"P&P Industries AG is the world’s # 1 in Spent Acid Regeneration (SAR) plants. Our technology enables customers to generate clean air from sulphur-containing waste gases or liquids - practically SO2 emission-free, with a conversion rate greater than 99.999 %".




P&P Industries has improved and optimized the Wet gas Sulphuric Acid (WSA) process.  The result is our Sulphur Oxidation Process (SOP) and Spent Acid Regeneration (SAR) process, which are currently the most effective methods for sulphuric acid treatment and recovery of sulphur from a wide range of process gases in the form of highly concentrated industrially usable sulphuric acid (H2SO4). At the same time, the heat generated is recovered by means of heat exchanger systems and any remaining waste gases are cleaned.

Sulphur Oxidation Process (SOP) plants are used in the industry wherever the cleaning of waste gas from sulphur-containing components (SO2, H2S, CS2, ...) is required. Spent Acid Regeneration (SAR) plants focus on the treatment of already spent sulphuric acid (H2SO4), e.g. in alkylation plants in petroleum refineries. Of course, waste gas desulphurization is also achieved in this case.

Gases, liquids and solid feedstock:

Our process uses all kinds of sulphur-containing gases such as acid gas, sour gas, stripper gas, rectisol gas, gases from amine regeneration units and Claus plants. These contain mainly H2S, CS2 and COS, which are converted to SO2.

The liquids can be molten sulphur, low concentration sulfuric acid, spent sulfuric acid of any concentration, or other sulphur-containing liquids that can be processed in any combination.

We are also able to process solids such as sulphur, sulphates and metal sulphates even with impurities.

Sulphur Oxidation Process (SOP) & Sulphuric Acid Recovery SAR systems are suitable for:

  • Sulphuric acid production
  • Sulphuric acid treatment
  • Viscose Productions
  • Alkylation plants in oil refineries
  • Carbon black production
  • Spent acid - plants
  • H2S Gas from e.g... Amine treatment plants
  • Waste gas from separators (e.g. sour water stripper)
  • Waste gas from Rectisol process
  • Waste gas from Claus processes
  • Waste gases from various processes
  • SNOx flue gas desulfurization
  • Metallurgical process gases
  • Cleaning of waste gases containing SO2


"Our SAR plants are highly energy efficient as a significant part of the available energy of catalytic oxidation, sulfuric acid hydration and condensation can be used for steam generation."


P&P can supply steam for all types of steam networks, whether low, medium or high-pressure steam, or generate electrical energy through steam turbines.

The product is clean waste gas the precious raw material - highly concentrated sulfuric acid (H2SO4) of industrial quality 98% or higher, if necessary.



"P&P will meet your targets by applying a cutting-edge technology based process reaching highest efficiency."


  • Ambient air or lean gas from your process is filtered (e. g. Bag House Filter, Scrubbers, Hg Absorbers) and preheated by passing through a gas-tight P&P glass tube heat exchanger. To save energy consumption a further Heat Transfer Salt System (HTS) increases the temperature up to more than 400 °C.
  • All sulfuric components are oxidized completely to SO2 guaranteed by a long residence time in the combustion chamber.
  • The Process gas containing inorganic impurities is filtered by Hot Gas Filters (HGF). These impurities can be recovered.
  • In the first converter the P&P Platinum-promoted Honeycomb catalyst converts more than 70 % of SO2 with low pressure drop and allows a wide-ranging operation temperature.
  • Cooling of the process gas and hydration of SO3 to H2SO4 in the gas phase by a heat exchanger operating with HTS recovers a large amount of energy.
  • Sulfuric acid is condensed on patented P&P glass tube heat exchanger modules in the first condenser.
  • Acid mist is separated in our WESP and going down by gravity into the condenser as acid condensate.
  • The process gas is preheated by the glass tube heat exchanger in the first condenser and by HTS from the incinerator for the second stage.
  • In the second converter and second condenser already 99,9 % of SO2 is converted to H2SO4.
  • Remaining SO2 is oxidized in the subsequent low temperature carbon catalyst stage (LTCC) before sent to the stack.
  • The total conversion rate of SO2 to H2SO4 is more than 99,999 %.

All these steps enable our customers to achieve the lowest possible emission levels at all times.



“Enjoy the highest possible return on investment!”


An example: a 100,000 t/year (Sulphur Oxidation Process) SOP-plant produces concentrated acid for 20 €/t. The spot market price for sulfuric acid of this grade can, in comparison, be anticipated to be 100 €/t (status Europe 2019). An amortisation period of less than 4 years is feasible if one estimates the value of energy and the sulphuric acid produced.

Less space demand  -  More yield

Less pressure drop  -  More acid

Less energy consumption  -  More profitability

Less emissions  -  More green




"Whatever your target emission level is – P&P will achieve it."

  • P&P was the first company to provide a wet catalytic, double stage process for waste gas treatment.
  • Thermal NOx emissions produced by all combustion process are tackled by well-proven Selective Catalytic Reduction technology (SCR).
  • The combination of P&P’s double stage technology together with its proprietary glass tube heat exchangers and condensers leads to a Sulphur recovery rate of more than 99.9 %.
  • The subsequent cold catalytic step enhances SO2 recovery to above 99.999 %. By applying our cutting-edge technology, emissions can be reduced by more than 90 % compared to our competitors current technology.

“Closing the Circle - protects the environment and delivers economic benefits for you.


P&P SOP plants are offered as complete solution – Full Turn-Key plant or as engineering package with delivery of important key equipment. We are happy to offer you a SOP plant solution tailored to your needs.


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