Accelerated testing with Advanced analytics
In the Flowrence platform, reactor products are kept in the gas phase as much as possible in order to be able to directly feed the complete sample stream into online GC’s. This allows for complete speciation as well as the best achievable determination of the mass balance. However, this approach calls for advanced GC methods to manage the analysis time to meet the required cycle times of the experiment.
Analysing all the components and shortening the cycle time, are two factors that need to be balanced with each application. This differs for each case, depending on whether more data points or more detailed component information is important. This choice is often a matter of which stage of R&D your application is tested for. Early stage catalyst scouting has less need for detail than the stage of process optimisation in which more complete product separation is required.
Another advantage of online analyses is to be able to analyse the non-condensable gasses when liquid samples are collected. This gives us the opportunity to achieve an even better mass balance, and to include an internal standard. The speed increase for the higher boiling components is often gained by making use of a multi-column approach, where the sample is pre-separated on the first column. Part of the sample continues onto a second column and the other part on a third column, where we can make use of the difference in the coatings/packings of the columns, to achieve the best resolution in the shortest amount of time.
Below there are some examples of different applications where short cycle times were established in different ways. Depending on the number of components, the number of reactors and the required cycle time, the best solution involved either multiple channels per sample line or multiple GC’s or even a combination of both.
In the Catalysis Insider issue of July 2017, the configuration and Design-of-Experiments of the IsoRON application was described. As an example of advanced analytics, we now focus on the online analytical method of RON. The RON analysis is one where you need to separate almost all paraffins, olefins, iso’s, naphthenes and aromatics from C1 to C12, to be able to calculate the Research Octane Number. The conventional way would be 2.5 hours offline analysis. This has already been improved by UOP in their ASTM method with a cycle time of 55 minutes, but we needed an even faster method and with more detail on the aromatics. Faster to be able to create a feedback loop to run reactions in an iso-RON controlled setup and more detail on the separation of xylenes was of specific interest for several customers. By optimizing the columns we ended up with a half an hour method, giving the fast feedback needed in our iso-RON control loop.
As shown below, the 1-column PONA on the left and our improved 2-column method on the right, by making use of different pre-column and analytical columns we can separate the aromatics from the rest and get a better separation between the different C8-aromatics, especially the difficult pair of meta and para-Xylene.
In conclusion, advanced GC set-up and methodology can significantly increase the speed of analysis, while providing desired separation of components. In some cases this can be crucial to enabling the application of high-throughput testing to specific catalytic processes. Please feel free to contact us to explore the possibilities to accelerate your analytics.