Dimethyl ether, pyrolysis

Fig. 5.2 The main crop-to-energy chains. BtL Biomass-to-Liquid, GtL Gas-to-Liquid, ETBE Ethyl tert-butyl ether, MTBE Methyl tert-butyl ether, MeOH Methanol, DME Dimethyl ether. Pyrolysis oil, HTU-Diesel (Hydro Thermal Upgrading), ethanol and hydrogen from ligno-cellulosic species are not considered here because of their minor practical relevance in the near future...

The reaction between isobutylene (separated from C4 fractions from cracking units or from cracking isobutane to isobutene) and formaldehyde produces a cyclic ether (dimethyl dioxane). Pyrolysis of dioxane gives isoprene and formaldehyde. The formaldehyde is recovered and recycled to the reactor. 

Fuel industry is of increasing importance because of the rapidly growing energy needs worldwide. Many processes in fuel industry, e.g. fluidized catalytic cracking (FCC) [1], pyrolysis and hydrogenation of heavy oils [2], Fischer-Tropsch (FT) synthesis [3,4], methanol and dimethyl ether (DME) synthesis [5,6], are all carried out in multiphase reactors. The reactors for these processes are very large in scale. Unfortunately, they are complicated in design and their scale-up is very difflcult. Therefore, more and more attention has been paid to this field. The above mentioned chemical reactors, in which we are especially involved like deep catalytic pyrolysis and one-step synthesis of dimethyl ether, are focused on in this paper. 

No products could be identified when 3-alkyl- or 3-aryl-4-methylene-3,4-dihydro-l,2,3-benzotriazines were refluxed in ethanol or p-xylene (75CJC3714). Flash vacuum pyrolysis of 3-adamantyl-l,2,3-benzotriazin-4-one (79) led to the isolation of 1-adamantylbenzazet-2(l//)-one (80) (73JCS(P1)868>. In most other cases the isolation of the benzazetone failed. When l,2,3-benzotriazin-4-one (21) is heated in diethylene glycol dimethyl ether, quin-... 

Pyridine, 3-amino, 30, 3 5-ETHYL-2-METHYL, 30, 41 4-Pyrimidol, 2,6-diamino-, 32, 45 Pyrogallol-1,3-dimethyl ether, 31, 92 Pyrolysis, of, V-a.zo-bis- -cyclohexane-nitrile to l,l -dicyano-l,l -bicyclo-hexyl, 32, 48... 

The first extended study made with the aid of a mass spectrograph was that of liCifer and Urey, who employed it in the study of the pyrolysis of dimethyl ether and acetaldehyde. While they were not successful in detecting radicals, they were able to demonstrate that formaldehyde is an intermediate in the decomposition of dimethyl ether and follow its concentration. 

Table XIII.14. Thermodynamic Data for Some Reactions of Interest in the Pyrolysis of Dimethyl Ether (All Gas Phase)... 

In 1881, Hofmann 6°) reported that the thermal decomposition of tetramethylammonium hydroxide gives trimethylamine and methanol. In 1964, a study by Musker 105> showed that the products resulting from the dry decomposition of tetramethylammonium hydroxide at 135— 140 °C were trimethylamine and dimethylether. Only a trace of methanol was observed. Trace amounts of dimethyl ether was reported as a product of the pyrolysis of cyclohexylmethyl-(3-d-trimethylammonium hydroxide and its formation was explained by a three step mechanism involving a sequence of Su2 reactions 31b An analogous mechanism for the decomposition of tetramethylammonium hydroxide, which would account for the observed products, was proposed by Tanaka, Dunning, and Carter... 

Many other catalytic fluidized-bed processes have been tested at various scales. These include catalytic low-temperature oxidation, catalytic gasification and pyrolysis of biomass and waste plastic, production of carbon nanotubes, dry reforming of methane, hydrogenation and dehydrogenation of hydrocarbons, methanol-to-gasoline (MTC) process, synthesis of dimethyl ether (DME), and selective catalytic reduction of nitrogen... 

The Curie Point flash evaporation-pyrolysis gas chromatography-mass spectrometric method [32] described in section 2.2.1.2 for the analysis of aliphatic hydrocarbons in soil has also been applied to the determination of polystyrenes in soil via identification and determination of their unzipping pyrolysis products, such as styrene monomer, a-methyl styrene, 3-methyl styrene, 4-methyl styrene, a-3 dimethyl styrene, 3-ethylstyrene, a-4 dimethyl styrene, 3.5 dimethyl-styrene, a-2 or 2,5 or 2.4 dimethyl styrene also various phenyl ethers. 

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