To increase the temperature of the autoclave higher than 160 or 200 C, we need thermally stable materials as the reaction container. So what kind of materials can be used??
Dear Dr. Bakhtyar K. Aziz,
the Hydrothermal Autoclave Reactor use to carry hydrothermal reaction at high pressure and high temperature. Hydrothermal synthesis reactor generally comes in a two variety; the first is Polytetrafluoroethylene (PTFE) or Teflon lined hydrothermal autoclave reactors and the second is PPL lined autoclave. Hydrothermal reactor mainly made up of two parts; outer high-quality stainless steel jacket and inner Teflon liner or Teflon chamber. In the Teflon-lined autoclave, the reaction is carried out at maximum 240-degree Celsius (428 Fahrenheit), while the safe temperature is 200-degree Celsius (392 Fahrenheit). PPL lined reactor use for the reaction operate at higher temperature, where the safe temperature will be 260-degree Celsius (500 Fahrenheit) and the maximum operating temperature is 280-degree Celsius (536 Fahrenheit). This product extensively used in the scientific laboratory, research and development labs, institutional organizations, quality analysis section in industries etc.
For more details please see the source at: https://www.techinstro.com/shop/hydrothermal-autoclave/teflon-lined-hydrothermal-autoclave/
Best regards, Pierluigi Traverso
Dear Dr. Bakhtyar K. Aziz,
the Hydrothermal Autoclave Reactor use to carry hydrothermal reaction at high pressure and high temperature. Hydrothermal synthesis reactor generally comes in a two variety; the first is Polytetrafluoroethylene (PTFE) or Teflon lined hydrothermal autoclave reactors and the second is PPL lined autoclave. Hydrothermal reactor mainly made up of two parts; outer high-quality stainless steel jacket and inner Teflon liner or Teflon chamber. In the Teflon-lined autoclave, the reaction is carried out at maximum 240-degree Celsius (428 Fahrenheit), while the safe temperature is 200-degree Celsius (392 Fahrenheit). PPL lined reactor use for the reaction operate at higher temperature, where the safe temperature will be 260-degree Celsius (500 Fahrenheit) and the maximum operating temperature is 280-degree Celsius (536 Fahrenheit). This product extensively used in the scientific laboratory, research and development labs, institutional organizations, quality analysis section in industries etc.
For more details please see the source at: https://www.techinstro.com/shop/hydrothermal-autoclave/teflon-lined-hydrothermal-autoclave/
Best regards, Pierluigi Traverso
I think, in, General, it depends, mostly on what is "hydrothermally" processed inside the container. And of course, all glasses are not made same- you need tough, strong glasses.
If you work with biochemicals , enzymes or simple inorganic salts (not too alkaline, silicious of fluoride containing), i think any suitable nonreactive glass would do (however, Glass reactivity changes with T,P; and since glass is metastable amorphous rather than stable crystalline product, its reactivity prediction would be quite tough. I am not sure about effect of alkali and alkaline earth ion substitution at this case, but even if they react with glass, their effect would be minimal (note, glass tempering at salt bath uses much higher temperature).
However, If you plan to use geochemical like silicates and aluminosilicates, i would certainly say NO. Because glass can react with many hydrous silicate minerals (know of glass disease of soil-buried glass artefacts?). Even hard/boiler water scales are quite complex and their formation is comparable to hydrothermal synthesis.
Depending on redox and pH conditions inside the vessel, metallic coating can be chosen. Pitting resistant molybdenum stainless steel , some Cu based alloys or Titanium alloys can handle hot oxidizing acids. NI alloys are better for alkaline environment. Very costly Ta coating is very effective but costly. You may find more specific alloys from materials handbook. Coating can be used of nonreactive carbides or nitrides if environment is not too oxidizing. For Polymer-based coatings, Extremely high T resistant Engineering Plastics like Vespel can be used-however, their chemical degradation environment must be taken into account.
I have also worked on the synthesis of nanoparticles with the hydrothermal. From my experience, we used the Temp. at 280 C and it worked properly.
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