Extracting value from transients observed during measurement of steady-state kinetics

• Transients after step changes during steady-state kinetic measurements are underreported. • Transients can reveal unexpected phenomena and aid modeling efforts. • Reporting transient data in machine readable tabular form is recommended. • Unique transients observed during oxidative coupling , oxychlorination, and butadiene formation. Increasing data availability is paramount to efforts to validate computational models of heterogeneous catalysts. In the course of experimental heterogeneous catalysis research, one large dataset that is often underreported are reaction rates collected over long times on stream during experiments designed to measure apparent kinetic parameters (e.g., apparent activation energies and apparent reaction orders). These data can allow comparisons of deactivation rates across classes of catalysts, which could be useful to largescale models of catalyst restructuring or carbon deposition. Beyond gradual decreases (or increases) in rates or selectivities with time on stream, these data can also include unique transients immediately following step changes from one operating condition to the next. These transients can go unreported entirely and could reveal information about reaction mechanisms that could validate (or invalidate) kinetic models of a given chemistry. In this contribution, we report examples of long time–on–stream data from three distinct classes of reactions: cascade reaction of ethanol and acetaldehyde over Lewis acidic zeolites, oxidative coupling of methanol and dimethylamine over Au-based bimetallic catalysts, and methane oxychlorination over supported palladium catalysts. We discuss possible origins for the various types of transients encountered in the course of collection of apparent kinetic parameters in these chemistries, with all of these data made available in tabulated format. Lastly, we provide an example for the data reduction from an example data set to parameters and figures that would typically be reported in a manuscript regarding reaction kinetics, as a demonstration of what information can go unreported during typical data processing.