Which is better as a precursor of aluminum oxide (dawsonite or scarbroite) for the production of highly active CoMo/Al 2 O 3 catalyst for the hydrotreating of feedstock SRGO?

In this work, the effect of using an additive of dawsonite NH4Al(OH)2CO3 or scarbroite Al5(OH)13(CO3)·5H2O in the preparation of alumina supports on the properties of CoMo/Al2O3 catalysts was investigated. It was established that the key factor influencing the composition and properties of the active component of the catalyst was the phase composition of the support, which changed depending on the added dawsonite and/or scarbroite powder. According to XRD and UV spectroscopy data, it was found that with the addition of dawsonite, the amorphous phase predominated in the support, which altered the nature of the interaction of the support and the active metals, namely, it reduced the amount of inactive cobalt aluminate compared to the catalyst sample based on the support with scarbroite. Furthermore, the change in the phase composition of the support affected the formation of the active component. For the sample prepared with dawsonite, XPS data showed the formation of more reactive sulfide sites. The addition of dawsonite led to the formation of a looser support surface, which increased the dispersion of the active component particles from 0.35 to 0.58 compared to the catalyst sample based on the support with scarbroite. The described changes in the characteristics of the catalyst with dawsonite led to an increase in catalyst activity, both in the hydrodesulfurization reactions of model feedstock and of real blended gasoil.