Isobutane n-butane ratio

Therefore, we have two effects on isobutane/ n-butane ratio that tend to offset each other. The result, with the California gas oil, is that there is... 

This relationship will vary with the aromatic content of the feedstock. With a highly aromatic feed, the catalyst with the higher hydrogenation activity may give a higher isobutane/n-butane ratio, although with the pentanes and hexanes the effect is reversed. 

No development of catalytic activity,however,was observed when pure HZSM-5 and GazOs+HZSM-S separated by a 0.5 cm long quartz wool bed were used as catalysts. From Table 2 it can also be seen that, after 1500 minutes on stream with propane the aromatic selectivity is enhanced by a factor of about 100 and there is a threefold increase in the total conversion compared with the HZSM-5 sample containing no Ga. While the methane yield does not change significantly, the content of saturated hydrocarbons increases steadily, reflected in the olefin/paraffin ratios shown in Table 2. Characteristic changes also occur in the isobutane/n-butane ratio. 

It is also clear that during periods of low surface ozone, chlorine atoms are a major reactant for hydrocarbons (e.g., Jobson et al., 1994 Solberg et al., 1996 Ariya et al., 1998). Figure 6.39, for example, shows the measured ratios of isobutane, n-butane, and propane during an ozone depletion event (Jobson et al., 1994). These particular pairs of hydrocarbons were chosen to differentiate chlorine atom chemistry from OH reactions. Thus isobutane and propane have similar rate constants for reaction with Cl but different rate constants for reaction with OH. If chlorine atoms are responsible for the loss of these organics, their ratio should remain relatively constant in the air mass, as indicated by the line marked Cl. Similarly, isobutane and n-butane have similar rate constants for removal by OH but different rate constants for reactions with... 

Calculate and plot the minimum external reflux ratio and the minimum number of equilibrium stages against percent product purity for the separation by distillation of an equimolal bubble-point liquid feed of isobutane/n-butane at lOOpsia. The distillate is to have the same 1C4 purity as the bottoms is to have nC4 purity. Consider percent purities from 90 to 99.99%. Discuss the significance of the results. 

Roat et al. (1986) analyzed the choice of manipulated variables for a complex, four-component distillation column. The four components were propane, isobutane, n-butane, and isopentane. There were six possible manipulated variables, and ratios of these variables were also permissible. Table 18.2 shows the condition numbers for six control configurations that were evaluated for the column. Note that the last three strategies have approximately the same low CN. Subsequently, these... 

The ratio of the amount of n-butane-2-13C to the amount of isobutane produced was, provided measurements were made under conditions where secondary reactions were unimportant (i.e., initial reaction products), constant and independent of temperature, and this ratio was 1/4. At the same time, no scrambling of the 13C occurred i.e, all of the isotopically substituted molecules remained singly labeled. Anderson and Baker (68) speculated that the butane isomerization might have occurred by a recombination of adsorbed surface residues produced by fragmentation of the... 

The general treatment of the hydrocarbon stream leaving the alkylation reactor is similar in all processes. First, the acid and hydrocarbon phases have to be separated in a settler. The hydrocarbon stream is fractionated in one or more columns to separate the alkylate from recycle isobutane as well as from propane, n-butane, and (sometimes) isopentane. Because HF processes operate at higher isobutane/alkene ratios than H2S04 processes, they require larger separation units. All hydrocarbon streams have to be treated to remove impurity acids and esters. 

Butane Isomerization—C4 isomerization will be limited to smaller refineries which do not contain hydrocracking facilities. Since the i-C4/ n-C4 ratio for hydrocracking is about 2/1 to 3/1 sufficient isobutane should be available from this source to alkylate all of the available (C3-, C4-, and C5-) olefins from catalytic cracking. 

The intensity ratio of the peaks 59/58 indicates C4 the intensity ratio 44/43 indicates C3 if the molecular peak occurs at 58 Th, peak 43 indicates a CH3 loss the crude formula C4H10 is thus proposed. The peak at 29 Th due to +C2Hs allows one to exclude isobutane the structure that is proposed is thus n-butane. The main peaks that are observed are due to a cleavages. 

The first alternative is currently the most widespread. It consists in setting up a series of four distillation columns grouped in pairs. The first with 65 trays each, separates isobutane at the top with a reflux ratio of 140/1. They operate at 0 to 0.9.10 Pa absolute, aroupd 60 C in series, to minimize the total pressure drop and hence the reboiling temperature. To do this, they comprise direct vapor phase injection of the top effluent from the first distillation column at the bottom of the second, and the use of a pump to draw off the liquid from this column to reintroduce it at the top of the first The second pair of columns operates under the same arrangements at 0.7 to 0.8 10 Pa absolute, around 60 C. with 70 trays for each column and a reflux ratio of 16/1. They serve to obtain Ubutene at the top at about 99.5 per cent purity, and a 2-butenes-rich cut at the bottom, in which the main impurity is n-butane. 

The gas approximates plug flow except in wide columns, but the liquid undergoes considerable backmixing. The latter effect can be reduced with packing or perforated plates. The effect on selectivity may become important. In the oxidation of liquid n-butane, for instance, the ratio of methyl ethyl ketone to acetic acid is much higher in plug flow than in mixed. Similarly, in the air oxidation of isobutane to tcrf-butyl hydroperoxide, where tert-butanol also is obtained, plug flow is more desirable. 

Photolysis of diazirine in the presence of a large excess of propane yielded n- and isobutane and in the presence of n-butane yielded n- and isopentane. From the relative rates of attack on the primaiy and secondary carbon-hydrogen bonds in these compounds, it was concluded that methylene derived from diazirine showed approximately the same discrimination as methylene formed by the photolysis of ketene. The results obtained, using methylene derived from the photolysis of diazomethane, gave a product ratio closer to the simple statistical ratio of the number of carbon-hydrogen bonds without correction factors for the type involved and indicated almost no differentiation between the types. 

Fig. 5. Isobutane isomerization. % conversion to n-butane as a function of Sn/Pt atomic ratio. Catalysts prepared by coimpregnation SI Pt/Al203 blank X SI without H2.

The flow rate of the overhead or bottoms product determines roughly which components go mostly in the overhead and which ones in the bottoms. This also defines the key components where the separation takes place. In this example, an overhead rate of 50 kmol/h would include most of the methane, ethane, propane, isobutane, and n-butane. The bottoms product would include most of the hexane, n-pentane, and isopentane. The n-butane is, therefore, considered the light key component and the isopentane, the heavy key component. The product compositions at a reflux ratio of 1.0 are given in Table 7.3. 

The cracking pattern on Pt-Ce is similar to the one observed on Platinum catalysts on Pt-Co catalysts, the demethylation reaction is more important than on Pt catalyst. When Ni is added, repetitive cracking reactions occur the ratio of isobutane over n-butane is lower than 1 on these latter catalysts which means that multiple processes occur on the catalytic surface because n-butane cannot be obtained from 2-methylpentane with only one carbon-carbon bond breaking. 

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