Steam cracking of hydrocarbons:3 straight-run naphtha

Steam cracking of straight-run naphtha from Romashkino crude oil was investigated in quartz and stainless steel reactors with a relatively large ratio of Inner surface to volume. The experiments were performed at atmospheric pressure at 780-800 OC for starting ratios of steam to naphtha between 0.5 and 1.0, with residence times of 0.1-0.4 s. The influence of the reactor material, the temperature, the ratio of steam to hydrocarbon, the residence tlme, and the presence of sulfur compounds is discussed in terms of coke formation and yields of various reaction products. The reaction products were analyzed by gas chromatography, using packed columns for the analysis of the gaseous products and capillary columns for the liquid products. About 200 compounds were identified in the liquid mixture. Reference standard hydrocarbons, published retention data, and mass spectrometry were used for the identifi&tiOn

Steam cracking of hydrocarbons: 2 pyrolysis of methylcyclohexane

The thermal decomposition of methylcyclohexane in the presence of steam was studied in a laboratory tubular reactor with large inner surface at atmospheric pressure. Experimental data were obtained at a temperature range of 700-790 OC and at residence times of 0.04-0.20 s. The overall kinetic analysis gives a value of 201.3 kJ mol-' for the activation energy and 0.532 X 10" s-' for the frequency factor. The pyrolysis products (more than 90) were identified with capillary gas chromatography by comparison of their retention indices with those of standard hydrocarbons and by mass spectrometry

Steam cracking of hydrocarbons:3 straight-run naphtha

Steam cracking of straight-run naphtha from Romashkino crude oil was investigated in quartz and stainless steel reactors with a relatively large ratio of Inner surface to volume. The experiments were performed at atmospheric pressure at 780-800 OC for starting ratios of steam to naphtha between 0.5 and 1.0, with residence times of 0.1-0.4 s. The influence of the reactor material, the temperature, the ratio of steam to hydrocarbon, the residence tlme, and the presence of sulfur compounds is discussed in terms of coke formation and yields of various reaction products. The reaction products were analyzed by gas chromatography, using packed columns for the analysis of the gaseous products and capillary columns for the liquid products. About 200 compounds were identified in the liquid mixture. Reference standard hydrocarbons, published retention data, and mass spectrometry were used for the identifi&tiOn

Steam cracking of hydrocarbons: 3 straight-run naphtha

Steam cracking of straight-run naphtha from Romashkino crude oil was investigated in quartz and stainless steel reactors with a relatively large ratio of Inner surface to volume. The experiments were performed at atmospheric pressure at 780-800 OC for starting ratios of steam to naphtha between 0.5 and 1.0, with residence times of 0.1-0.4 s. The influence of the reactor material, the temperature, the ratio of steam to hydrocarbon, the residence tlme, and the presence of sulfur compounds is discussed in terms of coke formation and yields of various reaction products. The reaction products were analyzed by gas chromatography, using packed columns for the analysis of the gaseous products and capillary columns for the liquid products. About 200 compounds were identified in the liquid mixture. Reference standard hydrocarbons, published retention data, and mass spectrometry were used for the identifi&tiOn

Steam cracking of hydrocarbons: 1 pyrolysis of heptane

The thermal decomposition of heptane in the presence of steam was studied in a flow reactor with large inner surface. The experiments were performed at atmospheric pressure in a temperature range of 680-760 OC for a mass ratio of steam to hydrocarbon 3:l. The reaction products were analyzed by gas chromatography. For the identification both comparison of retention indices with those of standard compounds and literature data and mass spectrometry were used. The conversion process appeared to be a first-order reaction with a frequency factor of 1.34 X 10'' s-' and an activation energy of 195.5 kJ mol-'. The composition of the mixture of reaction products was in agreement with the Rice-Kossiakoff theory, except for ethane and 1-hexene

Steam cracking of hydrocarbons: 1 pyrolysis of heptane

The thermal decomposition of heptane in the presence of steam was studied in a flow reactor with large inner surface. The experiments were performed at atmospheric pressure in a temperature range of 680-760 OC for a mass ratio of steam to hydrocarbon 3:l. The reaction products were analyzed by gas chromatography. For the identification both comparison of retention indices with those of standard compounds and literature data and mass spectrometry were used. The conversion process appeared to be a first-order reaction with a frequency factor of 1.34 X 10'' s-' and an activation energy of 195.5 kJ mol-'. The composition of the mixture of reaction products was in agreement with the Rice-Kossiakoff theory, except for ethane and 1-hexene

Steam cracking of hydrocarbons: 5. effect of thiophene on reaction kinetics and coking

The effect of thiophene on the kinetics and selectivity of the conversion of hydrocarbons by steam cracking was studied in a stainless steel tubular reactor with relatively large inner surface. Heptane was selected as a model and decomposed at 700 OC and 100 kPa with a mass ratio of steam to feed of 3:l. The rate of decomposition increased about 14% if 0.1 and 0.5% mass of thiophene was added, but was unchanged if 1 % was present. The influence of thiophene on the selectivity of the conversion of heptane to ethene appeared to depend on the residence time. The effect of thiophene on the formation of coke was investigated in the pyrolysis of a reformer raffinate in a stainless steel flow reactor at 820 OC, without steam. Coking is lessened with increasing amounts of thiophene in the feed (0.05-0.5 % mass). Reaction mechanisms are suggested

Steam cracking of hydrocarbons: 5. effect of thiophene on reaction kinetics and coking

The effect of thiophene on the kinetics and selectivity of the conversion of hydrocarbons by steam cracking was studied in a stainless steel tubular reactor with relatively large inner surface. Heptane was selected as a model and decomposed at 700 OC and 100 kPa with a mass ratio of steam to feed of 3:l. The rate of decomposition increased about 14% if 0.1 and 0.5% mass of thiophene was added, but was unchanged if 1 % was present. The influence of thiophene on the selectivity of the conversion of heptane to ethene appeared to depend on the residence time. The effect of thiophene on the formation of coke was investigated in the pyrolysis of a reformer raffinate in a stainless steel flow reactor at 820 OC, without steam. Coking is lessened with increasing amounts of thiophene in the feed (0.05-0.5 % mass). Reaction mechanisms are suggested

Steam cracking of hydrocarbons: 4 analysis of high-boiling products from naphtha in a quartz reactor

Part 3 of this series reported on the steam cracking of straight-run naphtha in a stainless steel and a quartz reactor. High-boiling polynuclear aromatic hydrocarbons were formed in a quartz reactor but were not found as products from a stainless-steel reactor. In this paper the analysis of the polynuclear aromatic hydrocarbons is discussed. The high-boiling fraction was separated by high performance liquid chromatography and by capillary gas chromatography. About 200 of the compounds present were separated by the latter method. Twenty profiling compounds, with boiling points up to 462 OC, were identified by the coelution technique and by combined gas chrmtography/mass spectrometry. The influence of the wall effects on the proceeding of secondary reactions in metal and quartz reactors is discussed

Genetics of growth, feed intake, and milk yield in Holstein cattle

International audienc