Phillips process discovery

In the mid-1950s a number of new thermoplastics with some very valuable properties beeame available. High-density polyethylenes produced by the Phillips process and the Ziegler process were marketed and these were shortly followed by the discovery and rapid exploitation of polypropylene. These polyolefins soon became large tonnage thermoplastics. Somewhat more specialised materials were the acetal resins, first introduced by Du Pont, and the polycarbonates, developed simultaneously but independently in the United States and Germany. Further developments in high-impact polystyrenes led to the development of ABS polymers. 

Since its discovery in 1956, the Phillips process [5] was an object of research in many parts of the world. Our own activity started in 1965 with redox studies [6]. These lead us to the discovery of coordinatively unsaturated chromium(ll) as a substantial constituent of the surface chromium in active catalysts [7, 8]. 

At about the same time that news of the Ziegler discovery was released, the Phillips Petroleum Company in the United States atmounced that it had developed a medium-pressure, catalytic process (500 psig) to produce a high-density, crystalline polyethylene. The process was discovered when traces of ethylene in a flue gas had polymerized over conventional cracking catalysts. The Phillips catalyst contained chromic oxide supported on silica. The Standard Oil Company of Indiana (later Amoco) also introduced a medium pressure process using a catalyst comprising molybdenum oxide supported on carbon or alumina, but it did not enjoy the success of the Ziegler or Phillips processes and was only operated in three full-scale plants. ... 

As it happens, little attention was paid to Phillips discovery because there was not much demand for sulfuric acid at the time. It was not until the invention of synthetic dyes a few decades later that the compound became commercially important. But even then, the lead chamber process was the preferred method for making sulfuric acid. Over time, improvements were made in the contact process, and it gradually became more and more popular. Today, nearly all of the sulfuric acid produced is manufactured by some modification of Peregrine Phillips method. 

These Phillips discoveries were commercialized rapidly and remain a major process today, in more advanced forms the PhiUips supported chromium catalyst is used to produce some 40-50 % of the world s HOPE. The first plants were brought on stream in 1955 and 1956. However, Phillips management concluded that no one manufacturer could develop the full market potential of the Phillips HOPE and therefore decided to license the process. By 1956, nine companies in seven countries had become licensees. 

As we saw previously, polypropylene was first made in June 1951, unintentionally as a solid polymer, by Phillips Petroleum, who were at that time seeking to convert excess refinery gases, ethylene and propylene, to high-octane fuel. Phillips developed their chromium olefin polymerization catalyst for linear polyethylene, but in fact, Phillips never entered the polypropylene manufacturing business. Paul Hogan and Robert Banks recorded the invention of the process by which they produced crystalline polypropylene about an hour after their discovery. As we shall see in more detail below, their January 1953 patent application was issued in March 1983 (32 years after their discovery) [11]. 

The high-pressure process relied on large and complex plants that required careful process control. Therefore, the discovery in 1953 of the appropriate catalysts that allowed the process to be carried under low pressure ( 500 psi) was welcomed by the industry [7]. Three types of catalysts were developed about that time the Ziegler-type catalysts typically obtained by reacting alkyl aluminum compounds with titanium chloride metal oxide catalyst systems, developed by Phillips Petroleum in the United States, typically made of chromium oxide supported on a silicaceous carrier [8]) and a different type of oxide catalyst developed by Standard Oil Company. The first plants based on the Ziegler catalyst went on line in Germany by 1955 and a plant based on the Phillips catalyst in Texas opened in 1957. The third catalyst system developed much slower and was picked up by the Japanese plastics industry in a plant opened in 1961. 

The Wacker oxidation was discovered by Smidt and co-workers at Consortium fiir Electrochemie (a subsidiary of Wacker Chemie and Farbwerken Bayer). It is actually a combination of known reactions and thus not a catalytic reaction in the strictest sense (Scheme 1). The first and most basic reaction, the oxidation of ethene in aqueous solution was first discovered by Phillips in 9AP The precipitation of palladium metal from a palladium(II) chloride solution was used as a test for olefins. However, it was the discovery by Smidt and co-workers that the Pd(0) formed could be regenerated by cupric chloride that made the reaction a commercial success. The final step, the oxidation of CuCl to CuCl2 is one of the fastest reactions in inorganic chemistry, The three reactions add up to the simple air oxidation of ethene to ethanal. At one point over two billion pounds a year of ethanal was produced by the Wacker process. Presently, the Monsanto acetic acid process has largely replaced the Wacker procednre.t" ... 

The Nobel Prize in Chemistry was awarded to Karl Ziegler and Giulio Natta in 1963 for their research in developing olefin polymerization catalysts primarily based on titanium compounds and aluminum alkyl compounds required for the catalyst initiation process. However, by 1963 the details on the discovery of the Cr-based catalyst system in which the chromium compound was supported on amorphous silica were widely published and commercially important for the manufacture of HDPE. In the view of this author, the 1963 Nobel Prize awarded in chemistry should also have included two additional scientists, John P. Hogan and Robert L. Banks from Phillips Petroleum. 

For example, prior to the discovery of this new single-site catalyst type, commercial grades of polyethylene were primarily manufactured over the compositional range of 0-4 mol% of comonomer (1-butene, 1-hexene or 1 -octene) that provided ethylene copolymers over the density range of 0.915-0.970 g/cc. Commercial catalysts were primarily the Cr-based Phillips-type of catalyst or a Ti-based Ziegler catalyst with the xmderstand-ing that both types of catalyst consisted of many different types of active sites. Each type of active site produced a different composition of polyethylene (different molecular weight and branching content) which resulted in a final polyethylene material with a complex molecular structure. These multi-site catalysts limited the composition of the polyethylene that was commercially available due to both process and product constraints imposed by such catalysts. 

Poly(p-phenylene sulfide), PPS, is produced by the coupling reaction(53) illustrated in Figure I. This process is practiced commerically by Phillips Petroleum Company (X=C1). PPS is a thermally processible, high molecular weight thermoplastic. The discovery of conducting compositions derived from PPS(I3,I4) was... 

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