I am looking for some solvent which can dissolve coke at room temperature just by passing solvent from 1'4" tube. The is formed due to hydrocarbon cracking @ 850degC and after that need to clean to do the next reaction ensuring no coke in tube as its develop pressure due to less space inside tube. Currently using Acetone to clean it even tried Benzene and toluene as well but not satisfield.
Plz give your suggestion.
Rahul.... You are facing a deposit of pyrolytic carbon on the walls of your tube. None of the known solvents can dissolve this sort of coke. You need to repeat the heating process at a higher temperature (around 1000o C) and pass air through the tube. This will oxidize the coke into CO2 and your tube will be clean. However, there are some wet oxidation procedures available, but first try the thermal oxidation. Please let me know how successful will be the treatment, before we go to the chemical wet oxidation... Good luck
I. If the tube is of well suited refractory material for sustaining the mentioned 850 ºC, so that it possibly not degraded beneath the surface, and either not curved and short enough; it may be worth to first try cleaning with a twisted-wire brush impregnated with petroleum jelly; followed by petroleum ether or ligroin.
II. If a harsher chemical cleaning method seems nevertheless required, you may consider; as long as the tube material (not indicated) can resist corrosion by such strong acid oxidant solutions: (i) hot nitric acid (10─20 wt%); (ii) sulfuric acid (300 ml; ≤ 90 wt%) with potassium dichromate (20 g); (iii) 40 ml conc. H2SO4 + 20 ml HNO3 (~60 wt%) + 10─20 g KClO3 (slowly added). Cleaning may take over 1 h. Safety note: the tube must be first clean from any previously tried organic solvent.
III. Alternatively, you could consider burning off the coke residue; if the material is refractory enough.
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