Laboratory-scale processing

For toluene fluorination, the impact of micro-reactor processing on the ratio of ortho-, meta- and para-isomers for monofluorinated toluene could be deduced and explained by a change in the type of reaction mechanism. The ortho-, meta- and para-isomer ratio was 5 1 3 for fluorination in a falling film micro reactor and a micro bubble column at a temperature of-16 °C [164,167]. This ratio is in accordance with an electrophilic substitution pathway. In contrast, radical mechanisms are strongly favored for conventional laboratory-scale processing, resulting in much more meta-substitution accompanied by imcontroUed multi-fluorination, addition and polymerization reactions. 

There is an additional point to be made about this type of processing. Many gas-phase processes are carried out in a continuous-flow manner on the macro scale, as industrial or laboratory-scale processes. Hence already the conventional processes resemble the flow sheets of micro-reactor processing, i.e. there is similarity between macro and micro processing. This is a fimdamental difference from most liquid-phase reactions that are performed typically batch-wise, e.g. using stirred glass vessels in the laboratory or stirred steel tanks in industrial pilot or production plants. 

The same features were found for pilot-size micro-reactor operation (Figure 4.59). Brightness and transparency were the same and color strength could be increased to 149% [55]. The mean particle size was even set to a lower value compared with the laboratory-scale processing (micro reactor, D5Q = 90nm, s= 1.5 ... 

OS 68] [R 19] ]P 50] The lower yield of the industrial batch process (6 m stirred vessel) of only 72% is due to limitations of the cooling system allowing processing only at -20 °C, and not at —40 °C as is possible for the better laboratory-scale batch process (0.5 1 flask 0.5 h 88% yield) [134], The industrial process had a surface-to-volume ratio of 4 m m , the laboratory-scale process of 80 and the micro... 

Conversion/selectivity/yield - benchmarking to industrial process and laboratory-scale processing... 

The solution of these problems is based on a simple idea the developed laboratory-scale process is used for manufacturing of a chemical product by parallelization of many small units. Although promising great advantages over scale-up, this procedure, denoted numbering-up , is not trivial by far. It cannot be carried out in a simple way due to the tremendous technological effort necessary a chemical plant with hundreds or even thousands of small-scaled vessels, stirrers, heaters, pumps. 

Impact on Process Engineering 51 Laboratory-scale Processing 51... 

It has been claimed that complexes of P-cyclodextrin with anionic surfactants, notably higher fatty alcohol ethoxylates, improve scouring efficiency on cotton and wool in laboratory-scale processing [34]. Residual surfactants carried over from preparation can have undesirable effects in subsequent processing. When cyclodextrins complex with surfactants, their surface activity is reduced. Hence cyclodextrins are potentially useful for the removal of residual amounts of surfactants from substrates [35]. The use of a- and P-cyclodextrins has been studied in this context with one cationic, one anionic and four... 

As discussed in Section 15.5.2, the separation of two or more sublimable substances by fractional sublimation is theoretically possible if the substances form true solid solutions. Gillot and Goldberger(10°) have reported the development of a laboratory-scale process known as thin-hlm fractional sublimation which has been applied successfully to the separation of volatile solid mixtures such as hafnium and zirconium tetrachlorides, 1,4-dibromobenzene and l-bromo-4-chlorobenzene, and anthracene and carbazole. A stream of inert, non-volatile solids fed to the top of a vertical fractionation column falls counter-currently to the rising supersaturated vapour which is mixed with an entrainer gas. The temperature of the incoming solids is maintained well below the snow-point temperature of the vapour, and thus the solids become coated with a thin film (10. im) of sublimate which acts as a reflux for the enriching section of the column above the feed entry point. 

Once an appropriate laboratory-scale process has been established, many of the key elements of the process should have been determined. Some operating parameters (such as inlet-air temperature, coating formulation to be used, and solids content of the coating solution/suspension) can be directly translated to the larger-scale process. Others, however, will have to change, and these include ... 

