Study on deactivation of Ni/Al2O3 catalyst for liquid phase hydrogenation of crude 1,4-butanediol aqueous solution

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Courtesy of Hiden Analytical

The deactivation of a commercial Ni/Al2O3 catalyst in the liquid phase hydrogenation of crude 1,4-butanediol aqueous solution was investigated. H2-TPD experiments have been performed over the fresh and deactivated catalysts in order to determine the change in metal dispersion. In this experiment the gaseous products were monitored as a function of temperature using a HIDEN model QIC-20 mass detector.

The TPD profiles are shown in figure 1. The profiles show two domains of H2 peaks, one below 623K referred to as type-1 peaks and the other between 623K and 823K denoted as type-2 peaks. The low temperature type-1 peaks are generally attributed to H2 desorbed from the metal particles and indicates the exposed fraction of Ni atoms. It could be seen that the type-1 peak area for the fresh catalyst was much larger than that for the deactivated one. This indicates that aggregation of Ni occurs in the deactivated catalyst leading to a decrease in the amount of chemisorbed H2. The high temperature type-2 H2 peak corresponding with a CO2 peak between 623K and 873K existed just in the deactivated catalyst. It was attributed to the pyrolysis of the oligomeric species deposited on the deactivated catalyst during the reaction.

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