And gaseous reactants

Hquid and gaseous reactants, Hquid products benzene chlorination, oxidation 0.01-0.2 1-30 100-500 100-500... 

Phase diagrams can be used to predict the reactions between refractories and various soHd, Hquid, and gaseous reactants. These diagrams are derived from phase equiHbria of relatively simple pure compounds. Real systems, however, are highly complex and may contain a large number of minor impurities that significantly affect equiHbria. Moreover, equiHbrium between the reacting phases in real refractory systems may not be reached in actual service conditions. In fact, the successful performance of a refractory may rely on the existence of nonequilibrium conditions, eg, environment (15—19). 

The carbon removal reaction supposedly takes place at two-phase boundary of a solid catalyst, a solid reactantfcarbon particulate) and gaseous reactants(02, NO). Because of the experimental difficulty to supply a solid carbon continuously to reaction system, the reaction have been exclusively investigated by the temperature programmed reaction(TPR) technique in which the mixture of a catalyst and a soot is heated in gaseous reactants. 

Figure 5.2 Principle of contacting liquid and gaseous reactants in a falling film micro reactor [5].

Slurry Reactors. Slurry reactors are commonly used in situations where it is necessary to contact a liquid reactant or a solution containing the reactant with a solid catalyst. To facilitate mass transfer and effective catalyst utilization, the catalyst is usually suspended in powdered or in granular form. This type of reactor has been used where one of the reactants is normally a gas at the reaction conditions and the second reactant is a liquid, e.g., in the hydrogenation of various oils. The reactant gas is bubbled through the liquid, dissolves, and then diffuses to the catalyst surface. Obviously mass transfer limitations can be quite significant in those instances where three phases (the solid catalyst, and the liquid and gaseous reactants) are present and necessary to proceed rapidly from reactants to products. 

Benefits of the technology include avoiding risks to public health and worker safety associated with excavation, surface treatment, transportation, and disposal and gaseous reactants increase permeability of soils to gases thereby allowing gaseous mixtures to invade smaller soil pores to react with soil contaminants. All information has been supplied by the developer and has not been independently verified. 

There are two main process categories for the direct hydration of ethylene to ethanol. Vapor-phase processes contact a solid or liquid catalyst with gaseous reactants. Mixed-phase processes contact a solid or liquid catalyst with liquid and gaseous reactants. Generally, ethanol is produced by a vapor-phase process mixed-phase processes are used for the analogous hydration of propylene to 2-propanol. Important exceptions to these two generalizations exist, but the discussion that follows emphasizes technology associated with the commercially important vapor-phase direct hydration of ethylene. 

The unit was designed for operation at temperatures up to 500 °C and at atmospheric pressure. It is possible to feed liquid and gaseous reactants. 

The above calculation is quite tedious and gets complicated by the fact that the properties which ultimately control the magnitude of these fourteen unknown quantities further depend on the physical and chemical parameters of the system such as reaction rate constants, initial size distribution of the feed, bed temperature, elutriation constants, heat and mass transfer coefficients, particle growth factors for char and limestone particles, flow rates of solid and gaseous reactants. In a complete analysis of a fluidized bed combustor with sulfur absorption by limestone, the influence of all the above parameters must be evaluated to enable us to optimize the system. In the present report we have limited the scope of our calculations by considering only the initial size of the limestone particles and the reaction rate constant for the sulfation reaction. 

Make-up cobalt enters the process via carbonyl generator (2) and is combined with the olefin stream from extraction column (8), which already carries the recycled HCo(CO)4. With syngas from the purification section (1), the hydro-formylation takes place under the usual conditions (160-190°C 25-30 MPa 0.1-0.5 % cobalt relative to olefin) in the reactor (3) equipped with an external loop. No mechanical stirring is applied circulation and mixing are provided by the stream of liquid and gaseous reactants (mammoth pump principle) and by the heat of reaction. 

In two-phase systems in which the catalytic reaction takes place in the liquid phase between a liquid reactant and gaseous reactants, the latter have to be transferred over the gas/liquid boundary layer into the liquid phase. In this situation the reaction engineering prediction described above can be performed in an analogous way as long as the rate of transfer of the gaseous reactants into the liquid phase is fast compared with the intrinsic catalytic reaction. Under these circumstances it can usually be assumed that the liquid-phase concentrations of the gaseous reactants correspond to gas/liquid thermodynamic equilibrium. 

Figure 8.2 Principle of liquid and gaseous reactants in contact in a falling-film microflow reactor...

Hydrogenation reactions have also been studied with catalytic membrane reactors using porous membranes. In this case the membrane, in addition to being used as a contactor between the liquid and gaseous reactants, could, potentially, also act as a host for the catalyst, which is placed in the porous framework of the membrane. As previously noted a triple-point interface between the three different phases (gas, liquid, and the solid catalyst) is then created in the membrane. The first application was reported by Cini and Harold... 

Figure 11.2 Various reactor types (schematic) for heterogeneous catalysts and gaseous reactants.

To develop a highly efficient AFC, an electrode stracture with more than one pore system or with a bimodal pore distribution is required. The liquid and gaseous reactants must reach the electrolyte that has direct contact with the anode and cathode catalysts. For AFCs, different electrode types have been used. The main types of electrodes are the PTFE-bonded GDE and the DSK. 

Here, the solid B is a non-catalytic reactant consumed in the reaction and the products are converted solid or gas or both solid and gas. The reactors used for this type of reaction are gas-solid contacting equipment such as a fluidised bed. The solid reactant B is usually the limiting reactant and gaseous reactant A is used in excess quantity. The fractional conversion of B, Xg achieved in the reactor determines the performance of the reactor. Any section of the reactor, shown in Figure 4.1, usually has solid particles suspended in a stream of gas containing reactant A. 

The reaction rate is first order both with regard to the solid and gaseous reactant... 

The rate of the chemical reaction is slow compared to internal and external diffusion, and concentration gradients both of the solid and gaseous reactant are negligible. 

If the chemical reaction is the rate-determining step, no concentration gradients of the solid and gaseous reactant will occur. Therefore, consumption of the gaseous and solid reactant is ... 

Most hydrotreaters and hydrocrackers are trickle-bed units. A classic article by Satterfield " describes the fundamental behaviour of such units, in which mixtures of liquid and gaseous reactants pass down over fixed beds of catalyst. In hydroprocessing units, the liquid reactants are petroleum fractions, and the gaseous reactant is hydrogen. 

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