Support granulation

The majority of studies of a two-component impregnation concerns the sorption of [PtClgj assisted by the anions of inorganic or organic acids. These anions adsorb competitively and thus regulate the force of platinum preciuwr interaction with alumina and, thus, platinum distribution over the support granule [2-3]. 

Adsorption isotherms were measured on the small support granules (0.5-1.0 mm) at the contact with the corresponding solutions of various concentrations thermostated at 25 °C (2 g of support/ 10 ml of solution) for 96 h. 

Fig. 1 shows the typical kinetics of Pt adsorption on inels. The sorption attains equilibrium not less than in 4 days. The crashing of support granules and the circulation of impregnation solution do not change significantly the adsorption rate. Evidently, neither external nor inner diffusion limit the process. Pt is known... 

After it is washed, dried, and granulated, this silica gel has a very high specific surface area (about 700 m2-g 1) and is useful as a drying agent, a support for catalysts, a packing for chromatography columns, and a thermal insulator. 

The stamp associated with the extreme hardness values (number 7, Fig. 4.12, left use STAMP.dat with program MULTI) is the next suspect It is identified and inspected on disassembly of the tablet press Due to mechanical wear, the movement of the stamp assembly is such that an above-average amount of granulate drops into cavity number 7, and is thus compressed to the limiting hardness supported by the granulate. The hardness for stamps 4, 8, and 11 tends to be low, and high for 12, but the data is insufficient to come to definite conclusions for these tools. The tablets from these stamps contaminated what would otherwise been a fairly acceptable product. Because... 

When performing catalytic reactions or reactions with immobilized reactants, a bed or support has to be fiUed into a tube or capillary. The fiUing may be a bed of powder, a bed of granules or a three-dimensional material network (e.g. a polymerized foam). By special choice of the filling, e.g. very regularly sized particles, it is attempted to improve the flow characteristics. 

In gas phase reactors, the monomer is introduced to the bottom of reactor where it percolates up through a fluidized bed of polymer granules and inert-media supported catalyst. A fraction of the monomer reacts to form more polymer granules, the remaining monomer being drawn from the top of the reactor, cooled, and recycled. Polymer granules are continuously wthdrawn from the bottom of the fluidized bed and the catalyst is replenished. 

If we accept a date of around AD 1000 for the commencement of the distillation of zinc on a large scale, then, following the work of Craddock (1978), all earlier brasses should contain less than 28% Zn, as this is the approximate upper limit for the calamine process at around 1000 °C. Above this temperature, the process is more efficient, but it is said that the brass produced melts and the active surface area for the process is thus reduced. By granulating the copper and therefore increasing the surface area, the maximum can be pushed to around 33% Zn, but it is unlikely that this was done in Europe until the 18th Century (see Section 6.4). This model is supported by the analytical data Craddock s work on Roman brass indeed shows an upper limit of about 28% zinc. 

Interesting and interrelated with the previous case is one of enclosed partitions, when one of two partitions can be further divided into two partitions. An illustrative example is shown in Figure 9.17a. A granule of catalyst can be divided into two partitions porous aggregates (secondary particles—partition 1) and pores between the aggregates (partition 2). Partition 1 can also be divided into two partitions nonporous particles (primary particles—partition 11) and pores between particles (partition 12), excluding pores between aggregates. Another case of enclosed partitions has already been considered the case of a porous supported catalyst, which can be divided into pores and a solid phase, while the solid phase can be divided into the support and the active component. 

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