Energy balance of CO2 dissociation

Two-Temperature Approach to Vibrational Kinetics and Energy Balance of CO2 Dissociation in Non-Equilibrium Plasma Major Energy Balance and Dynamic Equations... 

Let us analyze the energy balanee of CO2 dissociation stimulated in plasma by vibrational excitation in the two-temperature approximation, assuming one-dimentional gas motion with density p through the plasma in the x-direction with velocity u. Such an energy balance can be illustrated in the framework of the following equations describing major energy transfer, relaxation, and chemical reaction processes separately for different individual vibrational modes in the plasma-chemical system, which includes CO2 and products of its dissociation (Rusanov Fridman, 1984) ... 

VIBRATIONAL KINETICS AND ENERGY BALANCE OF PLASMA-CHEMICAL CO2 DISSOCIATION... 

Vibrational Kinetics and Energy Balance of Plasma-Chemical CO2 Dissociation... 

Kinetic analysis of (5-108) and the energy balance of CO disproportioning by itself and as a part of the plasma-chemical process of complete CO2 dissociation to elementaiy... 

The difference between vibrational and translational CO2 temperatures (Tv > 7 o)results in a maximum energy efficiency increase to 60% even in the case of the quasi-equilibrium balance of direct and reverse reactions (Evseev, Eletsky, Palkina, 1979), because direct endothermic reactions are mostly stimulated by molecular vibration, whereas reverse exothermic reactions are mostly stimulated by translational temperature (see the Fridman-Macheret a-model in Chapter 2). This efficiency corresponds to the case of super-ideal non-equilibrium (TV > To) quenching of the CO2 thermal plasma dissociation products (Potapkinetal., 1983). 

The balance of average vibrational energy, located on an asymmetric mode of a CO2 molecitle is mostly determined by eV and W -relaxation processes as well as dissociation itself ... 

The balance of average energy located on a CO molecttle, produced by CO2 dissociation, is... 

The one-temperature approximation (see Section 5.2.4) permits one to find out all major qualitative features of the plasma-chemical CO2 dissociation energy balance, including threshold, maximum, and decrease of energy efficiency dependence on specific energy input energy efficiency dependence on ionization degree, initial gas temperature,... 

If the ionization degree is sufficient (5 8), the stationary vibrational temperature Tf is established after a necessary time interval of about /ks n. The stationary vibrational temperature T - in the active discharge zone canbe found from the energy balance equation (5-44), taking the CO2 dissociation rate in the framework of the one-temperatuie approximation (compare to (5 6)) ... 

The true catalytically-active species is probably HCo(CO)3, a 16-electron complex. This intermediate results from 18-electron HCo(CO)4, 1, which in turn ultimately comes from Co(0) or Co(II), via Co2(CO)s, in the presence of a 1 1 mixture of CO and H2 (synthesis gas).16 Sometimes 1 is prepared in a separate step and introduced to the alkene in the presence of synthesis gas this allows the subsequent hydroformylation to be run at a lower temperature (90-120 °C rather than the usual 120-170 °C). The dissociation step to form the active catalyst occurs with a relatively high activation energy, and it is, of course, inhibited by a high concentration of CO (the overall rate law for hydroformylation typically shows the concentration of CO with a negative exponent, n, where 0 > n > -1). The reaction is run, however, under very high pressure (200-300 bar) to stabilize HCo(CO)3 and later intermediates in the catalytic cycle, thus demonstrating a balance in reaction conditions between the formation of sufficient HCo(CO)3 for hydroformylation to occur at a reasonable rate and the enhancement of the stability of catalytic intermediates.17 Calculations indicate that the preferred geometry... 

O2 (760 Torr = 1 atm) under differential reactor conditions, an apparent activation energy of 29 kcal mole for CO2 formation was observed. Near 900 K, selectivity to CO2, rather than CO, was about 75% or higher, and the reaction orders from a power rate law are given in Table 1. Propose a L-H-type model for CO2 formation with a sequence of elementary steps that results in a derived rate expression consistent with these results. It can be assumed that only the adsorbed reactants and products need be included in the site balance, and dissociative O2 adsorption occurs. Under low-conversion conditions, the surface concentrations of the products can be ignored, so what is the form of the rate equation Fitting this latter equation to the data produced the optimized rate parameters listed in Table 2, where k is the lumped apparent rate constant. Evaluate them to determine if they are consistent and state why. 

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