Stoichiometric feed

If air is used, then a single pass with respect to each feedstock is used and no recycle to the reactor (Fig. 10.4a).-Thus the process operates at near stoichiometric feed rates to achieve high conversions. Typically, between 0.7 and 1.0 kg of vent gases are emitted per kilogram of dichloroethane produced. ... 

The equilibrium constant can be determined at any temperature from standard state information on reactants and product. Considering the synthesis of NH3, the equilibrium conversion can be determined for a stoichiometric feed of Hj and Nj, at the total pressure. These conversions are determined by the number of moles of each species against conversion X by taking as a basis, 1 mole of N2. 

Reaction between NH3 and CH produces a high selectivity to HCN at high temperatures at nearly stoichiometric feed ratios, but only N2 Is produced In excess NH3 and no reactions occur In excess CH. Analysis by AES and TPD shows that the active surface contains approximately one monolayer of carbon and that a surface containing carbon multilayers Is Inert. 

From equations 3.3.3 and 3.3.4, one can see that at all times, with a stoichiometric feed ratio,... 

Figure 10. Rate comparison of periodic to steady-state operation for stoichiometric feed of C0/02 to Pt/AUO, catalyst (38,).

Carbon monoxide/hydrogen stoichiometric feed, production of methanol from, 25 303-305... 

Experimental conditions. Table 1 lists the experimental conditions. Co shows the apparent initial concentration of reactants in the crystallizer. Series I, and 1 were conducted with stoichiometric feed ratio, with changing the feed ratio of reactants and with sodium chloride addition under the constant Co of magnesium chloride and calcium hydroxide, respectively. 

A fluidized bed is to be designed to treat 1 ton/hr of solids to 90% conversion using a stoichiometric feed rate of A, fed at AO- Find the weight of solids in... 

The equilibrium conversion of NH3 was calculated for a stoichiometric feed of N2 and H2 at the total pressures shown. These conversions were calculated by writing the number of moles of each species versus conversion X, taking a basis of 1 mole of N2. 

The equilibrium conversion versus temperature and pressure for stoichiometric feed is shown in Figure 3-17. 

Consider methanol synthesis from CO and H2 with a stoichiometric feed at pressures of 10, 30, and 100 atm. 

A series of experiments have been performed with a stoichiometric feed ratio of acetic acid and methanol. The reflux ratio was kept constant at a value of 2.0, the feed flow rate at a value of 3.0 kg/h, while the heat duty to the reboiler was varied over a wide range. A comparison of experimental results and model prediction for the liquid-phase composition profiles along the column is given in Figure 27 for different reboiler duties (151). The theoretical values are displayed with continuous lines and empty symbols, whereas the experimental data measured along the... 

It is a combination of exothermic steam reforming and endothermic partial oxidation applying a stoichiometric feed ratio which allows for an overall zero energy balance. As the exothermic reaction is faster, a hot-spot is very common in... 

Table 6-5 shows the equilibrium constant Ket with the equilibrium partial pressure of NH3 starting with a stoichiometric mixture of H2 and N2 at pressures of 1, 10, and 100 atm. Figure 6-12 shows the relationship between equilibrium conversion Xe versus temperature and pressure for stoichiometric feed. 

For a stoichiometric feed concentration of acetic acid instead, the optimal resin capacity was calculated as 5 mEq g-1, which is the original Amberlyst 15 resin. Further optimization, including also the feed concentration of acetic acid as a decision variable, yielded an eluent requirement of ca. 3 mol methanol per mol methyl acetate for a 5 mEq g-1 resin and 60 40 acetic acid methanol feed stream (Fig. 6.17). 

In case of a bimolecular reaction of the type vaA +vbB —> Products, the composition of the feed mixture is an important free parameter. This can be conveniently expressed using a stoichiometric feed ratio X defined as follows ... 

To minimize these costs it is therefore necessary to maximize the conversion in the reactor and to avoid as far as possible inert substances in the reaction mixture. With irreversible reactions (e.g., partial oxidations) the trend is therefore towards a highly concentrated, approximately stoichiometric feed composition, which may occasionally be in the explosive range. The resulting problems are addressed in Sections 10.1.3.3 and 10.1.4.2) Since fixed-bed reactors constitute one of the most important classes of chemical reactors, much work has been devoted to their proper mathematical modeling as well as to the study of their stability, sensitivity and automatic control. The following standard text books and monographs can be recommended for further reference [1-4]. 

