Off-site catalyst regeneration and presulfiding of hydroprocessing catalysts

Abstract EN

An example of the regeneration of a typical CoMo/A1203 hydrodesulfurization catalyst is discussed, as well as the basic concepts of the off-site presulfiding of hydroprocessing catalysts.

Carbon and sulfur removed is a function of regeneration temperature: carbon is readily removed in a single step between 300-450°C while sulfur elimination starts as low as 150°C and is terminated only at very high temperatures (>600°C).

On the other hand, combustion is limited by oxygen diffusion through the catalyst porosity.

Dispersion of the active phase has been followed with a dynamic oxygen chemisorption (DOC) technique, using Surface Area (SA) BET measurements as a complementary technique to monitor support sintering.

It is found that DOC values start to decrease significantly at temperatures higher than 550°C, whereas substantial decrease of SA is only observed at temperatures higher than 620°C.

Upon hydrogen activation of presulfided catalysts in commercial units at high pressure (>20 bars), it has been established, by using a high pressure temperature programmed reduction (HP-TPR) technique at 20 bars, that generation of H2S from the decomposition of the sulfur compounds occurs at around 150-200°C.

Most of the water generated by the sulfiding reactions of the oxide species is also formed at this temperature.