Chemical feedstock acetylene production

Acetjiene has found use as a feedstock for production of chlorinated solvents by reaction with hydrogen chloride or chlorine (6). However, because of safety concerns and the lower price of other feedstock hydrocarbons, very Htfle acetylene is used to produce chlorinated hydrocarbons in the United States (see Acetylene-derived chemicals). 

In addition to its use as a chemical feedstock and intermediate, acetone is used extensively as an organic solvent in lacquers, varnishes, pharmaceuticals, and cosmetics. Nail polish remover is one of the most common products containing acetone. Acetone is used to stabilize acetylene for transport (see Acetylene). 

Approximately 80% of acetylene production is used in chemical synthesis. In the United States approximately 100,000 tons are used annually. Acetylene saw much wider use in the past, especially in Germany where it was widely used as in chemical synthesis. During recent decades, greater use of ethylene as a chemical feedstock and the development of more economical chemical production methods that eliminate acetylene has reduced acetylenes use in the chemical industry. Since 2000, use in the United States has decreased by approximately... 

Acetaldehyde is an intermediate in acetic acid and vinyl acetate production. Since 1916 it has been produced from the addition of water to acetylene, a reaction catalyzed by divalent mercury in sulphuric acid (20%)/water. Acetylene was made from coal. In Germany in particular, a lot of research was carried out on the use of acetylene as a chemical feedstock. 

Coal, considered a soHd hydrocarbon with a generic formula of CHq g, was explored by numerous workers (24—31) as a feedstock for the production of acetylene. Initially, the motivation for this work was to expand the market for the use of coal in the chemical process industry, and later when it was projected that the cost of ethylene would increase appreciably if pretroleum resources were depleted or constrained. 

Much more important is the hydrogenation product of butynediol, 1,4-butanediol [110-63-4]. The intermediate 2-butene-l,4-diol is also commercially available but has found few uses. 1,4-Butanediol, however, is used widely in polyurethanes and is of increasing interest for the preparation of thermoplastic polyesters, especially the terephthalate. Butanediol is also used as the starting material for a further series of chemicals including tetrahydrofuran, y-butyrolactone, 2-pyrrohdinone, A/-methylpyrrohdinone, and A/-vinylpyrrohdinone (see Acetylene-DERIVED chemicals). The 1,4-butanediol market essentially represents the only growing demand for acetylene as a feedstock. This demand is reported (34) as growing from 54,000 metric tons of acetylene in 1989 to a projected level of 88,000 metric tons in 1994. 

Catalysis has made possible the change in the chemical process industry from feedstocks of coal and acetylene, to ethylene. Activation of alkanes is now a major research topic. German industrial scientists led in the coal- and acetylene-based chemical industry developments. Many of the chemical products were for the dyestuffs industry. 

In the early part of this century, coal and coal tar products were the main source of bulk chemicals. Acetylene was the major feedstock, obtained by converting coal to calcium carbide followed by hydrolysis. As the petroleum and natural gas industries developed, ethylene and other products obtained by cracking hydrocar-... 

The synthesis of acetaldehyde by oxidation of ethylene, generally known as the Wacker process, was a major landmark in the application of homogeneous catalysis to industrial organic chemistry. It was also a major step in the displacement of acetylene (made from calcium carbide) as the feedstock for the manufacture of organic chemicals. Acetylene-based acetaldehyde was a major intermediate for production of acetic acid and butyraldehyde. However the cost was high because a large energy input is required to produce acetylene. The acetylene process still survives in a few East European countries and in Switzerland, where low cost acetylene is available. 

A typical steam cracker consists of several identical pyrolysis furnaces in which the feed is cracked in the presence of steam as a diluent.The cracked gases are quenched and then sent to the demethanizer to remove hydrogen and methane. The effluent is then treated to remove acetylene, and ethylene is separated in the ethylene fractionator. The bottom fraction is separated in the de-ethanizer into ethane and C3, which is sent for further treatment to recover propylene and other olefins. Typical operating conditions of ethane steam cracker are 750-800°C, 1-1.2 atm, and steam/ethane ratio of 0.5. Liquid feeds are usually cracked at lower residence time and higher steam dilution ratios compared to gaseous feeds. Typical conditions for naphtha cracking are 800° C, 1 atm, steam/hydrocarbon ratio of 0.6-0.8, and a residence time of 0.35 sec. Liquid feedstocks produce a wide spectrum of coproducts including BTX aromatics that can be used in the production of variety of chemical derivatives. 

