Glass Reactor vs PP Reactor: Chemistry First, Then Temperature
Both are used for lab and pilot leaching, but they fail in different ways. Glass gives visibility and broad acid resistance but is fragile and attacked by hydrofluoric acid and hot concentrated alkali. Polypropylene (PP) resists HF and alkali well but softens above roughly 100 °C and is attacked by strong oxidizing acids at temperature.
Selection table
| Condition | Borosilicate glass | PP |
|---|---|---|
| Sulphuric / hydrochloric acid, ambient to 100 °C | Good | Good up to ~90–100 °C |
| Hydrofluoric acid, any concentration | Not suitable | Good |
| Hot concentrated caustic | Not suitable | Good |
| Nitric acid, hot | Good | Poor |
| Oxidizing agents at temperature | Good | Poor — stress cracking |
| Visual observation of reaction | Excellent | None (opaque) |
| Pressure / vacuum | Limited; needs jacket and correct head | Limited; creep under load |
| Mechanical impact | Fragile | Tough |
| Temperature ceiling | ~150 °C (thermal shock limits) | ~100 °C continuous |
Practical selection logic
Step 1 — list the chemicals. If HF appears anywhere, glass is out, regardless of temperature. If hot nitric or a hypochlorite is present, PP is out.
Step 2 — check the temperature. Above 100 °C, only glass (or a lined/glass-lined steel vessel) is realistic among these two. PP creep accelerates sharply near its softening point, and a creeping flange is a leak waiting to happen.
Step 3 — decide whether you need to see. For kinetics development and phase behaviour, a transparent vessel saves weeks. For production duty, visibility is a nice-to-have that should not drive material choice.
Hybrid and third options
Glass-lined steel gives glass chemistry with mechanical robustness at larger scale. PVDF and PTFE-lined vessels cover the HF-plus-temperature corner that neither glass nor PP handles. If your process sits in that corner, specify a lined vessel rather than pushing PP beyond its limits.
Tell us the liquor composition, temperature and pressure, and we will confirm the wetted material and the gasket/valve package — the fittings usually fail before the vessel does.