Reactant Composition

The flow rate and the concenuaiion (dilution) of the feed stream entering the membrane reactor both have substantial influence over the reactor performance [Itoh et al., 1993 Collins et al., 1993]. The effect of flow rate of the reactant(s) will be treated later in this chapter. 

P reactant product(s) high 8. low Pp high Da feed location at Z O total permeate recycle independent of flow mode 

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The l-chloro-2-propanol isomer represents about 85% of the chlorohydrin produced. In order to minimise the formation of dichlotide coproduct and ether, the reactant compositions are chosen such that the effluent Hquid contains 4—5 wt % propylene chlorohydrin. Under these conditions, the yield of chlorohydrin, dichloride, and ether from the reactants is reported to be 87—90, 6—9, and 2%, respectively (109,110,112). 

The chemical reactions that occnr in flames transform an initial reactant mixtnre into final reaction prodncts. In the case of fnel-oxygen combns-tion, the final prodncts are principally water vapor and carbon dioxide, althongh nnmerons other prodncts snch as carbon monoxide may be formed, depending on the reactant composition and other factors. If the ratio of fnel-to-oxygen is stoichiometric, the final reaction prodncts, by definition, contain no excess fnel or oxygen. Theoretically, this means that partial oxidation prodncts snch as CO (itself a fnel) are not formed. In reality, partial oxidation prodncts snch as CO or OH are formed by high tem-peratnre reactions. For example, the molar stoichiometric reaction of methane is written ... 

Meanwhile, as shown in Figure 2, the conversion of H2S on V2O5 for the reactant composition B at 225 C was 17% lower than that for the reactant composition A. As we thought that the deterioration of activity of V2O5 under the influence of water vapor was not entirely due to the thermodynamic equilibrium, we conducted TPR/TPO experiments by varying the water contents of reactant flow. 

In the 1930s, Standard Oil of New Jersey (7) was the first company to employ on a commercial scale the indirect conversion of methane, the main component of natural gas, via steam reforming to give synthesis gas, which is a mixture of H2 and CO, with the H2/CO ratio depending on the reactant composition. C02 is also formed in synthesis gas production, and sulfur compounds are present as impurities. Synthesis gas can be used as a feedstock for numerous chemicals and fuels and as a source of pure hydrogen or carbon monoxide. 

Wheeler, Schmidt, and coworkers—kinetic model for Pt/Ce at short contact times over medium to high T range. In 2004, Wheeler and coworkers422 reported on the water-gas shift reaction over Pt/ceria at short contact times (0.008-0.05 sec) for temperatures between 300 and 1000 °C. The reactant composition for CO, H2, and H20 was 1/2/4. A Langmuir-Hinshelwood kinetic model was used to adequately fit the medium and high temperature shift data ... 

Component enthalpies are readily available on a per mass basis from data such as JANAF (4). Product enthalpy usually includes the heat of formation in published tables. A typical energy balance calculation is the determination of the cell exit temperature knowing the reactant composition, the temperatures, H2 and O2 utilization, the expected power produced, and a percent heat loss. The exit constituents are calculated from the fuel cell reactions as illustrated in Example 10-3, Section 10. 

Estimations. If one can find a process similar to the one of interest, then rates can be estimated from these data. For example, if one finds a reactor for which a specified conversion is obtained with a specified reactant composition and temperature, then one may guess the orders of the reaction with respect to each species (guess first order) and proceed to formulate a reasonable rate expression. 

To summarize the goal of this section, we must start with the microscopic description of the catalytic reaction, then consider diffusion in pores, and then examine the reactant composition around and within the pellet, in order finally to describe the reactor maSS-balance equations in terms of z alone. The student should understand the logic of this procedure as we go from micrscopic to macroscopic, or the following sections will be unintelligible (or even more unintelligible than usual). 

As the catalyst does not affect the thermodynamics of the reaction, it is futile to search for a catalyst to improve the situation. Instead the reaction conditions (temperature, pressure and reactant composition) must be optimized to maximize the equilibrium concentration of the desired product. Once suitable reaction conditions have been identified, the reaction rate is found to be too low, frequently by orders of magnitude. And the search for a suitable catalyst begins. 

Gaseous Reactant, Composition, mole % Cyclohexene Cyclohexene, Conversion ... 

Zeolite crystallization represents one of the most complex structural chemical problems in crystallization phenomena. Formation under conditions of high metastability leads to a dependence of the specific zeolite phase crystallizing on a large number of variables in addition to the classical ones of reactant composition, temperature, and pressure found under equilibrium phase conditions. These variables (e.g., pH, nature of reactant materials, agitation during reaction, time of reaction, etc.) have been enumerated by previous reviewers (1,2, 22). Crystallization of admixtures of several zeolite phases is common. Reactions involved in zeolite crystallization include polymerization-depolymerization, solution-precipitation, nucleation-crystallization, and complex phenomena encountered in aqueous colloidal dispersions. The large number of known and hypo-... 

Fig. 62. Oxidation of methacrolein catalyzed by H4PM01 V040, untreated (O) and treated ( ) with pyridine. Catalyst, 10 cm3 reaction temperature, 553 K SV, 1000 h. Reactant composition methacrolein 2%, oxygen 6%, water 20%. (From Ref. 335.)...

Ultraviolet spectroscopy has great utility in the characterization of expls and related materials, and serves as a primary analytical tool for the quantitative determination of reactant composition and purity. Additionally, it can provide the principal method of monitoring expl kinetics and reaction mechanisms, since the high temps characteristic of expins are effective in creating electronic excitations... 

Table 2.3 CO-PROX performances (conversion % and O2 selectivity %) of the 7.5 wt% Cu/Ce-CTAB catalyst at different W/F (gcat h mol-1), reaction temperature and reactant composition. 

The propellant combination is not completely specified by selection of the propellants. The reactant composition or mixture ratio remains as a primary and independent design parameter. The selection of mixture ratio may be influenced by concerns other than propellant performance as measured bv the specific impulse. 

Zeolite X System. It is well recognized that with a fixed reactant composition, zeolites of different frameworks can be formed.(12)... 

NMR using the Intensity for sodalite cages in ZK-4 (which are completely filled with TMA) as a standard. The results are compared in Table V with values calculated for random filling by one TMA ion or by either two or three sodium ions based on the reactant compositions. 

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