Rapid investigation of paraffin dehydrogenation catalyst by TPRn/SPI-TOF-MS technique for industrial application

Dehydrogenation of long chain paraffins over commercial Pt-Sn-K-Mg/Al2O3 and Pt-Sn-Na-Co/Al2O3 catalysts were investigated using a temperature programmed reaction/single-photon ionization time-of-flight mass spectrometry (TPRn/SPI-TOF-MS) system under realistic reaction conditions using model compound C120 and in the industrial PACOL dehydrogenation plant using n-C100-C130 mixture. The catalysts were characterized by BET, mercury intrusion porosimetry, CO-chemisorption and NH3-TPD. Catalytic activity, selectivity to various components and stability were compared between TPRn/SPI-TOF-MS measurement and industrial plant run data to explore the reliability, predictability and application of TPRn/SPI-TOF-MS for rapid catalyst testing and screening. Characteristics of the catalysts, such as Pt dispersion and acidity, affected paraffin dehydrogenation conversion and mono-olefin selectivity. This was reflected in the catalyst performance data obtained on TPRn/SPI-TOF-MS system, which was in good agreement with the data from industrial runs. It is shown that use of TPRn/SPI-TOF-MS measurements allows to identify the reaction temperature range for maximum mono-olefin yield. Further it is possible to judge onset temperature for all the products and help identify operation temperature for industrial plant operation. Investigation of aromatics formation over the catalysts establishes the consecutive reaction pathways of long chain paraffin dehydrogenation over modified Pt-Sn/Al2O3 catalyst.