Of n-heptane

A motor fuel has an octane number X if it behaves under tightly defined experimental conditions the same as a mixture of X volume % of isooctane and (100 - X)% of n-heptane. The isooctane-heptane binary mixtures are called primary reference fuels. Octane numbers higher than 100 can also be defined the reference material is isooctane with small quantities of tetraethyl lead added the way in which this additive acts will be discussed later. 

A mixture of n-heptane, tetrahydrofuran, 2-butanone, and n-propanol elutes in this order when using a polar stationary phase such as Carbowax. The elution order is exactly the opposite when using a nonpolar stationary phase such as polydimethyl siloxane. Explain the order of elution in each case. 

Katz et al. tested the theory further and measured the distribution coefficient of n-pentanol between mixtures of carbon tetrachloride and toluene and pure water and mixtures of n-heptane and n-chloroheptane and pure water. The results they obtained are shown in Figure 17. The linear relationship between the distribution coefficient and the volume fraction of the respective solvent was again confirmed. It is seen that the distribution coefficient of -pentanol between water and pure carbon tetrachloride is about 2.2 and that an equivalent value for the distribution coefficient of n-pentanol was obtained between water and a mixture containing 82%v/v chloroheptane and 18%v/v of n-heptane. The experiment with toluene was repeated using a mixture of 82 %v/v chloroheptane and 18% n-heptane mixture in place of carbon tetrachloride which was, in fact, a ternary mixture comprising of toluene, chloroheptane and n-heptane. The chloroheptane and n-heptane was always in the ratio of 82/18 by volume to simulate the interactive character of carbon tetrachloride. 

A solution of 1 g of the diacetate (III) in lOOcc of n-heptane containing 2.5 ccof cyclopentanol and 50 mg of p-toluenesulfonic acid is heated under reflux for 20 hours. After cooling, a few drops of pyridine are added and the solvent is eiiminated by evaporation under vacuum. The residue is taken up with methanol to give 3-cyclopentyl enolether of 17a-ethvnyl-19-nortes-tosterone ecetate which, after recrystalllzation from methanol, melts at 182°C to 1B4°C. 

Thermal stabilization of polyolefins has been first demonstrated for low-molecular models-normal structure alkanes [29]. It has been shown that metallic sodium and potassium hydroxide with absorbent birch carbon (ABC) as a carrier are efficient retardants of thermal destruction of n-heptane during a contact time of 12-15 s up to the temperature of 800°C [130]. Olefins and nitrous protoxide, previously reported as inhibitors of the hydrocarbon thermal destruction, are ineffective in this conditions. 

Table 2 Inhibition of n-Heptane and Hexadecane Cracking Under Pressure in Autoclave ...

Consider the equilibrium state of the system assuming that m grams of n-heptane are dissolved in the benzene phase. Then the mass fraction of n-heptanc in this phase is to. 2 = m/(400 + m). 

Octane. An octane number is a quantitative measure of a fuel mixture s resistance to knocking. The octane number of a particular sample is measured against a standard blend of n-heptane, which has zero octane, and iso-octane, which has 100 octane. The percent of isooctane that produces the same knock intensity as the sample is reported as the octane number. 

The types of interaction that can occur between the solute and the stationary phase surface when in contact with the pure solvents, n-heptane, chloroform or a mixture of n-heptane/chloroform are shown in figure 2. 

In pure n-heptane or pure chloroform the solute molecules can either interact directly with the surface of the adsorbed solvent or displace the adsorbed solvent and interact directly with the silica surface. In the case of the solvent mixture the solute molecules may interact with the surface of either solvent or displace either solvent and interact directly with the silica surface or any combination of these possibilities. For example some solute molecules might displace the layer of n-heptane and interact directly with the surface. At the same time, those solute molecules striking the layer of chloroform may interact only with the chloroform and not be capable of displacing it, as the molecular forces between the chloroform and the silica gel are greater than the molecular forces between the solute and the silica gel. 

Y zeolite from kaolin taken in Yen Bai-Vietnam synthesis, characterization and catalytic activity for the cracking of n-heptane... 

