The Pyrolysis of Trimethylthallium and Evaluation of D[(CH3)2Tl—CH3]

1973 ◽  
Vol 51 (9) ◽  
pp. 1397-1401 ◽  
Author(s):  
S. J. Price ◽  
J. P. Richard ◽  
R. C. Rumfeldt ◽  
M. G. Jacko
Keyword(s):  
Contact Time ◽  
Total Pressure ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Product Analysis ◽  
Carrier Flow

The pyrolysis of trimethylthallium has been studied in a mercury free toluene carrier flow system (452–536 °K, total pressure 6.7–39.3 mm, contact time 0.9–5.1 s, 5.4–90.2% decomposition). In a vessel cleaned with boiling concentrated HNO3 and coated by decomposing 0.1 g Tl(CH3)3 no heterogeneous reaction could be detected. The extent of reaction measured by product analysis (CH4, C2H6, C6H5C2H5) assuming three CH3 per Tl(CH3)3 undergoing reaction 1

scholarly journals The Pyrolysis of Tetramethyltin

1972 ◽  
Vol 50 (1) ◽  
pp. 50-54 ◽  
Author(s):  
R. P. Johnson ◽  
S. J. W. Price
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
First Order ◽  
Carrier Flow ◽  
Pressure Limit

The pyrolysis of tetramethyltin has been studied in a toluene carrier flow system from 803–941 °K using total pressures of 10.6 to 52.4 mm. Contact times varied from 0.49 to 13.8 s and the amount of decomposition from 1.35–98.7%. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed. No appreciable heterogeneous reaction was detected and the first order rates constants appear to have been determined at the high pressure limit. The quantity of undecomposed alkyl was also measured and was found to be in agreement with the product analysis if four methyl radicals are released for each molecule undergoing reaction.Least squares analysis gives[Formula: see text]with an estimated uncertainty in E of ± 1 kcal mol−1. The activation energy should be a good approximation to D[(CH3)3Sn—CH3].

Determination of Conditions for the Suppression of CH3 + Sb(CH3)2→Sb(CH3)3 and Evaluation of D[(CH3)2Sb—CH3]

1972 ◽  
Vol 50 (7) ◽  
pp. 966-971 ◽  
Author(s):  
S. J. W. Price ◽  
J. P. Richard
Keyword(s):  
Activation Energy ◽  
Least Squares ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of trimethylantimony has been studied in a toluene carrier flow system over the temperature range 690–803 °K (total pressures 3.6–173.4 mm, contact times 1.0–13.5 s, decomposition 3.9–89.5%). The progress of the reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. In 23 runs the undecomposed alkyl was also determined. The quantity found was in agreement with that expected from the product analysis if three methyl radicals are released for each molecule undergoing reaction. No heterogeneous reaction was detected.Deuterium labeling led to the conclusion that regeneration of the parent alkyl occurred during the course of the decomposition. This regeneration reaction was effectively eliminated by working at toluene pressures above 150 mm. Least squares analysis of the results obtained under conditions where regeneration should not be important givenLog10k/s−1 = 15.33 − (55 900 ± 1 000)/2.3RTThe activation energy should be a good approximation to D[(CH3)2Sb—CH3].Significant decomposition of SbCH3 probably does not occur. It seems most likely that free Sb is formed via 2Sb(CH3) → Sb(CH3)2 + Sb.

The pyrolysis of trimethylarsine

1970 ◽  
Vol 48 (20) ◽  
pp. 3209-3212 ◽  
Author(s):  
S. J. W. Price ◽  
J. P. Richard
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Rate Constants ◽  
Flow System ◽  
Heterogeneous Reaction ◽  
Methyl Radicals ◽  
Product Analysis ◽  
First Order ◽  
Carrier Flow ◽  
Pressure Limit

The pyrolysis of trimethylarsine has been studied in a toluene carrier flow system from 764 to 858 °K using total pressures from 6.35 to 35.5 mm. Contact times varied from 0.9 to 3.7 s and the amount of decomposition, from 1.2 to 73 %. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed. No heterogeneous reaction was detected and the first order rate constants appear to have been determined at approximately the high pressure limit. In seven runs the undecomposed alkyl was also measured. The quantity found was in agreement with the product analysis if three methyl radicals are released for each molecule undergoing reaction.Least squares analysis of the results gives[Formula: see text]The activation energy should be a good approximation to D[(CH3)2As—CH3]. The product analysis and the values of k4/k51/2 are consistent with the simple consecutive release of three methyl radicals but thermodynamic and kinetic considerations may preclude this possibility.

