Process for modifying the physical and chemical properties of faujasite Y-type zeolites

Abstract

The present invention relates to a process for modifying the physical and chemical properties of Faujasite Y-type zeolites (FAU), mainly used as a base material of catalyst used in the Fluid Catalytic Cracking (FCC) process, for the interest of the oil refining industry, in which the conversion of oil heavy fractions into lighter fractions, with a higher commercial value, is carried out. The process produces a modified Faujasite Y-type zeolite, with lower sodium content, as low as 75%, than that of the starting Faujasite Y-type zeolite. A mesoporous material associated with the modified Faujasite Y-type zeolite has an average pore size ranging from 2 to 100 nm, having a bimodal or multimodal pore size distribution. The proportion of modified Faujasite Y-type zeolite with respect to the meso-porous material associated to the Faujasite Y type Zeolite can be regulated through the process operation conditions.

Claims

1. A process for modifying the physical and chemical properties of Faujasite Y-type zeolites, comprising the steps of: a) contacting Faujasite Y-type zeolite with glycerol in an amount of 0.01 to 1 g per ml of glycerol at a temperature of 180 C. to 200 C. to form a gel; b) adding one or more ammonium salts to the gel of step a) in an amount of 0.01 to 3 g per gram of said zeolite at a temperature of 20 C. to 80 C. to form a mixture, hydrothermally treating said mixture at a temperature of 140 C. to 180 C. for 10 to 20 hours, and cooling the hydrothermally treated mixture to room temperature, and; c) recovering the product obtained in step b) by filtration and/or centrifugation, washing the resulting solid and drying at a temperature of 80 to 120 C., subjecting the dried solid to a thermal treatment in an air atmosphere at a temperature of 480 C. to 520 C. at a heating profile of 1 to 3 C./min to obtain a modified Faujasite Y-type zeolite, wherein a sodium is reduced up to 75% with respect to the Faujasite Y-type zeolite starting material, and said modified Faujasite Y-type zeolite has a mesoporous structure having a bimodal pore size distribution with an average pore size of 2 to 100 nm.

2. The process of claim 1, wherein the ammonium salts in step (b) are selected from group consisting of nitrate, chloride, bromide, acetate, sulfate, and mixtures thereof.

3. The process of claim 2, wherein said ammonium salts are selected from the group of nitrate salts, tetra-methyl ammonium bromide, cetyl-trimethyl ammonium bromide, ammonium nitrate, and mixtures thereof.

4. The process of claim 1, wherein the addition of ammonium salt of step (b) is carried out at a temperature ranging of 40 to 60 C.

5. The process of claim 1, wherein the drying in step (c) is at a temperature of 90 C. to 110 C.

6. A process for producing a Faujasite Y-type zeolite having modified physical and chemical properties, comprising the steps of: a) contacting a Faujasite Y-type zeolite with glycerol in an amount of 0.01 to 1 g of Faujasite Y-type zeolite per ml of glycerol at a temperature of 100 to 260 C. for 0.5 to 8 hours to form a gel; b) adding at least one ammonium salt to the gel of step a) in an amount of 0.1 to 1 g per gram of said zeolite to form a mixture, stirring the mixture at a temperature of 20 to 80 C., and subjecting the mixture to a hydrothermal treatment at a temperature of 95 to 220 C., and cooling the mixture to room temperature, and; c) recovering the resulting product obtained in step b), washing the recovered product and drying at a temperature of 90 to 110 C. to form a dried solid, subjecting the dried solid to a thermal treatment in an air atmosphere at a temperature of 350 to 550 C. for 2 to 8 hours at a heating profile of 1 to 3 C./min to obtain the modified Faujasite Y-type zeolite having a bimodal pore distribution having a first pore system of 2-20 nm and a second pore system of 30-100 nm, where the sodium is reduced up to 75% with respect to the Faujasite Y-type zeolite starting material.

7. The process of claim 6, wherein the modified Faujasite Y-type zeolite has a mesoporous structure with an average pore size of 2 to 100 nm.

8. The process of claim 6, wherein the ammonium salts in step (b) are selected from group consisting of nitrate, chloride, acetate, sulfate, bromide, and mixtures thereof.

