Catalyst additives commercial trials

Additive inhibitors have been developed to reduce the contaminant coke produced through nickel-cataly2ed reactions. These inhibitors are injected into the feed stream going to the catalytic cracker. The additive forms a nickel complex that deposits the nickel on the catalyst in a less catalyticaHy active state. The first such additive was an antimony compound developed and first used in 1976 by Phillips Petroleum. The use of the antimony additive reportedly reduced coke yields by 15% in a commercial trial (17). 

Antimony metals passivation technology has been utilized in a variety of FCC unit designs, with a wide range of FCC catalysts (14, 9). In addition, antimony metals passivation has been commercially proven over a broad range of catalyst metals concentrations. As the catalyst metals level increases, the passivation performance improves. A study of over 25 commercial trials revealed that the average hydrogen reduction improved from 35% to 45% as the metals levels increased from less than 6000 ppm (4Ni+V) to over 9000 ppm (4Ni+V), Figure 2. 

However, once a catalyst is identified for additional studies, usually a 1-10 gram quantity of catalyst is required and these preparations are carried out in dedicated catalyst preparation apparatus and are then evaluated in a 1-4 liter polymerization autoclave designed to produce 40-400 grams of polyethylene, which is required for a more detailed evaluation of polymer properties. Catalysts that provide polymer with improved properties are then scaled up for a pilot plant evaluation which is usually similar to commercial equipment already in operation. Approximately 100-1,000 grams of catalyst is required for a pilot plant study, which provides 10-100 Ibs/hour of polyethylene. A pilot plant trial will usually take place in a continuous mode lasting 1-5 days and producing a total of 200-1,000 lbs of polyethylene. 

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