Laboratory slurry reactor

Warna, J., Flores Geant, M., Salmi, T., Hamunen, A., Orte, J., Hartonen, R., and Murzin, D. (2006) Modelling and scale-up of sitosterol hydrogenation process from laboratory slurry reactor to plant scale. Ind. Eng. Chem. Res., 45, 7067-7076. 

Graver, V., Zhan, X., Engman, J., Robota, H. J., Suib, S. L., and Polverejan, M. 2004. Deactivation of a Fischer-Tropsch catalyst through the formation of cobalt carbide under laboratory slurry reactor conditions. Prepr. Pap.-Am. Chem. Soc. Div. Pet. Chem. 49 192-94. 

For laboratory slurry reactors the following correlation can be used to calculate the mass transfer coefficient [7] ... 

Internal diffusion limitations can generally be easily avoided in laboratory slurry reactors as the minimum of the pellet diameter is determined by the maximum of the pore size of the membrane filter used to maintain the catalyst in the reactor. Membrane filters allowing the use of pellets with a diameter of 1 pm are commercially available. 

Very precise kinetic experiments were performed with sponge Ni and Ru/C catalysts in a laboratory-scale pressurized slurry reactor (autoclave) by using small catalyst particles to suppress internal mass transfer resistance. The temperature and pressure domains of the experiments were 20-70 bar and 110-130°C, respectively. Lactitol was the absolutely dominating main product in all of the experiments, but minor amounts of lactulose, lactulitol, lactobionic acid, sorbitol and galactitol were observed as by-products on both Ni and Ru catalysts. The selectivity of the main product, lactitol typically exceeded 96%. 

Hydrogenation of lactose to lactitol on sponge itickel and mtheitium catalysts was studied experimentally in a laboratory-scale slurry reactor to reveal the true reaction paths. Parameter estimation was carried out with rival and the final results suggest that sorbitol and galactitol are primarily formed from lactitol. The conversion of the reactant (lactose), as well as the yields of the main (lactitol) and by-products were described very well by the kinetic model developed. The model includes the effects of concentrations, hydrogen pressure and temperature on reaction rates and product distribution. The model can be used for optinuzation of the process conditions to obtain highest possible yields of lactitol and suppressing the amounts of by-products. 

Boopathy, R. and Manning, J., A laboratory study of the bioremediation of 2,4,6-trinitrotoluene-contaminated soil using aerobic anaerobic soil slurry reactor, Water Environ. Res., 70, 80-86, 1998. 

Manning, J., Boopathy, R., and Kulpa, C.F., A Laboratory Study in Support of the Pilot Demonstration of a Biological Soil Slurry Reactor, Report no. SFIM-AEC-TS-CR-94038, U.S. Army Environmental Center, Aberdeen Proving Ground, MD, 1995. 

The numbers for the liquid acids are taken from Refs. (12,23,221). As zeolites are not used in industrial alkylation process, the given values represent the judgment of the authors extracted from laboratory and pilot scale data obtained in a slurry reactor. 

In high pressure work, slurry reactors are used when a solid catalyst is suspended in a liquid or supercritical fluid (either reactant or inert) and the second reactant is a high pressure gas or also a supercritical fluid. The slurry catalytic reactor will be used in the laboratory to try different catalyst batches or alternatives. Or to measure the reaction rate under high rotational speeds for assessing intrinsic kinetics. Or even it can be used at different catalyst loadings to assess mass transfer resistances. It can also be used in the laboratory to check the deactivating behaviour. 

Whatever the merits of each process in a continuous commercial operation, the slurry process is very convenient for batch polymerization studies in the laboratory. The diluent permits precise control of the temperature and serves to dissolve ethylene and other reactants that must contact the catalyst during polymerization. Most of the work reported here was done in a slurry reactor. 

We will now consider the design of an agitated tank slurry reactor which might be used industrially for this reaction. We will choose a particle size of 100 fim rather than the very small size particles used in the laboratory experiments, the reason being that industrially we should want to be able easily to separate the catalyst particles from the liquid products of the reaction. If we use spherical particles (radius ro, diameter dp), the Thiele modulus (see Chapter 3) is given by ... 

To date, the best results obtained for an iron catalyst in a slurry reactor have been reported by Kolbel with a precipitated iron catalyst promoted with potassium and copper.2 Current efforts in our laboratory have been aimed at developing a catalyst with activity and productivity superior to the catalyst used by Kolbel. Most research efforts have focused on precipitated and fused iron catalysts however, promising results have been reported for... 

The scale-up of monolith reactors is expected to be much simpler. This is due to the fact that the only difference between the laboratory and industrial monolith reactors is the number of monolith channels, provided that the inlet flow distribution is satisfactory. In slurry reactors, scale-up problems might appear. These are connected with reactor geometry, low gas superficial velocity, nonuniform catalyst concentration in the liquid, and a significant back-mixing of the gas phase. 

