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[*] posted on 14-3-2018 at 17:44
Hydrothermal reactor

eBay has titanium hydrothermal synthesis autoclave reactor thingys with Teflon inserts!
.my question is what exactly can these be used for?

Won't heating the vessel damage the Teflon???
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[*] posted on 14-3-2018 at 18:30

As far as I can tell, they're meant for pressurized reactions up to the numbers specified. I'm not sure if the pressure-temperature properties of Teflon mean it would degrade under those conditions, but I would assume not. They're typically used for organic reactions, though I've never found the specifics.

The reason I know even this was because I was looking into these for hydrothermal growth of crystals some time ago, and came across them. Unfortunately, their maximum pressure rating is too low by a factor of a few hundred, last I checked.

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[*] posted on 14-3-2018 at 18:49

take a look at some of the posts from user chironex:

al-khemie is not a terrorist organization
"Chemicals, chemicals... I need chemicals!" - George Hayduke
"Wubbalubba dub-dub!" - Rick Sanchez
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[*] posted on 14-3-2018 at 20:37

Yttrium2, please check your U2U.
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[*] posted on 17-12-2021 at 16:59

Quote: Originally posted by Yttrium2  
eBay has titanium hydrothermal synthesis autoclave reactor thingys with Teflon inserts!
.my question is what exactly can these be used for?

Won't heating the vessel damage the Teflon???

No , it won't.

Acid Digestion Vessels

Parr acid digestion vessels offer an alternative to the task of preparing analytical samples for analysis. By combining the unique chemical inertness of PTFE with the advantages of a sealed pressure vessel, these convenient vessels offer a rapid procedure for sample dissolution or digestion that has several important advantages over more traditional methods of sample preparation. By providing a convenient means for holding strong mineral acids or alkalis at temperatures well above normal boiling points, these sturdy digestion vessels will:

Accelerate digestions which otherwise would proceed slowly if conducted in an open container at atmospheric pressure.

Permit the use of strong acids, such as HF or aqua regia, which will attack most other conventional containers.

Dissolve analytical samples without losing trace elements and without adding unwanted contaminants from the container itself.

Generate a vigorous chemical action that is a great time saver in analytical procedures.

Obtain complete digestion or dissolution of samples that react slowly or incompletely when treated by other methods.

Chemists who have worked with sealed glass tubes and other cumbersome digestion devices will recognize the attractiveness of these convenient digestion vessels.

Hydrothermal Synthesis

Many sample preparation techniques require an aqueous mixture to be heated above 100°C resulting in the system having an associated vapor pressure. Examples of this are nanoparticle and zeolite synthesis. Many of these methods also require either acid or alkaline conditions where stainless steel would be readily corroded. Parr Instrument Company manufactures a range of pressure vessels that completely encapsulate the sample within a PTFE environment. This PTFE cup and cover allows the pressure vessel to be manufactured out of the inexpensive material T316SS without the worry of corrosion or loss of sample. These vessels can be heated up to 250°C. This is usually achieved by placing the vessels in a standard laboratory oven.

The popular models for this type of work are shown in the table below.

Models 4744 (45 mL) and 4749 (23 mL) Vessels with PTFE liners.

General Purpose (for anything)
45 mL, 250 °C, 1800 psig

The 4744 is a 45 mL modification of the 23 mL, 4749 PTFE lined vessel designed for users who want additional capacity in this popular model. It is made with the same closure as the 23 mL vessel, using a similar thick-walled PTFE cup, 3-3/4 inches deep inside, with a broad flanged seal. Safety blow out protection is provided with a blow-off disc that will release pressure through an opening in the cover. Its maximum temperature and pressure ratings, 250°C and vessel 1800 psig, are the same as for the 4749 Model. The 4744 Vessel is sealed by turning the screw cap down until it is hand tight, then tightening the cap not more than one-eighth turn with a hook spanner. The spanner and holding fixture required for this operation are the same as used with the 4749 Vessel. These accessories must be ordered separately.

125 mL & 200 mL, 250 °C, 1900 psig

The 4748 and 4748A vessels are the largest of all Parr acid digestion vessels. The 4748 has a 125 mL, removable PTFE cup in a stainless steel body with six cap screws in the screw cap to seal the flanged PTFE cup. An expandable wave spring maintains continuous pressure on the seal during the cooling cycle when PTFE parts might otherwise relax and leak. Stirring can be provided with a magnetic stir bar. The 4748A is a 200 mL modification of the 125 mL, 4748 PTFE lined vessel for users who want additional capacity in this model.

A safety blow-off disc above the PTFE cup will release pressure through an opening in the vessel head if pressure should accidentally reach the 3500 psi range. For safe operation, pressures in these vessels should never exceed 1900 psi and temperatures must not exceed 250 °C. Operations should be conducted well below these limits whenever possible due to the potential destructive forces in a large vessel charge. It also is advisable to test any new procedures for safety in one of the smaller vessels before scaling up to these sizes. A wrench for the cap screws is furnished with these vessels. No other accessories are required.

Price range:
Chinese 100-300ml PPL Lined Hydrothermal Synthesis Autoclave Reactor, 3Mpa US $166.89 - 339.70+shipping

Parr instruments 4748A Acid Digestion Vessel 200mL US $900.00

4744_Acid-Digestion_45mL-GP-214x300.jpg - 5kB Acid-Digest_4744-45mLA280AC2-4749_23mL_A280AC_700.jpg - 70kB
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