Acetylene acrylic acid process

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... 

This process, to which the raw materials are suppHed at low pressures, is continuous and gives good yields of acrylates (see Acrylic acid and derivatives). In the presence of catalytic amounts of Co2(CO)g, acetylene has been carboxylated in methanol yielding dimethyl succinate as the principal product (135). 

Reppe A family of processes for making a range of aliphatic compounds from acetylene, developed by W. Reppe in IG Farbenindustrie, Germany, before and during World War II. In one of the processes, acetylene is reacted with carbon monoxide to yield acrylic acid CH=CH + CO + H20 CH2=CH-COOH Acrylic esters are formed if alcohols are used instead of water ... 

The Reppe process was commercialized in the 1950s. It involves the reaction pf acetylene, carbon monoxide, and an alcohol (methyl, ethyl, etc.) to give an acrylic ester (an acrylate). The process is carried out at 125°F and 15—30 psi in a nickel carbonyl/aqueous hydrochloric acid solution. The nickel carbonyl acts as both a catalyst and a secondary source of carbon monoxide. 

Some acrylates are still produced by a modified Reppe process that involves the reaction of acetylene, the appropriate alcohol (in the case of butyl acrylate, butyl alcohol is used), and carbon monoxide in the presence of an acid. The process is continuous and a small amount of acrylates is made this way. The most economical method of acrylate production is that of the direct oxidation of propylene to acrylic acid, followed by esterification. 

The syntheses of carboxylic acids and esters are widely studied processes. Since the first examples of carboxylation in the presence of metal carbonyls were reported by Reppe, these reactions are sometimes referred to as the Reppe reactions. In his pioneering work125-127 stoichiometric or catalytic amounts of [Ni(CO)4] and ethylene or acetylene were reacted in the presence of water or alcohols to form saturated and unsaturated acids and esters. Commercial processes are practiced in the manufacture of propionic acid, acrylic acid and acrylates (see Section 7.2.4). 

Acrylic Acid and Acrylates. Acrylic acid and acrylates may be produced commercially by the Reppe reaction of acetylene.76,184-187 However, the industrial significance of these processes has diminished since acetylene is no longer a viable source and was replaced by ethylene. Acrylic acid and acrylates are now produced by propylene oxidation (see Section 9.5.2). 

REPPE PROCESS. Any of several processes involving reaction of acetylene (1) with formaldehyde to produce 2-butync-l,4-diol which can be converted to butadiene (2) with formaldehyde under different conditions to produce propargyl alcohol and, form this, allyl alcohol (3) with hydrogen cyanide to yield acrylonitrile (4) with alcohols to give vinyl ethers (5) with amines or phenols to give vinyl derivatives (6) with carbon monoxide and alcohols to give esters of acrylic acid (7) by polymerization to produce cyclooctatetraene and (8) with phenols to make resins. The use of catalysis, pressures up to 30 atm, and special techniques to avoid or contain explosions are important factors in these processes. 

Nickel catalysts are utilized for the industrial synthesis of acrylic acid or esters either in a semicatalytic process with Ni(CO>4 or a catalytic process with NiBft (equation 44).73 The reaction is carried out in THF containing water or alcohol (to avoid acetylene detonation at 60 bar). 

These processes have supplanted the condensation reaction of ethanol, carbon monoxide, and acetylene as the principal method of generating ethyl acrylate [140-88-5] (333). Acidic catalysts, particularly sulfuric acid (334—338), are generally effective in increasing the rates of the esterification reactions. Care is taken to avoid excessive polymerization losses of both acrylic acid and the esters, which are accentuated by the presence of strong acid catalysts. A synthesis for acrylic esters from vinyl chloride (339) has also been examined. 

In the 1930s, the Reppe group developed commercial processes for the production of carboxylic acids and esters by the carbonylation of alkynes and alkenes using metal carbonyls [4], In particular, an industrial process for producing acrylic acid or ester by the carbonylation of highly explosive acetylene, catalysed by extremely toxic Ni(CO)4, was established (eq. 1.3). 

The carbonylation of acetylene to produce acrylic acid or ester (22) catalysed by Ni(CO)4 was a historical industrial process developed by Reppe. 

In the presence of such catalysts as a solution of cuprous and ammonium chlorides, hydrogen cyanide adds to acetylene to give acrylonitrile (CH2=CHCN). However, this process has been replaced by processes involving ammoxidation of propylene. Similarly, the process for the manufacture of acrylic acid has been superseded by processes involving oxidation of propylene (Fig. 1) although, for some countries, acetylene may still be used in acrylate manufacture. 

Acetylene once was the raw material for commercial production of acrylic acid and esters, but in 1970 production of acrylic acid by oxidation of propylene was first practiced commercially. In a few years, the new process had essentially replaced the old. In 2000, acrylic acid production in the U.S. was of the order of 2.0 billion lb, and that of acrylate esters was of the order of 1.8 billion lb. 

