for example, polycarboxylic acids, polyacrylamides, polycarboxylates, natural organic products such as starches, molasses, lignin or other such related material. Following this addition, the product The mold is cured, dried and calcined at a temperature of about 550 ° C to about 650 ° C. Using faujasite particles with low silica content, high sodium content produced by the process described above create a product that is particularly useful for the adsorption of carbon dioxide and water vapor from gas streams. The preferred types of currents gas in which this type of faujasite crystals with low silica content can be used, with high sodium content include air, nitrogen, hydrogen, natural gas, individual hydrocarbons and monomers, such as ethylene, propylene, 1.3 butadiene, isopropane and other gas systems.

It has been surprisingly discovered that faujasite with low silica content, with high sodium content with a lower potassium content that approximately 2.5 percent (equivalent), when a conventional pre-purification process is used, reduces the level of carbon dioxide in the gas stream in a general manner to a range of 0.3 ppm to approximately 0.5. ppm, which is significantly lower over the same length of the adsorbent bed than that of the faujasites with low silica content, with a sodium content of approximately 62 percent to approximately 90 percent (equivalent). These conventional fajausitas with low silica content reduce the CO content; only up to approximately 2 ppm. Simultaneously the dynamic adsorption capacity of the faujasite with low silica content, with high sodium content for water also increases from about 1.5 percent to about 3.5 percent (by weight). Therefore, it has surprisingly been found that faujasites with low silica content with a potassium content of less than about 3.0 percent (equivalent), preferably less than 2.5 percent (equivalent), and more preferably, less than about 1.0 percent. hundred (equivalent) are highly efficient in the adsorption of both carbon dioxide and water vapor in conventional gas stream operations.

In order to illustrate the present invention and the advantages thereof, the following examples are provided, it is understood that these examples are illustrative and do not provide any limitation on the invention.

EXAMPLE 1 16. 8 1 of sodium hydroxide and 8.9 1 of potassium hydroxide with a molar ratio of Na20: (Na20 + K20) to equal 0.75 are added to 20 liters of a sodium aluminate solution so that the ratio of (Na. O + K20): A1203 equals 1.62. this solution is mixed with 16.5 1 of sodium silicate solution in such a quantitative ratio to provide a silica / alumina ratio of 2.0, where the sum of the moles of water to the alkali metal oxides equals 16.4. The obtained geleficada mixture is aged for one hour and crystallized at 92 ° C for 4 hours. After 18 minutes of heat treatment, a fine powder of montmorion (Rym®Kill 1 OMG with particle size 0.4-0.8 μm) is added in an amount similar to 0.6 percent of the weight of the final product. The crystals produced are filtered and washed with deionized water to reduce the pH of the product produced to approximately 10.6.

The product was analyzed and found to contain faujasite crystals with low silica content of 98 percent purity (X-ray analysis). The crystal size of the product is determined by electron microscopy analysis to be 1-3 μm. The product had a potassium ion content of approximately 26 percent (equivalent). A paste is formed and dried at 110 ° C for 3 hours. 8 kg of this dry powder is mixed with 2.0 kg of Min-u-gel 400® attapulgite, moistened and formed into pearls of approximately 1.6 mm in diameter by means of the machinery of the plate granulator. The beads are subsequently dried at 110 ° C for 2 hours and calcined first at 250 ° C for 2 hours, then at 350 ° C for 2 hours and at 600 ° C for one hour.

EXAMPLE 2 (the invention) 4. 0 Kg of the faujasite sodium / potassium beads with low silica content obtained from Example 1 are treated at room temperature with 16 liters of a 1.5 N sodium chloride solution. The product is washed with 80 1 deionized water and then it is treated again with 8 liters of sodium chloride solution at 2.2 N. The product is subsequently washed with deionized water to remove the chloride ions to a negative extent with a silver nitrate solution at 0.028 N. Then the procedure is repeated of operation of Example 1 for drying and calcining the adsorbent. The elemental analysis of the resulting product is shown at 7.5 percent (equivalent) 5 of the residual content of potassium ion. The analysis is done by means of an Inductively Coupled Plasma Atomic Emission Spectroscopy.

