# Combustion and pyrolysis of sulfides and organosulfurs

Last week there was a huge fire in french chemical factory Lubrizol, we now know the main products that burnt, to simplify the discussion I extracted a few compounds:

• isobutyl and isobutene polysulfide 500 tons,

• dithiophosphoric acid and corresponding zinc salt (R = isopropyl) 200 tons,

• various hydrocarbons (mainly mineral oil) 2000 tons

• as well as calcium sulfonate and calcium salt of methylphenol sulfide (100 tons), amides/esters of phosphoric acid, polymers, aromatic amines & alcohols, various reaction products of $$\ce{P2S5}$$ with isopropanol 400 tons

What kind of sulfur compounds should we expect to be emitted from pyrolysis and combustion of such organosulfur compounds?

Note the authorities claim the smoke analysis didn't show any $$\ce{H2S}$$ and that the $$\ce{SO2}$$ level wasn't higher than everyday measurements in cities.

There is a paper on the pyrolysis of polyethylenesulfide showing cyclization leads to a bunch of products, I wonder if it is applicable here (also I would like to know why no $$\ce{H2S}$$ is formed?)

• feel free to add any thoughts on combustion pyrolysis principles – reuns Oct 3 at 3:20

I'd expect $$\ce{H2O, CO, CO2}$$, and $$\ce{SO2}$$ to be created during the combustion of these compounds. I'd wager a decent amount of $$\ce{SO2}$$ was created, but was diluted in the atmosphere.
Regarding $$\ce{H2S}$$, maybe it was produced, but then reacted according to the following:
$$\ce{H2S + O2 -> SO2 + H2O}$$
Additionally, there were probably a wide variety of odd sulfur compounds, but their existence was transient as they reacted to form $$\ce{SO2}$$ for instance. Furthermore, the authorities may not even be looking for these more complex molecules.
• I think it is contradictory with their analysis, also $SO_2$ is 2 times heavier than air even if the density is lowered by the high temperature of the fumes. In one of their analysis there is organosulfur $<10\mu g/m^3$, same for $SO_2$. I can't make it consistent with those hundred of tons of sulfur that burnt. Where should I search for references showing $SO_2$ is always formed when burning organosulfurs ? – reuns Oct 3 at 5:36
• Also I was wondering if, due to the huge amount of fuels consuming all the $O_2$ in air, it would be more pyrolysis than combustion (it burnt for 12 hours so the temperature was extreme) – reuns Oct 3 at 5:41