I am operating a batch pressurised reactor. I am reacting liquid and powder but there is poor suspension of the powder. The agitator consists of radial flow impellers. Which type of impellers would effectively suspend the powder into the liquid during the course of the reaction?

Thank you very much Roberto

Depending on your vessel you might need to add baffels to direct the currents in the fluid to keep the powder in suspension. Other options are increase the rpms of your impeller, optimize the size of the impeller, add additional impellers depending on height of reaction vessel. Most design books cover the basics which would be a good place to start.

That's right, the baffles are really a requirement. In addition, recirculate to help keep them suspended

try different angle of impeller

why not try first to change the angle of impellers

Pitched blade turbine or Marine Propeller best suits the application, Use DynoChem software to identify the minimum suspension speed Njs for the given fluid and solid properties

If you don't have baffles, the entire mass will rotate at approximately the same rate as th agitator. There will be hardly any relative motion between the components. For turbulent mixing, baffles are necessary.
Partially mixed product (paste) may lodge in corners at the shell to baffle joints. To avoid this, baffles should be about 100 mm away from vessel shell, and baffle edges should be rounded. An even more effective way to eliminate buildup is to provide closed dip pipes from the top heads, extending up to or slightly below the bottom tan line. These will act as baffles. If possible, electropolish the pipes to minimise buildup.

Mix the powder with the liquid before it reaches the reactor in a Y mixer with the right quantity flow of powder and liquid to maintain the right consistency.