Acetylene-based Reppe process

The Reppe process is a method that was developed in the 1940s and typical manufacturers include BASF, Ashland, and Invista. Cu-Bi catalyst supported on silica is used to prepare the 1,4-butynediol by reacting formaldehyde and acetylene at 0.5 MPa and 90-110 C (Eq. (10.2)). The copper used in the reaction is converted to copper(I) acetylide, and the copper complex reacts with the additional acetylene to form the active catalyst. The role of bismuth is to inhibit the formation of water-soluble acetylene polymers (i.e., cuprenes) from the oligomeric acetylene complexes on the catalyst [5a]. The hydrogenation of 1,4-butynediol is accom-pUshed through the use of Raney Ni catalyst to produce 1,4-butanediol (Eq. (10.3)). The total yield of 1,4-butanediol production is 91% from acetylene [5b]. Since acetylene is a highly explosive compound, careful process control is necessary. 

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The 1,3-butadiene-based 1,4-butanediol process was reviewed in this chapter. This method ended the half-century monopoly of the acetylene-based Reppe method. This development was in line with the switch from coal to petroleum feedstock. Because the acetoxylation of 1,3-butadiene was the first successful commercial... 

Acetylene-Based Routes. Walter Reppe, the father of modem acetylene chemistry, discovered the reaction of nickel carbonyl with acetylene and water or alcohols to give acryUc acid or esters (75,76). This discovery led to several processes which have been in commercial use. The original Reppe reaction requires a stoichiometric ratio of nickel carbonyl to acetylene. The Rohm and Haas modified or semicatalytic process provides 60—80% of the carbon monoxide from a separate carbon monoxide feed and the remainder from nickel carbonyl (77—78). The reactions for the synthesis of ethyl acrylate are... 

The modified Reppe process was installed by Rohm and Haas at thek Houston plant in 1948 and later expanded to a capacity of about 182 X 10 kg/yr. Rohm and Haas started up a propylene oxidation plant at the Houston site in late 1976. The combination of attractive economics and improved product purity from the propylene route led to a shutdown of the acetylene-based route within a year. 

The most recent entrant-to the. club of commodity chemicals is 1,4-butanediol (BDO), a petrochemical used in some of the more specialized applications such as chemical intermediates for the production of tetrahydro-furane and gama-butyrolactone, polybutylene terephthalate, and the more familiar polyurethanes. Traditionally, the Reppe process was the primary route to BDO, based bn acetylene and formaldehyde feeds. More recently, the share of BDO from butane and propylene oxide based production has grown rapidly. 

Acrolein and condensable by-products, mainly acrylic acid plus some acetic acid and acetaldehyde, are separated from nitrogen and carbon oxides in a water absorber. However in most industrial plants the product is not isolated for sale, but instead the acrolein-rich effluent is transferred to a second-stage reactor for oxidation to acrylic acid. In fact the volume of acrylic acid production ca. 4.2 Mt/a worldwide) is an order of magnitude larger than that of commercial acrolein. The propylene oxidation has supplanted earlier acrylic acid processes based on other feedstocks, such as the Reppe synthesis from acetylene, the ketene process from acetic acid and formaldehyde, or the hydrolysis of acrylonitrile or of ethylene cyanohydrin (from ethylene oxide). In addition to the (preferred) stepwise process, via acrolein (Equation 30), a... 

The applied nickel catalyst, promoted by copper halides, required rather severe reaction conditions T = 220 °C, F = 10 MPa), but gave good AA yields up to 90% based on acetylene. This so-called catalytic Reppe process was commercially operated in Germany, the USA, and Japan. Due to the limited availability of cheap acetylene as feedstock and the severe reaction conditions involved in the carbonylation process, this process has lost the competition with (heterogeneously catalyzed) oxidation of readily available propene, even though a perfect selectivity to AA is not achieved in the latter process. 

The Reppe process is based on acetylene and formaldehyde feed originally, it was developed in Germany during World War II to form butadiene. The last step of the Reppe process was eliminated and the intermediate product was used to produce THF. The process is ... 

The Reppe process is based on acetylene as a raw material. These reactions were developed by Reppe et al. [2]. In accordance with the rise of the petrochemical industry, most processes switched from acetylene to olefins as raw material. However, only the 1,4-butanediol production process continued to rely on the Reppe process. Mitsubishi Chemical Corporation developed a totally different production method that uses 1,3-butadiene to produce 1,4-butanediol and THF. Commercial production was launched in 1982 and has been continued ever since. This process ended the over-half-century monopoly of the Reppe method. The Mitsubishi Chemical method has an advantage over the Reppe method with respect to the handling of raw materials and production costs, but in recent years, Chinese companies that can take advantage of inexpensive natural gas and coal have built a new production plant by using the Reppe method and international competition is getting more intense. 

As in any form of mediation, the result of this frequently complex process is often a compromise. The raw material may be scarcer or dearer than is desirable or, more often, the final product has to struggle to become profitable, as was the case with Buna S. In such cases, the industrial chemist may look for a more suitable raw material, as when Reppe strove to replace fermentation-based ethanol with middle oil as the feedstock for ethylene. Alternatively, he may retain the original starting material, but search for a reaction with a higher yield (the key to Buna ), or one with a more desirable outcome, such as the Reppe process, which conserved the dearly won triple bond. The Reppe process also featured the partial replacement of an expensive feedstock, since one of the costly acetylene molecules was replaced by two cheap formaldehyde molecules. It is thus clear that Reppe s work was strongly influenced by feedstock considerations. 

