The impact of sulfur content in calcined petroleum coke on titanium dioxide production

The impact of sulfur content in calcined petroleum coke on titanium dioxide production lies in the fact that, as the primary reducing agent in the chlorination process, its sulfur content directly affects product quality, equipment lifespan, and environmental compliance.

In current mainstream chlorination-based titanium dioxide production, calcined petroleum coke (CPC) plays an irreplaceable role. It reacts with titanium feedstock and chlorine gas at high temperatures of approximately 950–1,000°C to produce titanium tetrachloride (TiCl₄), a key intermediate used in subsequent production stages.

In this process, the impact of sulfur is primarily reflected in the following aspects:

Impact on Chemical Reactions and Product Quality

Introduction of Impurities: Under the high temperatures of the chlorination reaction, sulfur in petroleum coke forms impurities such as sulfur chlorides (e.g., S₂Cl₂). These impurities become mixed into the resulting TiCl₄, increasing the difficulty and cost of subsequent refining and purification.

Impact on Final Product Purity: If the refining process is incomplete, residual sulfides will ultimately affect key pigment properties of the titanium dioxide product, such as whiteness, hue, and hiding power.

Formation of Stable Complexes: Studies have shown that titanium dioxide (TiO₂) forms complexes with sulfur-containing compounds that remain stable at high temperatures (up to the graphitization temperature), which may have a lasting impact on product performance.

Impact on Production Equipment and Processes

Exacerbates Equipment Corrosion: Sulfides (such as HCl and H₂S) generated during the chlorination reaction are highly corrosive. They accelerate corrosion of equipment such as chlorination furnaces, pipelines, and condensers, shortening equipment lifespan and increasing maintenance costs.

Increased Process Control Difficulty: Fluctuations in sulfur content can lead to instability in process parameters such as temperature and pressure during the chlorination reaction, increasing the complexity of production process control.

Impact on Environmental Protection and Compliance

Increased Burden on Exhaust Gas Treatment: High-sulfur petroleum coke generates large amounts of sulfur-containing exhaust gases, such as sulfur dioxide (SO₂), during the reaction and when burned as fuel. This requires larger and more expensive exhaust gas desulfurization systems to meet environmental emission standards.