Oxidation of methanol formaldehyde

Fuji T, Tonomura K. 1972. Oxidation of methanol, formaldehyde and formate by a Candida species. Agnc Biol Chem 36 2297-2306. 

The surface activation consisting of zinc deposition, heat treatment, and subsequent leaching of zinc (63, 64) was applied to different amorphous iron-, cobalt-, nickel-, and palladium-based alloys (63, 64). SEM measurements indicated the formation of a porous surface layer. Cyclic voltammetric examinations suggested an increase of surface area by about two orders of magnitude. Heat treatments at higher temperatures resulted in thicker, more porous surface layers and higher electrocatalytic activities (Table II). Palladium-phosphorus alloys with Ni, Pt, Ru, or Rh proved to be the best specimens. Pd-Ni-P with 5% Ni, after treatment at 573 K, exhibited even higher activity than that of the Pt-Pt electrode (Table II). These amorphous alloy electrodes were active in the oxidation of methanol, formaldehyde, and sodium formate. 

In the 1920 s, E. MQller and his co-workers made a series of studies on the anodic oxidation of methanol, formaldehyde, and formic acid which represent the first extensive mechanistic investigation of these compounds, although the principles of electrode kinetics had not yet been formulated. Muller did not establish mechanisms for these reactions however, many of his observations have been later confirmed and his studies were among the first with a comparison of polarization curves on several noble metals including platinum, palladium, rhodium, iridium, osmium, rubidium, gold, and silver (cf. Figure 1). As was usual at that time, Muller discussed his results in terms of polarization, rather than in terms of current or reaction rate. 

R.P. Buck, L.R. Griffith, Voltammetiic and chronopotentiometric study of the anodic oxidation of methanol, formaldehyde, and formic add, J. Electiochem. Soc. 109 (1962) 1005-1013. 

The catalytic activities of various noble metals in the oxidation of methanol, formaldehyde, and formic acid were first compared by Muller and his co-workers [2-8]. It was found that silver was the best catalyst for oxidation of formaldehyde in alkaline solution. According to data in [8], the metals can be placed in the following order Pd > Rh > Au > Pt according to their activity towards the oxidation of methanol in alkaline solution. This order differs from that obtained recently [234] Pt>Pd>Ru = Rh>Ir... 

Oxidation of methanol to formaldehyde with vanadium pentoxide catalyst was first patented in 1921 (90), followed in 1933 by a patent for an iron oxide—molybdenum oxide catalyst (91), which is stiU the choice in the 1990s. Catalysts are improved by modification with small amounts of other metal oxides (92), support on inert carriers (93), and methods of preparation (94,95) and activation (96). In 1952, the first commercial plant using an iron—molybdenum oxide catalyst was put into operation (97). It is estimated that 70% of the new formaldehyde installed capacity is the metal oxide process (98). 

Oxidation Catalysis. The multiple oxidation states available in molybdenum oxide species make these exceUent catalysts in oxidation reactions. The oxidation of methanol (qv) to formaldehyde (qv) is generally carried out commercially on mixed ferric molybdate—molybdenum trioxide catalysts. The oxidation of propylene (qv) to acrolein (77) and the ammoxidation of propylene to acrylonitrile (qv) (78) are each carried out over bismuth—molybdenum oxide catalyst systems. The latter (Sohio) process produces in excess of 3.6 x 10 t/yr of acrylonitrile, which finds use in the production of fibers (qv), elastomers (qv), and water-soluble polymers. 

However, this advance has an important shortcoming the lack of context. More than one idea is expressed in a document a patent on oxidation catalysts, for example, could include examples of the oxidation of methanol to formaldehyde and of 2-propanol to acetone. A simple coordinate search for conversion of methanol to acetone would retrieve such a document from a file that provides no context. 

Oxidation catalysts are either metals that chemisorb oxygen readily, such as platinum or silver, or transition metal oxides that are able to give and take oxygen by reason of their having several possible oxidation states. Ethylene oxide is formed with silver, ammonia is oxidized with platinum, and silver or copper in the form of metal screens catalyze the oxidation of methanol to formaldehyde. Cobalt catalysis is used in the following oxidations butane to acetic acid and to butyl-hydroperoxide, cyclohexane to cyclohexylperoxide, acetaldehyde to acetic acid and toluene to benzoic acid. PdCh-CuCb is used for many liquid-phase oxidations and V9O5 combinations for many vapor-phase oxidations. 

