CN1044268A - Trace krypton, removal of nitrogen oxide adsorbent of molecular sieve in the xenon - Google Patents

Abstract

A kind of adsorbent of molecular sieve that is used for xenon trace krypton, removal of nitrogen oxide is made with the erionite or the mordenite of basic metal (K, Cs, Rb) or calcium exchange.This sorbent material is used to prepare ultrapure xenon, can make the rough xenon gas that contains 700PPm left and right sides krypton under 20～-60 ℃ of conditions, obtains 99.999% ultrapure xenon, the renewable repeated use of sorbent material.

Description

Trace krypton, removal of nitrogen oxide adsorbent of molecular sieve in the xenon

The present invention is a kind of sorbent material, exactly is a kind of molecular sieve that is used for adsorbs xenon trace krypton and oxynitride and preparation method thereof.

Xenon is called as gold gas, and industrial mainly is to obtain by being made with extra care by the thick xenon that obtains in the oxygen generating plant (containing xenon more than 99.9%).The process for purification of wherein, rectifying-catalysis-absorption is a kind of method of the ultrapure xenon of preparation comparatively generally taked.In this flow process, the krypton and the product after the catalyzed reaction of the trace in the thick xenon must be removed by sorbent material.Thereby xenon is purified.For example, the xenon purification techniques sorbent material of West Germany Linde Co (" external rare gas " 1977.1.1) employing is selected gac for use.But because gac is to xenon, the fractionation by adsorption coefficient of krypton only is 15, thereby sorbent material can be relatively poor to the adsorption selectivity of xenon, krypton, if when obtaining high-purity xenon, will significantly descend to the extraction yield of xenon.In addition, the amount of the sorbent used use of this method is bigger, and the regeneration of sorbent material is also relatively more difficult.Utilize molecular sieve also can select adsorbs xenon, krypton and oxynitride.For example on the CuY molecular sieve (" Zeoli-te molecular sieves structure; chcmistry and use " Donald W.Breck) krypton xenon-133 gas when dividing potential drop be 300torr, when adsorption temp is-80 ℃, the absorption krypton is 60ml/g, adsorbs xenon is 55ml/g, when adsorption temp was-65 ℃, the absorption krypton was 45ml/g, and adsorbs xenon is 65ml/g.Utilize the difference of molecular sieve to nitrogen xenon adsorptive capacity, can be used for the separate xenon krypton-85 gas, but the adsorptive capacity of xenon krypton differs less on this molecular sieve, its separation efficiency to the xenon krypton-85 gas is bad.Utilize the sorbent material separate xenon krypton-85 gas except that above-mentioned, also can remove trace krypton in the xenon with rectification method.But this method energy consumption is big, and extraction yield is low, and requirement condition is also harsh.Therefore, be very important work for the sorbent material for preparing ultrapure xenon, a kind of well behaved energy separate xenon krypton of preparation.

The objective of the invention is to prepare a kind of sorbent material, use it molecular diameter can be differed very little, xenon that molecular physical chemistry character is extremely similar and krypton are selected absorption, thereby krypton gas is separated from xenon.

The present invention select for use erionite or and mordenite, utilize the characteristics that the aperture of molecular sieve can modulation, carry out certain ion-exchange by the positively charged ion in different alkalimetal ions or alkaline-earth metal ions calcium and the molecular sieve, thereby make the sorbent material of krypton gas and oxynitride in a kind of high sampling adsorbs xenon, utilize this sorbent material can make 99.9% thick xenon, be refined into 99.99% ultrapure xenon.Specifically, this sorbent material is that the erionite and the mordenite that are expressed from the next mix by a certain percentage, wherein:

(1) erionite

X Na ₂O·（1-x）M ₂O·Al ₂O ₃·（6.4～7.4）SiO ₂·（6～8）H ₂O

In the formula: M is K, Rb, Cs,

X is 0.1～0.9;

(2) mordenite

X·Na ₂O（1-x）M ₂/nO·Al ₂O ₃·（10～12）SiO ₂·（6-9）H ₂O

In the formula: M is K, Ca,

X is 0.5～0.9;

N is 1 or 2.