9. The process of claim 6, wherein said ammonium salts are selected from the group of nitrate salts, tetra-methyl ammonium bromide, cetyl-trimethyl ammonium bromide, ammonium nitrate, ammonia and mixtures thereof.

10. The process of claim 6, wherein the hydrothermal treatment in step (b) is at atmospheric pressure at a temperature of 140 to 180 C. for 10 to 20 hours.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the pore size distribution of the pristine Faujasite Y-type zeolite, identified as F1-IMP.

(2) FIG. 2 shows the X-ray diffraction patterns of the modified zeolites identified as MMZ-34-SC and MMZ-34C.

(3) FIG. 3 shows the pore size distribution of the zeolite identified as MMZ-34C.

(4) FIG. 4 shows the X-ray diffraction patterns of the modified zeolites identified as MMZ-54-SC and MMZ-54C.

(5) FIG. 5 shows the pore size distribution of the modified zeolite labeled as MMZ-54C.

(6) FIG. 6 shows the X-ray diffraction pattern of the modified zeolite labeled as MMZ-51C.

(7) FIG. 7 shows the pore size distribution of the modified zeolite labeled as MMZ-51C.

(8) FIG. 8 shows the pore size distribution of the Faujasite Y-type zeolite, labeled as F2-G.

(9) FIG. 9 shows the X-ray diffraction pattern of the modified zeolites identified as MMZ-68-SC and MMZ-68C.

(10) FIG. 10 shows the pore size distribution of the modified zeolite identified as MMZ-68C.

SUMMARY OF THE INVENTION

(11) The process of the present involves a method of modifying the physical and chemical properties of Faujasite Y-type zeolites, comprising: a) contacting a Faujasite Y-type zeolite, with a short chain polyol, preferably glycerol, in a concentration ranging from 0.01 to 1 g of solid per milliliter of glycerol, at a temperature ranging from 100 to 260 C., for a time from 0.5 to 8 hours, to form a gel; b) adding one or more ammonium salts to the gel to form a mixture, stirring the mixture for 15 to 60 min., subjecting the mixture to hydrothermal treatment at 95-250 C., for from 5 to 40 hours, cooling the mixture to 15 to 25 C.; and c) recovering a solid by means of filtration and/or centrifugation, washing the solid with water, preferably bidistilled water, and drying at 80-120 C. to obtain a dried solid, then submitting the dried solid to a thermal treatment at 350 to 550 C., for 2 to 8 hours to obtain a product comprising a modified Faujasite Y-type zeolite having a sodium content as low as 75% below that of the Faujasite Y-type zeolite in step a) prior to contact with the glycerol, dispersed on a mesoporous material having an average pore size ranging from 2 to 100 nm.

DETAILED DESCRIPTION OF THE INVENTION

(12) The present invention relates to a process for modifying the physical and chemical properties of Faujasite Y-type zeolites (FAU), mainly used as an active material of the catalyst for the Fluid Catalytic Cracking (FCC) process, widely used in the oil refining industry, for conversion of oil heavy fractions into lighter fractions having a higher commercial value.

(13) More specifically the present invention relates to a process for producing in a single stage: a) A modified Faujasite Y-type zeolite, with a lower sodium content, as low as 75% below that of the starting Faujasite Y-type zeolite. b) A mesoporous material having an average pore size ranging from 2 to 100 nm associated with the modified Faujasite Y-type zeolite, which has a porosity below 1 nm; such produced materials present a bimodal or multimodal pore size distribution. The proportion of modified Faujasite Y-type zeolite with respect to the meso-porous material associated to the Faujasite Y-type Zeolite, can be regulated through the process operation conditions.