EXAMPLE 3 (the invention 2.3 kg of the beads produced from example 2 is treated under ion exchange conditions with 8 liters of a sodium chloride solution at 3.0 N at room temperature. water as shown in Example 2. Subsequently the operation procedure of Example 1 is repeated for drying and calcining.The product that is produced from this ion exchange operation is analyzed for r: tasium, and is determined to have a content of potassium of 2.4 percent (equivalent).

CJEMPLO 4 (the invention) 1. 0 kg of pearls prepared in Example 3 are treated at a temperature of 80 ° C with 2 liters of water. ___ a _.-.-.-_-.-__ a-.; __ * - * _; .. _ ^. 'i .. * s. asa ^ s.- "sodium chloride solution at 3.0 N. The operating procedure of Example 2 is repeated to wash, dry and calcine the adsorbent. The residual content of the potassium ion in the adsorbent was 0.3 percent (equivalent).

EXAMPLE 5 (Adsorption Balance Test) The samples of Examples 1 to 4 are tested for the carbon dioxide adsorption equilibrium. Adsorption isotherms are measured using a volumetric adsorption unit Micromerit ica ASAP 2010 at a temperature of 25 ° C. the samples are activated in a preliminary form at 400 ° C for 2 hours. The partial pressure of carbon dioxide is varied in the range of 1-100 torr.

The results obtained are shown in Figure 1.

As apparent from Figure 1, the residual content of the potassium ion in the faujasite with low silica content has a dramatic impact on the capacity of each of the adsorbents that adsorb carbon dioxide. This Figure shows that potassium ions are present to a lesser degree, increasing the equilibrium adsorption capacity for carbon dioxide in its full range of partial pressures. This Figure also confirms that only adsorbents having a potassium content of less than about 8.0 percent (equivalent) provide satisfactory adsorption capacity at room temperature and low partial pressures (1-10 torr.). The adsorbents, according to the present invention (Examples 2 to 4), show a better adsorption capacity than the previous adsorbent according to U.S. Pat. No. 5,531,808 (Ex. Example 1) which includes comparable amounts of both alkaline a.cs a.cs ions: sodium and potassium.

EXAMPLE 6 (Comparative) The operating procedure of Example 1 for the synthesis of faujasite with low silica content is repeated with a modification. Potassium and sodium hydroxide solutions are used for Na20: (Na20 + K20) have a final ratio of 0.72. the product produced contains 86 percent of a faujasite with low silica content under X-ray diffraction. The chemical analysis and XRD of the product shows significant amounts (-12 percent) of faujasite with high content of silica and zeolite A. The powder obtained from this process is exchanged three times with a sodium chloride solution as described in Example 3. The percentage of potassium in the exchanged product is 2.2 percent (equivalent). The operation procedure of Example 1 is repeated to mix the product with attapulgite binder 10 to form beads.

EXAMPLE 7 Adsorption Equilibrium Test The samples of adsorbents of Example 3 and 6 were tested for adsorption of carbon dioxide at partial pressures of 2, 5, 8 and 15 torr. In the process, the test procedure of Example 5 is employed. The results are reported in Table 1. 20 __ »É == ^ a = _____; '-i _--. -. «J-iafat» - *, ... -. .. . » < ,. - ^ ".,, Tá ^ u- ^ A ^, TABLE 1% Purity Adsorption Value, cm / g Examples of LSF Partial Pressure, torr 2.0 8.0 15.0 30.0 3 98 3 2. 6 4 4. 8 51. 3 6 1. 4 6 8 6 2 6. 5 4 1. 8 5 0. 2 61. 6 As in Example 7, the adsorbent according to the present invention, which has faujasite with low content of high purity silica, 98 percent, demonstrates a higher adsorption capacity at low partial pressures (2-10 torr) of dioxide carbon than that LSF adsorbent with lower purity.

