Propylene Pseudo-first-order rate

Figure 3 Dependence of pseudo-first-order rate constants measured at 0°C for propylene homometathesis, on the Re loading in 10 mg samples of two kinds of supported Re catalysts SnMe4-promoted perrhenate/silica-alumina (solid circles) and MeReOs on HMDS-capped silica-alumina (open circle).

The rate of reaction of propylene over the MeReOs/HMDS/silica-alumina catalyst (1.4 wt% Re) is shown in Figure 2b. The profile is similar to that of the Sn-promoted perrhenate catalyst, with kobs = (1-78 + 0.09) x 10" s, and the activity responds similarly to subsequent additions of propylene. In fact, the pseudo-first-order rate constant for the organometallic catalyst lies on the same line as the rate constants for the Sn-promoted perrhenate catalyst. Figure 3. Therefore we infer that the same active site is generated in both organometallic and promoted inorganic catalyst systems. 

Two different binuclear copperdi) complexes have been prepared recently, one with a bridging phenoxy ligand having two bis-benzi-midazole arms (12, Fig. 14), and the second having a bis-cyclen-naphthalene ligand (13, Fig. 15) (352, 353). Both of them show bimetallic cooperativity for the hydrolysis of phosphate diesters, contrary to studies with the dinuclear cobalt complex (354). The pseudo-first-order rate constants for hydrolysis of the para-nitrophenylphosphate ester of propylene glycol by bis-benzimidazole-based copper complexes... 

The relative n-ad intensity equations are identical to the chain end control model with the exception that the rate constants in the stereoselective copolymerisation scheme are pseudo first-order rates incorporating the concentration of propylene. 

Isopropylbenzene (A) is alkylated with propylene (P) using HF catalyst. The mono (B), di (C), tri (D) and tetra (E) derivatives are formed. Relative specific rates are given by Rodiguin Rodiguina (Consecutive Chemical Reactions, 1964) for the case of a large excess of propylene which makes the reactions pseudo first order. The relative specific rates used here are kx = 1.0, k2 = 0.5, k3 = 0.3 and k4 0.2. The system of linear differential... 

Metathesis activity. A quantitative comparison of metathesis activities was made in the gas phase homometathesis of propylene. The reaction kinetics are readily monitored since all olefins (propylene, ethylene, cis- and fra/3s-2-butylenes) are present in a single phase. Metathesis of 30 Torr propylene was monitored in a batch reactor thermostatted at 0 °C, in the presence of 10 mg catalyst. The disappearance of propylene over perrhenate/silica-alumina (0.83 wt% Re) activated with SnMe4 is shown in Figure 2a. The propylene-time profile is pseudo-first-order, with kob (1.11 + 0.04) X 10" slightly lower rate constant, (0.67 constants are linearly dependent on Re loading. Figure 3. The slope yields the second-order rate constant k = (13.2 + 0.2) s (g Re) at 0°C. 

To determine reaction rate parameters from the experimental data, the following differential equation was used to describe the reaction system in a constant-volume batch reactor assuming a pseudo-first-order equation for propylene epoxidation ... 

Experimental results were plotted according to Eq. (14.4), and straight lines passing through zero fit the experimental points quite well, as illustrated in Eig. 14.9. Therefore, propylene epoxidation with EBHP can be treated as pseudo-first order with respect to EBHP concentration (Ca)- The rate equation can therefore be written as... 

Under pseudo-first-order conditions, the rate of polymerization of propylene can be expressed (Huang and Rempel, 1995) as... 

The overall rate of propylene pyrolysis has been reported to be first order in some studies and as 3/2 order in others. Most studies conducted at low temperatures (up to 650C) tend to favor 3/2 order, while studies conducted at higher temperatures indicated mostly a first order rate. Clearly, the overall order of reaction is at best only a pseudo or an apparent order representing a combination of many elementary steps. 

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