Gas phase decomposition

In order for a soHd to bum it must be volatilized, because combustion is almost exclusively a gas-phase phenomenon. In the case of a polymer, this means that decomposition must occur. The decomposition begins in the soHd phase and may continue in the Hquid (melt) and gas phases. Decomposition produces low molecular weight chemical compounds that eventually enter the gas phase. Heat from combustion causes further decomposition and volatilization and, therefore, further combustion. Thus the burning of a soHd is like a chain reaction. For a compound to function as a flame retardant it must intermpt this cycle in some way. There are several mechanistic descriptions by which flame retardants modify flammabiUty. Each flame retardant actually functions by a combination of mechanisms. For example, metal hydroxides such as Al(OH)2 decompose endothermically (thermal quenching) to give water (inert gas dilution). In addition, in cases where up to 60 wt % of Al(OH)2 may be used, such as in polyolefins, the physical dilution effect cannot be ignored. 

The following mechanism has been postulated for the gas phase decomposition of acetaldehyde ... 

The gas phase decomposition A B -r 2C is conducted in a constant volume reactor. Runs 1 through 5 were conducted at 100°C run 6 was performed at 110°C (Table 3-15). Determine (1) the reaction order and the rate constant, and (2) the activation energy and frequency factor for this reaction. 

When the decomposition is carried out in an inert solvent, methyl acetate and ethane are formed, whereas in the gas-phase decomposition methyl acetate is completely absent and ethane is produced in much smaller quantity, It was suggested that the dimers in solution represent the recombination of methyl, and the combination of methyl and acetoxy radicals, within the solvent cage. ... 

The following data were obtained for the gas-phase decomposition... 

Two examples are (1) the thermal, gas-phase decomposition of acetaldehyde at high temperatures and (2) the reaction of the hydrated 2-propylchromium ion with molecular oxygen in aqueous solution. The reactions and their rate laws are as follows ... 

K. Franaszczuk, E. Herrero, P. Zelenay, A. Wieckowski, J. Wang, and R.I. Masel, A comparison of electrochemical and gas-phase decomposition of methanol on platinum surfaces, J. Phys. Chem. 96(21), 8509-8516 (1992). 

Consider the gas-phase decomposition A B -b C in an isothermal tubular reactor. The tube i.d. is 1 in. There is no packing. The pressure drop is 1 psi with the outlet at atmospheric pressure. The gas flow rate is O.OSSCF/s. The molecular weights of B and C are 48 and 52, respectively. The entering gas contains 50% A and 50% inerts by volume. The operating temperature is 700°C. The cracking reaction is first order with a rate constant of 0.93 s . How long is the tube and what... 

Ikeda, S., Kobayashi, H., Ikoma, Y., Harada, T., Yamazaki, S., and Matsumura.M. (2009) Structural effects of titanium(IV) oxide encapsulated in a hollow silica shell on photocatalytic activity for gas-phase decomposition of organics. Applied Catalysis A General, 369 (1-2), 113-118. 

Hinshelwood and Askey (6) have investigated the gas phase decomposition of dimethyl ether according to the following reaction. 

The gas phase decomposition of ozone is catalyzed by nitrogen pent oxide. Two mechanisms that purport to explain this process are given below. Can relatively simple kinetic measurements be used to eliminate one of the proposed mechanisms from further consideration Explain. 

Consider the homogeneous isothermal gas phase decomposition of CH3CHO. 

The gas-phase decomposition of beryllocenes has been examined for the doping of semiconductor materials and in the preparation of thin metal films. Molecular-beam expitaxy has been used with (MeC5H4)2Be to dope InP semiconductors only a small amount of carbon is found in the doped films.54 Beryllocene 9 has been explored as a precursor for coating capsules with beryllium metal for use as targets in experiments with inertial confinement fusion.55... 

Applications involving ring transfer or loss. The kinetic lability, volatility, and Lewis acidity of heavy alkaline earth metallocenes have been the properties most important to their applications. The gas-phase decomposition of volatile metallocenes is useful in the preparation of thin films of alkaline earth-containing materials and in doping semiconductors. Reviews are available on the use of group 2 organometallic compounds as precursors for chemical-vapour deposition (CVD).2 3... 

For the irreversible, gas-phase decomposition of dimethyl ether (CH3OCH3) to CH4, H2, and... 

At elevated temperatures, acetaldehyde (CH3CHO, A) undergoes gas-phase decomposition into methane and carbon monoxide. The reaction is second-order with respect to acetaldehyde, with kA = 22.2 L mol-1 min-1 at a certain T. Determine the fractional conversion of acetaldehyde that can be achieved in a 1500-L CSTR, given that the feed rate of acetaldehyde is 8.8 kg min-1, and the inlet volumetric flow rate is 2.5 m3 min-1. Assime T and P arc unchanged... 

In the catalyzed gas-phase decomposition A - B + C, suppose A also acts as an inhibitor of its own decomposition. The resulting rate law (a type of Langmuir-Hinshelwood kinetics, Chapter 8) is ... 

Consider the gas-phase decomposition of ethane (A) to ethylene at 750°C and 101 kPa (assume both constant) in a PFR. If the reaction is first-order with kA = 0.534s-1(Fro-ment and Bischoff, 1990, p. 351), and r is 1 s, calculate /a- For comparison, repeat the calculation on the assumption that density is constant. (In both cases, assume the reaction is irreversible.)... 

P3.01.02. TRUE CONTACT TIME OF FORMIC ACID REACTION The gas phase decomposition of formic acid,... 

Gas-phase analytical methods, flash vacuum pyrolysis and, 21 139-140 Gas-phase decomposition, of Group III organometallics, 22 156 Gas-phase grown carbon fibers, 26 736-737 Gas-phase height of a transfer unit (HG), 1 51-52... 

In some cases where the gas-phase decomposition has been studied by classical methods using static systems the question of the degree of homogeneity of the reactions is unsolved. 

NITROGEN PENTOXIDE 3.4.1 Thermal decomposition of N205 (a) Gas phase decomposition of N2Os... 

For temperatures in excess of 320 °C the gas-phase decomposition of anhydrous H0C103 (or of its dihydrate) is a homogeneous, unimolecular reaction close to its first-order limit at pressures in excess of 20 torr440. Levy440 obtained a value... 

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