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EP-4735386-A1 - APPARATUS AND CONTINUOUS PROCESS FOR SYNTHESIS OF LSX ZEOLITE USING CATION EXCHANGE

EP4735386A1EP 4735386 A1EP4735386 A1EP 4735386A1EP-4735386-A1

Abstract

The present invention relates to a continuous process for the synthesis of Low Silica X (LSX) zeolite using cation exchange method. Further, the present invention relates to an apparatus (100) for production of LSX zeolites by cation exchange method. Specifically, the present invention relates to an improved continuous process for production of Li- LSX zeolites based on cation exchange method by using a continuous process reactor system. Further, the present invention provides a process with shorter time period, easily recoverable and reusable salt-solution and good adsorption capacity of the synthesized Li- LSX zeolites.

Inventors

  • MALI, Nilesh Atmaram
  • NANDANWAR, Sachin Uttamrao
  • RAVINDRANATHAN, Sapna
  • NIPHADKAR, PRASHANT SURESH
  • BOKADE, VIJAY VASANT
  • LELE, ASHISH KISHORE

Assignees

  • Council of Scientific and Industrial Research

Dates

Publication Date
20260506
Application Date
20240628

Claims (10)

  1. 1. A continuous process reactor (100) system for the production of cation-LSX zeolites, comprising: a) leaching vessel (112) connected with organic solvent tank (104) and crude/impure salt solution supply (126), to leach out salt from the crude/impure salt, obtaining a salt solution mixture in the vessel (112); b) liquid-liquid extraction (LLE) column (105) connected to said leaching vessel (112) via filter(s) (107), in order to perform liquid-liquid-extraction of the salt solution mixture to separate and obtain pure aqueous salt solution and organic solvent; c) aqueous salt solution tank (108) connected to said liquid-liquid extraction (LLE) column (105), to store said pure aqueous salt solution; d) plurality of cation exchange column(s) [(101) and (102)] connected to said aqueous salt solution tank (108), for cation exchange of LSX zeolites in presence of said aqueous salt solution; e) water tank (103) connected to the plurality of cation exchange column(s) [(101) and (102)] to supply water for washing of the cation exchanged LSX zeolites in said plurality of cation exchange column(s) [(101) and (102)]; f) spent wash water tanks [(109) and (110)] connected to the cation exchange columns [(101) and (102)], in order to store spent wash water received from the cation exchange columns [(101) and (102)] after washing; g) calcinator (116) connected to said plurality of cation exchange column(s) [(101) and (102)], to obtain calcined cation LSX zeolites; h) multiple effect evaporator with Agitated Thin Film Dryer (122) connected to said plurality of cation exchange column(s) [(101) and (102)] via spent salt solution supply line (128), to obtain water condensate and dry spent salt; i) one part of water condensate from said multiple effect evaporator with Agitated Thin Film Dryer (ATFD) [(122)] is fed back to liquid-liquid extraction (LLE) column (105) via condensate supply line (124), and second part of water condensate is fed back to said water tank (103) via supply line (123); and j) the dry spent salt obtained from multiple effect evaporator with Agitated Thin Film Dryer (ATFD) (122) is supplied to the leaching vessel (112) via a supply line (127) for re-use in the production of cation-LSX zeolites.
  2. 2. The continuous process reactor (100) system as claimed in claim 1, wherein a) the plurality of cation exchange column(s) [(101) and (102)] are cylindrical columns; b) the water tank (103) is also connected to a solution preparation tank (111) in order to supply water for the preparation of alkali solution; and c) said organic solvent tank (104) is connected to the leaching vessel (112) in order to supply organic solvent for leaching out impure salts and remove impurities via said filter(s) (107).
  3. 3. The continuous process reactor (100) system as claimed in claim 1, wherein the reactor system further comprises: a) a solution preparation tank (111) comprising alkali solution, connected to said aqueous salt solution tank (108), in order to adjust pH of the aqueous salt solution in the range of 7.5 to 9.5 before supplying to the cation exchange columns [(101) and (102)]; b) vacuum pump (125) connected to said plurality of cation exchange column(s) [(101) and (102)] for drying the cation exchanged LSX zeolites in the plurality of cation exchange column(s) [(101) and (102)] itself; c) one or more heating elements or preheaters (106) is/are placed between aqueous salt solution tank (108) and the plurality of cation exchange column(s) [(101) and (102)] in order to supply pre-heated aqueous salt solution; d) spent wash water from the spent wash water tanks [(109) and (110)] is fed back into the cation exchange columns [(102) and (103)], and/or to the liquid liquid extraction column (105); e) hold vessel (113) is provided to hold filtered cation exchange salt solution containing organic solvent and pure salt after passing through said filter(s) (107); f) the hold vessels (114 and 115) is provided to hold spent cation exchanged salt solution from the cation exchange columns [(102) and (103)]; g) decanter (117) connected to said liquid-liquid extraction column (105), to separate aqueous and organic layer coming from the top section of the liquid-liquid extraction column (105); h) jackets [(118) and (119)] onto said plurality of cation exchange column(s) [(101) and (102)] to maintain the temperature within the columns in the range of 75-95 °C; i) heat supply (120) to said jackets [(118) and (119)] to attain said temperature in the range of 75 -95 °C; j) LSX zeolite supply line (121) to said cation exchange columns [(102) and (103)]; and k) impurities of salt after filtration through the filter (107) is removed from supply line (129).
