Contact Section - Catalysts - Haldor Topsoe A/S
January 13, 2018

Introduction Catalyst Types         VK38         VK48         VK58         VK59         VK69         VK701 LEAP5         VK-WSA

Associated Links Catalyst Unloading Catalyst Loading

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Introduction

During the second World War, Dr. Haldor Topsøe and Dr. Anders Nielsen developed an extruded vanadium pentoxide catalyst for use in Danish and Swedish sulphuric acid plants because they were not able to obtain new catalyst from their usual suppliers.  The catalyst operated successfully even though it was crudely manufactured.

Based on their research, it was revealed that the active ingredients of the vanadium pentoxide catalyst exists as melt within the pores of the porous silica carrier.  Dr. Topsøe and Dr. Nielsen also discovered that different alkali-metal promoters such as rubidium and caesium instead of potassium increased the activity of the catalyst.  Unfortunately, it wasn’t until 1988 that the first caesium-promoted catalyst was introduced by Haldor Topsøe A/S.

In 1976, Haldor Topsøe A/S introduced the first ring shaped extrudates.  The ring shaped catalyst provides several advantages over the traditional cylindrical catalyst.  The ring shape exposes more catalyst surface area to the process gas per catalyst volume than the cylindrical shaped.  Pressure drop across the catalyst bed is also reduced due to a higher void volume for the ring shape.

Further development in catalyst shapes occurred in 1984 when Haldor Topsøe A/S introduced the daisy shaped catalyst.  The daisy shape provides further enhancement of the ring shaped by creating ribs on the outside surface of the ring.  Pressure drops across daisy shaped catalyst are further reduced compared to equivalent beds of ring shaped catalysts.

A major advancement in sulphuric acid catalyst occurred in 1988 with the introduction of cesium-promoted catalyst.

Catalyst Types

The physical properties of the catalyst are provided in the following table and a brief description of each catalyst is given below.

	VK38	VK48	VK58	VK59	VK69
Shapes	6 mm pellets 10 mm rings 12 mm daisy 20 mm rings	6 mm pellets 10 mm rings 12 mm daisy	6 mm pellets 10 mm rings 12 mm daisy 14 mm rings	12 mm daisy	9 mm daisy
V2O5 Content	6-8 wt%	7-9 wt%	6-8 wt%	-	-
Alkali-metal oxides	11-15 wt%	11-15 wt%	20-25 wt%	-	-
Ignition Temperature	360oC	360oC		320oC	320oC
Operating Temperature	400-630oC	400-550oC	370-450oC	370-500oC	370-500oC

VK38

VK38 can be used throughout the converter in all beds but is optimized for use in the first two passes.   Fresh catalyst has an ignition temperature of 360^oC increasing to 380^oC for after years of operation.  Maximum continuous operating temperature is 630^oC with peaks up to 650^oC for short periods of time.

VK48

VK48 has been optimized for use in the final catalyst passes.  This is achieve by a higher vanadium pentoxide content combined with a change in the active phase.

VK58

VK58 is a caesium-promoted catalyst designed for use in the first pass as an ignition layer and in the final pass to enhance overall conversion.  Ignition temperatures are as low as 320-330^oC.

VK59

VK59 is the caesium catalyst optimised for medium to high-strength SO₂ gases.  This allows significant conversion improvements in single-absorption plants.  The improvements to VK59 result in a catalyst with a remarkably dry surface.  This formulation greatly reduces the risk of crust formation in any pass, even at elevated temperatures, and makes VK59 ideal as a top layer in first passes.

VK69

VK69 is a caesium-promoted catalyst optimized for operation in the last bed(s) of a double absorption process.  The catalyst is manufactured by a special extrusion process resulting in a highly porous catalyst.   The catalyst combines an increase in vanadium content with a revised composition of the active phase to achieve its enhanced performance.

	VK701 LEAP5
Shapes
V2O5 Content
Alkali-metal oxides
Ignition Temperature
Operating Temperature

VK701 Leap5

Haldor Topsøe has developed a new sulphuric acid catalyst designated VK701 LEAP5™. This new catalyst is optimised for operation in converted strong gasses. At these conditions VK701 LEAP5™ shows significant activity advantages compared to existing potassium- and caesium-promoted catalysts.  The high activity offered by VK701 LEAP5™ presents new conversion opportunities for any single- and double-absorption plant.

	VK-WSA	VK-WSX	VK-WH	VK-WL
Shapes	12 mm daisy 25 mm daisy	9 mm daisy	12 mm daisy	9 mm daisy
V2O5 Content	6-8 wt%	-	-	-
Alkali-metal oxides	11-15 wt%	-	-	-
Ignition Temperature	360oC	340oC	320oC	320oC
Operating Temperature	400-550oC	370-450oC	370-500oC	370-450oC

VK-WSA

VK-WSA catalyst was developed specifically for use in Haldor Topsøe’s WSA desulphurization process.   This process involves the direct oxidation of SO₂ and formation of sulphuric acid in humid process gases.  The catalyst possesses higher strength which is desirable in the water vapour containing process gases.