Above-mentioned erionite or mordenite, but single component also two kinds of zeolites can be mixed according to a certain percentage as sorbent material as sorbent material, the composition weight percent of its sorbent material is:

(1) above-mentioned (1) erionite 0～100%;

(2) above-mentioned (2) mordenite 0～100%;

The surface-area of this sorbent material is 10～140m ²/ gram, adsorpting water quantity is a 8-10%(weight), bulk density is 0.65～0.70g/ml, granularity φ 1～2mm, and intensity is greater than the 5Kg/ grain.This sorbent material is applicable to normal temperature, static, the dynamic adsorption of low temperature (20～-80 ℃).

This preparation of adsorbent process is:

(1) synthetic erionite is with 0.5～1.5N KNO ₃, CsCl or RbCl solution 85～95 ℃ of exchanges 0.5～2 hour, filter, and repeated exchanged is filtered for the second time again, and filter cake is washed till no No through deionized water ₃-or the Cl-ion, at 100～120 ℃ of dry 2-3 hours;

(2) synthesizing flokite is with 0.5～1.5N KNO ₃Or CaCl ₂Solution 85～95 ℃ of exchanges 0.5～2 hour, filters, and is washed till no No with deionized water - ₃Or Cl ^-Ion was at 100～120 ℃ of dry 2-3 hours;

(3) add the 15-20% clay in the product that above-mentioned (1), (2) are obtained, the mixing moulding after drying was in 500～600 ℃ of roasting 2-5 hours.

This Preparation of catalysts process and performance further specify by following example.

Example 1, K erionite preparation of adsorbent

Get 75 gram KNO ₃Be dissolved in the 1500ml deionized water, treat dissolving fully after, add 30 gram synthetic erionites, stir under 85～95 ℃ of conditions and carry out ion-exchange filtration in 1 hour, the same preparation 1500mlKNO solution carries out the exchange second time, after treating the solution cooling, filter, be washed till no NO with deionized water - ₃Till, filter cake was 100～120 ℃ of dryings 3 hours.After getting molecular sieve 24 grams after the exchange and adding 6 gram clays and mix, it is spherical to be shaped to φ 1～2mm, in 550 ℃ of roastings 3 hours finished product.Its composition can be represented by the formula:

0.3Na ₂O·0.7K ₂O·Al ₂O ₃·7SiO ₂·7H ₂O.

Example 2～5 preparation of adsorbent

The preparation process of example 2～5 is as described in the example 1, its exchanger and other condition and result such as table 1.

Table 1, preparation of adsorbent

	Exchanger (gram)	Deionized water (milliliter)	Synthetic zeolite (gram)	The exchange number of times	The sorbent material composition formula
						Example 2	KNO 32.5	250	Mordenite 20	1	0.9Na 2O·0.1K 2O·Al 2O 3·10SiO 27H 2O
Example 3	CaCl 72	700	Mordenite 40	1	0.5Na 2O·0.5CaO·Al 2O 3·10SiO 2·6H 2O
						Example 4	CsCl 1.94	100	Erionite 4	2	0.4Cs 2O·0.6K 2O·Al 2O 3·10SiO2·6H 2O
Example 5	RbCl 1.44	240	Erionite 4	2	0.6Rb 2O·0.4K 2O·Al 2O 10SiO 2·6H 2O

Example 6, the performance test of sorbent material

Use-case 1 gained sorbent material, sorbent material is seated in the copper pipe that adsorption column is φ 8 * 1m/m diameter, long 1 meter is the U type, and experiment is with the xenon that contains the 5000PPm krypton, in the time of-78 ℃, linear velocity is 1.35 cels, ventilated 10 minutes, krypton gas penetrates, operation when at 0 ℃, linear velocity is 0.85 cel, penetrates in 20 minutes.

With pack into the copper pipe of φ 10 * 1m/m diameter of example 2 gained sorbent materials, long 1 meter is the U type, and in the time of-78 ℃, experiment is with the xenon that contains the 5000PPm krypton, and linear velocity is 2.55 cels, and ventilating, krypton gas penetrates after 20 minutes.When linear velocity changes 0.85 cel into, ventilate after 110 minutes krypton content＜10PPm in the xenon.

Example 7: the application experiment of sorbent material

The sorbent material that makes with example 1 φ 47 * 4m/m diameter of packing into, length is made snakelike adsorption column for the 520m/m copper pipe, with 60 liters/time, thick xenon (the containing krypton 507PPm) adsorption column of flowing through, adsorption temp-60～-80 ℃, linear velocity is 1.0 cels, obtains 99.999% high-purity xenon, handles the experimental result of the thick xenon of 700 liters and lists in table 2.