THE PYROLYSIS OF TRIMETHYLTHALLIUM

1965 ◽  
Vol 43 (7) ◽  
pp. 1961-1967 ◽  
Author(s):  
M. G. Jacko ◽  
S. J. W. Price
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Total Pressure ◽  
Flow System ◽  
Total Darkness ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Homogeneous Process ◽  
Carrier Flow ◽  
Reaction Proceeds

The pyrolysis of trimethylthallium has been studied in a toluene carrier flow system from 458 to 591 °K using total pressures from 5.6 to 33.0 mm. The progress of the reaction was followed by measuring the amount of methane, ethane, ethylene, and ethylbenzene formed and, in 21 runs, by direct thallium analysis. All preparative and kinetic work was carried out in total darkness where possible. A shielded 10 W lamp was used when some illumination was necessary.The decomposition is approximately 80% heterogeneous in an unconditioned vessel and 14–27% heterogeneous in a vessel pretreated with hot 50% HF for 10 min. The reaction proceeds by the simple consecutive release of three methyl radicals. The rate constant depends only slightly on the total pressure in the system so that the activation energy of the homogeneous process, 27.4 kcal/mole, may be equated to D[(CH3)2Tl—CH3].

Determination of D[(CH3)3Pb—CH3] by the Toluene Carrier Method

1972 ◽  
Vol 50 (16) ◽  
pp. 2639-2641 ◽  
Author(s):  
K. M. Gilroy ◽  
S. J. Price ◽  
N. J. Webster
Keyword(s):  
Least Squares ◽  
Flow System ◽  
Methyl Radicals ◽  
Product Analysis ◽  
Method Of Least Squares ◽  
Temperature Range ◽  
Carrier Flow

The pyrolysis of tetramethyl lead has been studied in a toluene carrier flow system over the temperature range 671–753 °K (contact times 0.72–1.67 s, 3–77% decomposition). The reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. Comparison of the extent of reaction based on product analysis and on alkyl recovery indicates that approximately four methyl radicals are released for each molecule undergoing reaction 1.[Formula: see text]The method of least squares gives k1 = 5.0 × 1014 exp (−49 400/RT) sB1 with an estimated uncertainty of ± 1 000 cal mol−1 in E1. Under the conditions used E1 should be a reasonable measure of D[(CH3)3Pb—CH3].

Determination of D[(C2H5)3Sn—C2H5] by the toluene carrier method and studies of the reaction of C2H5 with toluene

1976 ◽  
Vol 54 (11) ◽  
pp. 1814-1819 ◽  
Author(s):  
Mary Daly ◽  
S. James W. Price
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Total Pressure ◽  
Flow System ◽  
Pyrolysis Products ◽  
Temperature Range ◽  
Carrier Flow ◽  
Full Analysis

The thermal decomposition of tetraethyltin in a toluene carrier flow System has been studied over the temperature range 725 to 833 K and decompositions of 3.4 to 98.0%. Total pressure in all runs were in the range 0.63 to 0.90 kPa and contact times of 0.59 to 4.2 s were used.The progress of the reaction was followed by carrying out full analysis of all pyrolysis products involving the C2H5 radical, assuming that all four C2H5 groups are released. In selected runs analysis for unreacted alkyl was also performed. The agreement between the two methods indicates that reaction 1 is followed rapidly by reactions 2, 3, and 4,[Formula: see text]or alternate reactions that result in the release of all four C2H5 groups each time reaction 1 occurs. The decomposition is essentially homogeneous and[Formula: see text]or −59 340/4.58T if the activation energy is expressed in cal rather than J. Combination of present values of k5 with data from previous studies

scholarly journals Flue Gas Desulphurization in Circulating Fluidized Beds

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3908 ◽  
Author(s):  
Deng ◽  
Ansart ◽  
Baeyens ◽  
Zhang
Keyword(s):  
Contact Time ◽  
Power Plants ◽  
Fluidized Beds ◽  
Circulating Fluidized Bed ◽  
Heterogeneous Reaction ◽  
Removal Rate ◽  
Waste Incineration ◽  
Circulating Fluidized Beds ◽  
Dry Process ◽  
So2 Removal

