RU2481268C2 - Method of producing hydrophobic zeolite - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to zeolites used as adsorbents or catalyst supports. The method of obtaining hydrophobic zeolite involves firing a fixed bed of zeolite Y in the presence of water vapour in steps: for 1-2 hours at temperature of 180-230°C, for 1.5-2.5 hours at temperature of 380-430°C, for 0.5-2 hours at temperature of 700-900°C.

EFFECT: method enables to obtain hydrophobic zeolite with hydrophobicity index for toluene H_0,1 of not less than 9, for benzene H_0,25 of not less than 5.

Description

The invention relates to zeolites, which are used as adsorbents or catalyst supports, in particular, to methods for producing hydrophobic zeolites.

A known method of producing a hydrophobic zeolite (RF patent 2213055, IPC СВВ 39/24, 2003) by calcining a zeolite precursor with a ratio of silicon dioxide to aluminum dioxide of at least 20, and preferably from about 25 to 150, under turbulence at high temperature and in the presence of water vapor. The term turbulent conditions refers to conditions in which there is sufficient mixing between the solid and gas phases, in which the gas passes through the dispersed solid phase without a noticeable interface between the solid and the gas. The zeolite precursor is calcined under turbulent conditions relative to the zeolite flow, preferably at a minimum fluidization rate through at least a significant fraction of the zeolite particles in contact with the gas phase, when the gas flow rate corresponds to a Reynolds number of at least 5, preferably at least 10. Significant part of the zeolite particles is in contact with the gas phase when at least 50%, preferably 85%, more preferably 95%, most preferably 100% zeolite particles ditsya into contact with the gas phase. The calcination temperature is in the range of about 650 ° C., preferably from about 700 to 1000 ° C., preferably to 850 ° C., the steam is preferably present in an amount of 10% by volume.

However, in order to obtain a hydrophobic zeolite in this way, the zeolite precursor must have a silica to alumina ratio of at least 20, as described in the patent specification of the Russian Federation No. 2213055, which makes it impossible to use zeolite with a silica to alumina ratio less than twenty.

Also, the implementation of this method requires creating during calcination a minimum fluidization rate of zeolite particles and at the same time a sufficiently large flow of reaction gas through the zeolite in order to ensure solid turbulence and the most complete contact of the zeolite particles with the gas phase. However, excessive turbulence must be prevented in order to avoid entrainment of the solid with the gas stream and removal of material from this furnace.

The objective of the invention is to simplify the method of producing a hydrophobic zeolite with the possibility of obtaining a hydrophobic zeolite Y from a zeolite precursor with an initial molar ratio of silicon dioxide to alumina from 10 to 18.

The problem is solved by the invention, according to which, in a method for producing a hydrophobic zeolite, comprising stepwise calcining a zeolite precursor in the presence of water vapor, the fixed layer of zeolite is calcined. As the zeolite precursor, stabilized zeolite Y is used with an initial molar ratio of silicon dioxide to alumina from 10 to 18. Calcination is carried out in a stepwise mode: 1-2 hours at a temperature of 180-230 ° C, 1.5-2.5 hours at a temperature of 380-430 ° C, 0.5-2 hours at a temperature of 700-900 ° C.

This method allows to obtain a hydrophobic zeolite Y from a zeolite precursor with a molar ratio of silicon dioxide to alumina from 10 to 18, in contrast to the method according to RF patent 2213055, in which the zeolite precursor must have a ratio of silicon dioxide to alumina of at least 20, and eliminates the need to create turbulent conditions for the flow of vapor-air mixture and zeolite and, accordingly, the use of sophisticated equipment - special furnaces for calcination in a fluidized bed. Moreover, the method allows to obtain a zeolite with a hydrophobicity index H of _0.1 greater than 7.

The method is as follows. Zeolite Y with a silica to alumina ratio of 10-18, with an initial hydrophobicity index H of _0.1 = 1-1.5, is placed in an alloy container (sample chamber), which is enclosed in a muffle furnace equipped with a steam supply system. The sample is calcined for 1-2 hours at a temperature of 180-230 ° C, 1.5-2.5 hours at a temperature of 380-430 ° C, 0.5-2 hours at a temperature of 700-900 ° C. Water vapor is fed into the oven at a temperature of 180-230 ° C. Steam consumption is 100-400 g / h. The sample chamber is an open steel container. After the calcination is complete, the steam supply is stopped, the muffle furnace is turned off, the chamber with the zeolite sample is unloaded and left to cool in air to room temperature.

