BASF methanol process

Future Methanol Processes. The process route for methanol synthesis has remained basically unchanged since its inception by BASF in 1923. The principal developments have been in catalyst formulation to increase productivity and selectivity, and in process plant integration to improve output and energy efficiency while decreasing capital cost. 

Methanol process. BASF introduced high-pressure technology way back in I960 to make acetic acid out of methanol and carbon monoxide instead of ethylene. Monsanto subsequently improved the process by catalysis, using an iodide-promoted rhodium catalyst. This permits operations at much lower pressures and temperatures. The methanol and carbon monoxide, of course, come from a synthesis gas plant. 

High pressure technology transfer and diversification took many avenues, though most new innovations continued to appear from BASF. First, in 1923, was methanol production at the Leuna ammonia factory, and based on the work of Matthias Pier. BASF had patented a high pressure methanol process in 1914, but no further studies were carried out until after G. Patart in France applied for a similar patent (1921). In this case the same equipment could be used to manufacture ammonia or methanol, according to demand. Synthesis gas, the mixture of hydrogen and carbon monoxide, was used directly, without separation, to prepare methanol. In a similar way, isopropanol was manufactured under high pressures. 

In the BASF carbonylation process, methanol and CO are converted in the liquid phase (solvent dimethyl ether, water) at 250 °C and 700bar. The reaction rate depends strongly on the concentration of methanol and the partial pressure of CO. The proposed mechanism for the Co-catalyzed carbonylation of methanol is presented in detail in Example 16.6.2. Acetic acid yields are typically 90% (based on methanol) and 70% (based on carbon monoxide). Selectivities are high, with the production of 100 kg of acetic acid affording 4 kg by-products (mainly CO2, CH4, ethanol, acetaldehyde, and propionic acid). 

First conmereial methanol pioeess by destructive distillation of wood Synflietic methanol route su sted by French chemist Paul Sabatier First synthetic methanol plant commericalizBd by BASF Synthetic methanol process introduced in United States Late 1940s Conversion from water g3s to natural g3s as source of synthetic g s for feed to methanol reactors 1966 Low-pressure methanol process announced by ICl... 

Subsequently, patents covering the conversion of synthesis gas to complex mixtures of organic oxygen compoimds, including methanol, were issued to BASF during 1913. This followed work by Mittasch and Schneider. Full-scale production of methanol was not attempted, however, imtil 1923. By that time high-pressure equipment had been in operation for several years in the new ammonia process. The methanol process was developed by Piers and the plant, built at Leima, used mixed zinc oxide-chromic oxide catalyst. The use of metallic iron for the internal parts of the reactor was avoided to prevent the formation of the volatile iron penlacarbonyl. The would have decomposed on the surface of the catalyst, to deposit finely divided iron metal, which in turn would have promoted the exothermic formation of methane. 

It has been known since the early 1950s that butadiene reacts with CO to form aldehydes and ketones that could be treated further to give adipic acid (131). Processes for producing adipic acid from butadiene and carbon monoxide [630-08-0] have been explored since around 1970 by a number of companies, especially ARCO, Asahi, BASF, British Petroleum, Du Pont, Monsanto, and Shell. BASF has developed a process sufficiendy advanced to consider commercialization (132). There are two main variations, one a carboalkoxylation and the other a hydrocarboxylation. These differ in whether an alcohol, such as methanol [67-56-1is used to produce intermediate pentenoates (133), or water is used for the production of intermediate pentenoic acids (134). The former is a two-step process which uses high pressure, >31 MPa (306 atm), and moderate temperatures (100—150°C) (132—135). Butadiene,... 

The first CO route to make adipic acid is a BASF process employing CO and methanol in a two-step process producing dimethyl adipate [627-93-0] which is then hydroly2ed to the acid (43—46). Cobalt carbonyl catalysts such as Co2(CO)g are used. Palladium catalysts can be used to effect the same reactions at lower pressures (47—49). 

An electrooxidation process was developed by Asahi Chemical Industry ia Japan, and was also piloted by BASF ia Germany. It produces high purity sebacic acid from readily available adipic acid. The process consists of 3 steps. Adipic acid is partially esterified to the monomethyl adipate. Electrolysis of the potassium salt of monomethyl adipate ia a mixture of methanol and water gives dimethyl sebacate. The last step is the hydrolysis of dimethyl sebacate to sebacic acid. Overall yields are reported to be about 85% (65). 

The carbonylation of methanol is currently one of the major routes for acetic acid production. The basic liquid-phase process developed by BASF uses a cobalt catalyst at 250°C and a high pressure of about 70... 

The oxidative dehydrogenation of methanol to formaldehyde was choosen as model reaction by BASF for performance evaluation of micro reactors [1, 49-51, 108]. In the industrial process a methanol-air mixture of equimolecular ratio of methanol and oxygen is guided through a shallow catalyst bed of silver at 150 °C feed temperature, 600-650 °C exit temperature, atmospheric pressure and a contact time of 10 ms or less. Conversion amounts to 60-70% at a selectivity of about 90%. 

