From
Oil Ch c.
al
E. MORRELL, Esso Research
and Engineering Corp., Linden, N. J.
A horizon:
TREND looms on the T h e petrochemicals industry is now exerting a profound impact on basic chemical technolog), This impact is being felt through the mechanism of development of important types of processes for converting crude oil and natural gases to petrochemical building blocksthe hydrocarbon intermediates. SIGNIFICANT
Cracking
O n e of the most important of these conversion processes is cracking. Cracking of natural gas or crude oil fractions is the backbone of hydrocarbon intermediate production. In volume, the most important intermediates are the lower olefins. ethylene. propylene: and the butenes. Installed catalytic cracking equipment in the U. S . today is capable of handling over 4.000,OOO barrels per day of feed. High-temperature. low-pressure thermal cracking of naphthas and gas oils, usually in the presence of steam. is a versatile producer of the more important hydrocarbon intermediates. All the lower olefins. as well as a variety of diolefins-butadiene. isoprene, cyclopentadiene. and piperylene-are produced in commercially attractive yields. Valuable aromatics. especially benzene. are also formed. Dehydrogenation
Removal of hydrogen from hydrocarbons a t high temperatures and in the presence of catalvsts is another important conversion process for synthesizing hvdrocarbon intermediates. Both saturated and unsaturated aliphatics and cycloaliphatics are dehydrogenated. \vhen the hydrocarbon undergoing reaction contains less than six carbon atoms, in a single straight chain or ring, the products are mostlv mono- and diolefins
Reprints of this group of artides may be purchased at $1.00 for single copies or for $0.75 in lots of ten or more. Address Special Issue Sales Department, American Chemical Society, 1155 16th St., N.W., Washington 6, D. C.
of the same. and to some extent lokver, carbon atom content. byhen a saturated h?-drocarbon, such as n-butane, is used as feed. the dehydrogenation can be carried out in tivo stages. yielding first mono-olefins and then diolefins. I t is also possible to establish conditions that produce mixtures of both these types of unsaturated h>-drocarbons. However, some commercially important catalysts, such as the FepO,-K,O-MgO and Ni3(P0J2-Ca3(P04)?-Cr,0a compositions. are very effective in dehydrogenating mono-olefinic hydrocarbons but have no or little effect on saturated ones. Others. such as AI?OJCr?Oa mixtures. are active with both olefinic and saturated hydrocarbons. Catalytic Reforming
147th hydrocarbons containing six or more carbon atoms, aromatics are the chief products of hydrogen removal reactions in the presence of solid catalysts. Numerous individual processes. such as Powerforming, Platforming and Fluid Hydroforming: have been developed to increase the value of crude fractions and other refinery products as components of gasoline. These catalytic operations are our main source of the lower aromatic hydrocarbons-benzene, toluene, and the xylenes. Even higher homologs, especially the po!ymethylated ones. such as durene and pseudocumene, can be made this \vay and promise to become important raw materials. Polymerizations
Olefins containing six or more carbon atoms are becoming more important as hydrocarbon raw materials, especially for alcohol manufacture by the oxo process and for synthetic detergents. The) are produced by catalytic polymerization of the readily available lower olefins, especially prop!.lene and the butenes. Polymerization v i t h a supported phosphoric acid catalyst is the most important commercially and supplies a series of olefin fractions containing from six to about 15 carbon atoms. Besides the simple polymerization reactions. other acid-catalyzed reactions such as isom-
erization and disPrclportionation occur. .4s a result, the products contain not only olefins having molecular \