EXAMPLE 8 (Comparative) The procedure of operation is repeated for the faujasite synthesis with low silica content of Example 1 with one exception: the montmorillonite powder is not added to the geleficated crystallization mixture. The adsorbent, of this i¿: .er_. prepared, contains faujasite crystals with a low silica content of 4-6 μm in size. The beads are produced with 20 percent attapulgite which are exchanged in an ionic form with a NaCl solution using the same procedure as that shown in Example 3.

EXAMPLE 9 Dynamic Capacity Test The adsorbents of Example 3 and 8 are tested by dynamic adsorption in the air purification using an adsorber tube with an adsorbent bed volume of 100 cm3 / g at a temperature of 25 ° C. The air, which has a 6 percent relative humidity and contains 340 ppm of C02, is fed through the adsorption unit at a linear velocity of 0.1 m / s. Penetration concentrations are assumed: for water -0.1 ppm, for carbon dioxide - 1 ppm. All measurements are carried out above the first penetration component. In this way, the capacity of the water is determined taking into account the time before the penetration of carbon dioxide occurs.

The results for the dynamic capacity of carbon dioxide and water of the tested samples are reported in Table 2.

-Ja-ss. J *. . 1 * -i ^ ¡u,. "- i,. _] "& ,. ^ »» ~ TABLE 2 Example Size of Potassium glass content Dynamic Capacity, μm equivalent% -c- by weight Water Carbon Dioxide 1.3 2.4 3.30 0.66 4-6 2.2 2.84 0.54 As in Example 9, the adsorbent, according to the present invention, has crystal sizes. predominantly in the range of 1-3 μm, with other similar characteristics, demonstrating substantially higher dynamic capacity for both recovered impurities than the conventional glass size adsorbent of 4-6 μm.

EXAMPLE 10 (Comparative) 4 kg of fajausite powder with low silica content of Example 1 is exchanged with NaCl solutions at 2.2 N and 3 N as described in Examples 2 and 3. 0.8 kg of the product produced is added to the product. has residual K + ion content of 2.5 percent (equivalent) to C 2 kg of attapulgite, Minugel 400, in B-BiiSiiiía --- ^ _____ t ____ t_ ^ ____ ". .. "__. , "_._ ..,. _.j¡ .. •.) - ^ L.j l? T .__ feM¡ai - í a worm blaster, Strand F4, for 1 hour. The resulting homogeneous mixture is mixed with 280 ml of water, and the resulting paste is extruded through a spinneret (spinning organ) to produce .extruded with a diameter of 1.6 mm. The extrudates are cured at room temperature for 24 hours, dried at 110 ° C for 2 hours and calcined at 250 ° C, 350 ° C and 600 ° C for 1 hour at each temperature.

The products produced have a volume of macropore (1000 -10000 Á) equal to 0.34 cm3 / g., According to the evaluation of the mercury porosimeter.

EXAMPLE 11 (According to the Invention; The operating procedure of Example 10 is repeated, except that the mixture of faujasite-attapulgite with low silica content is mixed with 220 ml of a 5 percent aqueous solution of polyacrylamide 1500. The procedures for extrusion, drying by extrusion and calcination are repeated from Example 10.

The product produced had a macropore volume (1000 -10000 Á) of 0.43 cm3 / g.

EXAMPLE 12 and 13 (Comparative) The faujasite powder with low silica content, with high sodium content of Example 10 is extruded through a spinneret (spinner organ) (1.6 mm diameter) with 20 percent kaolin Sperse 100, by weight (Example 12) and 20 percent activated alumina binders, by weight (Example 13). The binders are preliminarily peptized with 1.5 percent pol i- (2-carboxy ti 1) -acr ila to 170 based on the binder content. The remaining extrusion, extrusion drying and calcination processes are the same as those shown in Example 10.

The adsorbents produced had a macropore volume (1000 -10000 A): E jmplo 12 0.39 cm: 7g; Example 13 0.36 c? 3 / g.

EXAMPLE 14 (According to the invention) The AP-22 activated alumina from Porocel, which has a surface area of 270 m2 / g and a median particle size of 6 μm, is used as a binder. 0.2 kg of the binder is treated with 1 percent ammonium polycarboxylate 40 and added to 0.8 kg of the faujasite powder with low silica content, with low sodium content of Example 10. The mixture is extruded, dried and calcined in the same way as in Example 10.

