Multiple stage reactions

Continuous polymerization n. In polymer manufacture, linkage of the various stages of polymerization so that materials flow without interruption from the addition of raw materials to delivery of the finished polymer from the system. Extrusion as film, chip or fiber may be linked to a continuous polymerization line. Because there is no break in the process while the transition from low molecular weight to high occurs, multiple stage reaction vessels may be required and accurate process control is critical. 

The desulfurization process can be carried out either, in a dedicated reactor, or within a simple storage vessel, or during transportation (in pipelines) or intermediate processing vessels. Nutrients addition, pH, and aeration are adjusted as necessary. Multiple stages can be added to the reaction to enhance the sulfur removal process and decrease the reaction time below the probable 300 h required. The produced sulfates are removed by the addition of agents such as alkaline calcium, magnesium, aluminum, barium, and metal compounds such as oxides, hydroxides, and carbonates. 

Scheme 2.19 Multiple reagent combinations for sequential staged reactions.

Multiple-stage ozonization seems to be more effective than single-stage ozonization, both followed by biodegradation, for DOC ehmination in treatment of reservoir waters and secondary effluents of a domestic wastewater treatment plant . The fate of O3 in water ozonization consists of a fast reaction with the DOC and a slow first-order decay of unreacted O3. A method for optimization of a two-stage water ozonization process is based on control with a FIA unit, where the ozone concentration is continuously measured by oxidation of indigotrisulfonate(8) . The various fractions of DOC (in the ppm range) may react with the traces of bromide (sub-ppm) found in natural waters, as this anion... 

Patterns of cyclic carbopalladation. As discussed above, the fundamentally stoichiometric and living nature of carbopalladation imposes various difficulties to be overcome. Carbopalladation can, in principle, be either a single-stage process or double- or multiple-stage processes. Double-and multiple-stage carbopalladation reactions have often been called either domino or cascade carbopalladation reactions. In some cases, two-stage carbopalladation reactions have also been called tandem carbopalladation reactions. None of these three words is a chemical term, and choice between them is a matter of taste. In this chapter, the term cascade will be used for both double- and multiple-stage carbopalladation processes. 

Hence, this temperature depends on the composition of the reaction mixture, Therefore, for exothermic equilibrium reactions the temperature should be lowered as more reactant is converted, to keep the rate high. Thus this type of reaction is often carried out in multiple stages (e.g. multiple reactors or multiple zones within a reactor), each with its own temperature, adapted to the reaction mixture composition. 

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