Reactor solvent selection

High purity acetaldehyde is desirable for oxidation. The aldehyde is diluted with solvent to moderate oxidation and to permit safer operation. In the hquid take-off process, acetaldehyde is maintained at 30—40 wt % and when a vapor product is taken, no more than 6 wt % aldehyde is in the reactor solvent. A considerable recycle stream is returned to the oxidation reactor to increase selectivity. Recycle air, chiefly nitrogen, is added to the air introducted to the reactor at 4000—4500 times the reactor volume per hour. The customary catalyst is a mixture of three parts copper acetate to one part cobalt acetate by weight. Either salt alone is less effective than the mixture. Copper acetate may be as high as 2 wt % in the reaction solvent, but cobalt acetate ought not rise above 0.5 wt %. The reaction is carried out at 45—60°C under 100—300 kPa (15—44 psi). The reaction solvent is far above the boiling point of acetaldehyde, but the reaction is so fast that Httle escapes unoxidized. This temperature helps oxygen absorption, reduces acetaldehyde losses, and inhibits anhydride hydrolysis. 

For many different hydrogenation reactions also various solvents with different properties have to be used, specially with respect to vapour pressures and boiling points. Each reaction requires its own temperature range and also this demands for a great flexibility of a multiproduct reactor. Good selectivities... 

The pinacol rearrangement proceeds over metal-substituted aluminophosphate molecular sieves (APOs) under mild conditions (batch reactor, solvent, g diol/ g catalyst = 5, 383 K, 3 h) [32]. Catalytic performance is best for APO-5 (Table 2) and surpasses that that of VPI and APO-11. Of the metals used Fe, Ni, and Cu have the highest activity and selectivity. No direct correlation was found between activity and acidity determined by pyridine TPD. For example. 

The reaction of propionaldehyde, formaldehyde, and dimethylamine takes place in acetic acid solvent in the liquid phase at 160 C (320°F) and 40-80 bars (590-1180 psig). Both reactions, formation of the Mannich base salt and cracking to methacrolein, occur in the same reactor. The selectivity of the aldehydes to methacrolein is 98.7%. The yield of propionaldehyde to methacrolein is 98.1% and the overall yield of methyl methacrylate is nearly 90% [23,24]. 

The degradation of a poorly-soluble compound, anthracene, was carried out in a TPPB by the oxidative action of MnP. When dealing with biphasic reactors, the selection of the appropriate solvent is the first step in the optimization of the process. As well as with soluble compounds, the parameters involved in the catalytic cycle should be studied but also other operational parameters affecting mass transfer of the substrate. Finally, a model of the process will help to understand the whole process and to choose the most adequate operational parameters. 

Catalytic hydrogenation of an unsaturated ketone was studied by high-pressure kinetic experiments to provide an accurate model for the scale-up of an industrial pilot reactor. The selective reduction of the conjugated double bond was performed in supercritical carbon dioxide as a solvent in the presence of an industrial Pd on alumina catalyst. ... 

Pu (86 years) is formed from Np. Pu is separated by selective oxidation and solvent extraction. The metal is formed by reduction of PuF with calcium there are six crystal forms. Pu is used in nuclear weapons and reactors Pu is used as a nuclear power source (e.g. in space exploration). The ionizing radiation of plutonium can be a health hazard if the material is inhaled. 

Erom 1955—1975, the Ziegler-Natta catalyst (91), which is titanium trichloride used in combination with diethylaluminum chloride, was the catalyst system for propylene polymerization. However, its low activity, which is less than 1000 g polymer/g catalyst in most cases, and low selectivity (ca 90% to isotactic polymer) required polypropylene manufacturers to purify the reactor product by washing out spent catalyst residues and removing unwanted atactic polymer by solvent extraction. These operations added significantly to the cost of pre-1980 polypropylene. 

New chemical synthesis routes leading to a better productivity and increased selectivity could be defined with regard to the new opportunities offered by HEX reactors. For example, they can lead to solvent-free operation or operations with at least dramatically reduced amount of solvent, to increase the reaction temperature or to engage in more efficient catalysis. 

GL 1] [R 1] [R 3] [P le] The performance of a typical laboratory bubble column was tested and benchmarked against the micro reactors (Figure 5.17). Using acetonitrile as solvent, the conversion of the laboratory bubble column ranged from 6 to 34% at selectivities of 17-50% [3, 38]. This corresponds to yields of 2-8%. Hence the yields of the laboratory tool are lower than those of the micro reactors, mainly as a consequence of lower selectivities. 

Selectivity is determined by a number of factors, such as intrinsic properties of the catalyst complex (metal and ligands), reaction conditions (concentration, temperature, pressure), and reactor configuration (solvent, reactor, process). Here, we will focus on the catalyst properties. 

In reactor 1 2,6-xylenol is condensed with propylene oxide in the presence of NaOH at elevated temperature and pressure. The reaction is reasonably selective. However, some isomers are also formed in minor proportions. Therefore, the crude DMFP is dissolved in the organic solvent / and crystallized in tank 2, separated from the mother liquor in centrifuge 3, and dried in drier 4. 

Reaction detectors are a convenient means of performing online postcolumn derivatization in HPLC. The derivative reaction is performed after the separation of the sample by the column and prior to detection in a continuous reactor. The mobile phase flow is not interrupted during the analysis and reaction, although it may be augmented by the addition of a secondary solvent to aid the reaction or to conform to the requirements of the detector. Reaction detectors are finding increasing application for the analysis of trace components in complex matrices where both high detection sensitivity and selectivity are needed. Many suitable reaction techniques have been published for this purpose [641-650]. 

S Entropy (kJ-K-1, kJkg-1-K-1, kJkmol-1-K-1), or number of streams in a heat exchanger network (-), or reactor selectivity (-), or reboil ratio for distillation (-), or selectivity of a reaction (-), or slack variable in optimization (units depend on application), or solvent flowrate (kg s-1, kmol-s-1), or stripping factor in absorption (-)... 

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