Phillips Petroleum oxide catalyst

Preparations based on molybdenum oxide are called Standard Oil Co. catalysts, while those based on chromium oxide are known as the Phillips Petroleum Co. catalysts. Below is a description of a preparation of a molybdenum-based catalyst. Alumina is saturated with a solution of anunonium molybdate and then subjected to heating in air at 500 to 600 °C. The oxide that forms is reduced with hydrogen at 430 to 480 °C. Reducing agents like CO, SO, or hydrocarbons are also used. Hydrogen, however, is preferred at pressures of approximately 75 psi. The catalyst may contain between 5 and 25% of the molybdenum compound dispersed on the surface. " ... 

Second, in the early 1950s, Hogan and Bank at Phillips Petroleum Company, discovered (3,4) that ethylene could be catalyticaHy polymerized into a sohd plastic under more moderate conditions at a pressure of 3—4 MPa (435—580 psi) and temperature of 70—100°C, with a catalyst containing chromium oxide supported on siUca (Phillips catalysts). PE resins prepared with these catalysts are linear, highly crystalline polymers of a much higher density of 0.960—0.970 g/cnr (as opposed to 0.920—0.930 g/cnf for LDPE). These resins, or HDPE, are currentiy produced on a large scale, (see Olefin polymers, HIGH DENSITY POLYETHYLENE). 

Chromium Oxide-Based Catalysts. Chromium oxide-based catalysts were originally developed by Phillips Petroleum Company for the manufacture of HDPE resins subsequendy, they have been modified for ethylene—a-olefin copolymerisation reactions (10). These catalysts use a mixed sihca—titania support containing from 2 to 20 wt % of Ti. After the deposition of chromium species onto the support, the catalyst is first oxidised by an oxygen—air mixture and then reduced at increased temperatures with carbon monoxide. The catalyst systems used for ethylene copolymerisation consist of sohd catalysts and co-catalysts, ie, triaLkylboron or trialkyl aluminum compounds. Ethylene—a-olefin copolymers produced with these catalysts have very broad molecular weight distributions, characterised by M.Jin the 12—35 and MER in the 80—200 range. 

O-X-D [Oxidative dehydrogenation] A process for converting n-butane to butadiene by selective atmospheric oxidation over a catalyst. Developed by the Phillips Petroleum Company and used by that company in Texas from 1971 to 1976. See also Oxo-D. 

Phillips (1) A process for polymerizing ethylene and other linear olefins and di-olefins to make linear polymers. This is a liquid-phase process, operated in a hydrocarbon solvent at an intermediate pressure, using a heterogeneous oxide catalyst such as chromia on silica/ alumina. Developed in the 1950s by the Phillips Petroleum Company, Bartlesville, OK, and first commercialized at its plant in Pasadena, TX. In 1991, 77 reaction fines were either operating or under construction worldwide, accounting for 34 percent of worldwide capacity for linear polyethylene. 

It is now clear that, when propagation centers are formed, olefin polymerization by all solid catalysts (including the Phillips Petroleum catalyst from chromium deposited on oxides, and the Standard Oil catalyst of molybdenum oxide on aluminum oxide) essentially follows the same mechanism chain growth through monomer insertion into the transition-metal-carbon bond, with precoordination of the monomer. Interestingly,... 

A supported catalyst for ethylene polymerization which requires no alkyl aluminum for activation was first claimed by the Phillips Petroleum Company (32). It consists of chromium oxide on silica, reduced with hydrogen. Krauss and Stach (93) showed that the active sites are Cr(II) centers. The presence of solvent, or even aluminum alkyls, diminishes... 

The most active catalyst is chromium oxide [7]. Silica (Si02) or aluminosilicates (mixed Si02/Al203) are used as the support material. The support is sometimes modified with titania (Ti02). The chromium oxide (Cr Os) catalyst was originally developed by Phillips Petroleum Company and is referred to as Phillips catalyst. Other metal oxide catalysts were developed primarily at Standard Oil of Indiana, the best known among them being the molybdenum oxide (Mo Os) catalyst. 

High-density polyethylenes are formed from metal oxide initiation. These poly-ethylenes are stiffer, with much less branching. HDPE is used more in automotive applications due to this property. Phillips Petroleum uses a chromic oxide catalyst and Standard Oil of Indiana has developed a molybdenum oxide catalyst [5], These catalysts are not flammable, which presents an advantage over Ziegler-Natta. 

Commercial linear polyethylene, the most commonly used type of plastic, was bom more than half a century ago with the accidental discovery at Phillips Petroleum Company that chromium oxide supported on silica can polymerize a-olefins.1 The same catalyst system, modified and evolved, is used even today by dozens of companies throughout the world, and it accounts for a large share of the world s high-density polyethylene (HDPE) supply, as well as some low-density polymers. The catalyst is now more active and has been tailored in numerous ways for many specialized modem applications. This chapter provides a review of our understanding of the complex chemistry associated with this catalyst system, and it also provides examples of how the chemistry has been exploited commercially. It is written from an industrial perspective, drawing especially on the commercial experience and the research of numerous scientists working at Phillips Petroleum... 

