Method for producing catalysts and catalysts thereof

Abstract

The invention relates to a process to produce catalysts by powder injection moulding and the catalysts thereof, wherein the catalysts are made by preparing a ceramic formulation with temperature controlled rheological properties comprising catalytic components, heating the powder formulation up to at least the fluid state transition temperature, shaping a sample by injecting the fluid powder formulation into an injection mould followed by cooling the injected powder formulation below the fluid state transition temperature, de-binding the shaped sample, and sintering the shaped sample to form a ceramic catalyst. Alternatively the ceramic structure may be formed initially followed by a coating of the ceramic structure by one or more catalytic compounds.

Description

[0001]The invention relates to a cost effective method for manufacturing solid ceramic catalysts with enhanced catalytic performances, and catalyst thereof.BACKGROUND[0002]Ceramic catalysts may be employed to induce / increase a range of different chemical reactions such as synthesis of organic and inorganic compounds, decomposition of oxides, oxidation of compounds etc. One example of use of ceramic catalysts are in de-nitrification of exhaust / flue gases. Nitrogen oxides are unwanted bi-products often formed in combustion processes and other chemical reactions involving nitrogen and oxygen at high temperatures. Many of these oxides have detrimental effects on the environment. For example, N2O is a very strong greenhouse gas, and the Kyoto Protocol calls for strong reductions in the emissions of the gas. NO and NO2 are strong acidic oxides forming nitric acid when reacting with water, and is a major source for acidic rain. Nitrogen oxides may be catalytically reduced to elementary nit...

AI Technical Summary

Benefits of technology

[0017]The main objective of the invention is to provide a cost effective method for manufacturing solid ceramic catalysts with enhanced catalytic performances.

Problems solved by technology

Generating the shear stresses for this reversible rheological process becomes problematic when extruding monoliths with small channels and thick walls as sufficiently high shear stress can not be generated.

Therefore, it is presently not practical to extrude monolith catalysts with voidage fractions below 50%.

Thus conventional monolithic catalysts, due to their high voidage (>60%) are not ideal for processes that have rates that are low enough, such that they are significantly limited by bulk processes.

However, this technology does not allow forming objects larger than the pellet-like miniliths.

Sophisticated drying procedures, such as microwave drying, may be able to reduce this processing time a little, but the large process time is nevertheless a problem since it enhances the manufacturing costs.

Another problem with extrusion is that the method only allows forming objects with constant cross-sections along the centre axis.

This is a problem since it is known that turbulent flow increases the contact between the gas (reactants) and the catalyst(s) of the channel walls, and thus enhances the catalytic activity.

Unfortunately, segmenting by cutting extruded monoliths has several drawbacks.

They include deformation of the monolith, if it is cut before the extrudate is dried, and material loss and possible breakage if the monolith is cut after drying or high temperature sintering.

For extruded monoliths it may be impossible to recycle the material from defective pieces, after they have been dried.

PIM has been regarded as not suitable for catalyst production since the moulds were regarded to be expensive and not sufficiently durable.

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