Slurry reactors first-order reaction

Rate equation for a first-order reaction in a slurry reactor... 

The analysis of the effects of catalyst deactivation on CSTR performance is straightforward and there is really not too much to write about however, this can be of considerable importance in the design of slurry reactors, which will be discussed in Chapter 8. We can start with the familiar relationship for a first-order reaction given in equation (4-68)... 

Figure 8.10 Overall effectiveness factor for a first-order reaction in a slurry reactor. [After R.V. Chaudari and P.A. Ramachandran, Amer. Inst. Chem. Eng., JL, 26, 111, with permission of the American Institute of Chemical Engineers, (1980).]...

The usual and the most established design method of catalytic slurry reactors consists of a concept which assumes resistances in series(see Figure ).For instance,for a first order reaction this treatment given ... 

Kinetics and catalyst exploratory studies are sometimes conducted in a CSTR. Slurry-phase reactors or ebullating beds, used for upgrading of heavy oils and resids, can be approximated as a CSTR. In a CSTR, c k,f) = c k)l + kt) for first-order reactions and... 

A reactant of bulk concentration Cao reacts on the external surface of catalyst spheres of radius 7 in a slurry reactor. The first-order surface reaction rate coefficient is k , and the diffiisivity of A in the solution is Da- Find fhe effective rate coefficient in terms of these quantities, assuming that stirring is sufficiently slow that fhe fluid around particles is stagnant. 

A first-order irreversible catalytic reaction r" = k"C/ ) occurs in a slurry reactor (or fluidized bed reactor). Spherical catalyst particles have diameter R, density surface area/mass Sg, and a fraction g of the reactor is occupied by catalyst. The average pore diameter is d. Find an expression for r C ) in terms of these quantities. 

Probably, for most slurry reactor applications, information on the value of the product kLa is sufficient for design purposes. In some cases, however, information on the individual parameters a and/or ki, can be useful. For instance, the reactor capacity will depend on a, rather than on the product k a, if the reaction is so fast that all conversion takes place within the stagnant film (film theory) around the gas bubbles. For first-order conversion kinetics in the porous catalyst particles this will occur for... 

P12-21b The hydrogenation of 2-butyne-l,4-diol to butenediol is to be earned out in a slurry reactor using a palladium-based catalyst. The reaction is first-order in hydrogen and in diol. The initial concentration of diol is 2.5 kmol/m. Ihire hydrogen is bubbled through the reactor at a pressure of 35 atm at 35°C. The equilibrium hydrogen solubility at these conditions is 0.01 kmol/m, and the specific reaction rate is 0.048 m /kg kmol s. The catalyst charge is 0.1 kg/m with a particle size of 0.01 cm and pellet density of 1500 kg/m. ... 

Figure 8.11 Design chart for equation (8-112). Semi-batch slurry reactor with reaction first-order in both A and B. Parameter is 0 at r = 0.

E21.3 The hydrogenation of a diol is performed in a slurry bed reactor by adding 0.500 g of catalyst powder into reactor and the initial concentration of the diol is 2.5mol/cm. The reaction is first order with respect to both H2 and diol H2 is bubbled through distributor at 1 atm and 35°C. The concentration of H2 in equilibrium conditions is 0.01 mol/cm and the constant specific reaction rate is 4.8 x 10 (cm /(cm x s)). The flow rate of catalyst is 0.1 kg/m, the particle diameter is 0.01 cm, and its density is equal to 1.5 g/cm. Calculate the overall reaction rate. The pore diffusion can be neglected Verify if the mass transfer in the pores and the external transfer can be negligible (Adapted from Fogler, 2000). 

We want to develop a model for a slurry reactor. This is a stirred tank reactor with suspended catalyst particles. The rate of reaction is first-order and obeys the Arrhenius temperature dependency. The reaction... 

The slurry reactor has two significant advantages it has the highest volumetric capacity, and the best possibilities for heat transfer. It can often be operated under isothermal conditions (see section 8.3). A consequence is that scaling up is not too difficult. The combined effects of mass transfer and chemical reaction were presented in section S.S.2, eqs. (S.61) and (S.62). These can be used to estimate the quantitative effects for first order surface reactions. For other reaction orders, the same principle can be applied, but the calculations become more complicated. In practice, gas/liquid mass transfer is often the limiting factor, that is when a sufficient amount of finely divided catalyst is used. Therefore effective gas dispersion is essential (see section 4.6.4). 

For more complex kinetics, as e g Langmuir-Hinshelwood, see e g [6l] The numerical value of in Equation (25) will, in general, depend on the values of 2 3 above we may conclude that R and R are functions of the intrinsic reaction kinetics and the particle properties (a, ag, D, d ) whilst for non-first order kinetics also plays a role Consequently, R and R are independent of the hydrodynamics within the slurry reactor except indirectly via Rx, R2 and R3 in case of non-linear intrinsic reaction kinetics ... 

HDS activity of synthesized catalysts was studied in a tri-phasic slurry batch reactor (Parr 4575). The reaction mixture was prepared by adding 0.3 g of dibenzothiophene (99 mass %, from Aldrich) and 0,2 g of sieved catalyst (80-100 U.S. mesh) in 100 cm of -hexadecane (99 mass %, from Aldrich) Operating conditions, carefully chosen to avoid external diffusion limitations, were P= 5.59 + 0.03 MPa, T= 320 3°C and 1000 RPM. Samples taken periodically were analyzed by gas chromatography (Agilent 6890N, flame ionization detector and Econocap-5 capillary colunm (from Alltech). HDS kinetic constants were calculated assuming a pseudo-first order model referred to organo-S compound concentration and zero order with respect to excess H2. 

In the slurry process, the hydrolysis is accompHshed using two stirred-tank reactors in series (266). Solutions of poly(vinyl acetate) and catalyst are continuously added to the first reactor, where 90% of the conversion occur, and then transferred to the second reactor to reach hiU conversion. Alkyl acetate and alcohols are continuously distilled off in order to drive the equiUbrium of the reaction. The resulting poly(vinyl alcohol) particles tend to be very fine, resulting in a dusty product. The process has been modified to yield a less dusty product through process changes (267,268) and the use of additives (269). Partially hydroly2ed products having a narrow hydrolysis distribution cannot be prepared by this method. 

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