The product produced is characterized by a macropore volume of 0.47 cm3 / g.

EXAMPLE 15 Dynamic Capacity and Balance Test The adsorbents of Examples 10 to 14 were tested for dynamic adsorption and equilibrium capacity. The equilibrium adsorption value of carbon dioxide was measured at 25 ° C and partial pressure of C02 at 1.8 torr, using the instrumentation and method described in Example 5. The dynamic capacities of carbon dioxide and water are measured by means of the Test procedure of Example 9. r -? & ik? 4 »fe ^ 'The results are reported in Table 3 TABLE 3 Volume ADSORPTION CAPACITY Efficient Dynamic Balance Macroporous Carbon Dioxide Water Carbon Dioxide , cm '/ g mmol / g sen weight? in weight cmVg * by weight 0.34 1.33 5.9 2.48 2.47 0.49 11 0.43 1.29 5.7 3.42 3.42 0.68 12 0.39 1.34 5.9 3.09 3.07 0.61 13 0.36 1.32 5.8 3.16 2.66 0.53 14 0.47 1.34 5.9 3.48 3.65 0.72 Table 3 shows that without taking into account the type and chemical composition of the binder, the dynamic capacity of the adsorbent is controlled by its macro-porosity. At a larger macropore volume, the dynamic capacity for adsorption of carbon dioxide is greater. Due to the improvement in the adsorption capacity of carbon dioxide, the adsorbents are able to adsorb significant amounts of water vapor before the penetration of C02. This leads to an increase in the dynamic capacity of water above 40-50, of the potential.

As it is apparent, the efficiency of the adsorbents according to the present invention is 45 percent better than the performance of the prior art adsorbent, contrary to prior art, the adsorbents of the present invention can be used in TSA units. and PSA in an independent way, without an extra bed of desiccant.

EXAMPLE 16 (Comparative) This Example compares sodium LSF adsorbents exchanged for calcium with those of the invention. The carbon dioxide adsorption capacity of Group 2A form fajausite with low silica content 15 as claimed in U.S. Pat. No. 5,531,808, was compared with the adsorbents of the present invention. 0. 5 kg of faujasite sodium beads with low silica content of Example 4, which have 0.3 percent residual potassium ions, are exchanged with 5 1 of calcium chloride solution at 1 N at room temperature. The ICO analysis shows that the final product contains: Ca2 + -65 percent, Na * -35 25 percent and K + -0.16 percent. s? fS M? J », _ ^ í _________ i« * «,, _ ,, ___. , __, _._ _ & ". ,,,, _ ^ ..._ _ ___, _. .. _ KMt _ t. atast- * EXAMPLE 17 Test of the Adsorption Isotherm The adsorbent of Example 16 as well as other conventional adsorbents, standard molecular sieves 5A (US Patent No. 3,981,698), 10A (US Patent No. 4,986,835) and 13X (US Patent No. 5,156,657) were tested in an equilibrium of dioxide adsorption of carbon. The solvent according to the present invention of Example 4 was also tested. The adsorption isotherms were measured using the instrumentation and procedure of Example 5.

The results that were obtained are reported in Figure 2.

It is clear from Figure 2 that the adsorbent of the present invention exhibits better adsorption capacity of carbon dioxide to the adsorbents of the prior art. This correction is shown by the full range - > the partial pressures of carbon dioxide that includes very low pressures. The results also show that the substitution of sodium cations < -r, the structure of faujasite with low silica content by larger calcium cations leads to an appreciable loss of adsorption capacity.

EXAMPLE 18 Dynamic Capacity Test The adsorbents of Examples 14 and 16 in conjunction with the adsorbents of the prior art: Molecular sieves 5A, 10A and 13X are tested in the air purification for the adsorption of water and carbon dioxide. The technique and method of Example 9 are used. The results are reported in Table 4.

