The Application of Claus Catalyst

Claus is the core component of the Sulfur Recovery Unit (SRU), which converts H₂S in the sour gas into elemental sulfur. The Claus catalyst is divided into two types: aluminum-based and titanium-based.

1) Aluminum-based active alumina Claus catalyst (most commonly used, low cost)

Components: High-purity active Al₂O₃ (≥ 92%), white spherical, with a particle size of φ3 to 6mm as the main type.

Core feature

- The main reaction activity is high, with a specific surface area of ≥ 200 - 280 m²/g. It has a large pore structure, which is conducive to the desorption of sulfur molecules.

- Weaknesses: The hydrolysis activity of organic sulfur (COS/CS₂) is relatively low, and it is prone to sulfate poisoning (when oxygen exceeds the limit, aluminum sulfate is generated on the surface, causing permanent deactivation).

- Applications: Suitable for devices with low organic sulfur content and stable oxygen control. Both primary and secondary reactors can be used.

2) Titanium-based (TiO₂) Claus catalyst (high-end type)

Components: TiO₂ is the active core, and some aluminum-titanium composite spheres are included.

Core feature

- The hydrolysis activity of COS and CS₂ is much higher than that of aluminum-based materials; they have strong resistance to sulfate corrosion. Sulfates are unstable on the surface of TiO₂ and can be reduced and decomposed by H₂S. They have stronger resistance to oxygen fluctuations.

- Disadvantages: High price, slightly lower primary reaction activity than high-quality alumina.

- Selection strategy: Place in the primary reactor to specifically handle CS₂ and COS generated by the combustion furnace, and prioritize the use for acid gas from natural gas / coal chemical industry with high organic sulfur content.

Main application scenarios:

1. Refineries: Sulfur recovery from acid gas in catalytic cracking and hydrogenation units.

2. Natural gas purification plants: Acid gas from natural gas after H₂S removal for the Claus unit.

3. Coal chemical / coking: Sulfur recovery from coal gasification and coke oven gas acid gas, with high organic sulfur content, often using titanium-based materials.

4. Others: Sulfur recovery from synthesis ammonia, methanol plants, and smelting flue gas.