Hydrogen yield, increased

As severity is increased, C5+ gasoline yields decrease, with a corresponding increase in C, to C4 products. Hydrogen yields increase with severity until the level at which no further aromatics are produced as severity is increased even further, hydrogen yields then decrease. 

A small amount of nickel in the FCC feed has a significant influence on the unit operation. In a clean gas oil operation, the hydrogen yield is about 40 standard cubic feet (scf) per barrel of feed (0.07 wi /r ). This is a manageable rate that most units can handle. If the nickel level increases to 1.5 ppm, the hydrogen yield increases up to 100 scf per barrel (0.17 wt%). Note that in a 50,000 barrel/day unit, this corresponds to a mere 16 pounds per day of nickel. Unless the catalyst addition rate is increased or the nickel in the feed is passivated (see Chapter 3), the feed rate or conversion may need to be reduced. The wet gas will become lean and may limit the pumping capacity of the wet gas compressor. 

Figure 1 represents the effects of the changes in the HC1 concentration on hydrogen production yield at the fixed initial pH = 7 and substrate concentration 25 g/1. As can be seen from Figure 1, the cumulative hydrogen yield increased sharply with the increase of the concentration of HC1 in the range of 0.5-1.0%, and then decreased slowly with the increase of the HC1 concentration. 

DC1 solutions in cyclohexane have recently been studied (44, 52). Data similar to those from DI solutions have been obtained but can be more easily interpreted, at least in the low concentration region, since DC1 is a relatively poor hydrogen-atom scavenger. Here too, however, the total hydrogen yield increases upon adding DC1 [as noted earlier (II, 29)]. Allowing for a contribution of this excess to the HD yield, a value of aDci -— 10 can be estimated. 

After the steam reforming step, the product gas stream contains a considerable quantity of carbon monoxide which may undergo reaction with additional steam, thereby increasing the hydrogen yield ... 

Hydrogenation of 19-hydroxy-3a- and 3j5-substituted-A -steroids over platinum or rhodium yields increased amounts of 5j9-products as compared to the corresponding 19-desoxy series (hydroxyl group effect). In contrast, the A -19-carboxaldehyde (27) gives only the 5a-product when hydrogenated over either palladium or platinum. ... 

Dehydrochlorination of bis(tnfluoromethylthio)acetyl chloride with calcium oxide gives bis(trifluoromethylthio)ketene [5] (equation 6) Elimination of hydrogen chloride or hydrogen bromide by means of tetrabutylammonium or potassium fluoride from vinylic chlorides or bromides leads to acetylenes or allenes [6 (equation 7) Addition of dicyclohexyl-18-crown-6 ether raises the yields of potassium fluoride-promoted elimination of hydrogen bromide from (Z)-P-bromo-p-ni-trostyrene in acetonitrile from 0 to 53-71 % In dimethyl formamide, yields increase from 28-35% to 58-68%... 

In most units, the increase in hydrogen make does not increase coke yield the coke yield in a cat cracker is constant (Chapter 5). The coke yield does not go up because other unit constraints, such as the regenerator temperature and/or wet gas compressor, force the operator to reduce charge or severity. High hydrogen yield also affects the recovery of Cj-H components in the gas plant. Hydrogen works as an inert and changes the liquid-vapor ratio in the absorbers. 

Catalyst composition and feed chloride have a noticeable impact on hydrogen yield. Catalysts with an active alumina matrix tend to increase the dehydrogenation reactions. Chlorides in the feed reactivate aged nickel, resulting in high hydrogen yield. 

Hydrogen bromide is eliminated from 10,11-dibromo-l 0,1 l-dihydrodibenz[7>,/]oxepin with potassium tert-butoxide at room temperature to give 10-bromodibenz[i,/]oxepin (17a).160161 When the elimination reaction was performed in boiling toy-butanol the yield increased from 58 to 92%.261 Dehydrohalogenation of 10-chloro-2,3-dimethoxy-10,ll-dihydrodi-benz[/),/]oxepin afforded 2,3-dimethoxydibenz[6,/]oxepin (17b) in 52% yield.162... 

The problem of the diolefin formation was first solved with the introduction of the DeFine process, in which diolefins are hydrogenated to monoolefins by a contact (H-14). This catalyst was developed in 1984 and used on a large scale for the first time in 1986. With its help the diolefins are practically quantitatively removed and the monoolefin yield increased by about 4-5% [58]. The advantages of the DeFine step are [58,92] ... 

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