Advantages of STT® System relative to conventional reactor methods include the following:

Rapid and Uniform Mixing – The high shear flow that is responsible for the mixing within the STT® System is much more energetic than that achievable in a conventional volume-based mixer, resulting in mixing at the molecular level. This more vigorous type of mixing leads to faster reaction processes and higher yields. In addition, the flowing format results in less waste due to production failures. The system can process gases, viscous liquids, and solids, and is suitable for mixed-phase reactions. Use of our STT® System system can also reduce solvent and catalyst requirements.

Economic Optimization – The STT® System flowing film format approach permits an unprecedented level of control of reactions, resulting in the more efficient and less costly manufacture of products. The operating parameters of the STT® System can be adjusted to match those of the process being run, including matching the STT® System’s mixing speed with the reaction rate, control-ling the stoichiometry of the reaction through the proper introduction of reactants, adjusting the flow pattern of reactants in the STT® System with the reaction mechanism, setting residence time in the STT® System with the reaction time, and balancing the heat transfer characteristics of the STT® System with the reaction isotherm.

Precise Temperature Control – The two dimensional format of the STT® System enables precise temperature control. This differs from a conventional, three dimensional environment of a volume-based system where considerable temperature variations between one part of the mixing vessel and another may exist due to distance from the heating source. Precise temperature control increases yield and leads to better product quality control and less likelihood of batch loss.

Scalability and Commercialization – The STT® System is highly scalable because important reaction parameters of the STT® System that affect rate of mixing and heat transfer, such as the flow rate and the gap between the rotor and stator, are not altered by increasing the size of the system. Thus, the transition of the chemical process from pilot scale to production scale systems is seamless. We have demonstrated the scale-up from research bench to pilot plant levels in a single day.

Dynamic Monitoring - The STT® System allows for the progress of the chemical reaction to be monitored continuously and in real time. If a problem occurs, a process can be halted and the problem corrected with a minimal loss of valuable reagents. In contrast, conventional vol-ume-based systems require a significant degree of additional effort, expenditure and complexity to attain and maintain a continuous oversight of reactions. As such, a production problem generally leads to a loss of most or all of the reagents since they are all combined at one time.

Size – Our commercial scale STT® Systems and larger, derived complete STT® Production Units, are small in size but can produce the same amount of product as much larger conventional systems and production units respectively. This process intensification is possible due to the increase in reaction rates that we achieve from the intense shear generated in the STT® System.

Independent STT®System Variable Control

The STT® System allows for the isolation and independent control of reaction variables. The following is a list of reactor and reaction variables and how they have been used to engineer a faster, more selective and more complete transesterification reaction.

Shear Rate – This is responsible for the improved reaction rate and is the driving force of the technology. Shear Rate and Residence Time are independent. Shear Rate is measured in s-1. Typical shear rate values are 30,000/sec to 70,000/sec but higher or lower values are possible.

Residence Time – Residence Time is controlled by reactor gap size, reactor working volume, and feed rate of reactants. Again, Residence Time is independent of Shear Rate.

Temperature – The STT® System is able to maintain temperature as well as to rapidly add or remove large amounts of heat to control the temperature of the reaction. Several of the Company’s heat exchangers are patent pending and designed specifically to give the STT® React system tight temperature control.

Pressure – The STT® System can be run under pressure (up to 600 PSIG depending on the configuration and choice of seals), open to the atmosphere, or under vacuum. There is some flexibility in where gasses are added or removed from the reaction stream.

Port positioning and Use – The STT® System system be-haves in a plug flow manner, so multiple reactants can be introduced to the system as the reactions progress, if desired.

Reaction Initiation – Initiation of the reaction can be controlled by preheating the reactants and shearing one reactant into the other at a side port. This ensures the reactants cannot begin to react before they are mixed in the STT® System. Temperature sensitive reactants can also be mixed at a lower temperature in the STT® Reactor and then be allowed to rapidly reach the reaction temperature due to shear heating and heat transfer from external and/or internal heat exchangers.

Feed Rate – The STT® System permits easy metering of multiple feeds into the system with varying miscibility and phases (solid, liquid, gas, slurries) – more so than could be tolerated in a traditional stirred tank reactor (STR) or plug flow reactor (PFR) system. For example, one can ensure that a particular hydrogen or oxygen to reactant ratio is obtained so the reaction is not run reagent rich or lean versus the desired stoichiometry. This capability has broad implications in selectivity. Another advantage is the ease of mixing or blending of compo-nents with great differences in viscosity where other technologies struggle to achieve homogeneity under these conditions.

Types of feed – A broad range of feed materials is possible. Any mixture of gas, liquid and solid suspension; density; and miscibility can be accommodated as long as there is an adequate way of getting the feed to the reactor in a homogeneous state and particle size of solids is kept below one fourth of the gap dimension.

Reactor Positioning – Vertical or horizontal positioning can lead to different results depending on the reaction. In reactions where a gas is a reagent or a byproduct, a horizontal position is best if the desire is to keep the gas emulsified. In reactions where solids are present, such as the use of a heterogeneous catalyst, a horizontal reaction is best for keeping them suspended. Vertical positioning can enhance off-gassing when a gas byproduct is generated and separation is desired to promote reaction completion.

Working Volume – The working volume is the volume between the rotor and stator where the reaction actually occurs. It is determined from the last feed entry port to the product exit port. This is distinguished from the total volume of the STT® System cavity which includes the volume from where the first reactant enters the reactor to the last reactant port (this can be as little as a few milliliters) and the space that exists between the product exit port and the seal (minor volume). The working and total volumes are a function of the gap size (or annulus) and change as the size of the rotor is changed.

Materials of Construction – Typically the materials of construction are SS 316L, Hastelloy® C or titanium. Other materials are available based on the chemistry of the reaction and reactants..

Application Areas

STT® technology creates significant increases in reaction rates where momentum, heat or mass transfer are issues. The Applications Table on the reverse side provides a sampling of initial un-optimized reaction results when the STT® technology is applied in specific application areas. Comparative examples are provided that illustrate the difference between the performance of the STT® reactor and a batch process run under similar conditions.

Reaction rates, yield, and/or selectivity can be enhanced further when optimized reactor conditions have been empirically determined. A significant benefit of the STT® technology is that optimization can be determined on the bench scale (Magellan® series) which easily scales through the pilot production (Innovator® series) and then into the commercial scale.

Some of the advantages that the STT® reactor technology brings include:
	Rate enhancement
	Improved conversion
	Selectivity enhancement
	Reduced batch cycle time
	Improved temperature and reaction environment control
	Reduced catalyst consumption and solvent use
	Reaction of normally immiscible materials
	Mixing of materials with large relative viscosities
	Improved safety in handling toxic and explosive materials
	Rapid and efficient cleaning
	Small reactor foot print compared to conventional reactors

Other Applications
For those interested in more complex chemistry please request our Pharma, Agricultural and Specialty Chemical Applications Table for some examples of how the STT® reactor technology can benefit you.

Examples