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1.
2.
A series of 0.6 wt% Pt/BaL catalysts with different alkali cations have been tested for heptane reforming at 440 ° C, 0.16 atm heptane, 0.95 atm H2, 6.7 atm He, 3 to 5 h of reaction, and conversions between 2 and 10%. As the cations in the zeolite are progressively changed from lithium to cesium, the turnover rates for hydrogenolysis and dehydrocyclization increase by about 5–10 times, while the turnover rate for isomerization remains unchanged. Since the turnover rates for hydrogenolysis and dehydrocyclization are similarly affected, exchanging lighter alkali cations for heavier ones increases the aromatics selectivity by a small amount, from 72 to 82%. These results indicate that metal-support interactions have a moderate effect on the heptane reforming activity, but only a weak effect on the selectivity. 相似文献
3.
Alternative hydrocarbon solvents for cottonseed extraction 总被引:3,自引:0,他引:3
P. J. Wan D. R. Pakarinen R. J. Hron Sr. O. L. Richard E. J. Conkerton 《Journal of the American Oil Chemists' Society》1995,72(6):653-659
Hexane has been used for decades to extract edible oil from cottonseed. However, due to increased regulations affecting hexane
because of the 1990 Clean Air Act and potential health risks, the oil-extraction industry urgently needs alternative hydrocarbon
solvents to replace hexane. Five solvents,n-heptane, isohexane, neohexane, cyclohexane, and cylopentane, were compared with commercial hexane using a benchscale extractor.
The extractions were done with a solvent to cottonseed flake ratio of 5.5 to 1 (w/w) and a miscella recycle flow rate of 36
mL/min/sq cm (9 gal/min/sq ft) at a temperature of 10 to 45°C below the boiling point of the solvent. After a 10-min single-stage
extraction, commercial hexane removed 100% of the oil from the flakes at 55°C; heptane extracted 100% at 75°C and 95.9% at
55°C; isohexane extracted 93.1% at 45°C; while cyclopentane, cyclohexane, and neohexane removed 93.3, 89.4, and 89.6% at 35,
55, and 35°C, respectively. Each solvent removed gossypol from cottonseed flakes at a different rate, with cyclopentane being
most and neohexane least effective. Based on the bench-scale extraction results and the availability of these candidate solvents,
heptane and isohexane are the alternative hydrocarbon solvents most likely to replace hexane.
Presented in part at the AOCS Annual Meeting & Expo, Atlanta, Georgia, May 1994. 相似文献
4.
C. Kapseu G. J. Kayem D. Balesdent L. Schuffenecker 《Journal of the American Oil Chemists' Society》1991,68(2):128-130
Cold fractionation of cottonseed oil is made difficult by the high viscosity of the oil. This study was aimed at demonstrating
the effect of solvents on the viscosity of mixtures between 0°C and 25°C with a view to facilitating the fractionation of
refined cottonseed oil. The solvents used were acetone, methylethylketone, methylisobutylketone, hexane and heptane. Measurements
of viscosity were carried out by means of a capillary viscometer. The ratio of the viscosity of cottonseed oil to that of
pure solvents is of the order of 300. The viscosities of solutions of various ratios of solvent to oil (1/3, 1/1, 3/1) are
between those of cottonseed oil and the pure solvents. The effect of the solvent/oil ratio overrides that of solvent nature.
The effect of solvent in reducing the viscosity of cottonseed oil is by descending order: acetone, hexane, methylethylketone,
heptane, methylisobutylketone. 相似文献
5.
Experimental values of the thermal conductivity and the thermal diffusivity of six pure liquid n-alkanes (C
n
H2n+2; n=5 to 10) and toluene are presented in the temperature range of –20 to 70°C under atmospheric or saturation pressure. Measurements were made with the transient hot-wire method, and in the analysis, the temperatures T
and T
(associated with both and ) were used. In the present work, the values of thermal diffusivity were corrected by the factors k
f (=1.0076 to 0.9892) for data sets obtained with different configurations of the experiment, in which the factors were determined by reference to the thermal diffusivity of n-heptane [=
s/(c
p
)s] at 298.15 K calculated from the volumic heat capacity (c
p
)s as a reference material for heat capacity and the experimentally obtained thermal conductivity
s. The uncertainty of the data is estimated to be 0.48% for the thermal conductivity (absolutely measured) and about 1.8% for the thermal diffusivity (with a coverage factor of k
p
=2; p=95%). 相似文献
6.
