Compact Flow-Through Electrochemical Cell - A Novel Perspective in Industrial Manufacture of Perchlorates

Abstract

Sodium Perchlorate is one of the major starting intermediate product for the manufacture of various Perchlorates viz, Ammonium perchlorate as solid oxidizer and Strontium Perchlorate as Secondary Injection Thrust Vector Control (SITVC) in launch vehicles. This critical product is manufactured industrially by electrochemical oxidation of Sodium Chlorate solution at the anodic surface. Lead dioxide is preferred in various perchlorate cells because of its low cost. Infrequent detachment of Lead dioxide deposits from the substrate during electrolysis is a grave issue confronted by associated electrochemists in bulk manufacture of chemicals. Moreover, a cheaper alternative for continuous manufacture of Sodium Perchlorate using Lead dioxide electrodes has been an onus among various industrial electrochemists. Development of a suitable compact flow through electrochemical cell using superfluous or detached Lead dioxide crystals as ‘particle’ electrodes is the major objective of this paper. This compact bed electrochemical cell, is extraordinarily helpful when confronting with lesser reactant concentration or time consuming reactions. Besides, this proposal adds on flexibility in trimming the size of cells when compared with bulky design of conventional cells. Another objective was to demonstrate continuous electrosynthesis of Sodium perchlorate using Lead dioxide without resorting to expensive Platinum. A suitable single bed and a dual bed compact electrochemical cell was made using HDPE body, perforated Poly Propylene distributor, detached Lead dioxide particles, nylon mesh, etc. Four such dual bed cells were made for final demonstration for continuous electro synthesis application. From various experimental trials, an optimum values for temperature, flow rate and current load were determined as 600°C, 800 mL/min and 80 A respectively, in single bed system. Inorder to avoid current penetration issue, dual bed cells were employed. Subsequently, critical operational strategy and systematic configuration for arrangement of dual bed cells were made for demonstrating continuous bed electrochemical cells. An average current efficiency of about 78.5% could be achieved which is 20-25 % higher than conventional parallel plate electrode system.