Catalyst additives control technology

CATALYST ADDITIVES CONTROL TECHNOLOGY 16.3.1 SO, Reduction Additive Mechanism... 

When a phosphite is used as a catalyst modifier, it is susceptible to oxidation in the same manner as a phosphine. Unlike triphenylphosphine oxide, which is relatively innocuous except for precipitation when the solubility limit is reached, phosphite oxidation products may hydrolyze to give phosphoric acid. Since phosphites are esters, phosphoric acid can catalyst additional hydrolysis. Other than limiting formation of phosphite oxidation products, the best approach is to include some acidity control technology in the separation or reaction system. 

Share technical information to benchmark catalyst additive performance, control technology performance, and emission limits Facilitate improved communications with the EPA... 

While the commercial catalysts and technologies described above are successfully applied in the industry, some major drawbacks exist with these catalysts such as the low activity of the otherwise robust ferrochrome catalyst at low temperatures, and the susceptibility to poisoning and sintering of the CuZn shift catalyst. Additionally, both classes of catalysts are pyrophoric, generating serious safety problems in the case of accidental air exposure. Furthermore, both catalysts require a special, carefully controlled activation treatment in order to achieve the optimal active phase configuration, with the CuZn catalyst being particularly sensitive to accidental shutdowns, accidental water condensation, or temperature or concentration transients. 

An additional environmental control technology is the removal of NO from stack gases produced by combustion of fossil fuels for the generation of electricity. Small amounts of NH3 are added to the stack gases, which reacts with to form N2 and H2O under the influence of a catalyst such as vanadia-titania. 

A typical medium-size refinery has hundreds of pumps, heat exchangers and drums dozens of furnaces, compressors, and high temperature/high pressure reactors and thousands of control loops and associated advanced computer control technologies. This same typical refinery has dozens of different crudes and other feedstocks to choose from and dozens of products to maximize or minimize based on consumer demands and global market-place economics. In addition to daily decisions about feedstocks and products, there are also hundreds of decisions to be made each day about operahng temperatures, pressures, unit feed rates, catalyst addition rates, cycle times, dishllation cut points, product sjjedfications, inventory levels, etc. 

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