JPS5817654B2 - Manufacturing method of new composite adsorbent - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a separation method that can achieve effective separation through the synergistic effect of two types of cations, especially in the operation of separating aromatic hydrocarbon isomers consisting of 8 carbon atoms. The present invention relates to a method for producing an adsorbent for use in a commercially available product.

Faujasite-type zeolites are used as adsorbents for the separation of various hydrocarbon mixtures in adsorption operations, and are particularly effective in separating amounts of substances that are difficult to separate by distillation or other methods. Many are known.

It is also applied to aromatic hydrocarbon isomers having 8 carbon atoms (hereinafter abbreviated as C8 isomers).

The relative ratio of the adsorption power of each isomer (selective adsorption power) during adsorption operation is affected by the effects of the constituent elements of silicon, aluminum, miniram, oxygen, and hydrogen, and their main crystal structure, as well as the effects of the substituent cations. The effect is enormous.

Until now, the Group 1 cations include lithium, sodium, potassium, rubidium, cesium, silver, copper, and the Group Ⅰ cations include Beryl, magnesium, strontium, barium, zinc, cadmium, mercury, etc. In addition, titanium, vanadium, chromium, nickel, cobalt, iron, manganese, rare earths, uranium, lead, etc. are also known.

The selectivity between hydrocarbons, including each isomer of C8, is not fully understood, but in general, the effects of pores in zeolite, minute changes in pore diameter due to cation species, and surface The effect of electron density is considered.

It goes without saying that the absolute value of selectivity between isomers is an extremely important factor in adsorption operations.

Therefore, during zeolite synthesis, efforts were made to improve selectivity by replacing the zeolite, which is generally composed of sodium or potassium types, with the above cations, and to create complex cation types to achieve the acid addition effect. There are also examples.

The main groups being studied are Groups 1 and 2, but by combining two types of cations that have selectivity in one direction, it is possible to achieve higher selectivity than a single cation type. Several species are known to confer sex.

The present inventors investigated the cations of Group 1, Group Ⅰ, and Group Ⅰ, and found that cation type 1 has selectivity in one direction, and other cations have selectivity in one direction. In this system, when we combined two types of cations that showed selectivity in different directions, in some cases, surprisingly, the mutual selectivities did not cancel each other out, and on the contrary, the absolute value of selectivity increased significantly. I discovered something to do.

That is, when used alone, potassium ions have a selectivity to disparate xylene over meta-xylene, and when used alone, lithium ions, cadmium ions, zinc ions, iron ions, nickel ions, or cobalt ions have selectivity to meta-xylene. When a zeolite having a composition of potassium-lithium, potassium-cadmium, potassium-zinc, potassium-iron, potassium-nickel, or potassium-cobalt is created by combining the It also noticeably turned into a dog.

The adsorbent of the present invention can be produced by using faujasite type zeolite among zeolites as a starting material and subjecting it to complex ion exchange as described above.

The starting material, faujasite-type zeolite, is a type of crystalline alumina-silicate that is generally called a zeolite, and has a crystalline structure.

It belongs to the 4th group.

Due to its crystal structure, it is called a "double hexacyclic ring."

The fourth group includes zeolites called faujasite, chabasite, gmelinite, ZK-5, and L, of which faujasite is a type of polyhedral cage.

Characterized by β, 26-hedron.

In addition to natural faujasite, typical faujasites include oxides such as Na2O, Al2O3, 2,55i0
2.

6H20, unit cell constant display Na86 [(AlO2)8
6(Si02)106]-264H20 density 1.9
3g/c, c, , unit cell constant 2'5.02-
24.86 people, void volume 0.50 c, c, /c, c,
There are X-type synthetic zeolites, which are characterized by an aperture diameter of 12 rings - 7.4 people, a 6 ring - 2.2 people, and a velocity aperture diameter of 8.1 people.

Also, oxidation display Na2O, A403.4.8StO2,8
,9H20,.

Unit cell constant display Na 56 ((AAO2) 56 (S
iO□)t3i].

250H20, density 1.92 g/c, c, unit cell constant 24.85-24.61, void volume 0.4
8c, c, /c, c, , Opening diameter: 12 items 7.4 people, 6
Characterized by a ring of 2.2 people and a velocity aperture of 8.1 people, Y
There is a type synthetic zeolite.

Of the oxidation indicators, Na is used during zeolite synthesis mainly due to synthetic requirements, and after crystal formation,
It is used after being substituted with a cation such as an alkali metal ion if necessary.

Cation replacement can be achieved by dissolving a soluble metal salt in water and bringing it into contact with the starting material.

As the metal salt, chlorides, nitrate compounds, sulfate compounds, carbonate compounds, etc. are usually used, and the absolute amount of cations is 0% of the equivalent in the faujasite-type superolide to be exchanged.
．． It is desirable to include 8 times or more.

Further, the salt concentration of the solution for ion exchange is preferably from 0.01 weight to a saturated solution, but preferably from 5 to 20 weight.

