Hi Eren

When pressure drop has to be small, monolithic reactors are used in industrial scale. For example NOx treatment: Pressure drop is expensive in electrical consumption because of the large flow. So monolithic reactors are used. The problem is that, with a large section (required by low pressure drop) it is difficult to obtain a good repartition of flow over the whole section.

Another problem il the deposit of dusts in the channels.

But think of rotary recuperators. They are made of monoliths.

When pressure is low and pressure drop low : monoliths.

Discharging particles is easier than changing monoliths: example prereformers or autothermal reformers.

An when there is high pressure reactors with small openings are less expensive.

To be short : chemical engineers optimize their costs, CAPEX and OPEX.

Best regards

Paul

Hi Paul Gateau

thank you for your reply!

In some studies, i found out that monolithic catalysts in tubular reactors have better properties in the use case of a chemical synthesis

Compared to a conventionally used tubular fixed-bed reactor, exemplary the methanol production is higher with monolithic reactors if the tubes are long enough (due to the pressure drop with the fixed bed reactor).

So, with faster space velocity and longer tubes, the monolithic reactors are better.

But my question is: Why aren't there any monolithic catalysts used in the large industry for example for the methanol synthesis ?

Methanol synthesis (i.e. reaction between H2 and CO) is under high pressure.

Try to imagine you have to manufacture a high pressure reactor where you have to introduce and organise monoliths. For this you have to examine the Pressure Equipment Directive. I think this is the best way to understand the costs.

In large chemical industry you have a lot of metallurgical constraints. So the better properties of catalysts are not always the better answer.