Antimony metals passivation process

Phillips Petroleum Company discovered and developed the antimony metals passivation process in the early 1970 s, and successfully applied the process at its Borger, Texas heavy oil cracker (HOC) in 1976 (2). For catalytic cracking units with... 

Specific commercial performance benefits obtained with the antimony metals passivation process and methods used for evaluating potential benefits are discussed. Options for maximizing benefits are also presented. 

Anodes. Lead—antimony (6—10 wt %) alloys containing 0.5—1.0 wt % arsenic have been used widely as anodes in copper, nickel, and chromium electrowinning and metal plating processes. Lead—antimony anodes have high strength and develop a corrosion-resistant protective layer of lead dioxide during use. Lead—antimony anodes are resistant to passivation when the current is frequendy intermpted. 

Another approach used to reduce the harmful effects of heavy metals in petroleum residues is metal passivation. In this process an oil-soluble treating agent containing antimony is used that deposits on the catalyst surface in competition with contaminant metals, thus reducing the catalytic activity of these metals in promoting coke and gas formation. Metal passivation is especially important in fluid catalytic cracking (FCC) processes. Additives that improve FCC processes were found to increase catalyst life and improve the yield and quality of products. ... 

Metals passivation allows refiners to maximize the charge of lower value feeds. Injection of antimony into the Phillips Sweeny, Texas HOC decreased unit hydrogen production and decreased the process gas compressor speed about 500 rpm. This enabled the refinery to increase throughput 10% and process a more difficult to crack feedstock (14). Fifteen percent of Oriente crude from Ecuador was blended into the Phillips Borger, Texas refinery crude slate with the use of metals passivation at its HOC. Metals in the HOC feed and on the HOC catalyst increased significantly, but yield of hydrogen was still less than it had been prior to metals passivation (6). 

Metals passivation is an area of active research and development, and several passivation systems have been commercialized. Commercialized systems include addition of elements and combinations of elements to FCC catalysts, such as antimony, antimony plus phosphorus (6,. 14), antimony plus phosphorous plus tin, antimony plus tin, tin (19-21), and bismuth (22, 23). Other commercialized systems include process changes or catalyst changes such as the use of steam or light hydrocarbons as diluents in the reactor (24) and vanadium traps (25). Antimony has been used successfully in conjunction with these systems. Another metals passivation additive, containing ingredients that are proprietary, has also been introduced commercially (26) ... 

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