Express your view on space velocity ?

I presume you mean with activity, the amount of reactant converted per unit mass of catalyst (i.e. the integral rate of reaction)

The rate of reaction is a function of the concentration (or partial pressure) of the reactants/product.

In a plug flow reactor, the concentration of the reactants decrease with increasing bed length.

Increasing the flow rate will result in a lower concentration gradient in the catalyst bed,

thus the integral rate of reaction. At low levels of conversion, a low concentration gradient

thus the integral rate of reaction. At low levels of conversion, a low concentration gradient

the integral rate is independent of the flow rate (note: the conversion is not constant when changing the flow rate of the reactants,

the integral rate is independent of the flow rate (note: the conversion is not constant when changing the flow rate of the reactants,

In order to ascertain whether external mass transfer limitations affect your observed integral rate,

In order to ascertain whether external mass transfer limitations affect your observed integral rate,

you will need to vary the lienar veloctiy through the catalyst bed keeping the space time constant.

This can be achieved by carrying out the reaction using a mass m1 of the catalyst and a flow rate V1 of the reactants

then load 2.m1 of catalyst and feed the reactants with a flow rate of V2=2.V1.

Keep on increasing the flow rate of the reactants and the mass of catalyst, unitl the conversion is no longer a function of the volumetric flow rate of the reactants.

Many Thanks Profess0or

in fact, it also depends on your reaction, we have the same problem: during the study on the reaction: CO2 + H2 --> CH3OH + H2O

When we increase the flow rate (increase GHSV), the methanol production increase. But in the reation CO + H2 --> CH3OH + H2O

The increase of flowrate with decrease the catalyst performance.

In addition to the perfect answers of Prof. Kralik and Prof. van Steen,

I would like to point out another interesting effect of flow systems, which is the shear stress exerted on the catalyst surfaces.

I would like to point out another interesting effect of flow systems, which is the shear stress exerted on the catalyst surfaces.

he shear stress - which depends directly on the superficial velocity - can help increasing the conversion over fixed catalysts by introducing a "self-clean" effect; that is, the cleaning of the catalyst surface by shear-induced removal of adsorbed by-products that block the catalytic sites

he shear stress - which depends directly on the superficial velocity - can help increasing the conversion over fixed catalysts by introducing a "self-clean" effect; that is, the cleaning of the catalyst surface by shear-induced removal of adsorbed by-products that block the catalytic sites

hmmm I would like to recommend the following article: "Experimental methods in catalytic kinetics" (C. Perego, S. Peratello, Catalysis Today, 52 (1999) 133-145).