Rare earth material balance catalyst

Table II. Rare Earth Material Balance and Feedstock Contaminant Metals Material Balance on Equilibrium Catalyst...

Estimated changeover based on rare earth material balance - 88% Fresh Catalyst Addition Rate (see text) 2% of inventory/day... 

During the five months of operation with the zero rare earth octane catalyst, the effective fresh catalyst addition rate, after correction for catalyst loss from the unit as fines, was about 5 tons/day. Based on a rare earth material balance (Table II) that was used to give the best estimate of pedigree, the equilibrium sample consists of 88% USY octane catalyst. The remaining 12% should be a mixture of the prior two catalysts, the first of which contains a contaminant rare earth level of 0.5 wt% versus 0.1 wt% for the octane catalyst. The balance of this mixture is the rare earth-Y catalyst from the previous changeover which exhibits a rare earth level of 0.85 wt% (Table II). 

Metal-tolerant catalysts are formed by active matrices with macropores which can entrap large molecules such as the vanadium-containing compounds and, ideally, can produce metal agglomeration and a strong interaction with the matrix. However, most of these catalysts have to balance between metal tolerance and other desired catalyst characteristics such as yield and cost. Due to this, separate metal-trap additives have been used, and in the case of vanadium besides MgO-containing materials (von Ballmoos 1993) and a liquid vanadium passivator (Stonecipher 1997), anew rare-earth-based dual particle system has been introduced (Dougan 1994). 

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