Composite material

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This invention describes a composite material made from diatomaceous earth (a macroporous silicate-based structure) partially replaced with a small-pore zeolite (such as chabazite), which has been functionalised with copper, iron, or both. These composites are engineered as particles and are particularly useful as selective catalytic reduction (SCR) catalysts for treating exhaust gases, especially for the removal of nitrogen oxides (NOx). The method for producing the material maintains the favorable large-scale pore structure of diatomaceous earth while introducing catalytic zeolite properties at the microscopic level.

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• SCR catalysts in the exhaust treatment systems of diesel engines and lean-burn internal combustion engines for vehicles.
• Emission control in stationary sources of NOx, such as power plants and industrial furnaces.
• Catalytic converters in automotive emission treatment systems for reducing NOx emissions to meet environmental regulations.
• Components for multi-stage emission control systems combining SCR with other catalytic processes.
• Use in honeycomb monoliths or as a washcoat in emission treatment substrates for enhanced NOx abatement.

BenefitsContent extracted from patent full text and abstract with AI.

• Enhanced catalytic activity for SCR, especially for the reduction of NOx into nitrogen and water with high efficiency.
• Improved accessibility of reactant gases to catalytic sites due to the retained macroporous structure, leading to improved mass transfer and higher conversion rates.
• Greater selectivity and reduced production of undesirable by-products, such as nitrous oxide (N2O).
• Resistance to deactivation by hydrocarbons due to the small-pore zeolite structure, maintaining catalyst performance in real-world exhaust conditions.
• Mechanical robustness and scalability due to the use of diatomaceous earth, which is naturally abundant and has favorable physical properties.
• Versatility in catalyst composition through the ability to functionalise with copper, iron, or both, and compatibility with existing emission treatment architectures.

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Patent Abstract

A composite material comprises a macroporous silicate-based material at least partially substituted with at least one microporous zeolite, the microporous zeolite functionalised with either copper, iron or both copper and iron, and wherein the composite material is in the form of particles. The composite material is obtained using a method comprising the steps of: (i) providing a mixture comprising a silicate-containing scaffold having a macroporous structure, an aluminium source and an organic template; (ii) hydrothermally treating the mixture to form a microporous zeolite-containing structure substantially retaining the macroporous structure of the silicate-containing scaffold; (iii) incorporating copper, iron or both copper and iron into the zeolite. The silicate-containing scaffold can be a diatomaceous earth. The microporous zeolite is preferably an aluminosilicate, such as chabazite with a CHA framework type. The organic template may have a tricyclo ring structure such as admantyl trimethylammonium chloride. In step (ii) the mixture may be heated in an autoclave. Further aspects relate to an SCR catalyst composition comprising the composite material, use of the composite material in an SCR process and an emission treatment system.