Guelph Chemical Labs

A nonelectrolytic process for the production of sodium hydroxide and hydrochloric acid from sodium chloride is explored. This environmentally friendly process, in which production of chlorine and the use of hazardous mercury are eliminated, is based on the following principle. A thermally stable cation exchanger such as ZSM-5 zeolite in its H-form undergoes a cation-exchange reaction with a sodium chloride solution to liberate hydrochloric acid, and the resulting NaZSM-5 zeolite undergoes a cation-exchange reaction with a ammonium hydroxide solution to liberate sodium hydroxide. The ammonium ion-exchanged zeolite is converted into its H-form by deammoniation in the temperature range of 400−500 °C. The liberated ammonia is trapped in water to form ammonium hydroxide for reuse.