This paper is concerned with the synthesis of Y zeolite with Si02/Al203 ratio of 4.5 from kaolin taken in Yen Bai-Vietnam and their catal3dic activity for the cracking of n-heptane. The synthesized sample (NaYl) showed the Y zeolite crystallinity of 53% and PI zeolite crystallinity of 32%, and exhibited good thermal stability up to 880 C. The activity and the stability of HYl turned out to be lower than those of standard sample (HYs), but the toluene selectivity was higher. The conversion of n-heptane to toluene might be due to the metal oxide impurities, which was present in the raw materials and this indicates the potential application of this zeolite for the conversion of n-parafRn to aromatics. 

Y zeolites synthesized from pure chemicals have now been used as the main composition of FCC catalysts [1-4]. However, the application of Y zeolites synthesized from kaolin in the catalytic processes is still limited. The refinery and petrochemical industry is being built in Vietnam, so the synthesis of Y zeolites from domestic materials and minerals is necessary [4]. In this paper, the initial results in the synfliesis of Y zeolites with Si02/Al203 ratio of 4.5 fiom kaolin taken in Yen Bai-Vietnam and their catalytic activity for the cracking of n-heptane are reported. 

Conversion (C) of n-heptane, composition of products and selectivities of toluene and gas products at different temperatures are presented in Table 2 and Fig. 4. Clearly, the conversion of n-heptane and the selectivity of toluene increase with temperature, whereas the selectivity of gas products decreases. At the same temperature the conversion and selectivity of gas products on HYl are slightly lower than that on HYs, but the selectivity of toluene is higher. 

Conversion (C) of n-heptane and composition of products at different temperatures with the... 

Fig.4. Selectivities to toluene and gas products Fig.5. Influence of reaction time (t) on the at different temperatures (with reaction conversion of n-heptane (C) at 550°C.

The stability of catalyst is one of the most important criteria to evaluate its quality. The influence of time on stream on the conversion of n-heptane at SSO C is shown in Fig. 5. The conversion of n-heptane decreases faster on HYl than on FIYs with time, so the question is Could the formation of coke on the catalyst inhibit diffusion of reactant into the caves and pores of zeolite and decrease the conversion According to Hollander [8], coke was mainly formed at the beginning of the reaction, and the reaction time did not affect the yield of coke. Hence, this decrease might be caused by some impurities introduced during the catalyst synthesis. These impurities could be sintered and cover active sites to make the conversion of n-heptane on HYl decrease faster. 

Also, peak broadening appeared to increase with increased concentration of n-heptane. It is quite possible that mobile phase composition and/or polymer type affects axial dispersion. 

In order to verify the conditions of this averaging process, one has to relate the displacements during the encoding time - the interval A between two gradient pulses, set to typically 250 ms in these experiments - with the characteristic sizes of the system. Even in the bulk state with a diffusion coefficient D0, the root mean square (rms) displacement of n-heptane or, indeed, any liquid does not exceed several 10 5 m (given that = 2D0 A). This is much smaller than the smallest pellet diameter of 1.5 mm, so that intraparticle diffusion determines the measured diffusion coefficient (see Chapter 3.1). This intrapartide diffusion is hindered by the obstades of the pore structure and is thus reduced relative to D0 the ratio between the measured and the bulk diffusion coeffident is called the tortuosity x. More predsely, the tortuosity r is defined as the ratio of the mean-squared displacements in the bulk and inside the pore space over identical times ... 

Fig. 3.3.4 Variation of the tortuosity x inside the catalyst pellets during coking and regeneration, obtained by measuring the self-diffusion coefficient of n-heptane at room temperature.

In Figure 3.3.2, the strong dependence of the 3H relaxation time of n-heptane on coke content was shown for low magnetic field strengths although less pronounced, this 7 dependence still holds for high fields [2]. For large catalyst pellets... 

The activity of metals other than platinum for skeletal reactions of larger molecules is not well documented, particularly in a mechanistic sense. Carter, Cusumano, and Sinfelt (157) have recently studied the reaction of n-heptane on a series of group VIII metals in the form of hydrogen-reduced (300°C) metal powders. The nature of the reaction pathways is summarized in Table IX. Although many metals have been... 

Reaction of n-Heptane over Reduced Metal Powders ... 

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