Acid temperature control schematic

Bakr et al. reported the flow reactor synthesis of PbS quantum dots for applications in solar cells. They showed that the flow reactor products had comparable performance to the batch synthesized PbS nanoparticles. A dual-temperature-stage flow reactor synthesis was carried out to achieve optimum results. The flow reactor system is shown schematically in Fig. 11. In this method precursor A consists of lead oxide, oleic acid (OA), and octadecene (ODE) whereas precursor B contains bis(trimethylsilyl) sulfide (TMS) and ODE. The two precursors are injected under nitrogen. The mixed reactants proceed together to the nu-cleation stage that is temperature-controlled by thermocouple 1. The precursors react at the elevated temperatures to form nucleation seeds. The quantum dots are then isolated using acetone and re-dispersed in toluene. 

One possible arrangement for a hydrofluoric acid alkylation unit is shown schematically in Fig. 1. Feedstocks are pretreated, mainly to remove sulfur compounds. The hydrocarbons and acid are intimately contacted in the reactor to form an emulsion, within which the reaction occurs. The reaction is exothermic and temperature must be controlled by cooling water. After reaction, the emulsion is allowed to separate in a settler, the hydrocarbon phase rising to the top. The acid phase is recycled. Hydrocarbons from the settler pass to a fractionator which produces an overhead stream rich in isobutane. The isobutane is recycled to the reactor. The alkylate is the bottom product of tile fraetionater (isostripper). If the olefin teed contains propylene and propane, some of the isoshipper overhead goes to a depropanizer where propane is separated as an overhead... 

For a SERS experiment, the water-soluble cellular fraction from pollen can be obtained as shown in the schematic in Fig. 4.8. About 0.2 mg of freeze-dried pollen, which correspond to a few hundred pollen grains, was suspended in 100 dl water and incubated at room temperature. When water is added to intact pollen, the cellular interior bearing the allergens, but also other proteins, carbohydrates, pigments and nucleic acids is released [91] and hence should be contained in the aqueous supernatant. About 2 pi of the supernatant, which should contain the amount of soluble content of a few individual pollen grains can then be added to 20 pi of a solution of gold nanoparticles. The gold nanoparticles were prepared as described by Lee and Meisel [92]. In the control experiments, the volume of the nanoparticle suspension is replaced by pure water. 

In the fixed-bed -process, shown schematically in Fig. 11-12, soluble cobalt salts of fatty acids or naphthenates are pumped with the olefin to the top of the first reactor and flow countercurrent to the synthesis gas. One type of fixed-bed catalyst consists of 2 per cent metallic cobalt on a pumice carrier. Part of the cobalt is converted to carbonyl, leaves the reactor with the overhead product, and is replaced by the cobalt salts in the feed. A high recycle of cooled crude product to the converter mds in controlling the reaction temperature. Unreacted synthesis gas leaving the top of the reactor is coo ed, passed through a packed tower countercurrent to the olefin feed to remove cobalt carbonyl, and recycled to the reactor. 

Different feed gases, such as CO, methyl bromide, O2, toluene, xylene, acetic acid, benzene and balanced N2, were supplied by feed cybnders. Water was introduced by a water pump. Flow rates of the feed stteams were regulated by flow controllers. The flows of O2, N2 and water were pre-heated and combined with VOC streams before entering the reactor. Thermocouples were located above and below the catalyst sample to record the reaction temperatures. Gas samples taken immediately before and after the catalyst were sent to a GC equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID) to measure the concentrations of CO and various hydrocarbon compounds. The test unit was also equipped with continuous O2, CO and total hydrocarbon analyzers. A schematic of the test unit is shown in Fig. 7.7. For the high pressure unit, the tests were conducted up to 150 psig total pressure. The basehne feed composition was 7,000 ppm CO, 50 ppm toluene, 50 ppm benzene, 50 ppm methyl bromide, 3% O2, 2% H2O and balanced N2. The catalyst temperature varied from 150—450°C. 

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