The catalytic hydrogenation of methyl linoleate was carried out in a laboratory-scale slurry reactor in which hydrogen gas was bubbled up through the liquid and catalyst. Unfortunately, the pilot-plant reactor did not live up to the laboratory reactor expectations. The catalyst particle size normally used was between 10 and 100 pm. In an effort to deduce the problem, the experiments listed in Table E12-5.1 were carried out on the pilot plant slurry reactor at 121°C. 

The deactivation of methanol-synthesis catalyst was studied in laboratory and pilot-plant slurry reactors using a concentrated, poison-free, CO-rich feedstream. The extent of catalyst deactivation correlated with the loss of BET surface area. A model of catalyst deactivation as a function of temperature and time was developed from experimental data. The model suggested that continuous catalyst addition and withdrawal, rather than temperature programming, was the best way to maintain a constant rate of methanol production as the catalyst ages. Catalyst addition and withdrawal was demonstrated in the pilot plant. 

Since the rate of sintering depends strongly on temperature, a careful study of the effect of temperature on catalyst deactivatiort was necessary. The slurry reactors in both the laboratory and the pilot plant ware essentially Isothermal they provided an ideal vehicle for a controlled. easy-to interpret study of temperature effects. 

In the laboratory either integral or differential (see Sec. 4-3) tubular units or stirred-tank reactors may be used. There are advantages in using stirred-tank reactors for kinetic studies. Steady-state operation with well-defined residence-time conditions and uniform concentrations in the fluid and on the solid catalyst are achieved. Isothermal behavior in the fluid phase is attainable. Stirred tanks have long been used for homogeneous liquid-phase reactors and slurry reactors, and recently reactors of this type have been developed for large catalyst pellets. Some of these are described in Sec. 12-3. When either a stirred-tank or a differential reactor is employed, the global rate is obtained directly, and the analysis procedure described above can be initiated immediately. 

Larger scale Fischer-Tropsch synthesis runs were performed in a pilot plant slug-flow slurry reactor using 3-8kg catalyst as well as in a slurry phase bubble column demonstration unit using 500-1500kg catalyst. The reaction conditions were similar to those in the laboratory CSTR runs. The reactor wax production varied between 5 and 30kg per day for the pilot plant runs and up to 60 bbl/day for the demonstration unit. On-line catalyst samples were taken for particle size distribution measurements and Scanning Electron Microscope analyses. 

The maximum temperatures permissible for homopolymers in a number of diluents are listed in Table 75. These temperatures were determined in two ways, first, by laboratory swelling tests of a homopolymer in the particular hydrocarbon and, second, by actual experience in the production of homopolymers with the hydrocarbons in a pilot slurry reactor. Also shown in Table 75 is the degree of branching of each hydrocarbon, which is defined as the ratio of the number of methyl carbon atoms to the total number of carbon atoms. The swelling temperature correlates nicely with this ratio. Isobutane was chosen for commercial use as the best compromise between being highly branched and not too expensive. It permits a maximum operating temperature of about 111 °C for polyethylene homopolymer. 

Naturally, a computer implementation of this procedure is required. An example of the application of the algorithm is provided for the case of hydrogenation of D-xylose to xylitol, which was carried out in the laboratory of the authors in a batch wise operating slurry reactor. 

Chapters 7 and 8 present models and data for mass transfer and reaction in gas-liquid and gas-liquid-solid systems. Many diagrams are used to illustrate the concentration profiles for gas absorption plus reaction and to explain the controlling steps for different cases. Published correlations for mass transfer in bubble columns and stirred tanks are reviewed, with recommendations for design or interpretation of laboratory results. The data for slurry reactors and trickle-bed reactors are also reviewed and shown to fit relatively simple models. However, scaleup can be a problem because of changes in gas velocity and uncertainty in the mass transfer coefficients. The advantages of a scaledown approach are discussed. 

Tetrahydrofuran is obtained as byproduct of the hydrogenation of succinic anhydride on nickel-rhenium catalyst. The hydrogenation of y-butyrolactone to 1,U-butanediol is conducted at 250°C and 100 bar the presence of a nickel-cobalt-thorium oxide catalyst supported on silica. Slurry reactors have been used up to now for these hydrogenations, as it is often the case when new processes are extrapolated from small pilot plant or laboratory data, the more so as the actual capacities (a few thousands tons per year)are rather small. 

Respecting those simple rules, a sufficiently safe scale-up should be possible on the base of laboratory experiments, even not all details are known about agitated and aerated slurry reactors. Additional recommandations for an optimal operation of those reactors are given in [29]. 

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