The oxidation of an undisclosed methanol derivative to the corresponding formaldehyde compound is a large-scale BASF process which was established in recent years, whereas the similar methanol-to-formaldehyde process, performed on a much larger scale, has been practised at BASF for more than 100 years [1,49-51, 108]. The exact nature of the substituent(s) was not disclosed by BASF for reasons of confidentiality, although many publications on that topic appeared. The nature of the substituent makes the derivative, as the results of the investigations show, more labile to temperature. 

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. 

ENSOL A combined process for converting syngas to methanol and then to ethanol. Acetic acid is an intermediate. Developed by Humphries Glasgow, in conjunction with BASF and Monsanto. 

Pier-Mittasch A high-pressure, catalytic process for making methanol from carbon monoxide and hydrogen. Developed by M. Pier and A. Mittasch at BASF in the 1920s. 

This process was examined in detail by BASF [110], cf. also Ref. [10]. The direct oxidation of toluene in methanol leads in a 4e" process to the dimethoxylation of the methyl group. The product is readily hydrolyzed to the aldehyde [29]. 

The hydroquinone process was developed by BASF [12]. Hydroquinone-2,5-di-carboxylic acid is prepared by a modified Kolbe-Schmidt synthesis from hydroquinone and carbon dioxide. Subsequent reaction with arylamine in an aqueous-methanolic suspension in the presence of an aqueous sodium chlorate solution and a vanadium salt affords the product in good yield ... 

It is now nearly 40 years since the introduction by Monsanto of a rhodium-catalysed process for the production of acetic acid by carbonylation of methanol [1]. The so-called Monsanto process became the dominant method for manufacture of acetic acid and is one of the most successful examples of the commercial application of homogeneous catalysis. The rhodium-catalysed process was preceded by a cobalt-based system developed by BASF [2,3], which suffered from significantly lower selectivity and the necessity for much harsher conditions of temperature and pressure. Although the rhodium-catalysed system has much better activity and selectivity, the search has continued in recent years for new catalysts which improve efficiency even further. The strategies employed have involved either modifications to the rhodium-based system or the replacement of rhodium by another metal, in particular iridium. This chapter will describe some of the important recent advances in both rhodium- and iridium-catalysed methanol carbonylation. Particular emphasis will be placed on the fundamental organometallic chemistry and mechanistic understanding of these processes. 

BASF led the development of a route based on ethylene and synthesis gas. Its four step process begins with the production of propionaldehyde from ethylene, CO, and H2 using a proprietary catalyst mixture that they aren t telling anything about. Reaction with formaldehyde gives methacrolein. The last two steps are the same as above—oxidation with air yields the MAA subsequent reaction with methanol yields MMA. 

The concept that acetic acid can be prepared by carbonylation originated in use of routine acids. Carbonylation of methanol was first practiced in a high temperature and pressure process using boron trifluoride or phosphoric acid. A carbon monoxide pressure of 10,000 psi at 300 C was needed for the reaction (10). Metal salts came to replace acids as carbonylation catalysts. Carbonylation of methanol using a metal carbonyl catalyst was first discovered by Reppe and practised later by BASF. However, the process again required high pressure, 7500-10,000 psi, and the selectivity was low (11-14). 

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. 

Methanol was first produced commercially in 1830 by the pyrolysis of wood to produce wood alcohol. Almost a century later, a process was developed in Germany by BASF to produce synthetic methanol from coal synthesis gas. The first synthetic methanol plant was introduced by BASF in 1923 and in the United States by DuPont in 1927. In the late 1940s, natural gas replaced coal synthesis gas as the primary feedstock for methanol production. In 1966, ICI announced the development of a copper-based catalyst for use in the low-pressure synthesis of methanol. 

An industrial process to produce methanol from carbon monoxide and hydrogen was developed by BASF in 1923 using a zinc oxide-chromia catalyst.361 362 Since this catalyst exhibited relatively low specific activity, high temperature was required. The low equilibrium methanol concentration at this high temperature was compensated by using high pressures. This so-called high-pressure process was operated typically at 200 atm and 350°C. The development of the process and early results on methanol synthesis were reviewed by Natta 363... 

Acetic Acid. Carbonylation of methanol is the most important reaction in the production of acetic acid.189-192 BASF developed a process applying C0I2 in the liquid phase under extreme reaction conditions (250°C, 650 atm).122 193 The Monsanto low-pressure process, in contrast, uses a more active catalyst combining a rhodium compound, a phosphine, and an iodine compound (in the form of HI, Mel, or T2).122 194—196 Methanol diluted with water to suppress the formation of methyl acetate is reacted under mild conditions (150-200°C, 33-65 atm) to produce acetic acid with 99% selectivity at 100% conversion. 

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. 

---