Abstract: A charging device for a tube reactor has a plurality of metering chambers which can be filled with filling material, for example a catalytically coated carrier material. Each metering chamber is adjoined by a drop tube or some other filling device via which a tube of the filling device can be filled in each case. The metering chambers can each be filled via antechambers which are combined into one replaceable antechamber unit.

Abstract: A charging device for a tube reactor has a plurality of metering chambers which can be filled with filling material, for example a catalytically coated carrier material. Each metering chamber is adjoined by a drop tube or some other filling device via which a tube of the filling device can be filled in each case. The metering chambers can each be filled via antechambers which are combined into one replaceable antechamber unit.

Abstract: A high-density and mean-porosity catalyst, supported on a siliceous matrix, based on vanadium, iron, oxygen and alkali metals, wherein the V.sub.2 O.sub.5 content ranges from 6 to 9% by weight, the Me.sub.2 O content ranges from 8.5 to 12% by weight (Me being an alkali metal), the particle density ranges from 1.10 to 1.40 g/cm.sup.3 and furthermore:the pore volume ranges from 0.20 to 0.70 cm.sup.3 /g and the surface area ranges from 0.30 to 5 m.sup.2 /g, the average radius of the pores ranging from 600 to 2200 nanometers;the SiO.sub.2 content is lower than 75% by weight and the Fe.sub.2 O.sub.3 content is higher than 0.90% by weight.

Abstract: A process for preparing a high-density and, low-silica catalyst, supported on a siliceous matrix, based on vanadium, oxygen and alkali metals, wherein the V.sub.2 O.sub.5 content ranges from 6 to 9% by weight, the K.sub.2 O content ranges from 8.5 to 12% by weight and the particle density ranges from 0.90 to 1.40 g/cm.sup.3 and wherein furthermore:the volume of the pores is from 0.30 to 0.70 cm.sup.3 /g and the surface area is from 0.30 to 3 m.sup.2 /g, the average radius of the pores being from 650 to 2200 nanometers;the SiO.sub.2 content is equal to or lower than 75% by weight and the Fe.sub.2 O.sub.3 content is equal to or greater than 0.90% by weight.