The Reppe process, in which acetylene reacts with two equivalents of formaldehyde to form 1,4-butynediol, which is subsequently converted to BDO via hydrogenation. The Reppe process is the most widely used process for example by BASE. 

A variety of processes have been used for the production of esters of acrylic (propenoic) acid, including the solvolysis of acrylonitrile with c. H2SO4 and an alcohol. The Reppe process, commercialized by BASF and associated companies, is based on the reaction of acetylene with carbon monoxide, nickel carbonyl and an alcohol. However, the last U.S. operator of this process commissioned a propylene oxidation plant in October, 1982. 

Another classical example is the synthesis of cyclooctatetraene in one step from acetylene when using a nickel-based catalyst (a Reppe process), whereas the first classical synthesis required a painful, multistep approach. 

Coal was also the feedstock for synthesis gas vide infra). Many contributions to acetylene chemistry are due to Reppe. His work on new homogeneous metal (mainly nickel) catalysts for acetylene conversion, carried out in the period from 1928 to 1945, was not published until 1948. Under the influence of nickel iodide catalysts, acetylene, water and CO were found to give acrylic acid. A process based on this chemistry was commercialized in 1955. 

Even if new processes of synthesis were developed from alcohols, like catalytic vinylation with ethylene or vinyl exchange with vinyl acetate, the major commercial route for VE monomers seams to be still the Reppe method based on reaction, in basic conditions, of acetylene with the corresponding alcohols [96,97,100] ... 

The production of carboxylic acids via carbonylation catalysis is the second most important industrial homogeneous group of processes. Reppe developed most of the basic carbonylation chemistry in the 1930s and 1940s. The first commercial carbonylation process was the stoichiometric Ni(CO)4-based hydroxycarbonylation of acetylene to give acrylic acid (see Section 3.5 for details). This discovery has since evolved into a trae Ni-catalyzed process, used mainly by BASF. The introduction of rhodium catalysts in the 1970s revolutionized carboxylic acid production, particularly for acetic acid, much in the same way that Rh/PPhs catalysts changed the importance of hydroformylation catalysis. 

The reaction of an aUcene (or aUcyne), CO, and H2O to directly produce a carboxylic acid is called Reppe carbony-lation chemistry or, more recently, hydrocarboxylation (see Reppe Reaction). An excellent review of palladium-catalyzed Reppe carbonylation systems has been published recently by Kiss, and coverage of this important material will not be repeated here. This catalytic reaction has been known for quite some time, although the stoichiometric Ni(CO)4-based carbonylation of acetylene was the first commercial carbonylation process implemented (equation 13). The extreme toxicity of Ni(CO)4, however, has limited practical applications (see Nickel Organometallic Chemistry). Co, Rh, and Pd catalysts have certainly replaced Ni(CO)4 in smaller-scale laboratory reactions, though for historical reasons a number of the fim-damental mechanisms discussed in this section are based on Ni(CO)4. 

A further development of the Reppe acrylic acid synthesis is the reaction, described in recent literature, of the noble metal-catalyzed carbonylation of higher acetylenes to give the corresponding acrylic acid derivatives. Thus, for example, the Pd-catalyzed carbonylation of propyne (eq. (10)) in the presence of methanol leads directly to methyl methacrylate [23]. Based on this work. Shell has developed a new production process for methyl methacrylate [24]. The propyne required can be isolated from the product streams from crackers, (cf. Section 2.3.2.3). 

The carbonylation of acetylene with carbon monoxide and water to make acrylic acid is of historical interest, as it was the first carbonylation reaction carried out by Reppe. Until the mid-1980s, BASF operated an acrylic acid plant based on this technology to produce 110,000 metric tons per year at Ludwigshafen, Germany. The plant has been replaced with a propylene oxidation process. Today, the production of acrylic acid worldwide is exclusively by the propylene oxidation route. 

Walter Reppe also used his new base to expand the chemistry of acetylene. His first major breakthrough, in the summer of 1939, was the addition of carbon monoxide to acetylene in the presence of alcohols (or water) and a nickel catalyst to form acrylates. Carbon monoxide had attracted attention for many years as a readily available, cheap and reactive carbon compound. I.G. Farben employed it in the Pier methanol synthesis, Ruhrchemie used it in the Fischer-Tropsch synthetic petrol process, and Du Pont had carried out research on the addition of carbon monoxide to olefins at very high pressure and temperatures. Additional impetus for the use of carbon monoxide in acetylene chemistry was provided by the introduction of covered carbide furnaces at I.G. Farben s Knapsack plant in 1938, which permitted the collection of by-product carbon monoxide. The polymers of acrylic esters were already used for treating leather and for paint, but acrylic acid was made from ethylene oxide, and consequently was rather expensive. Reppe s process reached the pilot plant stage by 1945, and was subsequently used on a large scale by BASF and its American partners. 

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