Many low-molecular-weight aldehydes and ketones are important industrial chemicals. Formaldehyde, a starting material for a number of plastics, is prepared by oxidation of methanol over a silver or non oxide/rnolybdenurn oxide catalyst at elevated temperature. 

The main industrial route for producing formaldehyde is the catalyzed air oxidation of methanol. 

In the chemical industry, simple aldehydes and ketones are produced in large quantities for use as solvents and as starting materials to prepare a host of other compounds. For example, more than 1.9 million tons per year of formaldehyde, H2C=0, is produced in the United States for use in building insulation materials and in the adhesive resins that bind particle hoard and plywood. Acetone, (CH.3)2C"0, is widely used as an industrial solvent approximately 1.2 million tons per year is produced in the United States. Formaldehyde is synthesized industrial ) by catalytic oxidation of methanol, and one method of acetone preparation involves oxidation of 2-propanol. 

From this completed half-reaction we see that the conversion of methanol to formic acid involves the loss of four electrons. Since the oxidation of methanol to formaldehyde was only a two-electron change, it is clear that formic acid is a more highly oxidized compound of carbon than formaldehyde or methanol. 

Formaldehyde is prepared industrially (for the manufacture of phenol-formaldehyde resins) by the catalytic oxidation of methanol ... 

Neither the oxidation of methanol to make formaldehyde nor that of ethanol to make acetaldehyde is sensitive to the adjacency of redox sites in the catalysts the number of exposed vanadium serves well to normalize the reaction rate in both cases. This conclusion does not contradict a statement by other authors [23-25] that the selectivity of alcohol... 

The main reaction product is carbon dioxide, but under certain conditions, other oxidation products are observed for short periods of time, such as formaldehyde, formic acid, and others. The oxidation of methanol to CO2 yields six electrons, so that the specific capacity of methanol is close to 0.84 Ah/g. 

Breiter MW. 1967. A study of the intermediates adsorbed on platinized platinum during the steady-state oxidation of methanol, formic acid and formaldehyde. J Electroanal Chem 14 407-413. 

In 1978, Wachs and Madix34 drew attention to the role of oxygen in the oxidation of methanol being not completely understood at copper surfaces. They established the role of methoxy species as the favoured route to the formation of formaldehyde and that to a lesser extent some methanol was... 

Initial tests using the pulse reactor described in this paper have been done on the selective oxidation of methanol to formaldehyde using molybdate catalysts. 

Adkins-Peterson The oxidation of methanol to formaldehyde, using air and a mixed molybdenum/iron oxide catalyst. Not an engineered process, but the reaction which formed the basis of the Formox process. 

Walker A process for partially oxidizing natural gas or LPG, forming a mixture of methanol, formaldehyde, and acetaldehyde. Air is the oxidant and aluminum phosphate the catalyst. Invented by J. C. Walker in the 1920s and operated by the Cities Service Corporation, OK, in the 1950s. 

Formaldehyde (F) is made by partial oxidation of methanol (M). A side reaction of formaldehyde to CO and H20 (W) also occurs. Approximate forms of the two rate equations are... 

Figure 1.8 TPSR spectra obtained after saturation of a Mo03/AI203 catalyst with methanol at room temperature [61], Seen here are mass spectrometry traces corresponding to methanol (mle = 28 and 32), formaldehyde (mle = 28 and 30), water (mle = 18), and dimethyl ether (mle = 45). These data were used to propose a mechanism for the selective oxidation of methanol on Mo03-based catalysts. (Reproduced with permission from Elsevier.)...

The kinetic parameters for the oxidation of a series of alcohols by ALD are shown in Table 4.1 (74). Methanol and ethylene glycol are toxic because of their oxidation products (formaldehyde and formic acid for methanol and a series of intermediates leading to oxalic acid for ethylene glycol), and the fact that their affinity for ALD is lower than that for ethanol can be used for the treatment of ingestion of these agents. Treatment of such patients with ethanol inhibits the oxidation of methanol and ethylene glycol (competitive inhibition) and shifts more of the clearance to renal clearance thus decreasing toxicity. ALD is also inhibited by 4-methylpyrazole. 

There is no doubt that this reaction is made up of several series and/or parallel reactions. Mass spectroscopic measurement showed that formaldehyde and formic add are produced during the oxidation of methanol on platinum in add solution. Using gas chromatography, methylformate... 

CH00CH3)t carbon dioxide (C02>. formic acid (HCOOH), and formaldehyde (HCHO) are detected in the solution during the oxidation of methanol on platinum in sulfiiric add. While these are stable and detached spedes, spedes that are unstable or adsorbed on the electrode surface are also expected to be formed. 

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