The starting zeolite Y may be preformed into granules. To do this, zeolite Y with an initial ratio of silicon dioxide to alumina 10-18 and an initial hydrophobicity index for toluene H _0.1 = 1.1-1.8 is mixed with a binder, which is used as Sialite-20C (TU 2145-003- 43811938-97, manufacturer ZAO Silikat, Elabuga) and polyvinyl alcohol. The granules are calcined for 1-2 hours at a temperature of 180-230 ° C, 1.5-2.5 hours at a temperature of 380-430 ° C, 0.5-2 hours at a temperature of 700-900 ° C. Water vapor is fed into the oven at a temperature of 180-230 ° C. Steam consumption is 100-400 g / h. The sample chamber is an open steel container. After the calcination is complete, the steam supply is stopped, the muffle furnace is turned off, the chamber with the zeolite sample is unloaded and left to cool in air to room temperature.

For the obtained zeolite samples, the structure of the crystal lattice is determined by X-ray diffraction, the static sorption capacity is determined by the excitation method, and the hydrophobicity index is calculated from the ratio of the mass sorption of organic substances to the mass sorption of water at specific partial pressures of the two adsorbates. X-ray examination is carried out on the apparatus DRON-6. The lattice constants are determined by a standard test method to determine the unit cell size of type Y zeolite.

Example 1

190 g of stabilized type Y zeolite powder, with a lattice size of 24.37 Å, dealuminated, with a silica to alumina ratio of 18 and an initial hydrophobicity index for toluene H _0.1 = 1.2 and H _0.5 = 1.2 on an open stainless steel pan to a muffle furnace equipped with a steam supply system. At a temperature of 230 ° C, the steam supply is switched on, the steam flow rate is 290 g / h, calcined for 1 h, then calcined for 1 h at 410 ° C and 1 h at 760 ° C. The powder is unloaded. According to X-ray diffraction data, the obtained sample has a crystalline structure corresponding to a cubic lattice of type Y zeolite with an elementary cell parameter a = 24.25 Å. The static sorption capacity is determined by the desiccation method, the values are shown in table 1. The hydrophobicity index of the obtained sample for toluene H _0.1 = 13.

Table 1 Partial pressure of water vapor, p / ps Static sorption capacity of water vapor, a, cm ³ / g The partial vapor pressure of toluene, p / ps Static sorption capacity of toluene vapors a, cm ³ / g 0.1 0.02 0.1 0.26 0.5 0.14 0.5 0.32

Example 2

210 g of type Y zeolite powder, stabilized, with a crystal lattice size of 24.49 Å, dealuminated, with a silica to alumina ratio of 18 and an initial hydrophobicity index for toluene H _0.1 = 1.3 and H _0.5 = 1.3 on an open stainless steel pan to a muffle furnace equipped with a steam supply system. At a temperature of 210 ° C, the steam supply is switched on, the steam flow rate is 290 g / h, calcined for 1 h, then calcined for 1 h at 400 ° C and 1 h at 800 ° C. The powder is unloaded. According to X-ray diffraction data, the obtained sample has a crystalline structure corresponding to a cubic lattice of type Y zeolite with an elementary cell parameter of a = 24.27 Å. The static sorption capacity is determined by the desiccation method, the values are shown in table 2. The hydrophobicity index of the obtained sample for toluene H _0.1 = 20.

table 2 Partial pressure of water vapor, p / ps Static sorption capacity of water vapor, a, cm ³ / g The partial vapor pressure of toluene, p / ps Static sorption capacity of toluene vapors a, cm ³ / g od 0.01 0.1 0.20 0.5 0.09 0.5 0.32

Example 3

310 g of granules formed from type Y zeolite with a crystal lattice size of 24.47 Å, sialite-20С and polyvinyl alcohol, stabilized, dealuminated, with a silica to alumina ratio of 11 and an initial hydrophobicity index for toluene H _0.1 = 1.1 and benzene N _0.25 = 1.1 is placed on an open stainless steel tray in a muffle furnace equipped with a steam supply system. Upon reaching a temperature of 210 ° C, the steam supply is switched on, the steam flow rate is 240 g / h, calcined for 1 h, then calcined for 1 h at 400 ° C and 1 h at 780 ° C. The granules are unloaded.

