I've read many papers which use only a few milligrams of the solid catalyst. I'm thinking that the reactor bed is not covered with enough catalyst. Is it okay with that? Is the reaction catalyzed even for a few amount of the metal catalyst (especially powdered catalyst)?
It depends on what chemical reaction is tested, what is the catalyst and what is the scale. In the case of chemical reactions carried out in experimental tubular reactor with a fixed catalyst bed we usually used 1-2 g (synthesis of methanol, DME, higher alcohols, steam reforming). In the case of the esterification reactions, depending on the catalyst, it was from 50 mg to 10 g. On a quater technical scale it can be up to a kilogram. The enzymes are usually used in milligram quantities similar to so-called nanocatalysts - but maybe more. Regards,
Agree with Mirosław Grzesik Sir.
It depends upon the interaction between reactants and catalyst. The stationary phase may cause such issue as you stated in your question description but if we use mobile phase and prevent the fed-back-inhibition, very small quantity of a catalyst works good.
It all depends on the scale of the process and the type of catalyst used. In industrial tubular reactors or in fluidized bed reactors there may be several dozen tons of catalyst, and even more.
" I've read ........ is not covered with enough catalyst." Indeed, the amount of active ingredient on the carrier (not bed) can be small, even on the order of milligrams, but of course per kg of the carrier. - But there are many other catalysts. Regards,
I mean, for example, I have a circular plate. Is it okay if not the whole plate is covered with the catalyst?
You mean a disc whose material is inert to the chemical reaction? Does the disc rotate? What will the direction of the flow be. Too little information.
By the way, what is the type of reactor. Regards,
We cannot say that the amount of catalyst required will always be milligrams since we have to consider the type of the reaction, the scale of the process, and the type of reactor. I shall give examples about what is done in industry when reactors are to be selected for a certain chemical process.
In the case of an irreversible first-order reaction, a tubular reactor requires a lesser catalyst volume than does either a slurry reactor or a fluidized-bed reactor. When a fixed-bed reactor is to be used, we have to take into account that the w/w or v/w ratio of a catalyst to reactants has to be increased to allow for longer residence time and thus a reaction with high degree of conversion.
In heterogeneously- catalyzed industrial large-scale continuous processes, the amount of catalyst may be few kilograms up to hundreds of kilograms. I refer the interested RG colleague to fluidized-bed catalytic cracking in which heavy petroleum fractions are converted into lighter fractions for the sake of producing gasoline as done in refineries worldwide.
consider that few milligrams of nano material if well dispersed can cover your plate with a lot of active sites. This is the most important part of catalyst the density and dispersion of active sites
The amount of catalyst may vary from mg to g to kg depending on the application and configuration. Realize that the catalyst itself is fabricated on a large surface area substrate onto which reactants get adsorbed, come in close contact with each other and the catalyst decreases the activation energy so that the reaction kinetics on the surface is accelerated.
The vertical cylindrical reactor has a fixed-bed in the bottom. The direction of the gas is from the side. I'm asking if it is okay if the whole disc is not covered with the catalyst ( a nanopowder btw) because it is very few. Or should I add more catalyst to ensure that the whole plate is covered.
Thank you for the generous answers.
You ask further questions without providing sufficient information. Often the answer can only be obtained using the trial and error method. Maybe some drawing or scheme. Regards
I sent you a message, Sir Miroslaw Grzesik. Thank you. :)
Great answer out here alread but just to add; rate catalytic reaction is affected by surface coverage too - how much of the reactant contac the catalyst in a pass is important. I think the amount of catalyst you used should be dependent amongst many other factors, the size of the reactor, the nature of distribution of the catalyst and most importantly the contact time. Thus measurements used can vary a lot.
It depends about reactor that you can used and the interaction between reactants and catalyst (chemical reaction)
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