Using the specific surface area of the heterogeneous catalyst, the amount homogeneous catalyst obtained by titration, and mixing regime and intensity characteristics along with contact time, you should be able to come up good approximation.

very difficult to calculate. It depend on the catalyst type and you have to test through experiment. Based on our review paper, (will be published in BULLETIN OF CHEMICAL REACTION ENGINEERING AND CATALYSIS , Article Title: Solid catalysts and theirs application in biodiesel production), catalyst amounts vary from 1-20 wt%

You can calculate no. of active sites present in catalyst by analytical methods such as TPD (in case of solid acid catalysts) and so on. Using the stoichiometry of the no. of active sites required and TG, it is quite possible to get idea. However, people have practiced trial and error using various catalyst wt % (w.r.t oil) as suggested by Ramli Mat. Till date it is the only method used.

Thank you very much for your answers. but i cant understand the concept thoroughly. Dear Mohamed i am unable to understand your answer, Please explain in detail with suitable example.

Dear Krunal Shah

Please explain about TPD method and with anyone example

Baskar: The approach I'm about to outline is purely empirical, but conceptually correct. Let's say that your catalyst is truly homogeneous, then it can be assumed to interact with the reactants in its dissolved state. Therefore, the surface at which the catalyst/reactants interaction take place in this case is the catalyst's molecular interfacial area (m2/molecule) or molar area (m2/mole) in its dissolved state. This quantity can be found in the literature or can be estimates from thermodynamic tables.

Now let's say that through your titration, you found that you need, say, 5 g catalyst/100-g of oil to achieve good conversion in your experimental conditions. Dividing 5-g by the molecular weight of the catalyst and multiplying by Avogadro's number you get the number of catalyst molecules you need to complete your reaction in homogeneous conditions. Multiply the number of molecules by the molecular area you get the total catalyst interaction area you need for your reaction. Divide this number by the specific area of the heterogeneous catalyst (m2/g), you get a good initial estimate of the amount of heterogeneous catalyst you need to carry on the same reaction.

Note that this figure is an initial estimate, use this figure as a starting point while fine tuning through trial and error your reaction performance by varying contact time, mixing speed, specific area, temperature...etc etc.

Good luck