Desulfurization mechanism of zinc oxide desulfurizer

Zinc oxide desulfurizer is a conversion and absorption type desulfurizer, and sulfur has a strong affinity, and the product zinc sulfide has a high stability. Therefore, zinc oxide desulfurizer can fine remove the hydrogen sulfide and part of the organic sulfur in the raw material, and the reaction performance with thiol in organic sulfur is better.

The reaction is exothermic projection, the temperature increase is not conducive to the reaction to the product direction, the equilibrium constant decreases, the desulfurization accuracy decreases, conversely, reduce the temperature can improve the desulfurization accuracy. Therefore, zinc oxide desulfurizer is used for medium and high temperature desulfurization with higher sulfur capacity, while low temperature desulfurization with lower sulfur capacity, but higher desulfurization accuracy.

According to the relationship between water vapor content, temperature and H2S equilibrium concentration, if the operating temperature and water vapor content are high, the equilibrium concentration of H2S will exceed the requirements for desulfurization purification index. 

The actual application of zinc oxide desulfurization, the process gas in the water vapor content is high (such as before the low-temperature conversion), the use of lower operating temperature to ensure the accuracy of desulfurization, the process gas does not contain water basically, the use of higher operating temperature, in order to ensure the accuracy of desulfurization under the premise of giving full play to the effectiveness of the desulfurizing agent to achieve the highest possible sulfur capacity.

For example, desulfurization operation at 400 ℃, the general water vapor / dry gas (material ratio, the same below) is not more than 0.01, at this time, the equilibrium concentration of H2S is 0.02 * 10-6 (material fraction, the same below), at 200 ℃, water vapor / dry gas is 0.3 (low variation operating conditions) when operating, the equilibrium concentration of H2S is less than 0.005 * 10-6.

When hydrogen is present in the raw material, carbonyl sulfide, carbon disulfide, mercaptan and thioether will undergo conversion reactions at the reaction temperature and the generated hydrogen sulfide is further absorbed by zinc oxide. Thiophene and its derivatives have a low ability to undergo conversion reaction with hydrogen on zinc oxide, therefore, thiophene sulfides cannot be removed by zinc oxide alone and need to be converted to hydrogen sulfide with the help of cobalt-molybdenum catalyst hydrogenation before they can be removed by zinc oxide desulfurizer.

Zinc oxide desulfurizer is mainly used in the production of methanol, synthetic natural gas, coke oven gas, ammonia, petrochemical dry gas, fine chemical gas phase H2S removal and diesel/gasoline H2S removal.

The main indicators of PZT-01 room temperature zinc oxide desulfurizer and PZT-02 medium temperature (high temperature) zinc oxide desulfurizer are as follows.

Appearance and specification: The external form of ZnO desulfurizer is in the shape of yellow and white clover, and the specification is Φ4~5×3~20mm in diameter

Composition: The main components are ZnO and active components (more than 95%)

Specific surface area: the larger the specific surface area of ZnO desulfurizer, the larger the contact area with hydrogen sulfide gas and the faster the reaction speed

Sulfur capacity: is an important indicator of the quality of zinc oxide desulfurizer, refers to the number of kilograms of sulfur absorbed per 100 kilograms of zinc oxide desulfurizer, often expressed as a percentage. Shandong zinc oxide desulfurization agent penetration sulfur capacity of up to 35%, penetration sulfur capacity that unit volume of zinc oxide desulfurization agent in ensuring the process purification index can absorb the capacity of sulfur.

Crushing strength: The higher the percentage, the better the crushing resistance.