The temperature used during the exchange ranges from 2°C to 98°C, but a relatively high temperature is desirable in order to speed up the ion exchange time.

Although the cation of the starting material is usually in the sodium form, it is desirable to reduce the amount of sodium remaining after ion exchange to about 10% by weight or less.

Faujasite-type zeolite, which has been ion-exchanged through such operations, is usually dried to an appropriate amount of moisture through drying methods such as vacuum drying, freeze drying, hot air drying, and electric oven drying before use. .

Before use, an elemental analyzer is applied to confirm the constituent element ratio, cation composition ratio, substitution rate, etc., and an X-ray diffractometer is used to confirm the crystal structure.

The shape of the adsorbent of the present invention when used is from 2 microns to 20 microns.
Although it can be used in a very wide range up to μ-inch pellets containing an inorganic binder of about From the viewpoint of reducing pressure loss and facilitating operation, it is desirable to use particles or pellets with a large particle size.

Specific examples of substances to be separated for which the adsorbent of the present invention can be suitably used include mixtures of two to four of ethylbenzene, para-xylene, meta-xylene, ortho-xylene, and those obtained from petroleum naphtha. Examples include separation of aliphatic and aromatic mixtures, and there are no restrictions on composition, component ratio, etc.

The adsorbent of the present invention is used as a means of separation in adsorption operations. For example, by using adsorption beds in a batch manner, or by combining batch-type adsorption beds in multiple stages, a virtual moving bed or a virtual A countercurrent extraction operation, a displacement expansion separation operation, etc. are preferable, but the mode of use is not limited.

Example Commercially available faujasite zeolite (Y-type) was molded into 48 to 80 mesh, packed in a glass packed tower, and
At ~95°C, an ion exchange solution containing the cations shown in Table 1 was heated to a total metal salt concentration of 15 wt. over 4 hours to remove 50% of the cations in the exchangeable zeolite. Pour twice the amount of liquid.

After passing through the liquid, it was thoroughly washed with water in the same packed tower, extracted from the packed tower, and calcined at 420°C for 28 hours before being used as an adsorbent.

The mixed xylenes used in the equilibrium adsorption experiment are ethylbenzene (EB), para-xylene (pX), meta-xylene (
mX) and ortho-xylene (oX) at 20% and 2
Adjustments are made to contain 0%, 40%, and 20%, and no diluent is used.

The adsorbent is brought into contact with the adsorbent on a glass column at 20°C, and the adsorbent is washed with n-hexane immediately after the contact.

After washing, the xylene mixture adsorbed in the adsorbent is desorbed with methanol and quantitatively determined by gas chromatography.

The selective adsorption rate α between A isomer and B isomer is determined according to the following definition.

Comparative Example 1 Cation replacement shown in Table 3 was performed in the same manner as in Example,
Selectivity was measured.

The results are shown in Table 2.

Table 3 shows the elemental analysis results of the faujasite zeolite used in the above examples.

The analysis is performed after the zeolite is heated and dehydrated at 400° C. for 16 hours to completely remove volatile components.

The X-ray diffraction pattern of the faujasite zeolite used in the above examples is shown in Table 4.

These values were determined using standard methods.

The radiation was copper di-alpha doublet, and a Geiger counter spectrometer with a chart pen recorder was used.

The ultimate height ■ and the position as a function of twice the Bragg angle were read from the spectrometer chart.

From these, Io and the internal plane-to-plane distance measurement value d were calculated.

Comparative Example 2 In the same manner as in Example, the ion type was replaced with -Be (zeolite/16.15) and the ion type was replaced with -Ga (zeolite/16.16), and the selectivity was measured.

The results and elemental analysis results are shown in Table 5, along with other ion types to be compared.
represents the adsorption capacity of each zeolite, and from the weight percent (yox + ymx'yBB + ypx) of each xylene component in the adsorption phase measured during selectivity measurement as described in the example,
It was calculated using the following formula.

The complex ion substitution combinations of faujasite-type zeolite are combined with potassium-lithium, potassium-cadmium,
Potassium-zinc, potassium-iron, potassium-nickel,
When potassium-cobalt was used, an adsorbent with high selectivity not seen with single ion replacement was obtained.

Even in the case of similar complex ion exchange, the selectivity of potassium-beryllium and potassium-gallium combinations is inferior to that of potassium single ion exchange, so it can be said that the former combination has an effect unique to it.

These combinations found in the present invention are particularly effective when used for C3 isomer separation, and from Table 5,
It can be seen that the potassium-lithium system is particularly suitable for separation by chromatography since it has a significantly large adsorption capacity.

Claims (1)

[Claims] 1 Faujasite type synthetic zeolite with potassium,
A method for producing a composite adsorbent made of faujasite-type zeolite, characterized by performing composite ion substitution in combination with a metal selected from the group consisting of cadmium, lithium, zinc, iron, nickel, and cobalt. .