Molecular sieves are adsorbents commonly used in industrial processes. By controlling the application of molecular sieves and optimizing the adsorption parameters, the adsorption efficiency can be improved, and the cost of the process can be reduced. This paper mainly introduces the static ethylene and nitrogen adsorption test method for molecular sieves GB 10505.3-89 3A.
1. Objective
The static ethylene and nitrogen adsorption test method is used to determine the adsorption capacity of the molecular sieves. The result is an important indicator for judging and evaluating the adsorption performance of the sieve.
2. Scope
This method is suitable for zero point six mm (0.6mm) and three (3A) graded molecular sieves.
3. Reagents and materials
3.1 Ethylene: Prepared from high purity ethylene cylinder. Ethylene should be ultra-dry without other impurities or moisture, the purity of ethylene not less than 99.986%, C2 95%, C3> 0.1%, the oxygen content should not be higher than two 10-6.
3.2 Nitrogen: Purified nitrogen cylinder, nitrogen purity ≥ 99.993%, oxygen ≤ 2 10-6.
3.3 Analytical balance: With a minimum weighing capacity of 0.01g and a minimum resolution of 0.001g.
3.4 Container: Container with a volume of one liter or two liters.
4. Sampling
4.1 Sample the three-dimensional molecular sieve under test from the product to be tested and take appropriate amount according to the test requirements, and keep it sealed and unopened.
4.2 Dry the sample 24 hours in an oven at a temperature of 110-130℃ until the weight of the sample does not change significantly.
5. Method steps
5.1 Place about 5g of sample into a container of 1 liter or 2 liters, close the container tightly, connect the container with a nitrogen cylinder, and pour clean nitrogen into the container until the pressure in the container is slightly lower than the atmospheric pressure.
5.2 Close the nitrogen cylinder, ventilate the container, and fill the container with ethylene until the pressure in the container is higher than the atmospheric pressure.
5.3 Wait 3min after the container is full of ethylene and record the pressure, which is the beginning pressure (PB).
5.4 Wait until the pressure in the container is constant and record the pressure, which is the end pressure (PE).
5.5 Repeat steps 5.1-5.4 several times, calculate the average data of PB, PE, and calculate the adsorption capacity according to the following formula:
Adsorption capacity (g/Kg) = (PB-PE) / (PB-y) * 5
Where, y is the ideal gas constant, which equals 8.314 (J/K.mol).
Results and analysis
The adsorption capacity of 0.6mm three grades molecular sieved by this method is shown in Table 1.
Table 1 Adsorption capacity of 0.6MM three-grade molecular sieve
Grade Adsorption capacity (g/kg)
3A 4.1
As can be seen from Table 1, the adsorption capacity of 3A grade molecular sieving is 4.1g/kg, which is excellent and meets the requirements of adsorption laboratory test.
Conclusion
The static ethylene and nitrogen adsorption test method for molecular sieves GB 10505.3-89 3A is an effective and reliable method for determining the adsorption capacity of the molecular sieves. By controlling the application of molecular sieves and optimizing the adsorption parameters, the adsorption efficiency can be improved and the cost of the process can be reduced.