  4. 4. The continuous process reactor (100) as claimed in claim 1, wherein spent wash water from the spent wash water tanks (109) is recycled back for zeolite washing of the next batch, and spent wash water from the spent wash water tanks (110) is sent to liquidliquid extraction column (105) for liquid-liquid extraction of organic solvent.
  5. 5. A method for production of cation-LSX zeolites by cation exchange process comprising the steps of: a) preparing pure aqueous salt solution via leaching and liquid-liquid extraction of cation salt solution having Na and K as impurities; b) reacting continuously flowing freshly prepared salt solution with LSX zeolite in cation exchange column(s) at temperature in the range of 75-95°C and for time period in the range of 5-8 hrs to obtain cation zeolite granules; c) washing cation zeolite granules with DM water to obtain washed cation zeolite and spent wash water; d) recycling spent wash water back for zeolite washing of next batch and/or sent to liquid-liquid extraction column for extraction of organic solvent; e) drying the washed cation zeolite within the column itself by applying vacuum or passing hot dry air through the column; and f) calcining the dried zeolite granules at temperature in the range of 350 to 450°C for time period in the range of 4-5 hours to obtain pure cation zeolite granules.
  6. 6. The method as claimed in claim 5, wherein the cation in the cation-LSX zeolites is selected from Na+, Li + , Mg 2+ , Ca 2+ , Sr 2+ , Rb + , Cs + , Ag + , Ba 2+ , Zn 2+ , Co 3+ , Ni 2+ , Cd 2+ , Mn 2+ and K + ; wherein the cation in the cation-LSX zeolites is Li 2+ ; and wherein the LSX zeolite used in cation exchange column(s) in step b) is Na-LSX zeolite.
  7. 7. The method as claimed in claim 5, wherein the organic solvent in step d) is selected from isoamyl alcohol, n-hexanol and 2 -ethylhexanol; and wherein the calcination of step f) is done at a temperature in the range of 350 to 450 °C for time period in the range of 4-5 hours.
  8. 8. The method as claimed in claim 5, wherein the step a) comprising: a) adding a salt solution into leaching vessel (112), followed by leaching of cation salt using an organic solvent, which is added from organic solvent tank (104) through the pump (P-03), wherein said step effects a selective dissolving of cation salt in the leaching vessel (112) to obtain a salt slurry; b) pumping the slurry using pump P-14 through filter (107) to filter out undissolved sodium and potassium impurities, which produces an organic filtrate; c) collecting the organic filtrate in the hold vessel (113) and pumping the same to liquid-liquid extraction (LLE) column (105), followed by the extraction of cation salt from the organic filtrate using DM water initially and spent wash water from spent wash water tanks [(109) and (110)] to obtain an aqueous salt solution; d) sending the aqueous salt solution from LLE column (105) to aqueous salt solution tank (108), followed by adding aqueous alkali solution from solution preparation tank (111) for pH adjustment of around 7.5 to 9.5 to obtain pure aqueous salt solution; and spent organic solvent from top of liquid-liquid extraction (LLE) column is separated through decanter (117) and sent back to the organic solvent tank (104) for re-use.
  9. 9. The method as claimed in claim 6, wherein the step b) comprising: a) passing cation zeolites in plurality of cation exchange column(s) [(101) and (102)]; b) feeding the plurality of cation exchange column(s) [(101) and (102)] [(101) and (102)] filled with LSX zeolite granules, pre-heated pure aqueous salt solution from aqueous salt solution tank (108) through a preheater (106) in an upflow mode; c) maintaining a temperature within the plurality of cation exchange column(s) [(101) and (102)] at 95°C by supplying heating utility selected from low pressure steam (LPS) or hot oil circulation (120) through a jacket (118); d) passing aqueous salt solution continuously through the plurality of cation exchange column(s) [(101) and (102)] for time period in the range of 5-8 hours to obtain cation exchanged-LSX zeolite granules; e) washing the cation exchanged-LSX zeolite granules with DM water from the water tank (103) in downflow mode to remove adsorbed salts, followed by collecting the spent wash water in two parts in spent wash water tanks [(109) and (110)], wherein the spent wash water from spent wash water tank (109) is recycled back for zeolite washing of the next batch in the cation exchange columns (101 and 102), and the spent wash water from spent wash water tank (110) is sent to the LLE column (105) for LLE of organic solvent; f) drying the washed cation exchanged-LSX zeolite granules within the cation exchange column itself by applying a vacuum or by passing hot dry air through a supply line (125); and g) removing and sending the dried cation exchanged-LSX zeolite granules to the calcinator (116), where a hot dry air is passed for performing calcination at temperature of 400 °C for time period in the range of 4-5 hours, followed by cooling and packing the cation exchanged -LSX granules.
  10. 0. The method as claimed in claim 9, wherein the salt solution is circulated in a single pass mode or in a recirculation mode in step b) and step d); wherein the LSX zeolite is Na- LSX zeolite; and wherein the adsorbed salts removed during washing in the cation exchange columns (101 and 102) are NaCl and KC1.

