In the HPPO process hydrogen peroxide (H₂O₂) is used as the oxidizing agent to oxidize propylene to propylene oxide (PO) with only water as a byproduct. The catalyst system utilized is based on a specifically developed and custom tailored titanium silicalite-1 (TS-1) from Evonik. The HPPO technology provides the following advantages:

• Co-product free
• Optimized raw material usage through the use of a specially developed catalyst from Evonik
• Lower investment costs
• Efficient raw material consumption

The characteristics of the process are outstanding; it is more environmentally friendly than other competing technologies and does not produce any significant co-products besides water. Additionally the HPPO process comes with a considerably lower investment volume resulting in higher profitability than with a conventional production process for propylene oxide.

Propylene oxide is mainly used to produce polyurethane precursors, an attractive market which will grow outpaced GDP benefiting from several mega trends such as resource efficiency and globalization. It is used predominantly to make the polyurethane intermediates that are used in the manufacture of products such as upholstery for car seats and furniture or insulation material for the construction and refrigeration industry. 

The world's first industrial-scale HPPO plant, licensed jointly by Evonik Industries and ThyssenKrupp Industrial Solutions, was built by SKC in Ulsan, South Korea, it has been in successful operation since 2008, starting back then with an annual output of 100,000 metric tons of propylene oxide. The capacity of this first of its kind HPPO plant was even already increased to 130,000 metric tons of propylene oxide per year. 

SKC uses the capacity for further processing downstream and supplies as well the propylene oxide produced by the innovative HPPO process to the markets of Korea and its neighboring countries. H₂O₂ in Ulsan is directly "over the fence" delivered to the HPPO plant.

The first ever world-scale HPPO cooperation in China with 300,000 metric tons of propylene oxide by Jishen Chemical Industry Co. Ltd. is using as well the process of Evonik Industries and ThyssenKrupp Industrial Solutions and is the second of its kind. Evonik supplies its H₂O₂ directly to the adjacent propylene oxide plant run by Jishen via a pipeline that will link the two facilities. 

The new production plant has an annual capacity of 230,000 metric tons. Evonik Industries has invested over one hundred million euros in the site. To date, hydrogen peroxide has been used mainly as a bleaching agent by the textile and pulp industry. The HPPO process allows this eco-friendly oxidant to also be employed in the direct chemical synthesis of propylene oxide.

HPPO is the technology of choice for either setting up new PO capacity or replacing the PO capacity based on old pollutive chlorohydrin process. Hungarian MOL Group and Chinese Zibo Qixiang Tengda Chemical are two further examples, who are currently building up HPPO capacities, 200kta in Tiszaújváros, Hungary and 300kta in Zibo, China respectively, with Evonik/tkIS technology.