Comparison between deactivation pattern of catalysts in fixed-bed and ebullating-bed residue hydroprocessing units

Treatment of spent catalyst from the nitrogenous fertilizer industry—A review of the available methods of regeneration, recovery and disposal

“…If a suitable condition arises -such as high temperatures in the absence or presence of a suitable chemical environment -catalysts will rearrange to form the more favorable lower surface area agglomerates -a process known as sintering. The relative importance of the different deactivation processes has been reviewed by many researchers [7][8][9][10].…”

A preliminary process design and economic assessment of a catalyst rejuvenation process for waste disposal of refinery spent catalysts

“…A survey of literature revealed that the technology for reactivating spent catalysts from residue hydroprocessing operations is not yet well developed (Furimsky and Massoth, 1993;Furimsky, 1996;Trimm, 2001;Marafi and Stanislaus, 2003a). Catalysts are deactivated by pore blockage and fouling of the active surface with coke and metal (V and Ni) deposits originating from the heavy feedstock (Furimsky and Massoth, 1999;Kam et al, 2005;Al-Dalama and Stanislaus, 2006;Juraidan et al, 2006). Regeneration by conventional procedures using nitrogen-air or steam-air under controlled conditions does not result in complete reactivation of the catalysts.…”

“…While carbon deposits are removed completely, metallic impurities remain on the catalysts. The foulant metals are usually concentrated near the outer surface of the pellet, blocking pore mouths and markedly reducing the active surface area available within the inner pores of the catalysts (Quann et al, 1988;Al-Dalama and Stanislaus, 2006). If the contaminant metals can be removed selectively by chemical treatment without significantly affecting the chemical and physical characteristics of the original catalyst, then the spent catalyst could be rejuvenated and reactivated.…”

Hydration characteristics of waste catalysts used as pozzolanic materials

“…However, regeneration is sometimes impossible and over a few cycles of regeneration and reuse, the catalyst activity may fall to such low levels that further regeneration may not be economically feasible [1,2]. Such spent catalysts are discarded as solid waste [3][4][5][6]. In most of the previous studies, rejuvenation of spent residue hydroprocessing catalysts for reuse was addressed.…”