(14) The process of the present invention comprises: a) contacting a sodium Faujasite Y-type zeolite, which can be in a pure or pristine form or in a mixture with other materials, with a short-chain polyol, preferably glycerol, in a concentration ranging from 0.01 to 1 g of solid per milliliter of glycerol, at a temperature ranging from 100 to 260 C., preferably from 180 to 200 C., for a period of from 0.5 to 8 hours, preferably from 1.5 to 2 hours to form a gel; b) adding, an ammonium salt and/or a mixture of ammonium salts, which can be added in powder form and/or in an aqueous and/or an alcoholic solution, in a ratio of from 0.01 to 3 g of salt per gram of solid, at a temperature from 20 to 80 C., preferably from 40 to 60 C., and/or with structure directing agents, stirring the mixture for a period of time from 15 to 60 min., preferably from 25 to 30 minutes. Then the mixture is subject to hydrothermal treatment at 95-220 C., preferably ranging from 140 to 180 C., for from 5 to 40 hours, preferably from 10 to 20 hours, afterwards the mixture is cooled to room temperature and; c) recovering product obtained in b) by means of filtration and/or centrifugation techniques, washing with bidistilled water and drying at 80-120 C., preferably from 90-110 C. Then the solid is thermally treated at a temperatures ranging from 350 to 550 C., preferably from 480 to 520 C., for a time ranging from 2 to 8 hours, preferably from 3 to 5 hours, at a heating rate from 1 to 3 C./min, to obtain a modified Faujasite Y-type zeolite highly dispersed on the in-situ made mesoporous material.

(15) The ammonium salts used in stage b) can be a nitrate, chloride, acetate, sulfate, and/or an organic quaternary ammonium salt; while the ammonium salts incorporated in aqueous and/or alcoholic solutions, are selected from ammonium nitrate, tetramethyl ammonium bromide, and/or cetyl-trimethyl ammonium bromide.

(16) The process of the present invention is distinctive because in one stage the sodium can be removed up to a 75% with respect to the starting Faujasite Y-type zeolite, which may be pristine Faujasite Y-type zeolite; concomitantly, this treatment of the present invention produces a mesoporous material having an average pore size from 2 to 100 nm, with a zeolite content from 5-100% and displaying a bimodal pore distribution, due to a porosity lower than 1 nm inherent in the zeolite together with a porosity in the mesoporous region from 2-100 nm inherent in the mesoporous material, more specifically a pore system in the region from 2-20 nm and a second pore system in the region from 30 a 100 nm, where the proportion of the modified Faujasite Y-type Zeolite with respect to the mesoporous material associated to the modified Faujasite Y-type Zeolite, can be regulated by means of the process operation conditions.

EXAMPLES

(17) Once the basic aspects related to the present invention have been described a series of examples are offered to illustrate specific embodiments; notwithstanding, the invention should not be considered to be limited to said. Room temperature is defined herein after as temperature ranging from 10 and 30 C.

Example 1

(18) A sample of the Faujasite Y-type zeolite, identified as F1-IMP, was analyzed by means of atomic absorption spectroscopy, obtaining the following chemical composition:

(19) Sodium as Na: 8.7 weight %

(20) Si/Al atomic ratio: 2.35

Example 2

(21) The F1-IMP zeolite sample from Example 1 was studied by means of nitrogen adsorption at 77 K to determine its specific surface area by the Langmuir method (ASTM D3663-03 Method), and its micropore surface area, calculated by the t-plot method (ASTM D4365-95 Method), while the following results were obtained:

(22) Total Langmuir specific area: 944 m.sup.2/g

(23) t-plot micropore area: 890 m.sup.2/g

(24) External area: 54 m.sup.2/g

(25) Given that micropore surface area is related to the intra-crystalline area of the zeolite, the difference between Langmuir and t-plot values (54 m.sup.2/g) represents the external area, in this case related to the external area of the F1-IMP zeolite crystals. The pore size distribution of the F1-IMP zeolite is shown in FIG. 1.

Example 3

(26) 2 g F1-IMP zeolite from Examples 1 and 2 were placed in a glass vessel with 20 ml of glycerol and heating at 200 C. for 2 hours, obtaining a gel which was transferred to a 50 ml autoclave, adding 0.00835 moles of cetyl-trimethyl ammonium bromide (CETAB) dissolved in 1.67 moles of water, and then stirred at ambient temperature for 30 minutes; lately, the autoclave was sealed and heated at 150 C. for 15 hours. Finally, the autoclave and its content were cooled down and once at room temperature the solid was recovered by filtering, washed with bidistilled water and dried at 100 C. in a stove. The solid was recovered and identified as MM-Z-34-SC.

