Co-promoter

For many years, cat cracker operators have used additive compounds for enhancing cat cracker performance. The main benefits of these additives (catalyst and feed additives) are to alter the FCC yields and reduce the amount of pollutants emitted from the regenerator. The additives discussed in this section are CO promoter, SO reduction, ZSM-5, and antimony. 

The CO promoter is added to most FCC units to assist in the combustion of CO to COj in the regenerator. The promoter is added to accelerate the CO combustion in the dense phase and to minimize the higher temperature excursions that occur as a result of afterburning in the dilute phase. The promoter allows uniform burning of coke, particularly if there is uneven distribution between spent catalyst and combustion air. 

Regenerators operating in full or partial combustion can utilize the benefits of the CO promoter. The addition of the promoter tends to increase the regenerator temperature and NOx emission. The metallurgy of the regenerator internals should be checked for tolerance of the higher temperature. 

NOj, levels in the FCC flue gas typically range from 50-500 ppm. Nitrogen content of the feed, excess oxygen, regenerator residence time, dense phase temperature, and CO promoter all influence the concentration of NO. ... 

Further developments in the effectiveness of the FCC gasoline sulfur reduction additives will allow a number of refiners to meet the required reduction in gasoline sulfur without undertaking costly capital projects. Additionally, improvements in the CO promoter additives will reduce NO emissions when the promoter is used. Finally, other... 

Mixtures of sodium sulfide and finely divided carbon exhibit an exotherm on exposure to air. As indicated by the low MRH value, this is probably not a direct interaction, but arises from co-promotion of aerobic oxidation of the individual components. 

Shore and coworkers—nuclearity studies over Ru carbonyl catalysts. Shore et al.64 studied reactions of K[DRu3(CO)n] + CO + H20 <- HD + Ru3(CO)i2 + KOH. They found that, at room temperature and 1 atm pressure of Pco, HD is rapidly evolved. In the absence of CO, however, the HD was formed only in trace quantities. They proposed two possible mechanisms to account for this behavior, (a) a concerted mechanism where CO promotes hydride decomposition (Scheme 28), or (b) an associative mechanism involving a complex-CO adduct, which decomposes with H20 (Scheme 29). 

In animal studies, mirex (a nonmutagenic hepatocarcinogen) promoted mouse skin squamous carcinomas and papillomas after initiation with 7,12-dimethyl-benz[a]anthracene (DMBA) for 1 week. Mirex, also, potentiated the promotional potency of the phorbol ester tumor promoter, 12-0 -tetradecanoylphorbol-13-acetate (TPA). There was a 90% incidence (activation) of the c-Ha-ras tumor gene in these co-promoted tumors. When both mirex and TPA gave a similar tumor yield, only the TPA response was associated with biochemical markers of enhanced cell proliferation, induction of epidermal ornithine decarboxylase activity and increased DNA synthesis, and hyperplasia. Thus, there is evidence for a dual effect of mirex during co-promotion first, as an independent tumor promoter with a mechanism different than that of phorbol esters and second, as a compound that also potentiates skin tumor promotion by TPA (Meyer et al. 1993, 1994 Moser et al. 1992, 1993). 

Yields given in parentheses relate to Fe,(CO), promoted reductions [8]. 

Scheme 25 CO-promoted intramolecular allenylidene-alkynyl coupling...

Under co-promotion arrangements whereby companies jointly promote the same medicine and the promotional material bears both company names, each company should certify the promotional material involved as they will he held jointly responsible for it under the Code. 

Where two or more companies are ruled in breach of the Code in relation to a matter involving co-promotion, each company shall be separately liable to pay three-quarters only of the aidministrat-ive charge which would otherwise be payable. 

Since then MeOH carbonylation to AcOH has been developed to commercial scale so successfully that it has displaced other technologies for the manufacture of AcOH. The first of these processes, operated from the 1960s, was that of BASF using Co promoted by iodide [2]. However, Monsanto introduced their Rh and Mel catalysed process in 1968, which operated at lower temperatures and pressures and with much improved selectivity, and this immediately became the technology of choice, being licensed to a number of other companies [3],... 

Add CO promoter when operating in a partial CO burn mode... 

FCC units that use antimony to passivate the deleterious impacts of nickel poisoning can also passivate the platinum (Pt) in the CO promoter. Antimony use can lead to an increase in afterbum or higher amounts of promoter. 

The presence of CO promoter catalyzes the oxidation of SO2 to SO3 and therefore enhances the SO removal process. Higher concentrations of SO3 are also prodnced in the presence of excess oxygen, so SO rednction additives tend to be more effective in fnll combnstion regenerators. 

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