This invention has its roots in Reppe chemistry. In the late 1930s, Reppe in Germany had developed a number of manufacturing processes for bulk chemicals, where acetylene was used as one of the basic building blocks. Even today BASF and Rohm Hass manufacture large quantities of acrylic acid and its esters by hydrocarboxylation of acetylene. This reaction, 4.12, is catalyzed by a mixture of NiBr2 and Cul. It involves high pressure (100 bar) and temperature (220°C), and mechanistically is not fully understood. 

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. 

Acrylic Acid, Acrylates, and Acrylonitrile. Acrylic acid [79-10-7], C3H402, and acrylates were once prepared by reaction of acetylene and carbon monoxide with water or an alcohol, using nickel carbonyl as catalyst. I11 recent years tliis process has been completely superseded in the United States by newer processes involving oxidation of propylene (2). I11 western Europe, however, acetylene is still important in acrylate manufacture (see Acrylic acid and derivatives Acrylic ester polymers). 

Acetylene-Based Routes. Walter Reppe, die father of modem acetylene chemistry, discovered the reaction of nickel carbonyl with acetylene and water or alcohols to give acrylic acid or esters (75,76). This discovery7 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... 

Reppe s work also resulted in the high pressure route which was established by BASF at Ludwigshafen in 1956. In dais process, acetylene, carbon monoxide, water, and a nickel catalyst react at about 200°C and 13.9 MPa (2016 psi) to give acrylic acid. Safety problems caused by handling of acetylene are alleviated by the use of tetrahydrofuran as an inert solvent. In this process, the catalyst is a mixture of nickel bromide with a cupric bromide promotor. The liquid reactor effluent is degassed and extracted. The acrylic acid is obtained by distillation of the extract and subsequendy esterified to the desired acrylic ester. The BASF process gives acrylic acid, whereas the Rohm and Haas process provides the esters direcdy. 

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 Ni-catalyzed production of acrylic acid from acetylene produces 320 millionkg year. The BASF process operates at... 

Acrylic acid is by far the most important product prepared by carbonylation of acetylene. The processes employed industrially since the mid-1950s for the homogeneously catalyzed carbonylation of acetylene (eq. (9)) have enabled the broad use of acrylic acid derivatives as mass products. This reaction was first discovered in 1939 by Reppe [19] and was investigated intensively in the subsequent period [20]. 

As already mentioned, the processes for the homogeneously catalyzed carbony-lation of acetylene have opened up the way for acrylic acid to become a mass product for which worldwide production capacities are currently two million tonnes per annum. Acrylic acid and its esters are important monomers for polymer dispersions, whose use is widespread. Since the mid-1960s, however, the availability of propene, a less expensive feedstock than acetylene, has led to the development of an even more advantageous production process the heterogeneously catalyzed gas-phase oxidation of propene [21, 22]. Nowadays, acrylic acid is produced almost exclusively by this process (cf. Chapter 1). The Reppe acrylic acid plant at BASF is now the only one left in the world which still uses acetylene as feedstock. 

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). 

In the patent specification [147] there data on the chemical attachment to hydridesilica surface in the presence of the Reney nickel, chloroplatinic acid or metallic platinum deposited on activated carbon as a catalyst of the following unsaturated functional compounds divinylbenzene, ethylene glycol diacrylate, acetylene, allyl alcohol, allyl glycidyl ether, allyl isocyanate, acrylic acid. The chemical reactions result in the transformation of Si-H bonds of hydridesilica surface into Si-C bonds. Such transformations may be also classified as processes of solid-phase catalytic hydrosilylation of functional olefins. 

Three important processes have evolved from Reppe s work. Vinylation, the formation of vinyl derivatives by reaction of such compounds as acids, glycols, and alcohols with acetylene, produces the important vinyl esters and vinyl ethers. Ethinylation is defined as the reaction of acetylene with the carbon atom of a reactant without loss of the triple bond. A major application of the ethinylation reaction is to aldehydes and ketones to give alkynols and alkyndiols—e.g., the reaction of acetylene with formaldehyde to give propargyl alcohol and butyn-2-diol-l,4. Carboxylation (also referred to as carbonylation), the reaction of acetylene with carbon monoxide in the presence of metal carbonyls, has been applied to the production of acrylic acid, acrylates, and hydroquinone. 

Control of reactivity by catalysis provides the capability to shift to lower cost feedstocks. In the twentieth century, advances in catalysis have allowed the substitution of acetylene with olefins and subsequently with synthesis gas as primary feedstocks. For example, production of acrylic acid, traditionally produced by the Reppe process from acetylene and CO, has now been replaced by catalytic oxidation of propylene. The emergence of paraffins, the hydrocarbon feedstock of the future, will depend on development of catalysts for selective alkane C-H activation (2). 

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