Catalyst for the conversion of liquid ammonia precursor solutions to gaseous ammonia avoiding the formation of undesired side products

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This invention describes a novel catalyst designed for efficiently converting liquid ammonia precursor solutions (especially formate-containing or formic acid-derived compounds) into gaseous ammonia for use in selective catalytic reduction (SCR) of NOx in exhaust gas treatment. Unlike previous catalysts, this catalyst minimizes the formation of unwanted and hazardous side products such as formic acid, methanamide, carbon monoxide, and hydrogen cyanide. The catalyst is composed of a high-surface-area metal oxide support (e.g., TiO2, Al2O3) doped with very small, finely dispersed amounts of noble metals (like Au, Pd, Ag, or Cu) that are specifically chosen and distributed to promote efficient conversion while not oxidizing the produced ammonia. The invention also demonstrates remarkable resistance to hydrothermal aging and sulfur dioxide poisoning, ensuring reliable long-term performance in harsh exhaust environments.

Use CasesContent extracted from patent full text and abstract with AI.

• Automotive exhaust after-treatment systems for diesel or gasoline vehicles using SCR to reduce NOx emissions.
• Stationary power plants employing SCR technology for NOx reduction with alternative ammonia storage compounds.
• Industrial processes requiring safe and efficient on-demand ammonia generation from liquid precursors.
• Hydrogen production or fuel cells where hydrogen-containing gas generated via ammonia decomposition is needed.
• Applications where corrosion or emissions regulations restrict the use of traditional ammonia storage and release methods.

BenefitsContent extracted from patent full text and abstract with AI.

• Substantially reduces or eliminates the formation of toxic and corrosive side products (such as HCN, CO, methanamide, and formic acid) during ammonia precursor decomposition.
• Enables the use of safer, less hazardous ammonia storage and delivery methods (as compared to direct ammonia handling).
• Highly stable under harsh thermal and chemical environments, with strong resistance to aging and sulfur dioxide (SO2) poisoning, ensuring long operational life.
• Provides high selectivity and yield for ammonia production without simultaneously oxidizing ammonia into undesired byproducts.
• Flexible catalyst forms and compositions make it suitable for a wide range of reactor geometries and industrial setups.
• Improves environmental safety and compliance with stringent emission norms in transportation and stationary sources.

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Patent Abstract

The presented invention is related to a catalyst which can be used for the conversion of ammonia precursor solutions to gaseous ammonia and other gases to provide ammonia for the selective catalytic reduction process. Especially formate-containing or formate-related ammonia precursor compounds can be decomposed to unproblematic reaction products using the presented catalyst. Prior art catalysts produced toxic and/or corrosive reaction products from decomposition of formate-containing or formic acid derived ammonia storage compounds. The reaction products evolving with the presented novel catalyst may not exclusively be used as ammonia for the selective catalytic reduction process, but may also be used as hydrogen-containing gas with additional hydrogen stored as ammonia for further release. The catalyst is composed of a metal oxide which is required for efficient hydrolysis. On the metal oxide support, a noble metal catalyst for the decomposition of side products is deposited. The noble metal must not be active in the oxidation of ammonia. The catalyst is highly resistant to hydrothermal aging and shows good stability versus SO 2 poisoning, making it perfectly suitable for exhaust gas after-treatment purposes.