Analytical results behind table 2, the thick xenon adsorption cleaning

Example 8: by example 7 adsorption test condition and methods, handle the pure xenon 5.2Kg(of the thick xenon of 5.73Kg (content 655.5PPm) acquisition and contain krypton less than 19PPm), yield is greater than 90%.

Example 9: the performance of sorbent material

With the sorbent material of example 2 preparations, static adsorbs xenon, krypton down, the adsorptive capacity when under 80mmHg, measuring differing temps, the results list 3.

The absorption property of table 3, K mordenite

Example 10

With the prepared sorbent material of example 1, example 2, static adsorbs xenon krypton down, the adsorptive capacity result when under 80mmHg, measuring 0 ℃ and-80 ℃.As a comparison, under similarity condition, with the experiment of making comparisons of synthetic erionite and mordenite raw material, if as table 4.

The absorption property of table 4, sorbent material

Sorbent material	0 ℃-80 ℃ of adsorption temps	Adsorptive capacity (mg/g) xenon krypton
			Erionite (raw material)	0℃	200 40
－80℃	300 175
		Mordenite (raw material)		0℃	100 90
－80℃	18 15
			Embodiment 1 erionite	0℃	90 140
－80℃	65 90
		Real row 2 mordenites		0℃	10 43.3
－80℃	31.7 59.4

The life-span of example 11 sorbent materials

Erionite and the mordenite of getting example 1 and example 2 preparations in 8: 2 ratio mix the back as sorbent material, experimentize by example 7 described conditions, when krypton content is greater than 19PPm in purifying xenon, sorbent material is regenerated, the regenerated condition is: under 240～280 ℃ of the temperature, be evacuated to 10mmHg, 2 hours.Repeat experiment after the regeneration.Its result such as table 5.

Table 5, sorbent material life-span

Example 12, sorbent material are used for the oxynitride fractionation by adsorption

With the sorbent material of example 3 preparations, static adsorbs xenon, krypton, oxynitride down, adsorptive capacity when under the 80mmHg condition, measuring differing temps, result such as table 6.

The absorption property of table 6 Ca mordenite

Above-mentioned example can be seen, the alkali metal containing (K, Cs, Rb) that the present invention is used or the adsorbent of molecular sieve of alkaline-earth metal (Ca) can be selected krypton and nitrogen oxide in the adsorbs xenon gas in enclosing in that wider temperature is general. Iterative regenerable keeps absorption property after the adsorbent adsorbed gas. Use adsorbent of the present invention to make to contain the industrial crude xenon of 700PPm left and right sides krypton, be refined into 99.999% ultrapure xenon. The xenon recovery rate is greater than 83%.

Claims (2)

1, a kind ofly being used for removing erionite and the mordenite molecular sieve sorbent material that xenon krypton, oxynitride are used, is that erionite and the mordenite that is expressed from the next mixes by a certain percentage, wherein:

(1) erionite

XNa ₂O.(1-X)M ₂O.Al ₂O ₃.(6.4～7.4)SiO ₂.(6～8)H ₂O

In the formula: M is K, Rb, and Cs,

X is 0.1～0.9;

(2) mordenite

X.Na ₂O(1-X)M ₂/nO.Al ₂O ₃.(10～12)SiO ₂.(6-9)H ₂O

In the formula: M is K, Ca,

X0.5～0.9，

N is 1 or 2;

(3), above-mentioned two kinds of zeolites are pressed column weight amount percentage mix:

(a) following formula (1) erionite 0～100%;

(b) following formula (2) mordenite 0～100%.

2, the described Preparation of catalysts method of a kind of preparation claim 1, its method is:

(1) synthetic erionite is with 0.5～1.5N KNO, and CsCl or RbCl solution filtered 85～95 ℃ of exchanges in 0.5～2 hour, and repeated exchanged is filtered for the second time again, and filter cake is washed till no No through deionized water ₃-or the Cl-ion, at 100～120 ℃ of dry 2-3 hours;

(2) synthesizing flokite is with 0.5～1.5N KNO ₃Or CaCl ₂Solution filtered 85～95 ℃ of exchanges in 0.5～2 hour, was washed till no NO with deionized water ₃-or the Cl-ion at 100～120 ℃ of dry 2-3 hours;

(3) add the 15-20% clay in the product that above-mentioned (1), (2) are obtained, the mixing moulding after drying was in 500～600 ℃ of roasting 2-5 hours.