How To Identify and Analyze the Coke on Ru-Based Catalyst during Acetylene Hydrochlorination?

Coke formation during acetylene hydrochlorination has been recognized as one of the main factors responsible for the deactivation of mercury-free catalysts. Identifying the nature of coke and quantifying its contribution to deactivation are crucial for designing stable catalysts yet remain challenging due to the interference of activated carbon. In this study, we showed that coke on a Ru-based mercury-free catalyst originated from acetylene polymerization through combined characterizations using mass spectrometry and nuclear magnetic resonance, and then developed a quantitative area-based method for coke analysis based on the derivative thermogravimetry curve. Interestingly, under different kinetic conditions, the degree of acetylene polymerization varies, altering its decomposition temperature. Experiments under different kinetic conditions analyzed coke formation, identifying an optimal acetylene-to-hydrogen chloride ratio where in-situ diffuse reflection Fourier transform infrared spectroscopy showed that Ru sites provided superior acetylene adsorption. This work provides fundamental insight into assessing the deactivation contribution of coke for mercury-free catalysts during acetylene hydrochlorination.