Shyman Project

Sustainable Hydrothermal Manufacturing of Nanomaterials

Large-scale green & economical synthesis of nanoparticles and nanostructures

 

The Shyman Process

The Shyman Project is focussed on the scale up of the hydrothermal synthesis process.

This process is an alternative route to manufacture that offers unique opportunities for the synthesis of high quality nanoparticles and their formulation.

Hydrothermal synthesis presents a significant number of advantages since it:

  • Does not tend to use noxious chemicals – with water soluble precursors and water as a solvent.
  • Uses relatively simple chemistry – generally following hydrolysis and dehydration stages.
  • Allows straightforward downstream processing - the process is dispersion based.
  • Uses relatively cheap chemical precursors – acetates, nitrates and phosphates.
  • Can produce stoichiometric compounds.
  • Can produce non-stoichiometric materials where precise alloying or doping can be achieved.
  • Can avoid agglomeration - the dispersed materials can be stabilised with additives, in situ.
  • Size and shape distribution can be narrow and well controlled.

Process Overview

Making the process continuous

Continuous hydrothermal synthesis produces nanoparticulate materials by mixing superheated/supercritical water with a solution of a metal salt. i.e. rather than slowly heating the entire contents of a batch vessel, two fluids are continuously mixed together.

When water is heated towards its critical point (374oC, 218 atm.), the ionic product [H+][OH-] increases and the superheated fluid is technically supercritical, rather than near-critical.

The enhanced levels of OH- were first exploited for continuous nanoparticle production by Adschiri and Arai, in 1992, who showed that under these conditions hydrolysis of metal salts (MLx) is immediately followed by a dehydration step.




The step from batch to continuous hydrothermal synthesis has been held back by engineering issues around mixing the heated fluid and the aqueous metal salt flow. T piece reactors (Figure 5) were originally used but these are now, generally accepted as problematic.

The project will scale up the system used by Promethean Particles (www.prometheanparticles.co.uk) from its current scale of 1-10 tons per year to over 100 tons per year.

Nucleation

Equipment Breakdown

Full KitBack Pressure RegulatorBack Pressure Regulator and liquidCapping feedCapping and particlesCooling jacketHeater controlWater feedMetal feedPressure monitoringReactorReactorParticles formedCovered particles