Example 4

(27) The MM-Z-34-SC solid, obtained in Example 3, was submitted to a thermal treatment in static atmosphere in a muffle at 500 C. for 4 hours, heating from room temperature at 1 C./min rate. The solid obtained from the thermal treatment was identified as MMZ-34C.

Example 5

(28) The MM-Z-34-SC and MMZ-34C solids, obtained from Examples 3 and 4 respectively, were characterized by X-ray powder diffraction, obtaining the diffraction patterns presented in FIG. 2, leading to identify crystalline structures corresponding to a Faujasite Y-type zeolite, according to JCPDS card 12 0246 reference. The wide peak observed at 2q values <2.5 indicates the presence of a mesoporous material.

Example 6

(29) The MMZ-34C solid, obtained in Example 4, was studied by means of nitrogen adsorption at 77 K, with the purpose of determining its total specific area from the Langmuir method (ASTM D3663-03 Method), its total pore volume by the BJH method (ASTM D4641-94 Method) and its micropores area calculated from the t-plot method (ASTM D4365-95 Method), while obtaining the following results:

(30) Langmuir total specific area: 856 m.sup.2/g

(31) t-plot micropore area: 742 m.sup.2/g

(32) Total pore volume: 0.467 cm.sup.3/g

(33) External area: 114 m.sup.2/g

(34) Comparing these textural results with those obtained for the pristine F1-IMP zeolite from Examples 1 and 2, MMZ-34C shows a decrease in the Langmuir specific surface area by 88 m.sup.2/g and by 148 m.sup.2/g in the micropore surface area. The increase of the external surface area by 60 m.sup.2/g is attributable to the presence of the mesoporous material. From the micropore area values, the amount of zeolite with respect to the total amount of material produced was equivalent to 83%.

(35) The pore size distribution of the mesoporous material in the MMZ-34C sample, FIG. 3, presents a trimodal pore size distribution with maximums at 32 (3.2 nm), 120 (12 nm) and 650 (65 nm).

Example 7

(36) The chemical composition of MMZ-34C solid, obtained in Example 4, and studied in Examples 5 and 6, was analyzed by means of the atomic adsorption spectroscopy, obtaining the following results:

(37) Sodium as Na: 8% weight

(38) Si/Al atomic ratio: 2.20

(39) These results show that comparing with the pristine F1-IMP zeolite (Example 1), the MMZ-34C modified Faujasite Y-type zeolite presents a decrease in the sodium content equivalent to 8%.

Example 8

(40) 2 g of F1-IMP zeolite of Examples 1 and 2 were placed in a glass vessel with 20 ml of glycerol, and heating at 180 C. for 2 hours, obtaining a gel which was transferred to a 50 ml autoclave, adding 0.030 moles of powdered ammonium nitrate, equivalent to 1.14 grams of ammonium nitrate per gram of zeolite, at 40 C., then stirred for 19 hours at room temperature. Afterwards, 1.11 moles of distilled water were added, the autoclave was hermetically sealed, and heated at 150 C. for 15 hours. Finally, the autoclave and its content were cooled down to room temperature, the solid was recovered by filtering, washed with distilled water and dried at 100 C. in a stove. The solid was recovered as powder and identified as MM-Z-54-SC.

Example 9

(41) The MM-Z-54-SC solid, obtained in Example 8, was submitted to a thermal treatment in air static atmosphere in a muffle at 500 C. for 4 hours, heating from room temperature at 1 C./min rate. The solid obtained from the thermal treatment was identified as MMZ-54C.

Example 10

(42) The MM-Z-54-SC and MMZ-54C solids, obtained from Examples 8 and 9 respectively, were characterized by X-ray powder diffraction, obtaining the diffraction patterns presented in FIG. 4, leading to identify one crystalline structure corresponding to a Faujasite Y-type zeolite, according to the JCPDS Card 12 0246 reference.

