In Situ Hydrogen Temperature-Programmed Reduction Technology Based on the Integrated Microcantilever for Metal Oxide Catalyst Analysis

Hydrogen temperature-programmed reduction (H2-TPR) technique is significant for catalyst characterization. The available instruments typically measure the H2 consumption using a thermal conductivity detector (TCD), which is strongly affected by the produced H2O molecules. Herein, we demonstrate an in situ TPR technology based on a silicon microcantilever, in which resonance exciting/detecting components and heating electrodes for catalyst samples are integrated. The microcantilever-based H2-TPR technology requires only 20 ng of the sample and eliminates the requirements of TCD and cold trap. During the self-heating up to 1000 °C, reduction-induced mass change of the sample can be in situ measured with picogram-level resolution. Compared with the available instruments, the microcantilever-based H2-TPR technology directly and in situ measures the mass change of the sample, without using H2 consumption to indirectly represent the reduction process, thus significantly improving the characterization accuracy. The microcantilever-based TPR technology has been successfully used to characterize various metal oxide catalysts with satisfactory accuracy. The in situ TPR results of the three CuO samples with different grain sizes clearly distinguish their different maximum temperatures, revealing the size effect of the catalyst. The microcantilever can also be placed in a low-temperature test chamber, enabling successful frozen H2-TPR analysis of catalysts with low reduction temperatures, such as PdO. Featuring simplified operation but high detecting accuracy, the microcantilever-based in situ H2-TPR technology is promising in the analytic applications of advanced catalysts.