Formaldehyde synthesis from methanol

The reactions involved in formaldehyde synthesis from methanol are ... 

Stull, Westrum, and Sinke devote a chapter to the discussion of the applications of thermodynamics to industrial problems. Subjects covered include the petroleum industry, chemicals from methane, styrene manufacture, acrylonitrile and vinyl chloride syntheses, methanol synthesis, formaldehyde production from methanol, acetic acid manufacture, the Gatterman-Koch reaction, and catalyst selection. 

Historically, formaldehyde has been and continues to be manufactured from methanol. EoUowing World War II, however, as much as 20% of the formaldehyde produced in the United States was made by the vapor-phase, noncatalytic oxidation of propane and butanes (72). This nonselective oxidation process produces a broad spectmm of coproducts (73) which requites a complex cosdy separation system (74). Hence, the methanol process is preferred. The methanol raw material is normally produced from synthesis gas that is produced from methane. 

By far the preponderance of the 3400 kt of current worldwide phenolic resin production is in the form of phenol-formaldehyde (PF) reaction products. Phenol and formaldehyde are currently two of the most available monomers on earth. About 6000 kt of phenol and 10,000 kt of formaldehyde (100% basis) were produced in 1998 [55,56]. The organic raw materials for synthesis of phenol and formaldehyde are cumene (derived from benzene and propylene) and methanol, respectively. These materials are, in turn, obtained from petroleum and natural gas at relatively low cost ([57], pp. 10-26 [58], pp. 1-30). Cost is one of the most important advantages of phenolics in most applications. It is critical to the acceptance of phenolics for wood panel manufacture. With the exception of urea-formaldehyde resins, PF resins are the lowest cost thermosetting resins available. In addition to its synthesis from low cost monomers, phenolic resin costs are often further reduced by extension with fillers such as clays, chalk, rags, wood flours, nutshell flours, grain flours, starches, lignins, tannins, and various other low eost materials. Often these fillers and extenders improve the performance of the phenolic for a particular use while reducing cost. 

The carbon dioxide removed in synthesis gas preparation can be reacted with ammonia, to lonn urea CO(NH2)2- This is an excellent fertilizer, highly concentrated in nitrogen (46.6%) and also useful as an additive in animal feed to provide the nitrogen for formation of meat protein. Urea is also an important source of resins and plastics by reacting it with formaldehyde from methanol. 

Let us note once again that comparison of the results on methanol oxidation with hydrogen peroxide with methane oxidation data under atmospheric pressure (refer to Table 4.3, Figures 4.10 and 4.11) indicates significant differences in these processes. Methane is oxidized to formaldehyde at a higher rate and higher selectivity than at methanol oxidation. Low methanol yields at methane oxidation compared with formaldehyde confirm parallel proceeding of formaldehyde and methanol synthesis from methane. 

In this problem, we will determine the degrees of freedom of a process circuit conqjosed of several process units by examining a methanol-synthesis process. Methanol was first synthesized from carbon monoxide and hydrogen on a commercial scale in 1923 by Badische Anilindund Soda-Fabrik (BASF) in Germany [25]. Methanol is an important basic bulk chemical used in the synthesis of formaldehyde and acetic acid [28] and it has been proposed as an automobile fuel and fixel additive [26]. Methanol has also been proposed as a substrate to produce a bacterium suitable as a protein source (single-cell protein). The bacterium would be a soy meal and fishmeal substitute for animal and poultry feeds [27]. If these applications should ever develop, the demand for methanol will increase considerably. 

The recent interest in chemical production is based on a higher return expected for chemical [uoducts versus fuels. For example, biomass gasification can be used to produce a synthesis gas of hydrogen and carbon monoxide. This gas can be used in catalytic synthesis of a range of chemicals, from methanol and formaldehyde to higher hydrocarbons, in the same way that synthesis gas derived from natural gas can be used. However, by breaking down the biomass to the basic building blocks all product differentiation relative to fossil fuels is lost. 

Because formaldehyde synthesis is exothermic, the reactor requires a coolant to remove the excess enthalpy of reaction. Thermodynamically, we should run the reaction at as low a temperature as possible to increase conversion, but at low temperatures, however, the rate of reaction decreases. At high reaction temperatures unwanted side reactions occur. Commercially, the reaction occurs from 600 °C (1110 °F) to 650 °C (1200 °F), which results in a methanol conversion of 77 to 87 % when using a silver catalyst [24]. Because formaldehyde and methanol can form flammable mixtures with oxygen, we should carry out the reaction with mixture compositions outside of its flammability range. The oxygen used is less than the stoichiometric amount. 

Conversion of air-based processes into oxygen-based processes in vapor-phase oxidation to reduce polluting emissions. Examples are (i) synthesis of formaldehyde from methanol, (ii) etheneepoxidation to ethene oxide and (iii) oxychlorination of ethene to 1,2-dichloroethane. 

