Sulfur recovery catalysts serve as the core medium for desulfurization and sulfur production in Claus units. Their operational stability directly affects the sulfur recovery rate and tail gas compliance of the whole plant. These catalysts are highly sensitive to process conditions, medium composition and operating procedures. Standardized operation throughout the process is required to prevent deactivation, poisoning, coking and sulfur deposition, so as to maintain catalytic activity and extend service life.
During normal operation, key process parameters shall be strictly controlled. Keep the molar ratio of H₂S to SO₂ at approximately 2:1, and avoid excessive oxygen content. Excess oxygen will cause sulfate poisoning of catalysts, covering active sites and leading to permanent activity loss. Bed temperature shall also be well regulated. Low temperature will result in liquid sulfur condensation and pore blockage, while overheating will cause carrier sintering and grain growth, bringing irreversible damage to the catalyst structure.
Standard start-up, shutdown and intermittent operation are essential for catalyst protection. During shutdown and cooling, never let air enter the reactor directly. Use nitrogen for inert purging and maintain sealed pressure to prevent oxidation of sulfided active components. Maintain slight positive pressure for short-term shutdown to avoid backflow of moisture and air. For long-term outage, thoroughly purge the bed to remove residual sulfur deposits and impurities, then seal the equipment properly. After loading fresh or regenerated catalysts, level the bed and remove fine particles to prevent gas maldistribution and channeling.
In daily maintenance, control impurities in feed gas including heavy hydrocarbons, dust and moisture to avoid carbon deposition from heavy hydrocarbon cracking and pore clogging by dust. Regularly monitor bed pressure drop and tail gas indicators. Perform thermal regeneration and purging timely to remove deposited sulfur and restore pore permeability, ensuring long-term stable and efficient operation of the unit.