Sulphur dioxide (SO2) is mostly emitted from coal-fueled power plants, from waste incineration, from sulphuric acid manufacturing, from clay brick plants and from treating nonferrous metals. The emission of SO2 needs to be abated. Both wet scrubbing (absorption) and dry or semi-dry (reaction) systems are used. In the dry process, both bubbling and circulating fluidized beds (BFB, CFB) can be used as contactor. Experimental results demonstrate a SO2-removal efficiency in excess of 94% in a CFB application. A general model of the heterogeneous reaction is proposed, combining the external diffusion of SO2 across the gas film, the internal diffusion of SO2 in the porous particles and the reaction as such (irreversible, 1st order). For the reaction of SO2 with a fine particulate reactant, the reaction rate constant and the relevant contact time are the dominant parameters. Application of the model equations reveals that the circulating fluidized bed is the most appropriate technique, where the high solid to gas ratio guarantees a high conversion in a short reaction time. For the CFB operation, the required gas contact time in a CFB at given superficial gas velocities and solids circulation rates will determine the SO2 removal rate.

Diffusive and convective flow in a hydrogen-atom flow system

1968 ◽  
Vol 46 (24) ◽  
pp. 3899-3902 ◽  
Author(s):  
Philip B. Rudnick ◽  
Sidney Toby
Keyword(s):  
Hydrogen Atom ◽  
Surface Area ◽  
Flow Rate ◽  
Convective Flow ◽  
Total Pressure ◽  
Flow System ◽  
Linear Flow ◽  
Flow Signal ◽  
Concentration Time ◽  
Diffusive Flow

Diffusive and convective flow was studied in a hydrogen-atom flow system using an isothermal calorimetric detector. By varying detector area, total pressure, and linear flow rate, the importance of axial diffusion in the system was investigated. Under conditions of predominantly diffusive flow, signal–distance plots were independent of flow rate. When convective flow predominated, concentration–time plots were independent of flow rate. The efficiency of a detector was clearly dependent on its surface area within wide limits, but diffusion gradients produced by the presence of even large detectors did not appear to be important.

scholarly journals An air carrier flow system for the spectrophotometric determination of water in biodiesel exploiting bleaching of the cobalt chloride complex

Talanta ◽  
2015 ◽  
Vol 131 ◽  
pp. 21-25 ◽  
Author(s):  
Andréia C. Pereira ◽  
Boaventura F. Reis ◽  
Fábio R.P. Rocha
Keyword(s):  
Spectrophotometric Determination ◽  
Cobalt Chloride ◽  
Flow System ◽  
Chloride Complex ◽  
Carrier Flow ◽  
Air Carrier

THE PYROLYSIS OF TOLUENE

1962 ◽  
Vol 40 (7) ◽  
pp. 1310-1317 ◽  
Author(s):  
S. J. Price
Keyword(s):  
Activation Energy ◽  
Rate Constant ◽  
Rate Constants ◽  
Contact Time ◽  
Flow System ◽  
Kcal Mole ◽  
Homogeneous Process ◽  
First Order ◽  
Order Rate ◽  
Toluene Concentration

The pyrolysis of toluene has been studied in a flow system from 913 to 1143 °K. First-order rate constants are independent of the toluene concentration but decrease approximately 9% when the contact time is reduced from 1.0 to 0.41 second. Increasing the contact time from 1.0 second to 2.07 seconds does not affect the rate constant. The overall rate has been resolved into homogeneous and heterogeneous components. It is suggested that the activation energy of the homogeneous process, 85 kcal/mole, may be associated with D(C6H5CH2—H).

Sign in / Sign up

Export Citation Format

Share Document