Pyrolysis of triethylgallium by the toluene carrier technique

1979 ◽  
Vol 57 (24) ◽  
pp. 3178-3181 ◽  
Author(s):  
Michellene C. Paputa ◽  
Stanley James W. Price
Keyword(s):  
Thermal Decomposition ◽  
Pressure Range ◽  
Hydrogen Abstraction ◽  
Significant Extent ◽  
Rate Determining Step ◽  
Surface Catalysis ◽  
Gas System ◽  
One Step ◽  
Gallium Hydride ◽  
Ethyl Radicals

The pyrolysis of triethylgallium has been studied in a toluene carrier gas system in the temperature range of 464.7 to 700.7 K and a pressure range of 0.82 to 3.73 kPa. From the data obtained from this work, the following mechanism for the thermal decomposition of the metal alkyl is proposed:[Formula: see text]where [1] is the rate determining step. After runs below 606 K were corrected for the contribution of a concurrent residual reaction, a least-squares analysis of experimental results from 567 to 651 K based on both product and residual alkyl analysis gave[Formula: see text]at 1.60 kPa.The rate constant, k1, is very slightly pressure-dependent as revealed by tests at 648.0 K (80% and 45% decomposition). Studies indicate there is no detectable surface catalysis effect. Similarly, no effect was observed for changes in concentration or contact time.The mechanism for the formation of polymeric gallium hydride in reaction [4] is not clearly defined and may consist of more than one step. Reaction [5] is slow but based on the C2H4:H2 ratio must occur to a significant extent (40–80%) during a run. Further decomposition occurs between runs, causing a build-up of H2 in the reaction vessel.Experimental data for the hydrogen abstraction by ethyl radicals from toluene[Formula: see text]yield the equation[Formula: see text]

Global Reaction Model to Describe the Kinetics of Catalytic Pyrolysis of Coffee Grounds Waste

2017 ◽  
Vol 899 ◽  
pp. 173-178 ◽  
Author(s):  
Ronydes Batista Jr. ◽  
Bruna Sene Alves Araújo ◽  
Pedro Ivo Brandão e Melo Franco ◽  
Beatriz Cristina Silvério ◽  
Sandra Cristina Danta ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Large Scale ◽  
Catalytic Pyrolysis ◽  
Petroleum Products ◽  
Reaction Model ◽  
Heating Rates ◽  
Coffee Grounds ◽  
One Step ◽  
Global Reaction ◽  
The One

In view of the constant search for new sources of renewable energy, the particulate agro-industrial waste reuse emerges as an advantageous alternative. However, despite the advantages of using the biomass as an energy source, there is still strong resistance as the large-scale replacement of petroleum products due to the lack of scientifically proven efficient conversion technologies. In this context, the pyrolysis is presented as one of the most widely used thermal decomposition processes. The knowledge of aspects of chemical kinetics, thermodynamics these will, heat and mass transfer, are so important, since influence the quality of the product. This paper presents a kinetic study of slow pyrolysis of coffee grounds waste from dynamic thermogravimetric experiments (TG), using different powder catalysts. The primary thermal decomposition was described by the one-step reaction model, which considers a single global reaction. The kinetic parameters were estimated using nonlinear regression and the differential evolution method. The coffee ground waste was dried at 105°C for 24 hours. The sample in nature was analyzed at different heating rates, being 10, 15, 20, 30 and 50 K/min. In the catalytic pyrolysis, about 5% (w/w) of catalyst were added to the sample, at a heating rate of 30 K/min. The results show that the one-step model does not accurately represent the data of weight loss (TG) and its derivative (DTG), but can do an estimative of the activation energy reaction, and can show the differences caused by the catalysts. Although no one can say anything about the products formed with the addition of the catalyst, it would be necessary to micro-pyrolysis analysis, we can say the influence of the catalyst in the samples, based on the data obtained in thermogravimetric tests.

One-step synthesis of CoO/g-C3N4 composites by thermal decomposition for overall water splitting without sacrificial reagents

2017 ◽  
Vol 4 (10) ◽  
pp. 1691-1696 ◽  
Author(s):  
Mumei Han ◽  
Huibo Wang ◽  
Siqi Zhao ◽  
Lulu Hu ◽  
Hui Huang ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Visible Light ◽  
Water Splitting ◽  
Visible Light Irradiation ◽  
Photocatalytic Performance ◽  
Light Irradiation ◽  
Overall Water Splitting ◽  
One Step ◽  
Good Photocatalytic Performance

10%CoO/g-C3N4 exhibits good photocatalytic performance under visible light irradiation without any sacrificial reagents.