According to X-ray diffraction data, the obtained sample has a crystalline structure corresponding to a cubic lattice of type Y zeolite with an elementary cell parameter of a = 24.22 Å. The static sorption capacity was determined by the desiccation method, the values are shown in table 3. The hydrophobicity index of the obtained sample for benzene H _0.25 = 5, for toluene H _0.1 = 9. The adsorption isotherms of water vapor and benzene are shown in the figure, in which 1 is a curve of the dependence of the static sorption capacity of water on the partial pressure of water vapor, 2 is a curve of the dependence of the value of the static sorption capacity of benzene on the partial pressure of benzene vapor. It can be seen from the figure that the obtained sample predominantly absorbs benzene.

Table 3 Partial pressure of water vapor, p / ps Static sorption capacity of water vapor, a, cm ³ / g Partial vapor pressure of benzene, p / ps Static sorption capacity of benzene vapors a, cm ³ / g 0 0 0 0 0.09 0.024 0.23 0.185 0.25 0,036 0.35 0.323 0.35 0,042 0.50 0.349 0.56 0,061 0.64 0.401 0.75 0.141 one 0.450 one 0.371

Example 4

280 g of granules formed from type Y zeolite with a lattice size of 24.50 Å, sialite-20С and polyvinyl alcohol, stabilized, dealuminated, with a silica to alumina ratio of 10 and an initial hydrophobicity index for toluene H _0.1 = 1.8 and H _0.5 = 1.8 is placed on an open stainless steel tray in a muffle furnace equipped with a steam supply system. Upon reaching 200 ° C, steam supply is switched on, steam consumption is 300 g / h, calcined for 1 h, then calcined for 1.5 h at 420 ° C and 0.5 h at 815 ° C. According to the data of the X-ray diffraction study, the obtained sample has a crystalline structure, a cubic lattice with an elementary cell parameter a = 24.27 Å. The static sorption capacity is determined by the desiccation method, the values are shown in table 4. The hydrophobicity index of the obtained sample for toluene H _0.5 = 8, and at a relative pressure of OD the sample does not absorb water at all.

Table 4 Partial pressure of water vapor, p / ps Static sorption capacity of water vapor, a, cm ³ / g The partial vapor pressure of toluene, p / ps Static sorption capacity of toluene vapors a, cm ³ / g 0.1 0.00 0.1 0.12 0.5 0.02 0.5 0.16

Example 5

300 g of granules formed from type Y zeolite with a crystal lattice size of 24.35 Å, sialite-20С and polyvinyl alcohol, stabilized, dealuminated, with a silica to alumina ratio of 14 and an initial hydrophobicity index for toluene H _0.1 = l, 4 and benzene N _0.25 = 1.4 is placed on an open stainless steel tray in a muffle furnace equipped with a steam supply system. Upon reaching 220 ° C, steam supply is switched on, steam consumption is 300 g / h, calcined for 1 h, then calcined for 1.5 h at 400 ° C, 1 h at 750 ° C and 0.5 h at 815 ° C. According to the data of the X-ray diffraction study, the obtained sample has a crystalline structure, a cubic lattice with an elementary cell parameter a = 24.26 Å. The static sorption capacity is determined by the desiccation method, the values are shown in table 5. The hydrophobicity index of the obtained sample for toluene H _0.5 = 9.6, and at a relative pressure of 0.1 the sample does not absorb water at all.

Table 5 Partial pressure of water vapor, p / ps Static sorption capacity of water vapor, a, cm ³ / g Partial vapor pressure of toluene, p / ps Static sorption capacity of toluene vapors a, cm ³ / g 0.1 0.00 0.1 0.14 0.5 0,03 0.5 0.29

As can be seen from the presented data, the method allows to obtain a hydrophobic zeolite Y with the desired characteristics from a precursor zeolite with a molar ratio of silicon dioxide to alumina 10-18 without the use of complex technological equipment.

Claims (3)

1. A method of producing a hydrophobic zeolite, including calcining zeolite Y in the presence of water vapor, characterized in that the fixed layer of zeolite Y is calcined in a stepwise mode: for 1-2 hours at a temperature of 180-230 ° C, 1.5-2, 5 hours at a temperature of 380-430 ° C, 0.5-2 hours at a temperature of 700-900 ° C, while the zeolite Y has a molar ratio of silicon dioxide to alumina of 10-18. 2. The method according to claim 1, in which the initial zeolite type Y with a ratio of silicon dioxide to alumina 10-18 in the form of a powder is subjected to calcination. 3. The method according to claim 1, in which the zeolite is subjected to zeolite Y with a ratio of silicon dioxide to alumina 10-18 in the form of granules.

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