Theoretical energy consideration of the gas-phase polymerization of sodium acrylate
The kinetics of the spray polymerization of sodium acrylate were investigated. The technique in which the heat of polymerization was used for solvent removal showed better energy efficiency than the solution or emulsion polymerization methods for preparing sodium polyacrylate. The monomer solution was injected into the nozzle of the spray machine via a venturi effect to siphon up the solution. Two siphon tubes feeding through two control valves into a mixing chamber before the spray operation resulted in separate feeds of a sodium hydroxide solution and a mixture of acrylic acid, water, and a catalyst. These two feeds generated the heat of neutralization of sodium acrylate. This heat raised the temperature of the monomer solution to the reaction temperature, thereby initiating the exothermic polymerization reaction. Theoretical calculations of these energy sources were compared with the energy required to give a dry product. The results revealed that the energy cost for spray polymerization was 4783.5 kJ kg-1, whereas the energy cost was 7830.4 kJ kg-1 for the conventional system. © 2003 Wiley Periodicals, Inc.