After World War II, when the big oil companies installed a large number of refineries in industriahzed countries, lower olefins, particularly ethylene, became available in large quantities. Chemical companies replaced successively their acetylene-based processes for the production of aliphatic C2, C4, and C3 compounds by much cheaper processes with ethylene as the feedstock. Researchers of the Consortium fiir elektrochemische Industrie GmbH, the research organization of Wacker Chemie GmbH, succeeded in finding a new process for the manufacture of the important industrial intermediate acetaldehyde from ethylene [1, 2]. 

Although a feedstock, or a particular feedstock source, is initially taken up because it is produced in excess or is even a waste product, its success can result in the need to manufacture it specially for that process, thereby losing the rationale for its original adoption. One can see this progression at work with coal-tar (in particular phenol ) and synthetic dyes, with coke-based ammonia and the Solvay process, with calcium carbide and acetylene-based chemicals, and, more recently, with refinery gases and petrochemicals. Conversely, butanol became such a major by-product of butadiene production that I.G. could only sell a quarter of it by 1943. ... 

The following impurities sometimes present in the hydrocarbon feedstocks also promote CP production acetylenes, dienes, and cyclopentene. Little experimental information is available relative to the chemical steps involved when such impurities react. Carbon and hydrogen balances indicate that the relative amounts of the CPs and the pseudo alkylate often differ with these impurities, assuming that the compositions of the two by-products remain unchanged, which is probably fairly true. Additional investigations of CPs and pseudo alkylate production are needed. Radioactive carbon atoms in the feedstocks and the hydrocarbon impurities would provide valuable information. 

Yearly production of acetic acid in the United States is approximately 10 kg, a volume that ranks it at the top of the list of organic chemicals manufactured by the US chemical industry. The first industrial synthesis of acetic acid was commercialized in 1916 in Canada and Germany, using acetylene as a feedstock. The process involved two stages (1) hydration of acetylene to acetaldehyde followed by (2) oxidation of acetaldehyde to acetic acid by molecular oxygen, catalyzed by cobalt (III) acetate. 

Conventional processes for the production of 1,4-butanediol use fossil fuel feedstocks such as acetylene and formaldehyde. The biobased process involves the use of glucose from renewable resources to produce succinic acid followed by a chemical reduction to produce butanediol. PBS is produced by transesterification, direct polymerization, and condensation polymerization reactions. PBS copolymers can be produced by adding a third monomer such as sebacic acid, adipic acid and succinic acid, which is also produced by renewable resources [34]. 

The shift from coal to oil, of course, had major consequences for the chemical industry. Alkenes, instead of synthesis gas and acetylene, became the basic building blocks. Homogeneous catalysis became increasingly important for the production of chemicals. We already mentioned the Reppe chemistry, based on acetylene as the main feedstock. In 1938, the same year that Reppe started his work, another German scientist, Otto Roelen, discovered the reaction of olefins with carbon monoxide and hydrogen over a cobalt carbonyl catalyst to form aldehydes, known... 

Ethylene. The largest potential chemical market for n-butanc is in steam cracking to ethylene and coproducts. n-Butane is a supplemental feedstock for olefin plants and has accounted for 1 to 4 percent of total ethylene production for most years since 1970. It can be used at up to 10 to 15 percent of the total feed in ethane/propane crackers with no major modifications. n-Butane also can be used as a supplemental feed at as high as 20 to 30 percent in hea y naphtha crackers. The consumption of C s has fluctuated considerably from year to year since 1970, depending on the relative price of butane and other feedstocks. The yield of ethylene is only 36 to 40 percent, with the other products including methane, propylene, ethane, butadiene, acetylene, and butylenes. About 1 to 2 billion lb of butane are consumed annually to produce ethylene. 

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