Example 11

(43) The MMZ-54C solid, obtained in Example 9, was studied by means of nitrogen adsorption-desorption isotherms at 77 K, with the purpose of determining its total surface area, calculated from the Langmuir method (ASTM D3663-03 method), its total pore volume from the BJH method (ASTM D4641-94 method), its micropores area, calculated from the t-plot method (ASTM D4365-95 method), while obtaining the following results:

(44) Langmuir total specific area: 899 m.sup.2/g

(45) t-plot micropore area: 825 m.sup.2/g

(46) Total pore volume: 0.428 cm.sup.3/g

(47) External area: 74 m.sup.2/g

(48) Comparing these textural results with those obtained for the pristine F1-IMP zeolite of Examples 1 and 2, MMZ-54C shows a decrease in the Langmuir specific surface area by 45 m.sup.2/g and in the micropores by 65 m.sup.2/g. The increase by 20 m.sup.2/g in the external area of MMZ-54C solid is attributable to the presence of mesoporous material. From these micropores area data, the amount of zeolite in the total material was equivalent to 93%.

(49) The pore size distribution of the mesoporous material in the MMZ-54C solid, which is illustrated in FIG. 5, presents a bimodal pore size distribution of 82 (8.2 nm) and 675 (67.5 nm).

Example 12

(50) The chemical composition of the MMZ-54C solid, obtained in Example 9 and studied in Examples 10 and 11, was analyzed by means of atomic absorption spectroscopy, obtaining the following results:

(51) Sodium as Na: 3.3% by weight

(52) Si/Al atomic ratio: 1.75

(53) These results show that comparing with those of the pristine F1-IMP zeolite (Example 1), the MMZ-54C modified Faujasite Y-type zeolite presents a decrease in the sodium content equivalent to 62%.

Example 13

(54) 2 g of the F1-IMP zeolite of Examples 1 and 2 were placed in a glass vessel with 20 ml of glycerol, and heating at 180 C. for 2 hours, obtaining a gel which was transferred to a 50 ml autoclave, adding 0.017 moles of ammonium nitrate dissolved in 0.25 moles of methanol, equivalent to 0.646 g of ammonium nitrate per gram of zeolite, at 40 C., then aged for 19 h at room temperature. Afterwards, the autoclave was hermetically sealed and heated at 150 C. for 15 hours. Finally the autoclave and its content were cooled down and once at room temperature the solid was recovered by filtering, dried at 110 C. for 2 hours, and submitted to a thermal treatment in air static atmosphere in a muffle at 500 C. for 4 hours. The solid obtained was identified as MMZ-51C.

Example 14

(55) The MMZ-51C solid, obtained from Example 13, was characterized by X-ray powder diffraction, obtaining the diffraction pattern presented in FIG. 6, leading to identify a crystalline structure corresponding to a Faujasite Y-type zeolite, according to the JCPDS Card 12 0246 reference.

Example 15

(56) The MMZ-51C solid, obtained in Example 13, was studied by mean of nitrogen adsorption-desorption isotherms at 77 K, with the purpose of determining its total surface area, calculated from the Langmuir method (ASTM D3663-03 method), its total pore volume from the BJH method (ASTM D4641-94 method), its micropores area, calculated from the t-plot method (ASTM D4365-95 method), while obtaining the following results:

(57) Langmuir total specific area: 865 m.sup.2/g

(58) t-plot micropore area: 765 m.sup.2/g

(59) External area: 100 m.sup.2/g

(60) From these micropores area data, the amount of zeolite in the total material was equivalent to 86%

(61) The pore size distribution of the mesoporous material in the MMZ-51C sample shown in FIG. 7, presents a bimodal pore size distribution at 116 (11.6 nm) and 680 (68 nm).

Example 16

(62) The chemical composition of the MMZ-51C solid, obtained in Example 13 and studied in Examples 14 and 15 was analyzed by means of atomic adsorption spectroscopy, obtaining the following results:

(63) Sodium as Na: 3.5% by weight

(64) Si/Al atomic ratio: 2.85

(65) These results show that comparing with the pristine F1-IMP zeolite (Example 1), the modified Faujasite Y-type zeolite presents a decrease in the sodium content, equivalent to 59.8%.

