Methanol cobalt catalyzed BASF process

One process that capitalizes on butadiene, synthesis gas, and methanol as raw materials is BASF s two-step hydrocarbonylation route to adipic acid(3-7). The butadiene in the C4 cut from an olefin plant steam cracker is transformed by a two-stage carbonylation with carbon monoxide and methanol into adipic acid dimethyl ester. Hydrolysis converts the diester into adipic acid. BASF is now engineering a 130 million pound per year commercial plant based on this technology(8,9). Technology drawbacks include a requirement for severe pressure (>4500 psig) in the first cobalt catalyzed carbonylation step and dimethyl adipate separation from branched diester isomers formed in the second carbonylation step. 

Mankind has produced acetic acid for many thousand years but the traditional and green fermentation methods cannot provide the large amounts of acetic acid that are required by today s society. As early as 1960 a 100% atom efficient cobalt-catalyzed industrial synthesis of acetic acid was introduced by BASF, shortly afterwards followed by the Monsanto rhodium-catalyzed low-pressure acetic acid process (Scheme 5.36) the name explains one of the advantages of the rhodium-catalyzed process over the cobalt-catalyzed one [61, 67]. These processes are rather similar and consist of two catalytic cycles. An activation of methanol as methyl iodide, which is catalytic, since the HI is recaptured by hydrolysis of acetyl iodide to the final product after its release from the transition metal catalyst, starts the process. The transition metal catalyst reacts with methyl iodide in an oxidative addition, then catalyzes the carbonylation via a migration of the methyl group, the "insertion reaction". Subsequent reductive elimination releases the acetyl iodide. While both processes are, on paper, 100%... 

A cobalt/iodide catalyzed process to make acetic acid from methanol, introduced by BASF around 1960, grew out of the carbonylation studies by... 

The low-pressure acetic acid process was developed by Monsanto in the late 1960s and proved successful with commercialization of a plant producing 140 X 10 metric tons per year in 1970 at the Texas City (TX, USA) site [21]. The development of this technology occurred after the commercial implementation by BASF of the cobalt-catalyzed high-pressure methanol carbonylation process [22]. Both carbonylation processes were developed to utilize carbon monoxide and methanol as alternative raw materials, derived from synthesis gas, to compete with the ethylene-based acetaldehyde oxidation and saturated hydrocarbon oxidation processes (cf. Sections 2.4.1 and 2.8.1.1). Once the Monsanto process was commercialized, the cobalt-catalyzed process became noncom-... 

The process based on the cobalt-catalyzed reaction was commercialized by BASF [3,4] but proved not to be so selective as subsequent processes, with an acetic acid yield of 90% (based on methanol feedstock) and 70% (based on CO). The major organic by-products were higher alcohols, aldehydes, and carboxylic acids that required demanding and expensive separation procedures to give acetic acid of sufficient purity. 

Meanwhile, Wacker Chemie developed the palladium-copper-catalyzed oxidative hydration of ethylene to acetaldehyde. In 1965 BASF described a high-pressure process for the carbonylation of methanol to acetic acid using an iodide-promoted cobalt catalyst (/, 2), and then in 1968, Paulik and Roth of Monsanto Company announced the discovery of a low-pressure carbonylation of methanol using an iodide-promoted rhodium or iridium catalyst (J). In 1970 Monsanto started up a large plant based on the rhodium catalyst. 

As mentioned in the previous section, the carbonylation of methanol to acetic acid is an important industrial process. Whereas the [Co2(CO)s]-catalyzed, iodide-promoted reaction developed by BASF requires pressures of the order of 50 MPa, the Monsanto rhodium-catalyzed synthesis, which is also iodide promoted and which was discovered by Roth and co-workers, can be operated even at normal pressure, though somewhat higher pressures are used in the production units.4,1-413 The rhodium-catalyzed process gives a methanol conversion to acetic acid of 99%, against 90% for the cobalt reaction. The mechanism of the Monsanto process has been studied by Forster.414 The anionic complex m-[RhI2(CO)2]- (95) initiates the catalytic cycle, which is shown in Scheme 26. 

The BASF cobalt/iodide catalyzed process for methanol carbonylation was quite quickly superseded by a rhodium/iodide catalyzed process discovered at Monsanto and first commercialized in 1970 at a plant in Texas City. The Monsanto process was a significant advance and became one of the few large tonnage processes to use a homogeneous transition metal catalyst. It was later... 

Following the intense work on the carbonylation reaction during the 1920s by BASF and British Celanese [1], Reppe and his research group discovered that cobalt diiodide operating at 680 bar and 250 °C catalyzes this reaction [2, 3]. But it was necessary to solve harsh corrosion problems, until 1950, when highly resistant molybdenum/nickel alloys (whose trademark is Hastelloy ) were discovered and commercialized [1]. The process developed by BASF in 1960 was not selective as the yield in acetic acid was 90% based on methanol and 70% based on CO [4] due to the large amounts of CO2 coproduced by the water-gas shift (WGS) reaction (Eq. 20.2). 

The discovoy of methanol carbonylation to acetic acid, with cobalt iodide as the catalyst, goes back to 1913. In 1960 BASF operated a small Co-based methanol carbonylation plant. The Co-catalyzed process requires high pressure and temperature ( 00 bar, 230°C) and is of moderate selectivity. The selectivity with respect to CO and methanol are -70% and -90%, respectively. Acetic acid production is accompanied by unwanted side products such as acetaldehyde, ethanol, and propionic acid. 

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