Formaldehyde is now made from CH4, but through a series of separate processes steam reforming, methanol synthesis, and methanol oxidation. This complex process route leads to low efficiency and high cost. Direct partial oxidation to formaldehyde is a worthy proce.ss objective. We need a catalyst with high activity and selectivity for reaction (5.1). 

Desulfurization of petroleum feedstock (FBR), catalytic cracking (MBR or FI BR), hydrodewaxing (FBR), steam reforming of methane or naphtha (FBR), water-gas shift (CO conversion) reaction (FBR-A), ammonia synthesis (FBR-A), methanol from synthesis gas (FBR), oxidation of sulfur dioxide (FBR-A), isomerization of xylenes (FBR-A), catalytic reforming of naphtha (FBR-A), reduction of nitrobenzene to aniline (FBR), butadiene from n-butanes (FBR-A), ethylbenzene by alkylation of benzene (FBR), dehydrogenation of ethylbenzene to styrene (FBR), methyl ethyl ketone from sec-butyl alcohol (by dehydrogenation) (FBR), formaldehyde from methanol (FBR), disproportionation of toluene (FBR-A), dehydration of ethanol (FBR-A), dimethylaniline from aniline and methanol (FBR), vinyl chloride from acetone (FBR), vinyl acetate from acetylene and acetic acid (FBR), phosgene from carbon monoxide (FBR), dichloroethane by oxichlorination of ethylene (FBR), oxidation of ethylene to ethylene oxide (FBR), oxidation of benzene to maleic anhydride (FBR), oxidation of toluene to benzaldehyde (FBR), phthalic anhydride from o-xylene (FBR), furane from butadiene (FBR), acrylonitrile by ammoxidation of propylene (FI BR)... 

From the point of view of the utilization of methanol in the production of formaldehyde by oxidation and in other processes in which methanol is subjected to the action of catalysts at elevated temperatures, it is of more importance to consider the equilibria, the mechanism, and the catalysis of the synthesis from water-gas than to consider the more industrial aspects of the process. Hence, no attempt will be made here to picture completely the various commercial aspects of methanol synthesis. 

Encouraged by the interesting results obtained in the high-pressure synthesis of acetic acid from methanol and carbon monoxide using nickel, cobalt, and iron halides as catalysts (5-7), the synthesis of glycolic acid from formaldehyde, carbon monoxide and water has been studied using various nickel, cobalt, and iron catalysts. 

Comparatively the synthesis of long-chain oxygenated from methanol has attracted relatively low attention because very low selectivity was obtained in previous work, but more recent studies, using decomposed hydrotalcite (MgO/AlgOg mixed oxides) and ZnO promoted Cu as catalysts, concluded that a mixture of alcohols, ketones, aldehydes, esters and ethers, with two to nine carbon atoms (79% of the total oxygenates products) can be obtained. In addition, in this study it is proposed that the first C-C carbon bond formation goes via formyl and formaldehyde intermediates. 

Similar IR experiments were performed to establish the reaction mechanism for methanol oxidation on unsupported and sihca-supported vanadia, which are more selective catalysts for formaldehyde synthesis than vanadia-titania. The formation of methoxy groups from methanol dissociative or condensative adsorption was determined while it was established that formaldehyde (directly adsorbed or produced by methoxy group oxidation) mainly adsorbs in the form of dioxymethylene species, stable only at relatively low temperatures. It was concluded that dioxymethylene can react with methanol at low conversion to give rise to dimethoxymethane while it preferentially desorbs as formaldehyde at higher conversions and temperatures. The weakness of the adsorption of formaldehyde was considered to be the key feature of catalysts allowing high selectivity in formaldehyde synthesis. 

Methanol me-tho- nol, - nol n [ISV] (1894) (carbi-nol, methyl alcohol, wood alcohol) CH3OH. A colorless, toxic liquid usually obtained by synthesis from hydrogen and carbon monoxide. It is sometimes called wood alcohol, but the methanol obtained from the destructive distillation of wood also contains additional, contaminating compounds. Methanol is used as an intermediate in producing formaldehyde, phenolic, urea, melamine, and acetal resins, and as a solvent for cellulose nitrate, ethyl cellulose, polyvinyl acetate, and polyvinyl butyral. Also known as Methyl Alcohol, Carbinol, Wood Alcohol, Colonial Spirits, and MeOH. Syn Formaldehyde. 

Ozonization of A -steroids usually gives complex mixtures (however, see ref. 48). Ozonolysis became a practical step in the general synthesis of B-norsteroids with the discovery that added methanol" (or formaldehyde ) improves yields significantly. Thus, Tanabe and Morisawa prepared 5/ -hydroxy-6/ -formyl-B-norsteroids (74) from cholesterol acetate, dehydroepiandrosterone acetate and pregnenolone acetate in overall yields of 64-74% by the reaction sequence represented below. 

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. 

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