Electrochemical synthesis energy requirements

Electrochemical synthesis, 645 cell types, 648,653,654 energy requirements, 653 fuel cells, 646, 655 overvolfage, 654 reactions, 646 Electrodialysis, 508, 517 equipment, 513, 514 performance, brackish water, 515... 

Molten Salt Electrochemical Processes Directed Toward a Low Carbon Society 525 Table 7.1.1 Comparison of energy required for ammonia synthesis... 

The individual steps of the multistep chemical reduction of COj with the aid of NADPHj require an energy supply. This supply is secured by participation of ATP molecules in these steps. The chloroplasts of plants contain few mitochondria. Hence, the ATP molecules are formed in plants not by oxidative phosphorylation of ADP but by a phosphorylation reaction coupled with the individual steps of the photosynthesis reaction, particularly with the steps in the transition from PSII to PSI. The mechanism of ATP synthesis evidently is similar to the electrochemical mechanism involved in their formation by oxidative phosphorylation owing to concentration gradients of the hydrogen ions between the two sides of internal chloroplast membranes, a certain membrane potential develops on account of which the ATP can be synthesized from ADP. Three molecules of ATP are involved in the reaction per molecule of COj. 

For a given pair of electrode reactions of known thermodynamic and kinetic characteristics, electrochemical engineering procedures must provide a reactor design in which these reactions can occur with high material and energy efficiencies. Simultaneously, appropriate provisions have to be made for the input of reactants and outflow of products and for the addition (or removal) of electric and thermal energy. The emphasis here is on the complete system and the inter-related surface reactions and transport processes. System analysis and design of electrochemical reactors require elaborate computer-implemented process simulation, synthesis, and optimization. 

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