Larox has supplied well over 100 filters for catalyst processes of all types including:

• alumina, silica or alumina/silicate based carriers

• active metal salts including nickel, cobalt, copper, zinc, molybdenum and precious metals

• zeolites

• hydroprocessing or fluid cracking catalysts

The large majority of the installations are based on the Pannevis RT filter from Larox, which is ideally suited for almost all catalyst applications as the filter provides excellent cake washing results. For many catalysts including zeolites, ion exchange can also be carried out on the filter. The Larox "DS" and "C" series automatic pressure filters are also finding greater application for catalysts especially where higher dry solids in the filter cake are desirable.

The RT filter provides continuously operation and the most efficient cake washing using the minimum amount of wash liquid. This is normally achieved by using a counter-current washing scheme as it reduces the amount of wash liquid required. More typical for fluid cracking catalyst applications based on zeolites, the filter is configured to wash the filter cake, carry out a multi-stage counter-current ion exchange and finally wash the cake free of the ion exchange medium. For metal salt based catalysts the RT also offers superior washing with the ability to reduce impurity levels to parts per million in most cases.

The RT filter is available with various enclosure options to handle the more difficult applications. As a minimum for elevated temperature operation, a vapour hood can be fitted over part or all of the filter. For more hazardous processes such as ammonia-based reactions the RT-FT Fume Tight design provides total process containment. The filter can be operated with a slight under-pressure in the housing to ensure only in-leakage and therefore total operator safety. Corrosion resistant designs are also available.

The Larox C Series and DS Series automatic pressure filters have also been used for catalyst filtration. Where the moisture content of the discharged cake is critical the pressure filter offers the ability to mechanically squeeze and/or airblow the filter cake at high pressures resulting in much lower residual moisture contents. The Larox C Series offers optimum performance in obtaining the driest cake with excellent cake washing.

The Larox DS Series provides total contained automatic pressure filtration and can also be made gas tight for hazardous or toxic processes, while still providing all the advantages of automatic pressure filtration.