Reactor concentration product removal during reaction

The writer [53] invented the approach of continuous nitration of nitric acid vapor to prepare ethyl nitrate. The solution of alcohol and nitric acid was added dropwise into a reactor, in which a protective agent of carbonyl groups was contained. The products were continuously distilled out of the reaction system during the process of nitration reaction. Thus, the removal of ethyl nitrate makes the concentration of products low, favoring the forward reaction and increasing the yield of nitration. Meanwhile, because the retention time of nitrate esters in the thermal reactor is shortened, the amount of nitrous acid, as well as intermediates, is reduced, improving the safety of the production process. The reaction process can be described by the following equation. 

Semi-Batch Reactor (SBR) a type of batch reactor from which at least one reactant is withheld and then added at a controlled rate, usually to control the rate of heat generation or gas evolution both heat generation and concentrations vary during the reaction process products are removed from the reactor only upon conclusion of the reaction process. 

The cross aldol condensation of citral (Millennium Chemicals, 40 % cis-isomer + 55 % trans-isomer) with acetone (Merck, PA) was carried out at 353 K in N2 atmosphere under autogenous pressure ( 250 kPa) in a batch PARR reactor, using an acetone/citral = 49 (molar ratio) and a catalyst/(citral+acetone) = 1 wt.% ratio. Catalysts were pre-treated ex-situ in flowing N2 at 773 K for 2 h to remove adsorbed water and carbon dioxide and then quickly transferred to the reactor without exposing them to air. Reaction products were analyzed by gas chromatography. Selectivities (Sj, mol of producty /mol of citral reacted) were calculated as (%) = Cj X 100/ TCj where Cj is the concentration of product j. Product yields rjj, mol of product y/mol of citral fed) were calculated as Tfj = SjXat- Thirteen samples of the reaction mixture were extracted and analyzed during the 6-hour reaction. The main reaction product of citral conversion was pseudoionone, PS (cis- and trans- isomers). 

The chemical shim system uses the soluble neutron absorber boron (in the form of boric acid), which is inserted in the reactor coolant during cold shutdown, partially removed at startup, and adjusted in concentration during core lifetime to compensate for such effects as fuel consumption and accumulation of fission products which tend to slow the nuclear chain reaction. The control system allows the plant to accept step... 

At the beginning dialcohol and dicarboxyiic acid are charged to the reactor. Then the reactor is heated up to operating temperature. A further amount of dialcohol is fed to the reactor during the batch. Water is distilled fi-om the reboiler and an excess of dialcohol is used to shift the reaction equilibrium to the product side. In the first period the pressure is kept constant. The distillate, nearly pure water, is accumulated in the first vessel. As the reaction progresses it gets more difficult to remove the condensate. Hence, the pressure is reduced in the second period to evaporate the remaining water. The concentration of dialcohol in the distillate increases. In this period the distillate is accumulated in the second vessel. The end of the batch is reached when the product shows a required acid value, carboxyl number and viscosity. 

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