Figure 17 Drug release characteristics of pellets coated on various scales of the Wurster process when the laboratory-scale process, used as the basis for scale-up, has been fully optimized.

Taking a laboratory-scale process (hopefully one that has been appropriately optimized) and transferring the processing technology first to the pilot scale and ultimately to full production scale... 

As with pan coating, the key to successfully scaling up the fluid bed process involves the design of a completely optimized laboratory-scale process on which key decisions can be based. As discussed earlier, Turkoglu and Sakr [8] have provided an appropriately relevant example of how such an optimized fluid bed process (in this case, a tangential-spray process) may be designed. 

The hydroformylation of alkenes generally has been considered to be an industrial reaction unavailable to a laboratory scale process. Usually bench chemists are neither willing nor able to carry out such a reaction, particularly at the high pressures (200 bar) necessary for the hydrocarbonylation reactions utilizing a cobalt catalyst. (Most of the previous literature reports pressures in atmospheres or pounds per square inch. All pressures in this chapter are reported in bars (SI) the relationship is 14.696 p.s.i. = 1 atm = 101 325 Pa = 1.013 25 bar.) However, hydroformylation reactions with rhodium require much lower pressures and related carbonylation reactions can be carried out at 1-10 bar. Furthermore, pressure equipment is available from a variety of suppliers and costs less than a routine IR instrument. Provided a suitable pressure room is available, even the high pressure reactions can be carried out safely and easily. The hydroformylation of cyclohexene to cyclohexanecarbaldehyde using a rhodium catalyst is an Organic Syntheses preparation (see Section 4.5.2.5). 

Laboratory-scale processes Industrial-scale processes... 

A pilot plant scale starch solution, approximately 300 l, was prepared in a stainless steel container equipped with a paddle wheel electric stirrer, steam-heated coils, steam injection, an external gear pump with recirculation capability, insulation surrounding the container, a container lid, and a vent. The starch solution was prepared with the same percentage composition and duration of heating as described for the laboratory scale process. The first batch was pimped into the "sizing box" of the slasher and utilized immediately hot as a conventional yarn treatment. 

Centrifuges can function in batch-mode and continuous mode. Batch-mode works well for laboratory-scale processes, whereas continuousmode can handle larger volumes and is thus... 

Individual sample from mn, analysed unwashed Same sample as 41b, but washed with water to remove inorganic chlorides Note, these experiments were carried out using a laboratory-scale process... 

P4-9 Sargent Nigel Ambercromby. Scoundrels Incorporated, a small R D company has developed a laboratory scale process for the elementary, solid-cata-lyzed-gas-phase reaction A + B C -F D (names coded for proprietary reasons). The feed is equal molar in A and B with the entering molar flow r e of A is 25 mol/min and the volumetric feed is 50 dm /min. Engineers at Scoundrels calculated that an industrial scale packed bed reactor with 500 kg of a very rare and expensive metal catalyst will yield a 66% conversion when run at 32 C and a feed pressure of 25 atm. At these conditions the specific reaction rate is 0.4 dm /mol-min-kg catalyst. Scoundrels sells this process and catalyst to Queless Chemicals who then manufactured fee packed bed. When Oueless put the process onstream at the specifications provided by Scoundrels, they could only achieve 60% conversion with 500 kg catalyst. Unfortunately the reaction was carried out at 3U°C rather than 32°C. The... 

While most laboratory scale reactions are run in a batch mode there are a large number of commercially important processes that are run in a continuous manner. Since some of the continuous reactors described in Chapter 6 are potentially useful for laboratory scale processes and many lab scale reactions will have to be adapted to large scale continuous flow systems, a knowledge of the effect that reaction variables can have on heterogeneously catalyzed reactions run in a continuous manner is important. 

Fig. 1.4 Screening-based directed evolution. The process involves the cyclic iteration of mutation, selection and amplification of improved variants in a stable laboratory-scale process.

Microreactor Laboratory-scale Process Developments for Future Industrial Use... 

Microreactor Laboratory-scale Process Developmentsfor Future Industrial Use I 111... 

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