(126a) Carbon Disulfide (CS2): A New Challenge for Steam Cracker Complexes

Chemical companies are continuously exploring new opportunities in order to increase competitiveness.  In today’s market this can be attained through integration of upstream and downstream, energy recovery, among others. Another opportunity is via feedstock flexibility and its accessibility.
It is this feedstock flexibility that allows companies to look for advantageous opportunities and cheaper imported feeds. However, cheaper raw material introduces new challenges to crackers and downstream operations, especially raw Pygas processing units.
The newest challenge for steam crackers is CS2 contamination. Recently several companies have reported that they see a substantial increase in CS2 contamination particularly impacting the Pygas units. Sulfur molecule coordination with Palladium and Nickel catalysts exhibit activity inhibition, such inhibition decreases as sulfur molecules size increase, H2S>CS2>Mercaptans>sulfides. Currently, there are multiple technologies that allow the removal of H2S before reaching a Pygas unit however the same does not apply to CS2.  
Catalyst technology is gearing to develop catalysts with higher tolerance to such a contaminant while maintaining optimum performance.  
In this paper, CRI based upon a real example will discuss the impact of CS2 on Palladium catalyst. In addition, this presentation shows a plant example on the performance and the importance of partnering with the operating plant. The plant example will show that a more proactive operating approach instead of a reactive one is required, in order to achieve the desired competitive edge.