Petrochemical applications, ethylene plants

Olefin/paraffin selectivities of 5 to 10 appear quite modest compared to the claims of some reports [32, 33]. However, much of the literature selectivity data has been calculated from the ratio of the permeabilities of pure olefin to pure paraffin. Olefin/paraffin selectivities measured with gas mixtures under conditions likely in a real process show that using pure gas permeabilities overestimates the membrane selectivity by a factor of 2 to 10. Therefore, it will be some time before olefin/paraffin-selective membranes are used in ethylene plants, although some nearer-term applications exist in petrochemical and refinery operations. 

For example, as the result of a great effort in Europe in the fifties, there was a switch from coal to oil as the feedstock. Only the petrochemical industry was able to supply the increasingly large amounts of raw materials for plastics. This is particularly true of benzene and ethylene, the two starting materials for styrene monomer and polystyrene. Ever-growing capacities and plants supplied these chemicals up to 1973 at ever lower prices which brought down the price of polystyrene and opened up further fields of applications. 

As can be deduced from plant purchases, the PRC is still at the formative stage where emphasis is on producing only the most basic petrochemicals. No plants were purchased for producing dibasic acids (phthalic and maleic anhydrides, etc.) and fluro-carbon or tetrafluoro ethylene or some of the advanced engineering plastics like ABS polyacetals, polycarbonates, polyimides or any other unsaturated polyesters. Another important area of low Chinese activity is thermoplastics for space and defense applications. ... 

The chemical uses for ethylene prior to World War II were limited, for the most part, to ethylene glycol and ethyl alcohol. After the war, the demand for styrene and polyethylene took off, stimulating ethylene production and olefin plant construction. Todays list of chemical applications for ethylene reads like the WTiat s What of petrochemicals polyethylene, ethylbenzene (a precursor to styrene), ethylene dichloride, vinyl chloride, ethylene oxide, ethylene glycol, ethyl alcohol, vinyl acetate, alpha olefins, and linear alcohols are some of the more commercial derivatives of ethylene. The consumer products derived from these chemicals are found everywhere, from soap to construction materials to plastic products to synthetic motor oils. 

Ethylbenzene is a high volume petrochemical used as the feed stock for the production of styrene via dehydrogenation. Ethylbenzene is currently made by ethylene alkylation of benzene and can be purified to 99.9%. Ethylbenzene and styrene plants are usually built in a single location. There is very little merchant sale of ethylbenzene, and styrene production is about 30x10 t/year. For selective adsorption to be economically competitive on this scale, streams with sufficiently high concentration and volume of ethylbenzene would be required. Hence, although technology has been available for ethylbenzene extraction from mixed xylenes, potential commercial opportunities are limited to niche applications. 

The petrochemical plant and refinery integration schemes offer lower cost routes to incremental ethylene/propylene production either via revamp modifications or in grassroots application [5,6],... 

Commodities are large-volume, low-price, homogeneous, and standardized chemicals produced in dedicated plants and used for a large variety of applications. Prices are cyclic and fully transparent. Petrochemicals, basic chemicals, heavy organic and inorganic chemicals (large-volume) monomers, commodity fibers, and plastics are all part of commodities. Typical examples of single products are ethylene, propylene, caprolactame, methanol, BTX (benzene, toluene, xylenes), phthalic anhydride, poly (vinyl chloride) soda, and sulfuric acid. 

Petrochemical plants, especially olefins plants that can manufacture numerous products in different proportions from the same feedstock, have had probably the greatest success at delivering value from sophisticated online plant-wide models Cutler and Perry, 1983 Rejowski et al., 2009 Paules and Meixell, 1994 Fatora and Ayala, 1992 Fatora et al., 1992a Fatora et al., 1992 Houk et al., 1992 Kelly et al., 1991. Over 50 ethylene RTO applications have been deployed, as well as several others on nonolefin petrochemical processes. 

The latest industrial application of metathesis was developed by Phillips who started up a plant in late 1985 at Cbannelview, Texas, on the L ondell Petrochemical Complex with a production capacity of 135,000 t/year of propylene from ethylene. This facility carries out the disproportionation of ethylene and 2-butenes, in the vapor phase, around 300 to 350°C, at about 0.5.10 Pa absolute, with a VHSV of 50 to 200 and a once-througb conversion of about 15 per cent 2-butenes are themselves obtained by the dimerization of ethylene in a homogeneous phase, which may be followed by a hydroisomerization step to convert the 1-butene formed (see Sections 13.3.2. A and B). IFP is also developing a liquid phase process in this area. 

PCL -OCH CH CH CH CH CO-ln) is a partially-crystalline polyester that is biodegraded by microbial lipases and esterases. The plastic is made from petrochemical feedstocks. It has too low a melting point (60°C) to be useful in any packaging applications. Higher aliphatic polyesters such as poly(butylene succinate) (PBS) (-0(CH2) OC(CH2)2CO-)n and poly(ethylene succinate) (PES) (-OCCH l OOCCCH l CO-) are also biodegradable at a rate that depends on environmental factors (Kasuya et al., 1997). They have higher melting points of 112-114°C and 103-106°C, respectively, and the properties compare well to those of polyolefins. As succinic acid can be derived from plant sources, the polysuccinates can be potentially a bio-based polymer. 

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