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Infrared thermography is a powerful tool to investigate the dynamic evolution of temperature in chemical reactions. The CO 2 hydrogenation reaction is an ideal model reaction to assess the presented technique due to its high exothermicity. Various dynamic experiments are performed in a newly designed reaction cell with an infrared transmitting ZnSe window. In particular, the gas exchange reactions between CO 2 and H 2 , the coinjection of the two reactants, and the study of the effect of inert gas addition are investigated. Here, we show that the reaction rate on the surface of a catalyst can be localized in time and space by means of infrared thermography. This opens the way to the precise description of reaction dynamics, in particular for reactions operating in intermitting conditions. Furthermore, we show that the combination of infrared thermography with other analytic techniques such as rapid and quantitative mass spectrometry enables a holistic understanding of the transient reaction phenomena.

The promoting effect of Mn and Zn on the performance of Fe-based catalysts has been comparatively investigated in the CO x hydrogenation to heavy hydrocarbons in the presence of H2-deficient streams. To this scope, two catalysts have been prepared by coprecipitation, followed by impregnation with Cu and K, and tested at 220 °C and 30 barg after an activation treatment with syngas. Both catalysts have been found to be active and selective to long-chain hydrocarbons in the presence of either H2/CO or H2/CO2 mixtures. Despite lower catalyst reducibility, the presence of Zn has resulted in higher CO x conversion rates. Furthermore, the Zn-promoted catalyst converted CO x into heavier and less-saturated hydrocarbons. These results are consistent with a role of Zn in promoting the catalyst basicity, which is a key property to keep low the superficial H/C ratio and to slow chain termination reactions as well as secondary olefin hydrogenations.

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