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Contact Section - Catalysts
- BASF
February 23, 2003
Introduction
In 1901, Badische
Anilin- & Soda-Fabrik (BASF) was issued German Patents 113933 and 133933 which
described their pioneering activities in the development of the contact process which
employed a catalyst to promote the oxidation of SO2
and O2 to give SO3. At
this time the active ingredient in the catalyst was platinum. Platinum catalysts exhibit high activity but were
costly and were easily deactivated by poisons such as arsenic trioxide (As2O3).
Development continued
into alternative catalysts that did not suffer the disadvantages of platinum and were less
costly to manufacture. In 1913, BASF was
issued German Patent 291792 and Swiss Patent 71326 for a catalyst consisting of vanadium
pentoxide and alkali metal oxides on a porous silica carrier. This new catalyst was first used in a commercial
scale plant in 1915. The results were
successful and the remaining platinum catalysts was soon replaced with vanadium pentoxide
catalyst.
Today, BASF offer 3
different types of catalyst in a variety of shapes for various situations in sulphuric
acid plants.
Catalyst Types
The physical properties of the catalyst are provided in the
following table and a brief description of each catalyst is given below.
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04-110 |
04-111 |
04-115 |
| Shapes |
S6:
6 mm pellet
S8: 8 mm pellet
SS11x4: 11 x 4 mm star ring
SR10x5: 10 x 5 ring
SR11x4: 11x 4 ring |
S6:
6 mm pellet
S8: 8 mm pellet
SS11x4: 11 x 4 mm star ring
SR10x5: 10 x 5 ring
SR11x4: 11x 4 ring |
SR10x5:
10 x 5 ring
SS11x4: 11 x 4 mm star ring |
| V2O5 Content |
6 wt% |
8 wt% |
- |
| Bulk Density - Pellets |
600 kg/m³ |
550 kg/m³ |
5.5 |
| Operating Temperature |
400 to 600°C
(752 to 1112ºF)
depending on gas composition |
415 to 630°C
(779 to 1166ºF)
depending on gas composition |
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| Ignition Temperature |
minimum 360°C (680°F)
depending on gas composition |
minimum 380°C (716°F)
depending on gas composition |
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04-110
Type 04-110 is a proven
catalyst primarily used in the first converter bed. The
catalyst is suitable for sulphur combustion gases and for waste gases from metallurgical
plants or from H2S combustion (i.e. wet catalysis). The catalyst possesses a low ignition temperature
of 380oC which is useful during initial plant start-ups. Normal inlet temperatures are in the range of 410
to 430oC. Maximum operating
temperature is 630oC which makes it suitable for treating gases containing up
to 13% SO2.
04-111
Type 04-111 is a highly
active catalyst for use in catalyst beds after the first bed. The higher activity results in closer approaches
to the thermodynamic equilibrium. Ignition
temperatures can be as low as 360oC depending on the gas composition. Maximum operating temperatures are limited to 600oC.
04-115
Type 04-115 is a caesium
based catalyst which allows normal inlet temperature down to 370 to 385oC
depending on gas composition. The catalyst
can be used as an ignition layer in the first pass or in the final pass. The lower inlet temperatures allow gases
containing up to 16% SO2 without thermally overloading the
subsequent beds. The ignition temperature of
the catalyst is about 340oC with a maximum operating temperature of 630oC.
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