Example 17

(66) A sample of the Faujasite Y-type zeolite, identified as F2-G, was analyzed by means of atomic adsorption spectroscopy, obtaining the following chemical composition:

(67) Sodium as Na: 7.15% by weight

(68) Si/Al atomic ratio: 2.57

Example 18

(69) The F2-G zeolite sample from Example 17 was studied by means of nitrogen adsorption-desorption isotherms at 77 K, with the purpose of determining its total surface area, calculated from the Langmuir method (ASTM D3663-03 method), its total pore volume from the BJH method (ASTM D4641-94 method), its micropores area, calculated from the t-plot method (ASTM D4365-95 method), while obtaining the following results:

(70) Langmuir total specific area: 903 m.sup.2/g

(71) t-plot micropore area: 857 m.sup.2/g

(72) Total pore volume: 0.359 cm.sup.3/g

(73) Average pore diameter: <3 nm

(74) External area: 46 m.sup.2/g

(75) Since the micropore surface area is related to the intra-crystalline area of the zeolite, the difference between Langmuir and t-plot values (46 m.sup.2/g) represents the external area.

(76) The pore size distribution of the F2-G zeolite is shown in FIG. 8.

(77) From the total specific area and micropores area data, the amount of zeolite in the total material was equivalent to 94.9%.

Example 19

(78) 2 g of the F2-G zeolites of Examples 17 and 18, were placed in a glass vessel with 20 ml glycerol, and heating at 250 C. for 2 hours, obtaining a gel. The reaction mixture was transferred to a 50 ml autoclave, adding 0.030 moles of powdered ammonium nitrate, equivalent to 1.14 grams of ammonium nitrate per zeolite gram, at a 40 C., then cooled down and stirred for 19 hours at room temperature. Afterwards, 1.11 moles of distilled water were added, the autoclave was hermetically sealed, and heated at 150 C. for 15 hours. Once cooled the resulting product was recovered by filtering, washed and dried at 100 C. The obtained solid was identified as MMZ-68-SC.

Example 20

(79) The MMZ-68-SC solid, obtained in Example 19, was submitted to a thermal treatment in static air atmosphere at 500 C. muffle for 4 hours, heating from room temperature at 1 C./min rate. The solid obtained from the thermal treatment was identified as MMZ-68C.

Example 21

(80) The MMZ-68-SC and MMZ-68C solids, obtained from Examples 19 and 20 respectively were characterized by X-ray powder diffraction, obtaining the diffraction patterns shown in FIG. 9, leading to identify the crystalline structure corresponding to a Faujasite Y-type zeolite, according to the JCPDS Card 12 0246 reference.

Example 22

(81) The MMZ-68C solid, obtained in Example 20, was studied by means of nitrogen adsorption-desorption isotherms at 77 K, with the purpose of determining its total surface area, calculated from the Langmuir method (ASTM D3663-03 method), its total pore volume from the BJH method (ASTM D4641-94 method), its micropores area, calculated from the t-plot method (ASTM D4365-95 method), while obtaining the following results:

(82) Langmuir total specific area: 692 m.sup.2/g

(83) t-plot micropore area: 578 m.sup.2/g

(84) Total pore volume: 0.427 cm.sup.3/g

(85) External area: 114 m.sup.2/g

(86) Comparing these textural results with those obtained for the pristine F2-G zeolite (Example 18), it can be observed a decrease in the Langmuir specific surface area by 211 m.sup.2/g and in the micropore surface area by 279 m.sup.2/g and the increase in the external area (68 m.sup.2/g) which is attributable to the presence of mesoporous material, which agrees with the pore size distribution presented in FIG. 10. From the micropore area data, the amount of zeolite with respect to the total amount of the material was equivalent to 67%.

(87) Since the micropore surface area is related to the intra-crystalline area of the zeolite, the difference between Langmuir and t-plot values

(88) Based on the fact that micropores area is related to the amount of zeolite in the material, MMZ-68C contains 33% lower than the pristine F2-G solid.

Example 23

(89) The chemical composition of MMZ-68C solid, obtained in Example 20 and studied in Examples 21 and 22 was analyzed by means of an atomic adsorption spectroscopy, obtaining the following results:

(90) Sodium as Na: 1.85% by weight

(91) Si/Al atomic ratio: 2.64

(92) These results show that comparing with those of the pristine F2-G zeolite, (Example 17) the MMZ-68C modified Faujasite Y-type zeolite presents a decrease in the sodium content equal to 74%.