TABLE 4 Example Molecular Sieve DYNAMIC CAPACITY Water Carbon Dioxide? L NaLSF (0.3-K ~) 3.48 0.72 16 CaNaLSF (65 Ca ') 1.52 0.39 5A (94.8 - Ca *) 2.40 0.46 10A (CaX) 1.64 0.41 13X (NaX) 1.43 0.37 The adsorbents, according to the present invention, in comparison to the previous adsorbents, - »-.-» * #,; they exhibit superior performance in the dynamic processes of air purification. Its capacities for the adsorption of carbon dioxide and water of 1.7-2.0 times exceed the adsorption characteristics of conventional 5 adsorbents. As in Example 15, the results of Table 4 confirm that the adsorbent, according to the invention, provides extensive and reliable gas purification without the use of an additional layer of desiccant. This provides an opportunity for a substantial decrease in capital investments and operating costs, which is used by the present adsorber in commercial gas purification units TSA and PSA.

Accordingly, the invention provides a simple, reliable and highly effective adsorbent for carbon dioxide and water vapor that can be used in PSA and TSA gas purification plants to increase commercial performance. The adsorbent can be used in existing or new plants. Therefore, the combination of faujasite with low silica content, with high sodium content and with a low content of residual potassium ions has a number of advantages: 1) provides a high level of vapor adsorption jagMJB-M-MÉi -h-h-h-- ___________________,. "_-. _____ ^ _. ".-... _fe-. The water and carbon dioxide for gas purification; (2) allows effective adsorption of carbon dioxide at ambient temperatures and low partial pressures of carbon dioxide, which reduces capital and operating costs in air pre-purification and inorganic gas manufacturing; (3) provides satisfactory dynamics for both Adsorption by Temperature Oscillation and Adsorption by Pressure Oscillation processes; (4) allows the gas purification units to have only one bed without the supplemental use of desiccants, such as silica gel, activated alumina, molecular sieves 3A, 4A, etc. (5) provides safe output and operating current technology for the manufacture and preparation of adsorbent.

The adsorbent can be formed as spheres, beads, cylinders, extrusions, pellets, granules, rings, multilayers, grids or in monolithic form. _. ___ ^ áá ___ ^? t ^ t__t _____ St _ ?? ___? Although the invention has been described in terms of several preferred embodiments, these should not be construed as limitations on the scope of the invention. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, the content of the following claims is claimed as property: fifteen twenty _RIMk_MÍ_K_teÉIÍ

Claims (25)

