Hydrochloric Acid Solutions

At a glance

Chlorine is used as an oxidizing agent in several organic processes and hydrogen chloride is often generated as a by-product or co-product. The recovery of chlorine from hydrogen chloride or hydrochloric acid has several advantages:


  • General commitment in terms of sustainability, careful use of resources and therefore ecological responsibility.
  • Business is made independent from chlorine and hydrochloric acid prices.
  • Avoids the need to develop traditional chlor-alkali plants with significantly higher investment costs.
  • Interesting for regions with high chlorine demand or excess caustic soda (NaOH); use of a chlor-alkali plant would not be expedient due to further NaOH production in saturated markets.
  • Eliminates the risks of chlorine transports (as a further alternative).
  • No costs related to hydrochloric acid neutralization or disposal.

Membrane electrolyzer technology using oxygen-depolarized cathode (ODC)

The ODC (oxygen-depolarized cathode) process cuts energy consumption by about 30% compared with conventional processes. This reduces the indirect carbon dioxide emissions involved in production, accordingly. The ODC process does not produce hydrogen.

Diaphragm electrolyzer technology

Our diaphragm technology produces chlorine gas on the anode side and hydrogen on the cathode side – the ideal choice if you also need hydrogen. The process was developed jointly by the former Hoechst AG and Bayer AG as well as thyssenkrupp nucera. The collaboration between Covestro and thyssenkrupp nucera continues today.

Areas of application

Toluene diisocyanate plants (TDI)

TDI is used, amongst others, for the production of flexible foam or for manufacturing coatings and adhesives. In addition, TDI material helps make car parts lighter, improving vehicle fuel efficiency and thus saving energy.

Methylene diphenyl diisocyanate plants (MDI)

MDI is used for the production of polyurethane materials, amongst others, for manufacturing rigid polyurethane foams, e.g. for home and refrigerator insulation. It can also be used for producing coatings or adhesives.

Recycling of HCI from other sources

HCl recycling can be implemented in many production processes, including fumed silica production, PVC production, chlorination of PVC, fertilizer production (e.g. potassium sulfate), metal pickling, to name but a few.

Execution concepts

Compact cell-house design 

This largely standardized design is optimized to deliver low total investment costs, minimize space requirements and ensure easy maintenance. 

Services at a glance

  • Feasibility studies / technology selection 
  • Project management 
  • Arrangement of financing schemes 
  • Financial Guidance based on an intimate knowledge of local laws, regulations and tax procedures 
  • Environmental studies 
  • Licensing, incl. basic / detail engineering 
  • Utilities / offsites / infrastructure 
  • Procurement / inspection / transportation services 
  • Civil works and erection 
  • Commissioning 
  • Training of operating personnel 
  • Plant operation support / plant maintenance 
  • Full service 
  • Long-term partnership 
  • Spare parts supply & management 
  • Upgrade and retrofit 
  • Revamps 
  • Digital plant monitoring and optimization (web-based evaluator and remote condition monitoring) 
  • Consulting 
  • Service center & field services 
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