Canadian Journal of Chemical Engineering, Vol.99, No.2, 423-434, 2021
Experimental methods in chemical engineering: Temperature programmed surface reaction spectroscopy-TPSR
Temperature programmed surface reaction spectroscopy (TPSR) is a powerful technique to determine the surface chemistry of bulk metal, supported metal, bulk metal oxide, supported metal oxide, zeolite, and molecular sieve catalysts. It can provide both qualitative and quantitative analysis of the surface active sites present on the catalyst surface, the reaction mechanisms, and kinetics occurring on the catalyst surface by using chemical probe molecules such as alcohols, carboxylates, and specific acidic-basic reacting gases. In this tutorial review, the highly informative CH3OH chemical probe molecule was used to highlight the information that can be obtained from CH3OH-TPSR experiments. The CH3OH molecule readily interacts with the catalyst surface to form surface CH3O center dot and HCOO center dot intermediates that react to produce HCHO/HCOOCH3/(CH3O)(2)CH2, CH3OCH3, and CO/CO2 products related to the surface redox, acid and basic nature, respectively. Integration of the CH3OH-TPSR spectra peaks provide the number of surface active sites. The surface kinetic information provided by CH3OH-TPSR allows to discriminate between different reaction mechanisms (first-order, second-order, Langmuir-Hinshelwood, and Mars-van Krevelen). We discuss the uncertainty inherent in CH3OH-TPSR experiments and address source of errors and detection limits. Web of Science indexed over 800 articles citing TPSR since 1990. A bibliometric analysis identified four clusters of reactions and catalysts: the dominant catalysts for partial oxidation and water gas shift were Ni, Ru, and Pt; CeO2, Co, Cu, Rh, Pd, and perovskites were the main catalysts for combustion and hydrogenation; Ag and zeolites were grouped with reduction; and, Al2O3, ZrO2, SiO2, and V2O5 were applied for dehydrogenation.