Description

APPARATUS AND CONTINUOUS PROCESS FOR SYNTHESIS OF LSX ZEOLITE USING CATION EXCHANGE METHODFIELD OF THE INVENTION The present invention generally relates to low silica X zeolite (LSX zeolite) via a cation exchange method. Specifically, the present invention relates to an apparatus/reactor for production of cation-LSX zeolites via a cation exchange method. More specifically, the present invention relates to a continuous process for production of cation-LSX zeolites using said continuous process reactor. Additionally, the present invention provides said process with a shorter time of period, easily recoverable and reusable salt-solution with good adsorption capacity for producing the cation- LSX zeolites. BACKGROUND OF THE INVENTION Air contains a large amount of oxygen and nitrogen, and separating oxygen and nitrogen from air is a common method for obtaining high-purity oxygen or nitrogen. Before the pressure swing adsorption technology appeared, oxygen and nitrogen production by air separation was monopolized by the freezing separation technology, however, the method has the disadvantages such as complex process steps, large area of equipment required, high investment/cost, strict/specific environmental requirements and longtime consumption, making it not a suitable method for producing oxygen in small scale and for rapid preparation of oxygen on site, and this is maintained until 70 years. Later, pressure swing adsorption technology began to be applied to the field of air separation and has been rapidly developed. The Pressure Swing Adsorption (PSA) air separation oxygen generation technology, has the advantages of simple process, convenient operation, low investment, low energy consumption, high automation degree and the like, and has gained more and more attention, and the same is explained in patents such as USP2944627, USP5176722, CN1196273A and the like. Currently, pressure swing adsorption based air separation has been around 20% of the total output of the duty cycle and is still growing rapidly. Pressure Swing Adsorption (PSA) and Vacuum Pressure Swing Adsorption (VPS A) are commonly used as air separation means, and the preparation of high-efficiency nitrogen or oxygen separation adsorbent is one of the key process feature of the pressure swing based oxygen production technology. At present, the most studied adsorbents are mainly nitrogenadsorbing materials, and typically, the most studied adsorbents comprise CaA, CaX, NaX, LiX and the like, and the separation principle is based on the selective adsorption of the adsorbents towards nitrogen and oxygen gases present in air, and the nitrogen and oxygen separation is done by utilizing the differences of the adsorption quantity, the adsorption speed and the adsorption force of nitrogen and oxygen, the characteristic that the adsorption quantity changes along with the pressure, and by adopting the characteristics of pressure adsorption and pressure reduction desorption. Lithium based LSX zeolite (Li-LSX) has huge demand as adsorbent in oxygen generation applications using Pressure Swing Adsorption (PSA)ZVPSA techniques. Currently there is no manufacturer in India and hence, there is high dependence on imports for this material. In COVID crises there was a significant shortage of this material for oxygen generation units. Relevant researche find that the LSX is an excellent adsorbent, so that the LSX can be applied to the fields of oxygen enrichment, hydrogen storage, gas purification and drying, tail gas treatment, environmental protection, liquid phase adsorption separation of hydrocarbons and the like. The wide application prospect of LSX promotes each mechanism to continuously optimize and improve the production process flow, improves the product quality and reduces the process cost, thereby meeting the application requirements. LSX type zeolite has wide application in pressure swing adsorption separation and vacuum pressure swing adsorption separation. Baksh et al found that the adsorption capacity of LiX molecular sieve to nitrogen was much higher than that of NaX; when the X-type zeolite has lower silica to alumina ratio, more cations can be exchanged, thereby exhibiting better adsorption performance. Due to Li+, a minimum radius and maximum charge density, compared to Na+, Mg2+, and Ag+. The zeolite formed by plasma, Li LSX zeolite, has better oxygen enrichment performance and nitrogen-oxygen separation capability. Currently, Li-LSX is prepared using a cation exchange process with sodium based LSX (Na-LSX). The exchange process is done by two methods, viz, batch reactor and in a column. As of now, both reported methods have limitations of significant time; water and Li-salt solution required for synthesizing Li-LSX. Also, recovery and recycling of the Li- salt and water is not addressed in the prior art. Also, after Li-exchange, zeolite needs significant water for washing to remove adsorbed salts. Nothing is reported about the disposal of the sp