Grades ethylene

Redistil laboratory grade ethylene glycol under reduced pressure and collect the fraction of b.p. 85-90°/7 mm. for use as a solvent for the potassium fluoride. 

Tetrafluoroethylene of purity suitable for granular or dispersion polymerizations is acceptable for copolymerization with ethylene. Polymerization-grade ethylene is suitable for copolymerization with tetrafluoroethylene. Modifying termonomers, eg, perfluorobutylethylene and perfluoropropylene, are incorporated by free-radical polymerization. 

CP grade ethylene (Matheson) was used without purification. A flow of ca. 100 raL/min of ethylene for 2-3 hr is adequate for saturation. Gas flow is continued throughout the irradiation in order to maintain a high concentration of ethylene and for stirring. 

Laboratory-grade ethylene glycol is redistilled under diminished pressure, and the fraction boiling at 85-90°/7 mm. is used as the solvent for the potassium fluoride. 

Polymer fume fever, 18 304 Polymer gasoline, 4 423 propylene in, 20 782-783 Polymer gels, smart, 22 718 Polymer-grade ethylene, specification for, 10 624t... 

In Figure 23—6, polymer grade ethylene and any comonomers are blown into the-base of a fluidized bed reacton A very reactive catalyst (based on-titanium and magnesium chlorides) is injected and admixes with the ethylene. Polymerization takes place at 150-212 F and 300 psi, and polymer particles stay in the fluidized state as the ethylene swirls through the reactor. Since the temperature is controlled at or below the melting point, the particles form a white powder. 

Technical grade ethylene glycol such as that sold by Union Carbide Corp. is suitable for this purpose. 

A simplified flow sheet of the industrial process is shown in Fig. 5.1-1. In the first section fresh ethylene is mixed with the low-pressure recycle at 5 MPa and is compressed to 15 -35 MPa by means of a five-stage piston compressor. Fresh ethylene should have a high purity of above 99.9 vol.%. Further specifications of polymerization-grade ethylene are given in Table 5.1-1. 

The costs assume the production of pellets on 1997 German prices. Polymerization-grade ethylene is available at 5 MPa. The on-stream time is 8,000 h/a. The tubular reactors equipped with multiple feeds of ethylene and peroxide initiators are operated at 200 MPa. The initiators are a mix of dicyclohexyl peroxy dicarbonate, /-butylperoxy pivalate, /-butylperoxy 2-ethylhexanoate, and di(/-butyl)peroxide, which is fed in after the heating zone and at two further locations downstream. 

Between 1976 and 1996 the average price of polymer-grade ethylene was about 500 US per ton. As shown in Figure 8.2-5, top, the global price of ethylene varies greatly. During this period, a first maximum of about 750 US /t was observed in Western Europe in 1980. The ethylene feedstock prices increased to 900 US /t in 1991. A minimum of 300 US /t in 1976, followed by two further minima of 350 and 400 US /t in 1986 and 1994, were reported [2]. 

The first commercial application of olefin disproportionation was in 1966 87) Shawinigan Chemicals Ltd. at the Varennes complex near Montreal, Quebec brought onstream the Phillips Triolefin Process88) for converting propylene into polymerization-grade ethylene and high-purity butenes. Pilot plant development, reported by Johnson 89), showed that during a 20-hour test propylene conversion remained nearly constant at 43 per cent and efficiency of converted propylene to ethylene and n-butenes increased from 93 to 99 per cent. 

CP grade ethylene (Matheson) was used without purification. A flow... 

Completeness and Color of Solution A solution of 5 g of sample in 50 mL of water is colorless. It is clear for liquid grades and not more than slightly hazy for solid grades. Ethylene Glycol and Diethylene Glycol... 

Description Polymer-grade ethylene is oligomerized in the liquid-phase reactor (1) with a catalyst/solvent system designed for high activity and selectivity. Liquid effluent and spent catalyst are then separated (2) the liquid is distilled (3) for recycling unreacted ethylene to the reactor, then fractionated (4) into high-purity alpha-olefins. Spent catalyst is treated to remove volatile hydrocarbons and recovered. The table below illustrates the superior purities attainable (wt%) with the Alpha-Select process ... 

Commercial plants Three commercial plants are in operation in Argentina and Canada with capacities from 140,000 to 816,000 mtpy. They process ethylene feedstocks with purities ranging from 75% ethylene to polymer-grade ethylene. An 850,000-mtpy unit using dilute ethylene is currently under construction. 

Application To produce polymer-grade ethylene (99.95 vol%). Major byproducts are propylene (chemical or polymer-grade), a butadiene-rich C4 stream, C6 to C8 aromatics-rich pyrolysis gasoline and high-purity hydrogen. 

Acetylene in the deethanizer overhead is hydrogenated (10) or recovered. The ethylene-ethane stream is fractionated (11) and polymer-grade ethylene is recovered. Ethane leaving the bottom of the ethylene fractionator is recycled and cracked to extinction. 

Cracked gases are cooled and fractionated to remove fuel oil and water (2-5) then compressed (6), processed for acid-gas removal (8) and dried (9). The C3 and lighter material is separated as an overhead product in the depropanizer (10) and acetylene is hydrogenated in the acetylene converter (11). The acetylene converter effluent is processed in the demethanizer system (12-14) to separate the fuel gas and hydrogen products. The demethanizer bottoms is sent to the deethanizer (15) from which the overhead flows to the C2-splitter (16), which produces the polymer-grade ethylene product and the ethane stream, which is typically recycled to the furnaces as a feedstock. The deethanizer bottoms flows to the C3-splitter (18) where the polymer-grade propylene is recovered... 

Application To produce polymer-grade ethylene and propylene by thermal cracking of hydrocarbon fractions—from ethane through naphtha up to hydrocracker residue. Byproducts are a butadiene-rich C4 stream, a Cg— Cg gasoline stream rich in aromatics and fuel oil. 

The heavier C2 stream is deethanized (7) and C2 overhead passes to the MP ethylene-ethane fractionator (9) integrated with C2 refrigeration system. The lighter C2 stream is routed directly to the ethylene-ethane fractionator (9). Polymer-grade ethylene product is sent overhead from the ethylene-ethane fractionator. Acetylene recovery may optionally be installed upstream of the ethylene-ethane fractionator (8). 

Application To produce polymer-grade ethylene and propylene, a butadiene-rich C4 cut, an aromatic C6-C8 rich raw pyrolysis gasoline, and a high-purity hydrogen by steam pyrolysis of hydrocarbons ranging from ethane to vacuum gas oils. 

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