Olefin manufacturing polyethylene producers

Polymerization. Supported catalysts are used extensively in olefin polymerization, primarily to manufacture polyethylene and polypropylene. Because propylene can polymerize in a stereoregular manner to produce an isotactic, or crystalline, polymer as well as an atactic, or amorphous, polymer and ethylene caimot, there are large differences in the catalysts used to manufacture polyethylene and polypropylene (see Olefin polymers). 

Ethylene glycol is commonly used as antifreeze in automobiles. The feedstock includes pure water and refined ethylene oxide. This system combines a blending feed tank, glycol reactor, and a series of distillation columns. Olefin manufacturing includes three major processes the first converts natural gas to ethylene, propylene, or butane the second produces isobutylene and isoamy-lene from hydrocarbon feedstocks the third converts gas oil feedstocks into high-octane gasoline, distillates, and C2-C5 olefins. Plastics manufacturing employs a number of polymer processes that handle polyethylene, polypropylene, and butyl polymers. 

About 35% of total U.S. LPG consumption is as chemical feedstock for petrochemicals and polymer iatermediates. The manufacture of polyethylene, polypropylene, and poly(vinyl chloride) requires huge volumes of ethylene (qv) and propylene which, ia the United States, are produced by thermal cracking/dehydrogenation of propane, butane, and ethane (see Olefin polymers Vinyl polymers). 

High density polyethylene (HDPE) is defined by ASTM D1248-84 as a product of ethylene polymerisation with a density of 0.940 g/cm or higher. This range includes both homopolymers of ethylene and its copolymers with small amounts of a-olefins. The first commercial processes for HDPE manufacture were developed in the early 1950s and utilised a variety of transition-metal polymerisation catalysts based on molybdenum (1), chromium (2,3), and titanium (4). Commercial production of HDPE was started in 1956 in the United States by Phillips Petroleum Company and in Europe by Hoechst (5). HDPE is one of the largest volume commodity plastics produced in the world, with a worldwide capacity in 1994 of over 14 x 10 t/yr and a 32% share of the total polyethylene production. 

The chemical iadustry manufactures a large variety of semicrystalline ethylene copolymers containing small amounts of a-olefins. These copolymers are produced ia catalytic polymerisation reactions and have densities lower than those of ethylene homopolymers known as high density polyethylene (HDPE). Ethylene copolymers produced ia catalytic polymerisation reactions are usually described as linear ethylene polymers, to distiaguish them from ethylene polymers containing long branches which are produced ia radical polymerisation reactions at high pressures (see Olefin POLYMERS, LOWDENSITY polyethylene). 

Mixed C4 olefins (primarily iC4) are isolated from a mixed C olefin and paraffin stream. Two different liquid adsorption high-purity C olefin processes exist the C4 Olex process for producing isobutylene (iCf ) and the Sorbutene process for producing butene-1. Isobutylene has been used in alcohol synthesis and the production of methyl tert-butyl ether (MTBE) and isooctane, both of which improve octane of gasoHne. Commercial 1-butene is used in the manufacture of both hnear low-density polyethylene (LLDPE) and high-density polyethylene (HDPE)., polypropylene, polybutene, butylene oxide and the C4 solvents secondary butyl alcohol (SBA) and methyl ethyl ketone (MEK). While the C4 Olex process has been commercially demonstrated, the Sorbutene process has only been demonstrated on a pilot scale. 

Random ethylene copolymers with small amounts (4-10 wt-%) of 7-olefins, e.g. 1-butene, 1-hexene, 1-octene and 4-methyl- 1-pentene, are referred to as linear low-density polyethylene, which is a commercially relevant class of polyolefins. Such copolymers are prepared by essentially the same catalysts used for the synthesis of high-density polyethylene [241]. Small amounts of a-olefin units incorporated in an ethylene copolymer have the effect of producing side chains at points where the 7-olefin is inserted into the linear polyethylene backbone. Thus, the copolymerisation produces short alkyl branches, which disrupt the crystallinity of high-density polyethylene and lower the density of the polymer so that it simulates many of the properties of low-density polyethylene manufactured by high-pressure radical polymerisation of ethylene [448] (Figure 2.3). 

Mobil Chemical Company was formed in 1960. In 2000, the principal products included all the basic aromatics and olefins for the petrochemical industry, ethylene glycol and polyethylene. The company produced synthetic lubricating oils, additives, propylene packaging films and catalysts. Manufacturing facilities were located in 10 countries. 

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]. 

Examination of the data in Table 3.11 shows that Cr(I I) complexes 1-7 and 11-13, that are based on the (N,N,N) donor set, produce mostly 1-butene, 2-butene, mixtures of linear 1 -olefins or relatively very low molecular weight polyethylene and waxes. Ihe catalysts that provide 1-butene or mixtures of linear 1-olefins may have important commercial applications for the manufacture of 1-olefins. For example, complexes 11,12 and 13, acted as ethylene oligomerization catalysts producing 1 -butene in 99% purity for complex 11 and mixtures of linear 1 -olefins for complexes 12 and 13. 

Chromium-based catalysts that polymerize ethylene while simultaneously producing a 1-olefin such as 1-hexene, provide a method of preparing polyethylene homopolymers that contain short-chain branching without adding a 1 -olefin directly to the manufacturing process. 

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