Chromium/organoaluminum catalysts

Pyrrolyl-Based Chromium/Organoaluminum Catalysts New Insight into the Phillips Ethylene Trimerization Catalysf ... 

In 1951, Robert Banks and J. Paul Hogan at Phillips Petroleum discovered a chromium trioxide-based catalyst, which was a landmark breakthrough in the commercial production of PE at mild temperature and pressure. In 1953, the German chemist Karl Ziegler, who shared the Nobel Prize for Chemistry in 1963 with Italian chemist Giulio Natta, developed a catalytic system based on titanium halides and organoaluminum compounds that worked at even milder conditions than the Phillips catalyst. The Phillips catalyst is less expensive and easier to work with, however, and both methods are widely used industrially. 

---