Developed jointly by Phillips Petroleum and Rhone-Poulenc (PRP), this is a modification of the Henkel 2 process, using benzoic add instead of sulfuric add to liberate the potassium terephthalate from its salt It conducts the disproportionation reaction of potassium benzoate in suspension in an organic dispersant, consisting of a mixture of terphenyls, in the presence of zinc oxide as catalyst The three steps of the process are illustrated below ... 

Phillips Petroleum [28] describe a two step trickle column reactor process via succinic anhydride (SAN). The preferred catalyst for the first step is a 0.6% Pd, 25% cobalt-oxide on silica catalyst operating at 120°C and 900-1500 psig. The more demanding second step uses a 4% nickel, 2.5% nickel as nickel oxide on silica catalyst operating at 220°C and 900-1500 psig. The reaction is very exothermic and the best result quoted in the patent is a 93.2% conversion of SAN with a 91% selectivity to GBL. 

Low-pressure Processes. Three processes for the polymerization of ethylene have recently been developed. The commercial process of the Phillips Petroleum Company for the polymerization of ethylene is carried out at relatively low pressures (100-500 psi) in either fixed-bed or slurry-type operations. The catalyst consists of 2-3 weight per cent chromium as oxide on silica alumina, and the reaction temperature varies from 90— 180°C. In fixed-bed operation, purified ethylene and hydrocarbon solvent streams are passed downflow, liquid phase over the catalsrst bpd. Solvent and polymer are collected, and the solvent is flashed overhead. Unreacted gases are removed from the solvent, taken overhead, and metered the solvent is recycled to the reactor. The solvent and polymer in the first receiver are cooled to room temperature to precipitate the polymer, which is then filtered and dried in a vacuum oven. In the slurry-type operation (indicated in Fig. 15-33 by a proposed flow diagram), solvent and a small... 

Other kinds of coordination catalytic systems developed few years before the Ziegler-Natta catalysts were based on chromium and molybdenum oxides supported on SiOj AI2O3 and other supports. The catalysts were patented by Phillips Petroleum and Standard Oil companies of Indiana for the synthesis of polyolefins. Although Phillips catalysts were the first to produce a fraction of crystalline polypropylene, these systems were more useful for the production of polyethylene. In fact, the Phillips and the Ziegler-Natta catalysts are currently the two commercial systems that dominate the production of HDPE [2]. 

The Phillips-type catalyst, first reported by Hogan in the early 1950s at the Phillips Petroleum Co., is defined as chromium oxide (Cr03) supported on activated mixtures of silica and alumina particles with a ratio Si/Al = 87 13. Usually, the support particles have high surface area around... 

Characterization of in situ and ex situ synthesized catalysts on a silica support confirms the presence of tin oxides and tin hydroxyl species [80]. In the same report, the authors determined that a 1 2 Pd Sn stoichiometry is optimal and implicated PdSn2 particles as being important for effective catalysis. It was proposed that in situ catalyst formation is a two-step process that involves the formation of a Pd Sn 2(OAc)g complex followed by the decomposition of this complex to give oxygenated PdSn2 clusters. Other Pd-based catalysts have also been developed. The addition of Bi [71,81], persulfate/Sn (Phillips Petroleum Co.) [82], Sn/Sb (BP) [83], and ultrafine Au [84] have been shown to be beneficial. 

Chromium oxide-based catalysts from Phillips Petroleum Co. these are mixed silica titania support containing 2-20 wt% of titania and a co-catalyst (i.e., trialkylaluminum compounds). These catalysts produce LLDPEs of very broad MWD (M v/Mp in the range of 12-35) and MI in the 80-200 range... 

The loop reactors, which are recycled tubular reactors, are used by the Phillips Petroleum Co. and Solvay et Cie. The Phillips process is characterized by the use of a light hydrocarbon diluent such as isopentane or isobutane in loop reactors which consist of four jacketed vertical pipes. Figure 1 shows the schematic flow diagram for the loop reactor polyethylene process. The use of high-activity supported chromium oxide catalyst eliminates the need to deash the product. This reactor is operated at about 35 atm and 85-110° C with an average polymer residence time of 1.5 hr. Solid concentrations in the reactor and effluent are reported as 18 and 50 wt %, respectively. The reactor diameter is 30 in. (O.D.) and the length of the reactor loop is about 450 ft. 

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. 

Although little is known about the actual mechanism of action of these catalysts, they are industrially utilized to produce high-density polyethylene (HOPE) in significant quantity. Phillips catalysts (so called because they were patented by Phillips Petroleum Cy) consisted of chromium oxide (CrOa) deposited onto a silica support the system is activated by air-drying and by a progressive heating... 

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