Pseudo-first-order reaction rate constants

Fig. 2 shows the plot of ln[(CEcVCEc] vs. time during first 2 h. Quite good straight lines were obtained, and the pseudo first-order reaction rate constants for 120,130 and 140 °C were 0.002421, 0.002481 and 0.002545 h, respectively. From the Arrhenius plot of the first order reaction rate constants, one can estimate the activation energy as 41.5 kJ/mol. 

The overall reaction between CO2 and GMA was assumed to consist of two elementary reactions such as a reversible reaction of GMA and catalyst to form an intermediate and an irreversible reaction of this intermediate and carbon dioxide to form five-membered cyclic carbonate. Absorption data for CO2 in the solution at 101.3 N/m were interpreted to obtain pseudo-first-order reaction rate constant, which was used to obtain the elementary reaction rate constants. The effects of the solubility parameter of solvent on lc2/k and IC3 were explained using the solvent polarity. 

Peijnenburg et al. (1992) investigated the photodegradation of a variety of substituted aromatic halides using a Rayonet RPR-208 photoreactor equipped with 8 RUL 3,000-A lamps (250-350 nm). The reaction of 1,3-dichlorobenzene (initial concentration 10 M) was conducted in distilled water and maintained at 20 °C. Though no products were identified, the investigators reported photohydrolysis was the dominant transformation process. The measured pseudo-first-order reaction rate constant and corresponding half-life were 0.008/min and 92.3 min., respectively. 

When Cg (i.e., concentration of B which reacts with A) is much larger than C, Cg can be considered approximately constant, and k Cg) can be regarded as the pseudo first-order reaction rate constant (T ). The dimensionless group y, as defined by Equation 6.23, is often designated as the Hatta number (Ha). According to Equation 6.22, if y > 5, it becomes practically equal to E, which is sometimes also called the Hatta number. For this range. 

Determine the (pseudo-)first-order reaction rate constants, kh, for this reaction at pH 5.0 and pH 8.5 at 22.5°C using the data sets given below ... 

Photolysis pseudo-first order reaction rate constant for direct photolysis k = 0.009 min1 with t, = 76.8 min. in dilute aqueous solution (Peijnenbuig et al. 1992). 

Photolysis measured pseudo-first-order reaction rate constant k = 0.014 min- for direct photolysis in aqueous solutions with = 50.7 min. (Peijnenburg et al. 1992). 

Benner WH, Bizjak M. 1988. Pseudo first-order reaction rate constant for the formation of hydroxymethylhydroperoxide from formaldehyde and hydrogen peroxide. Atmos Environ 22 2603-2605. 

FIGURE 4.6 Dependence of (pseudo) first-order reaction rate constants (k) on temperature (T). Approximate examples for heat inactivation of alkaline phosphatase and plasmin, for killing of Clostridium botulinum spores, and for the formation of a certain small amount of Maillard products. t 0A is the time needed for the reaction to proceed for 0.1 times the final value (not for the Maillard reaction). 

The calculated specific pseudo-first order reaction rate constants for HDS activity are shown in Fig. 1 and Fig. 2. Whereas Fig. 1 shows the results concerning non-stabilized supports, Fig. 2 presents the HDS activity for the series of stabilized Y-zeolites. All studied catalysts show a rather rapid activity decay during the first hour of run time, followed by slow deactivation. The highest stability among the nickel-free supports was found for CsY, NaY and KY supports, indicating higher activity than CsY, show however lower stability and faster deactivation. 

A decrease in the characteristic dimension of the system (see schematic of parallel plate microreactor in Figure 10.4c) increases the rate of mass transport from the bulk gas to the reactor walls and changes Da. When Da <0.1, surface reaction is limiting and when Da > 10, mass transfer is limiting. The pseudo-first-order reaction rate constant is estimated from k, = a S/C, where o is the rate of fuel consumption (coming from a detailed model), a = 2/dis the catalyst area per unit volume and C is the concentration of the fuel. 

Figure 11.7 Observed pseudo-first-order reaction rate constant for hydrogenation in a monolith pilot reactor. The reaction was not completely mass transfer limited, but external mass transfer limitation did strongly affect the observed rate for these experiments, feobs,H2 kcLw/2. Note that the reaction rate decreases with decreasing throughput [44].

Figure 4 shows the kinetic spectrum obtained for the reaction in Fig. 1. The distribution function A (k) is plotted versus the logarithm of the pseudo-first-order reaction rate constant (log k) that is characteristic for the exchange kinetics at each site. According to Sparks [1], exchange reactions at suspended particles with an inner surface or a porous structure could be controlled by three types of processes firstly, the di sion through the solution to the...

TABLE 8.4 Pseudo-First-Order Reaction Rate Constants of TCE Degradation by Ni/Fe Nanoparticles... 

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