Entwicklung von Schutzschichten mit erweiterten katalytischen Eigenschaften und verbesserter Lebensdauer

Crackers are utilized to convert the hydrocarbon feedstock with the aid of water vapor into higher-value products such as ethylene or propylene, which are preliminary products for plastics, paints, solvents, pesticides, and many other things. As a side product, coke is formed, which deposits on the inner wall of the tubular coils, affecting the cracker process negatively. Major drawbacks are the diminished heat transfer from the furnace to the reactor due to the highly insulating coke layer and the reduced cross-sectional area of the tubular reactor. The former leads to an increased furnace temperature and, thus, to reduced coil life time. The latter results in a high pressure drop over the reactor and therefore to a change in product selectivity. Hence, coke formation has a significant impact on the energy efficiency and profitability of the steam cracking process.

A good amount of research has been conducted in recent years to reduce coke formation. The main focus has been on coatings, which can be distinguished in barrier coatings -passivating the inner coil wall - and catalytic coatings - converting coke to carbon oxides. All coatings have in common that they prevent the formation of catalytic coke by passivating the catalytically-active sites of the metallic reactor alloy. However, the formation of pyrolytic coke, which is formed non-catalytically, is thereby not impeded. Catalytic coatings gasify the deposited coke forming carbon dioxide.

For this purpose, catalytic coatings reveal a promising opportunity to prolong the cracking process to a longer run length, making the process greener and more cost-effective.

The aim of the current project is to develop coatings with advanced catalytic properties and improved life-time.