As far as i know, the decomposition temperature of DMDS is around 900’F(482),which means it will be broken down in the H2S. H2S can work as passivation to prevent catalytic coking.
However, we already have lots of sulfur in the feed which can also work as passivation of metal surface.
Are there any other concerns if you inject more DMDS?
Would you give your e-mail address so that we can talk more in detail?