Formaldehyde synthesis from methane

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. 

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. 

As we learned in Chapters 3 and 4, many inorganic compounds, not just ammonia, are derived from synthesis gas, made from methane by steam-reforming. In the top 50 this would include carbon dioxide, ammonia, nitric acid, ammonium nitrate, and urea. No further mention need be made of these important processes. We discussed MTBE in Chapter 7, Section 4, and Chapter 10, Section 9, since it is an important gasoline additive and C4 derivative. In Chapter 10, Section 6, we presented -butyraldehyde, made by the 0x0 process with propylene and synthesis gas, which is made from methane. In Chapter 11, Section 8, we discussed dimethyl terephthalate. Review these pertinent sections. That leaves only two chemicals, methanol and formaldehyde, as derivatives of methane that have not been discussed. We will take up the carbonylation of methanol to acetic acid, now the most important process for making this acid. Vinyl acetate is made from acetic... 

The activation of methane [1] is also included as one of the most desired yet not technically viable reactions. Abundant amounts of methane occur with crude oil and as gas in remote locations it is also produced in large quantities during hydrocarbon processing. A large fraction of this methane is flared, because economical use or transportation is not possible. This gas and the abundant resources of methane gas hydrates would make a very suitable feedstock for higher hydrocarbons, if its activation to produce molecules other than synthesis gas were feasible. Despite enormous fundamental and practical efforts [1-5], no applicable method has yet been found for creation of ethylene, methanol, or formaldehyde from methane. 

The partial oxidation of natural gas, consisting chiefly of methane, currently holds tremendous industrial potential. Possible routes for the direct synthesis of formaldehyde from methane, either via chlorine-based catalysts or with the use of chlorine-containing compounds in the gas feed (both using chlorine-modified supported palladium catalysts and at temperatures of 450-650°C) gave formaldehyde yields less than 7.7% under optimum conditions... 

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. 

Sergio R, Thornton JD. Synthesis of formaldehyde and methanol from methane and water in an electrical discharge two-phase reactor. J Appl Chem 1967 17 325—8. 

An interesting preparation of alkyl carboxylates in high yield (Table 3.14) from the sodium salt of the carboxylic acids under mild phase-transfer catalytic conditions involves their reaction with alkyl chlorosulphate [50] and has been used with success in the preparation of alkyl esters derived from p-lactam antibiotics. The procedure is also excellent for the production of chloromethyl esters, particularly where the carboxylic acids will not withstand the classical Lewis acid-catalysed procedure using an acid chloride and formaldehyde, or where the use of iodochloromethane [51] results in the formation of the bis(acyloxy)methane. The procedure has been applied with some success to the synthesis of chloromethyl A-protected a-amino carboxylates [52],... 

Methane is an important starting material for numerous other chemicals. The most important of these are ammonia, methanol, acetylene, synthesis gas, formaldehyde, chlorinated methanes, and chlorofluorocarbons. Methane is used in the petrochemical industry to produce synthesis gas or syn gas, which is then used as a feedstock in other reactions. Synthesis gas is a mixture of hydrogen and carbon monoxide. It is produced through steam-methane reforming by reacting methane with steam at approximately 900°C in the presence of a metal catalyst CH4 + H20 —> CO + 3H2. Alternately, methane is partially oxidized and the energy from its partial combustion is used to produce syn gas ... 

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)... 

The next most important demand for methyl alcohol is as a raw material in the synthesis of many important organic compounds, including formaldehyde acetic acid chloro-methanes, compounds in which the hydroxyl group and/or one or more hydrogen has been replaced by fluorine, chlorine, bromine, and/or iodine methyl methacrylate, a compound from which acrylic plastics are made methylamines, the source of another important class of plastics, dimethyl terephthalate, the monomer for yet another class of plastics and other products. 

The total plasma-chemical process of methane synthesis (9-63) can be considered a continuation of the carbon monoxide hydrogenization sequence, which starts with the production of formaldehyde from syngas (9-56), then proceeds to production of methanol from formaldehyde (9-57), and finally leads to the production of methane (9-62) in the following reaction ... 

There have also been claims for a prebiotic synthesis of porphyrins. An electric discharge applied to a gaseous mixture of methane, ammonia, and water gives large yields of formaldehyde, small amounts of pyrrole, and tiny amounts of porphyrin. More efficient syntheses of porphyrins, especially those related to protoporphyrins and uroporphyrins, seem likely. One possibility has been demonstrated by Albert Eschenmoser, who managed to synthesise a mixture of porphyrins in the absence of oxygen and water, from a-amino nitriles using montmorillonite clay as a catalyst. ... 

Methanol and formaldehyde were the main product and by-product of the gas-phase methanol synthesis, respectively, as shown in Table 2. For SC n-hexane, the selectivity of methanol was as high as 98.1% and very small amount of methane was found. In case of 2-butanol, the conversion was as high as 48.1% with 90.7% methanol selectivity and ester was the only by-product which formed from esterification in step (2). 

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