Catalytic Oxidation of Sulphide Species

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This invention provides a catalytic process for oxidizing sulphide compounds (such as hydrogen sulphide, H2S) in liquids or gases using a specific type of chelate complex. These complexes consist of a metal ion (like iron, manganese, cobalt, or nickel) held within a ring-shaped, highly charged organic ligand (porphyrin, phthalocyanine, or porphyrazine) that carries cationic (positively charged) substituents. When exposed to oxygen, these catalysts can rapidly and efficiently convert toxic sulphides to safer, more manageable substances such as elemental sulfur or thiosulfate, operating effectively at low concentrations and in a broad pH range. The chelate complexes can be dissolved in solution or immobilized on various supports (like glass, clay, polymers, or dendrimers), making the process adaptable to several industrial scenarios.

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• Removal of hydrogen sulphide from natural gas streams in natural gas processing plants.
• Desulfurization of industrial waste gases (e.g., from petroleum refineries, coke plants, and chemical manufacturing).
• Treatment of biogas to eliminate toxic and corrosive H2S, improving quality for energy use.
• Purification of wastewater or sewage with sulphide contamination (e.g., from mining, food processing, or municipal sources).
• Industrial conversion and recovery of elemental sulfur for reuse or safe disposal.
• Air treatment systems in environments (such as sewers or landfills) where sulphide gases are a problem.
• Purification of ionic liquids contaminated with sulphide species.

BenefitsContent extracted from patent full text and abstract with AI.

• Rapid and highly efficient oxidation/removal of toxic and malodorous hydrogen sulphide and similar sulphide species, even at low concentrations.
• Catalyst is not consumed during the process and does not require complex regeneration steps—simply uses ambient oxygen or air for re-oxidation.
• Operates effectively in a broad range of conditions (aqueous or non-aqueous, various pH, homogeneous or immobilized/heterogeneous setups).
• Flexible implementation: catalyst complexes can be dissolved, or immobilized onto solids or within polymers, providing adaptability to different process needs.
• Lower catalyst loads required (micromolar vs. millimolar in previous approaches), reducing costs and environmental impact.
• By-products (elemental sulfur or thiosulfate) can be easily separated, collected, or even reused as industrial commodities.
• Enables the treatment of sulphide-containing gas or liquid streams that are difficult to process by existing high-temperature or high-investment technologies (like the Claus process), especially when sulphide levels are low or variable.

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Patent Abstract

The present invention relates to a process for the catalytic oxidation of sulphide, mono- and/or dihydrogen sulphide, comprising the step of contacting the sulphide, mono- and/or dihydrogen sulphide in the presence of oxygen with a chelate complex comprising (i) a metal cation selected from the group consisting of Fez+, Mnz+, Niz* and Coz+, where z = 2 or 3, and (ii) a chelate ligand containing a porphyrin, a phtha!ocyanine or a porphyrazine ring coordinated to the metal cation, and at least one cationic substituent covalentiy attached to the ring in the chelate ligand.