High-p,T Processing

Fig. 6. Process intensification of the aqueous Kolbe-Schmitt synthesis of resorcinol using high-p,T processing. (Courtesy of ACS)...

Thus, there is a small process window where high-p,T processing is effective and process control may have an important role here to maintain processing at optimal conditions. 

V. Hessel, C. Hofmann, P. Lob, J. Lohndorf, H. Lowe, Minimizing reaction times for the Kolbe-Schmitt synthesis with resorcinol using high p.T-processing in a microreactor setup, Chem. Eng. Trans. 2005, 6, 49-54. 

In less than one minute, half of the 2,4-dihydroxy benzoic acid is decomposed already at 160°C in the micro-reactor setup [18]. Thus, a study was conducted to find optimal process parameters for T and t to achieve efficient high p,T operation via discrimination between the desired electrophilic substitution and undesired decarboxylation routes. The best operation point was at (200°C 40 bar 2000 ml h" 16 s). 

Infrared measurement of additive concentrations is a more complex analysis than initially expected, as some additives may undergo a variety of chemical reactions during processing, as shown by Reeder et al. [128] for the FTIR analysis of phosphites in polyolefins. Some further examples of IR work refer to PVC/metal stearates [129], and PE/Santonox R [68,130]. Klingbeil [131] has examined the decomposition of various organic peroxyesters (TBPB, TBPP, TBPA and TBPO) and a peroxidicarbonate (BOPD) as a function of pressure, temperature and solvent by means of quantitative FTIR using an optical high p, T reaction cell. 

Hessel V, Hofmann C, Lob P, Lohndorf J, Lowe H, Ziogas A (2005) Aqueous Kolbe-Schmitt synthesis using resorcinol in a microreactor laboratory rig under high-P,T conditions. Org Process Res Dev 9 479-489 Inoue T, Schmidt MA, Jensen KF (2007) Microfabricated multiphase reactors for the direct synthesis of hydrogen peroxide from hydrogen and oxygen. Ind Eng Chem Res 46 1153-1160... 

Using the high-p,T microreactor processing, the Kolbe-Schmitt synthesis was completed within less than 1 min at comparable yields, i.e., a reaction time reduced by a factor of approximately 2,000 was achieved (see Fig. 6). This corresponds to an increase in space-time yield by a factor of 440. 

Jadhavrao, P. (2007) Suzuki Coupling Based Polycondensation Using Enhanced Dispersing in High-p, T Micro Process Technology Devices, Technical University of Dortmund, Dortmund. 

P. Loeb, V. Hessel, H. Loewe, C. Hofmann, K. Mazanek, H. Klefenz, Brominations in micro reactors using high and low p,T-processing, in Proceedings of the 8th International Conference on Microreaction Technology (IMRET 8), Atlanta, GA, 2005, p 1341. 

The P/T process will be coupled after an improved PUREX process that puts all technetimn, iodine, and neptunium into the waste fraction or into special fractions. Thus, the waste will contain fission products and minor actinides (americium and curium). The process will probably be a solvent extraction process although molten salt systems are also studied as an alternative. The main issue will be to obtain pure Am and Cm fractions for subsequent destruction, i.e., fractions that do not contain any lanthanides. Some of the lanthanides, which are chemically very similar to trivalent actinides, have very high neutron cross sections. Therefore, they must be removed to make actinide burning possible. In some cases, it may also be desirable to transmute some long-lived fission products, e.g., Tc and l, to more shortlived nuclides. 

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