ABSTRACT
In laboratory preparation of catalysts there are several types of equipment used for the calcining operation. Furnaces heated with a nichrome coil are, of course, limited to temperatures below 1100°C. If operating temperatures up to 1400-1500°C are desired, the heating can be accomplished by the use of platinum rhodium or other precious metal alloy as the heating element. The containers for the catalyst must be either fused silica or fused alumina to withstand temperatures in this range. It is also possible to heat the furnace by means of silicon carbide rods (globars), which also permit operation up to 1400-1500°C. In addition, there is usually a thermocouple on the heater side of the tube to determine the difference in temperature between the interior of the tube and the furnace heating element. This, of course, has the purpose of minimizing overheating which could occur because both the catalyst and the refractories used are comparatively good insulators.