1. Claims An adsorbent molecular sieve for gas purification, characterized in that it comprises a 5 sodium form faujasite with low silica content, which has a ratio of yes 1 ice: alumina of about 1.8-2.2 with a residual content of potassium ions less than about 8.0 percent (equivalent), and a binder, where the faujasite 10 with low silica content has crystal sizes, wherein the crystal size of at least about 80 percent of the faujasite is in the range of about 1-4 μm and where the adsorbent has a volume of macropores with a radius 15 from about 1000 to 10000 A of at least about 0.4 cm3 / g.
2. 2. The adsorbent molecular sieve of claim 1, characterized in that the silica to alumina ratio is from about 2.0 to about 2.23.
3. The adsorbent molecular sieve of claim 1, characterized in that the ratio of 25 silica to alumina is approximately 2.0 aüi-approximately 2.1
4. 4. The adsorbent molecular sieve of claim 1, characterized in that the residual content of potassium ions is less than about 2.5 percent (equivalent).
5. 5. The adsorbent molecular sieve of claim 1, characterized in that the residual content of potassium ions is less than about 1.0 percent (equivalent).
6. 6. The adsorbent molecular sieve of claim 1, characterized in that the faujasite with low silica content comprises from about 60 to about 85 percent, and the binder comprises from about 15 to about 40 percent of the adsorbent.
7. 7. The adsorbent of claim 1, characterized small faujasite with low silica content comprises 10.0 weight percent zeolite type A, "aujasite type X with high content of silica and other amorphous and crystalline mixtures. * _-t - - • • - < > 8. The adsorbent of claim 1, characterized in that the faujasite with low silica content comprises less than 2.0 percent by weight of zeolite type A, faujasite type X with high content of
8. 5. silica and other amorphous and crystalline mixtures.
9. 9. The adsorbent of claim 1, characterized in that the faujasite with low silica content has crystal sizes, wherein the size of the The crystal of at least about 80 percent of the faujasite is in the range of about 1-3 μm.
10. 10. The adsorbent of claim 1, characterized in that the faujasite with low silica content has crystal sizes, wherein the crystal size of at least about 80 percent of the faujasite is in the range of about 1-2 μm.
11. 11. The adsorbent of claim 1, characterized in that the binder is selected from the group consisting of caolonite, bentonite, montmorillonite, and attapulgite clays, silica, 25 alumina, alumosilicates, and cements.
12. 12. The adsorbent of Claim 1, characterized in that the adsorbent has a volume of macropore with a radius of from about 1000 to 10000 A of at least about 0.4 cm3 / g to about 0.5 cm3 / g.
13. 13. A process for the production of an adsorbent molecular sieve, characterized in that it comprises the preparation of a sodium form of a faujasite with low silica content, where the faujasite with low silica content has a silica-alumina ratio of about 1.8 to about 2.2 and a residual content of potassium ions of less than about 8.0 by percent (equivalent), and where the faujasite with low silica content has crystal sizes, where the crystal size of at least about 80 percent of the faujasite is in the range of approximately 1-4 μm, and in wherein the adsorbent has a volume of macropores with a radius of about 1000 to 10000 A of at least about 0.4 cm3 / g. mixing the resulting product with a binder; the formation of the mixed product towards a moldable article; and the ~ "drying and calcination of the article to produce the adsorbent product.
14. 14. The process of claim 13, characterized in that faujasite is prepared by mixing sodium aluminate, sodium silicate and sodium hydroxide, wherein the ratio of the components expressed as oxide mixtures are within the following ranges: Si02: A120. 1.9-2.2; Na2o +? 2o: Si02 3.0-3.4 H20 (Na20 + K20! 15.5-17.5 Na20; Na2o +? 2o; 0.72-0.78
15. 15. The process of claim 13, characterized in that it further comprises mixing a montmor powder 1 length in the amount of from about 0.6 to about 1.5 percent, based on the final weight of the reaction product, with faujasite having a low content of silica that was prepared. -tl -___ U_i? ? _í__HÍiÉ_ «É_
16. 16. The process of claim 13, characterized in that it additionally comprises the ion exchange of the faujasite sodium factor with low silica content which was prepared with a sodium chloride solution.
17. 17. The process of claim 13, characterized in that it additionally comprises the ion exchange of the faujasite sodium form with low silica content which was prepared with a solution comprising sodium chloride and sodium hydroxide.
18. 18. The process of claim 15, characterized in that the sodium form of the faujasite with low silica content is by ion exchange from about 1 to about 3 times.
19. 19. The process of claim 16, characterized in that, the sodium form of faujasite with low silica content is by ion exchange at a temperature from about 60 ° C to about 85 ° C.
20. 20 The process of claim 13, ______________ t ______ ^ ___ __i ___ ^ __. . . »? . ...,. ... . . .. .. , .. ¿.., .. . ? . . . ^ ?. . t. fefc. ^ "characterized in that it further comprises mixing the sodium form of the faujasite with low silica content that was prepared and the binder with a peptizer.
21. 21. The process of claim 20, characterized in that it additionally comprises the treatment of the sodium form of faujasite with low silica content that was prepared and the binder with a pore-forming additive.
22. 22. The rei-indication process 21, characterized in that the pore-forming additive is selected from the group consisting of natural and synthetic materials, including mineral acids, polyalkylene glycols, polyacrylamides, polycarboxylates, starch, molasses and lignin.
23. 23. The process of claim 21, characterized in that the peptizer and pore forming additives comprise from about 0.5 to about 2.0 percent of the adsorbent product, based on the total weight of the adsorbent product.
24. 24 The process of claim 13 It is also characterized in that it further comprises mixing faujasite with low silica content with a peptizer.
25. 25. The rei-indication process 13, characterized in that it comprises analogously mixing the binder with a peptizer.