The influence of the Pt and sulfate concentration on the activity of Pt containing sulfated zirconia for n-heptane conversion was investigated. Pt was deposited on the support by impregnation and by photocatalytic deposition. The
amount deposited was 2.5 and 0.4 wt% respectively. For comparison a hybrid catalyst consisting of sulfated zirconia and Pt
on SiO2 was prepared. As supports a commercial sulfated zirconia with a fixed sulfate concentration, a commercial and self synthesized
Zr(OH)4 were used. The sulfate content varied between 20 and 60% of a monolayer.
The shifts to higher frequency in the IR spectra of CO adsorbed on Pt correlate with the increasing amounts of sulfates on
zirconia and are attributable to the changes in the electron density of the supported metal, i.e. the electron deficiency
of Pt increases with increasing concentration of acid sites.
After activation in air and reduction in hydrogen two SO2 peaks were detected by a temperature programmed heating procedure (TPE—temperature programmed evolution). The lower the desorption
temperature of the first SO2 peak, the higher the activity. The shift to lower temperature is connected with a higher Pt and sulfate concentration, furthermore
with the proximity of the metal to acid sites.
The catalysts with a low sulfate concentration possess only Lewis acid sites and are inactive for n-heptane conversion. At higher sulfate concentration, Br?nsted acid sites are present and the catalysts are active. The concentration
of these acid sites is related to the concentration of sulfates, which desorb at lower temperature.
Dedicated to Professor Konrad Hayek. 相似文献
7.
The dynamic viscosity η and the density ρ of the ternary mixture heptane (mole fractionx
1)+methylcyclohexane (mole fractionx
2) + 1-methylnaphthalene (mole fractionx
3) were measured as a function of temperatureT (303.15, 323.15, and 343.15 K) and pressureP(≤100 MPa). The experimental results correspond to 378 values of η and ρ. With reference to the 54 values previously published
on pure substances and 378 values for the three associated binaries. the system is globally described by 810 experimental
values for various values ofP, T, and compositon. 相似文献
8.
常用轻烃参数正、异庚烷值应用中的问题 总被引:2,自引:0,他引:2
用采自中国国内25个油区的772个原油轻烃分析数据,结合其中338个样品的饱和烃GC/MS分析数据,就原油正、异庚烷值与烃源岩干酪根类型的关系以及与C29甾20S/(20S+20R)成熟度参数的相关性,对影响参数值发生异常变化的因素等作了研讨。研究认为,正、异庚烷值确实与母源干酪根类型有关,但相关关系与Thompson的图版有所差别,研究中国陆相原油时不宜直接引用;原油次生蚀变和混源是使原油正、异庚烷值发生异常变化的重要因素,在用正、异庚烷值作研究时必须备加注意;正、异庚烷值标示原油成熟度的范围大于C29甾20S/(20S+20R)所能标示的;落入Thompson图版"Biodegraded"区域的油样可能有3类:原生的未熟油,已遭蚀变的原油和成熟度不同的混源油,对于未落入该区域内的生物降解油,认为油藏存在二次注入的可能性。图6表2参26 相似文献
9.
10.
Equilibrium extraction behavior for a series of representative tervalent lanthanide ions, La, Pr, Eu, and Yb, using chloroform solutions containing halogenated derivatives of 4-acyl-l-phenyl-3-methyl-5-pyrazolone have been studied. The results demonstrate that these lanthanides are extracted as simple chelates, LnL?3?. The equilibrium constants of these extraction reactions have been calculated. The relationships between the acid dissociation constants, K?a?, determined by a two-phase titration method, distribution constants, K?DR?, and the extraction equilibrium constants, K?ex?, discussed. 相似文献