H J Sevot, G F Versteeg, W P M van Swaaij, A non-permselective membrane reactor for chemical processes normally requiring stnet stoichiometric feed rates of reactants, Chem Eng Set 1990,45,2415 2421... 

We first analyze the case where the mixing times of A and B are equal, i.e. rjA — riB — ri. Figure 11 illustrates how the conversion X(— 1 — CA>m(z — 0)/ CA m iC) varies with the Damkohler number Da for different values of the dimensionless mixing time r, for the case of stoichiometric feeding of reactants. 

Table S.2.1 Turnover rates of ammonia synthesis at 678 K, stoichiometric feed, 1 atm.

The conditions chosen for the microkinetic analysis correspond to an industrial reactor with 2.5 cm of catalyst operating at 107 bar with a stoichiometric feed of... 

A novel application of a symmetric porous membrane as a catalyst carrier but not as a permselective barrier is to use the membrane itself as the reaction zone for precise control of the stoichiometric ratio [Sloot et al., 1990]. In this case, the reactants are fed to the different sides of the membrane which is impregnated with a catalyst for a heterogeneous reaction. The products diffuse out of the membrane to its both sides. If the reaction rate is faster than the diffusion rate of the reactant in the membrane, a small reaction zone or theoretically a reaction plane will exist in the membrane. An interesting and important consequence of this type of membrane reactor is that within the reaction zone the molar fluxes of the reactants arc always in stoichiometric ratio and the presence of one reactant in the opposing side of the membrane is avoided. The reaction zone can be maintained inside the membrane as long as the membrane is symmeuic and not ultrathin. Therefore, membrane reactors of this fashion are particularly suited for those processes which require strict stoichiometric feed rates of premixed reactants. A symmetric porous a-alumina membrane of 4.5 mm thick was successfully tested to demonstrate the concept [Sloot et al., 1990]. 

In a CNMR/ORG as shown in Figure 10.15 [Sloot et al.. 1990], the reactants A and B introduced to a catalytic membrane from its opposite sides react inside a small reaction zone in the membrane. If the reaction is instantaneous and irreversible, the reaction zone shrinks to a reaction plane theoretically. At the reaction zone or plane, the molar fractions of both reactants will be very low. In principle, it is possible to control the location of the reaction zonc/plane so that slip or penetration of one reactant to the opposing side of the membrane is avoided. The molar fluxes of the two reactants are then always in stoichiometric ratio. Thus, the CNMR s are particularly attractive to those chemical processes which normally require strict stoichiometric feed rates of reactants. An example is the Gaus reaction which involves hydrogen sulfide and sulfur dioxide. 

P3-21b The gas-phase reaction between cMotine and methane to form carbon tetrachloride and hydrochloric acid is to be carried out at 75 C and at 950 kPa in a continuous-flow reactor. The vapor pressure of carbon tetrachloiide at 75°C is approximately 95 kPa. Set up a stoichiometric table for this reaction with phase change. Calculate the conversion of methane at which condensation begins. Plot the concentrations and molar flow rates of each species as well as the total molar flow rate as a function of conversion for a stoichiometric feed, The volumetric flow rate is 0.4 dm /s. 

The opposing reactant contactor mode applies to both equilibrium and irreversible reactions, if the reaction is sufficiently fast compared to transport resistance (diffusion rate of reactants in the membrane). This concept has been demonstrated experimentally for reactions requiring strict stoichiometric feeds, such as the Claus reaction, or for kinetically fast, strongly exothermic heterogeneous reactions, such as partial oxidations. Triphasic (gas/liquid/solid) reactions, which are limited by the diffusion of the volatile reactant (e.g., olefin hydrogenation), can also be improved by using this concept. 

Figure 8 Calculated dependence of SO2 conversion on catalyst surface area and pore volume distribution. Case of stoichiometric feeds a 1 AV = 11 Nm/h c i = volume fraction of micropores. (From Ref. 40.)...

This reactor concept was first demonstrated to be promising for those reactions that require strict stoichiometric feed of reactants (i.e., selective catalytic reduction of NO, with NH3, SO2 abatement to elemental gaseous sulfur with H2S [124,136]). These studies showed some promising features of this reactor setup, though the reactor was not amenable from the economic viewpoint due to the very low specific conversions per unit membrane surface it guaranteed. 

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