Experimental Methods in Chemical Engineering: Temperature Programmed Reduction-TPR

Temperature programmed reduction (TPR) characterizes the oxido‐reduction properties of bulk and supported catalysts. H2 or CO pass over a pre‐conditioned solid sample as a furnace ramps the temperature at a constant rate. A thermal conductivity detector (TCD) or mass spectrometer records the effluent concentration. In the pre‐conditioning step, Ar or He flushes residual air and absorbed water from the solids sample to maximize the signal‐to‐noise ratio of the TCD signal. We calculate the number of active sites based on the detector signal that correlates with how much hydrogen reacts. The temperature at which it begins to react represents the minimum activation temperature. TPR is cheap, fast, easy to run, and the data is straightforward to interpret. The technique is more popular with chemical engineers than with the broader scientific community. Among the 27 articles that Can. J. Chem. Eng. published in 2016 and 2017[1] that apply TPR to analyze catalysts, 22 mention reactors, 20 report XRD spectra, 18 mention gas chromatography, and another 15 quantify surface area by BET. Synergy with other temperature programmed methods is lower, as only 5 mention temperature programmed desorption, 5 thermal gravimetric analysis, and 3 temperature programmed oxidation.