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Automating a Combinatorial Hydrothermal Synthesis and Characterization with LabVIEW

Author(s):

Martin Plassen, SINTEF

Industry:

Oil and Gas/ Refining/ Chemicals

Product:

Compact FieldPoint, Distributed I/O, FieldPoint, LabVIEW

The Challenge:

Automating as much as possible of a combinatorial hydrothermal synthesis work process.

The Solution:

Developing a program in LabVIEW, which together with an advanced hardware setup provides an integrated work process both in data handling and station scheduling.


Introduction
A chemist doing hydrothermal inorganic synthesis typically can accomplish 200 to 300 syntheses per year, due to limitations of manual handling of individual samples. Such syntheses are performed at elevated temperature and pressure, normally in Teflon-lined steel-autoclaves. The autoclaves are placed in ovens at temperatures up to 225 degrees Celsius for up to several days, which means pressures in the range of 10 to 15 bars. Normally the crystallization gives a yield of two to 20 percent of the starting gel weight. The resulting product is isolated, washed and characterized by x-ray diffraction.

In the search for new materials, the number of possible starting reagents, together with the different parameters that influence the synthesis (order of addition of reagents, aging, stirring, shaking, synthesis temperature), the number of possible ways to perform these syntheses rapidly exceeds 10 18 . Discovering new materials can be an insurmountable workload for a chemist. Molecular sieves possess unique properties because of their microporosity and are used in many fields of the chemical industry both as catalysts and adsorbents. The discovery and commercialization of new microporous materials has the potential of generating value worth millions of dollars. With all this in mind, automating this search for new materials in such a way that a chemist could perform a multitude of syntheses and characterizations each year at a reduced cost compared to the traditional approach was an exciting challenge.

System Hardware
The MultiAutoclave is an essential component for running this combinatorial system because the MultiAutoclave is specially designed to withstand the high temperature, pressure, and aggressive reagents used in some syntheses.Adding the different reagents using a pipetting robot to form the reactive gel acts as a starting point for the synthesis. When purchasing the robot, we wanted to find a multi-pipette robot with software that we could control from other software via DDE communication. We implemented a shaker into the pipette-robot to allow mixing during addition of reagents. We used a simple balance to record the weight of the MultiAutoclave before and after addition of reagents, and after the crystallization was finished, to monitor possible leakage. We used a photo station to record images of the MultiAutoclave after we added the reagents, and after we completed the crystallization.

Ovens for aging and crystallization were necessary for elevated temperatures. We implemented several small ovens instead of few larger ones to have a more dynamic system. Serial communication controls the ovens.
The XRD instrument for characterization of the resulting products needs some of the same possibilities as the pipetting robot. To make the XRD instrument run a characterization of a 2-D array of samples on one plate in one run, we purchased an instrument with an XYZ-stage. A National Instruments FieldPoint system monitors temperatures and humidity during aging and crystallization.

System Software
Because LabVIEW has been our standard for lab automation for several years , using NI LabVIEW as the main programming tool for the overall control of this system was never a matter of discussion. We knew NI LabVIEW had adopted all the newest software technologies that we needed on this project.
The main program features the following attributes:

  • Integration with pipetting software via DDE
  • Reporting and logging of experiments in Excel via ActiveX
  • Selection of reagents from a database
  • Taking photos automatically via the VfW -standard, stored as JPG-format
  • Import of experimental design from statistical software
  • Matrix calculation of volumes to pipette
  • Build up of XRD method, and collection of resulting data and search and match results into Excel files
  • Use of Intranet to connect the main PC and the PC controlling the XRD
  • Use of e-mail to notify operator of future events that require manual intervention (autoclaves to be removed from ovens), or serious error situations.

Benchmark Measurement
In three days 240 syntheses were performed with associated XRD-analyses. This would take approximately a man-year in the traditional way. Roughly one can estimate the costs of one traditional synthesis and characterization as $500. This system was able to run 48 of these at about the same price.

Conclusion
We are already in the process of setting up the second-generation automation, however this system has already demonstrated with convincing power how much can be achieved in this field of chemical research, using a flexible and powerful software tool as LabVIEW.

[1] D.E. Akporiaye, I.M. Dahl, A. Karlsson, R. Wendelbo, Angew. Chem. 1998, 110, Nr 5, 629-631.
[2] Patent PCT/NO98/00051

For more information, contact:

Martin Plassen

SINTEF

P.O.Box 124

Blindern, 0314 Oslo, Norway,

Tel: (+47) 22067690

Fax: (+47) 22067350

E-mail: martin.plassen@chem.sintef.no.

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