In the sulfur-recovery industry, the conventional Claus process has been widely adopted. Nevertheless, constrained by thermodynamic equilibrium, the reversible reaction between H₂S and SO₂ cannot achieve complete conversion of hydrogen sulfide to elemental sulfur. Even with continuous optimization of operating parameters, the overall sulfur-recovery efficiency is capped by reaction equilibrium. Sulfide species remain in tail gas. Enterprises are often required to install complex tail-gas hydrogenation sections to meet environmental emission requirements, which brings higher capital investment and operating energy consumption.
The H₂S selective-oxidation-to-sulfur technology breaks the inherent limitations of Claus equilibrium and upgrades the process route from the perspective of reaction mechanism. Instead of relying on the reversible equilibrium reaction between H₂S and SO₂, this technology directly and selectively oxidizes hydrogen sulfide into elemental sulfur, enabling nearly complete H₂S conversion in theory. However, the reaction system contains complex components including H₂S, O₂, sulfur vapor and water vapor. Deep-oxidation side reactions readily occur to produce sulfur dioxide, which directly reduces elemental sulfur yield. The industrial feasibility of the whole process hinges on the catalyst's capability for directional reaction regulation.
In this system, H₂S is first converted into elemental sulfur, which can be further oxidized into SO₂. To achieve favorable sulfur-production performance, it is critical to accelerate the main reaction and suppress subsequent deep-oxidation side reactions. The catalyst shall minimize side-reaction probability over a broad temperature window, guarantee sufficient H₂S conversion and high selectivity to curb SO₂ formation. Meanwhile, sound mechanical properties such as adequate crush strength and low attrition rate are required to adapt to industrial reactor loading and gas-flow erosion for long-term stable operation.
Shandong Xunda Chemical Industrial Group Co., Ltd. has developed proprietary catalysts for H₂S selective oxidation to sulfur. The catalyst modulates reaction-rate ratios across a wide operating-temperature range, restrains deep-oxidation of sulfur to cut SO₂ generation, and balances conversion efficiency and sulfur-production selectivity. It is suitable for sulfur-recovery working conditions of various sulfide-containing gas sources in refinery and coal-chemical industries.
Faced with increasingly stringent global environmental standards, sulfur-recovery facilities pursue not only emission compliance, but also optimized capital expenditure, energy consumption and economic benefits from sulfur resource recovery. The selective-oxidation process offers an alternative viable technical solution for sulfur-recovery projects.