One-Step Extrusion to Minimize Thermal Decomposition for Processing PLA-Based Composites

2018 ◽  
Vol 27 (1) ◽  
pp. 158-164 ◽  
Author(s):  
Qingfei Duan ◽  
Linghan Meng ◽  
Hongsheng Liu ◽  
Long Yu ◽  
Kai Lu ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
One Step

Efficient oxidation of ethers with pyridine N-oxide catalyzed by ruthenium porphyrins

2015 ◽  
Vol 19 (01-03) ◽  
pp. 411-416 ◽  
Author(s):  
Nobuki Kato ◽  
Yu Hamaguchi ◽  
Naoki Umezawa ◽  
Tsunehiko Higuchi
Keyword(s):  
Isotope Effect ◽  
Kinetic Isotope Effect ◽  
Hydrogen Abstraction ◽  
Oxide System ◽  
Cyclic Ethers ◽  
Rate Determining Step ◽  
Kinetic Isotope ◽  
Oxidized Products

We found that oxidation of cyclic ethers with the Ru porphyrin-heteroaromatic N-oxide system gave lactones or/and ring-opened oxidized products with regioselectivity. A relatively high kinetic isotope effect was observed in the ether oxidation, suggesting that the rate-determining step is the first hydrogen abstraction.

Sensitization of nitrocompounds by amines

1992 ◽  
Vol 339 (1654) ◽  
pp. 403-417 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Charge Transfer ◽  
Nitro Group ◽  
Picric Acid ◽  
Isotope Analysis ◽  
Ionization Mass ◽  
Scanning Calorimetry ◽  
Absorption Bands ◽  
Rate Determining Step ◽  
The Impact

A study has been carried out of the sensitization of nitromethane, trinitrotoluene, trinitrobenzene, picric acid and tetryl by the addition of small amounts of amines. The sensitization has been confirmed using dropweight impact experiments and a new method has been found, using differential scanning calorimetry, of making reproducible and quantitative measurements of the effect. It is found that the nitrocompound-amine mixtures decompose at temperatures lower than those of either of the pure components and show a drop in the impact energy required to cause initiation of ignition. The thermal decomposition experiments also yield substantially lower activation energies and an empirical sensitization factor (defined in the text) for nitromethane mixtures that decreases as the nitromethane aci-anion concentration increases. Kinetic deuterium isotope analysis points to C-N bond scission as the rate-determining step in the thermal decomposition of nitromethane and nitromethane-amine mixtures. Laser ionization mass analyses of the solid nitrocompound-amine mixtures indicate significant changes in the fragmentation patterns, with removal of the nitro-group occurring in all cases as the first step in the breakdown of the mixtures, which is not the case for the pure materials. Absorption bands appear in the UV / visible spectra of all the sensitized materials. These bands are ascribed to an intermolecular charge transfer from the nitrogen of an amine group to the antibonding orbital of the nitro-group. It is shown that, with small amounts of amines present, each amine molecule can form a complex with as many nitrocompound molecules as there are amine groups on it. The formation of this charge transfer complex is shown to weaken the nitrocompound C-N bond involved. The weakening of the C-N bond increases directly with increasing binding energy of the complex. Combined with the knowledge that the C-N bond breakage is the rate- ­determining step in the thermal decomposition of these materials and the suggestion that the dominant mechanism in their ignition/detonation is most likely thermal in origin, the sensitization is explained. This explanation deviates from the theories which have been previously proposed.

The thermal decomposition of benzoic acid

1970 ◽  
Vol 48 (24) ◽  
pp. 3797-3801 ◽  
Author(s):  
Keith Winter ◽  
Donald Barton
Keyword(s):  
Thermal Decomposition ◽  
Benzoic Acid ◽  
Pressure Range ◽  
Initial Rate ◽  
Material Balance ◽  
Reaction Vessel ◽  
Radical Processes

The thermal decomposition of benzoic acid has been studied in a Pyrex reaction vessel at 475, 486, and 499 °C over the pressure range 5 to 40 Torr. The main products, CO2 and C6H6, were accompanied by smaller quantities of CO, H2, and biphenyl. The percentage of conversion varied from less than 1% for initial rate experiments to over 90 % in attempts to obtain a material balance. Moderately reproducible initial rates of formation of CO2 were obtained after the vessel had been conditioned by pyrolysis of benzoic acid. The order for the initial rate of formation of CO2, 1.20 ± 0.03 at 475 °C and 1.28 ± 0.04 at 499 °C, is discussed in terms of a combination of first and three-halves order reactions. Formation of both C6H5D and C6H6 in the presence of C6D5CD3 is accepted tentatively as evidence of formation of benzene by both molecular and radical processes.

Construction of amorphous interface in an interwoven NiS/NiS2 structure for enhanced overall water splitting

2018 ◽  
Vol 6 (18) ◽  
pp. 8233-8237 ◽  
Author(s):  
Qun Li ◽  
Dewen Wang ◽  
Ce Han ◽  
Xiao Ma ◽  
Qingqing Lu ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Water Splitting ◽  
Nickel Sulfate ◽  
Overall Water Splitting ◽  
One Step

Here, we describe the synthesis of a novel interwoven NiS/NiS2 structure with an amorphous interface accomplished by carrying out a one-step thermal decomposition of nickel sulfate and thiourea.

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