Hello dear Scientists,
I would like to ask to everyone about a technical aspect in the preparation of catalysts using incipient wetness impregnation.
¿Can change drastically the properties of the material if I do not use atmosphere of nitrogen in the impregnation of metal over a support?
Always it is necessary the use of nitrogen or other inert atmosphere during impregnation of the metal?
Thanks a lot for your answer,
With kind regards,
Julián Sánchez.
Depends of the catalyst You are preparing, including metal(s) and support used. Normally no protective atmosphere is needed during the impregnation step. The properties of the catalyst will be affected of , among others, the support and especially the porosity of the support, the solvent used. Can the solvent be removed without withdrawing the metals. Later on drying conditions and especially calcination conditions (temperature, temperature ramp and atmosphere) will affect the dispersion of the metal.
I fully agree with the answer given by Henrik Romar. Think about the possible reactants you have in air: CO2 and oxygen, mostly (not water vapor if you are using an aqueous solution for impregnation). If you are using a basic solution for the impregnation, absorption of CO2 will take place; if you are using a solution of a metal cation in a rather low oxidation state, oxidation by atmospheric O2 can take place as well. You should know in advance the porosity available to the solution
The metal content in the impregnation method is usually insignificant (2-5%w), also due to the low solubility of the atmospheric gases in the impregnation solvents (H2O, EtOH, ...) it can be say the atmosphere effects on impregnation are negligible.
use of ultrasonic method, surfactant assisted method and calcination condition (temperature and atmosphere) are more important parameters for enhancing of metal dispersion on supports.
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