Methanol dimethyl ether

Use Learning By Modeling to make models of water methanol dimethyl ether and di tert butyl ether Mini mize their geometries and examine what happens to the C—O—C bond angle Compare the C—O bond dis tances in dimethyl ether and di tert butyl ether... 

Fig. 5. Methanol-to-hydrocarbons reaction path at 371°C, where (A ) is methanol ( ), dimethyl ether (), water (D), paraffins (and Cg...

The conversion of methanol to hydrocarbons (MTHC) on acidic zeolites is of industrial interest for the production of gasoline or light olefins (see also Section X). Upon adsorption and conversion of methanol on calcined zeolites in the H-form, various adsorbate complexes are formed on the catalyst surface. Identification of these surface complexes significantly improves the understanding of the reaction mechanism. As demonstrated in Table 3, methanol, dimethyl ether (DME), and methoxy groups influence in a characteristic manner the quadrupole parameters of the framework Al atoms in the local structure of bridging OH groups. NMR spectroscopy of these framework atoms under reaction conditions, therefore, helps to identify the nature of surface complexes formed. 

The process, referred to as methyl alcohol-to-gasoline conversion, involves initial dehydration of methyl alcohol to dimethyl ether, with a subsequent carbenoid-type reaction. It goes probably through an oxonium ylide-type intermediate that is readily methylated by excess methanol (dimethyl ether) producing the crucial Ci —> C2 conversion and then cleaves to ethylene. Once a C precursor is converted into a C2 derivative (i.e., ethylene), the further conversion to higher hydrocarbons of the gasoline range (or to aromatics) follows well-known chemistry. 

The carbonylation of methanol, dimethyl ether and methyl acetate using as catalyst precursors [RuI2(CO)4] and [Ru(acac)3] (88) with Nal, HI or Mel as promoter has been reported.381 The major products were ethanol from methanol, methyl acetate from dimethyl ether, and acetic anhydride plus acetic acid from methyl acetate (equations 67-69). 

At first the calculations were performed on eleven simple molecules ethane, propane, isobutane, neopenthane, ethene, 2-butene, methanol, dimethyl ether, dimethoxymethane, trimethoxymethane, and tetramethoxymethane. The correlation between calculated and experimental principal values is shown in Figure 1. The correlation coefficient is R2 = 0.97 and the root mean square deviation of the calculated from the experimental values is 13 ppm. 

The initial dehydration reaction is sufficiently fast to form an equilibrium mixture of methanol, dimethyl ether, and water. These oxygenates dehydrate further to give light olefins. They in turn polymerize and cyclize to form a variety of paraffins, aromatics, and cycloparaffins. The above reaction path is illustrated further by Figure 3 in terms of product selectivity measured in an isothermal laboratory reactor over a wide range of space velocities. ( 3) The rate limiting step is the conversion of oxygenates to olefins, a reaction step that appears to be autocatalytic. In the absence of olefins, this rate is slow but it is accelerated as the concentration of olefins increases. 

Still another multi-reactor approach is to divide the MTG reaction into two steps as shown in Figure 7. In the first step, methanol is partially dehydrated to form an equilibrium mixture of methanol, dimethyl ether and water over a dehydration catalyst. About 15% of the reaction heat is released in this first step. In the second step, this equilibrium mixture is converted to hydrocarbons and water over ZSM-5 catalyst with the concomitant release of about 85% of the reaction heat. Though this two step approach does not have any of the inherent complications of the previously mentioned multibed reaction systems, it leaves one with a substantial amount of the reaction heat (85%) still to be taken over one catalyst bed. This requires a fairly high recycle stream to moderate the temperature rise over the second reactor. Such a high recycle design would require careful engineering in order to transfer heat efficiently from the reactor effluent to the recycle gas and reactor feed. However, this two stage reactor system is the simplest of the fixed-bed systems to develop. 

Low temperature methanol Dimethyl ethers of polyethylene glycol Di-isopropanolamine dissolved in sulfolane and water Monoethanolamine (MEA) or diglycolamine... 

Gas chromatography was employed for analysis of the reaction products Hi, CO and CO2 were analyzed by thermal-conductivity detector (TCD) methanol, dimethyl ether, methyl formate and hydrocarbons were analyzed by the flame ionization detector (FID). 

Chloromethane can be produced by either chlorination of methane or reaction of methanol with hydrogen chloride. In an integrated production of silicones hydrogen chloride obtained by hydrolysis of methylchlorosilanes is recycled to the Direct Process via a chloromethane synthesis. The losses are compensated by make-up chloromethane or hydrogenchloride. Impurities, tike water, methanol, dimethyl ether or oxygen, must be kept at as low a level as possible. 

Syngas produced from gasification of coal, biomass, petroleum coke, and other types of feedstock can be used to generate electricity or to produce hydrogen and other liquid fuels or chemicals (ammonia, methanol, dimethyl ether, and diesel fuel) by... 

Dioxane, water, methanol, dimethyl ether, cyclohexene, benzene, tetrahydrofuran (HCOOH) Fluorescence excitation spectra R2PI, IR-UV, DF 574... 

Using non-traditional feedstocks to produce synthetic ultra-clean fuels, including F-T liquids, methanol, dimethyl ether, and hydrogen has numerous benefits including (4) ... 

The fixed-bed reactor system was comprised of two reactors. The first reactor was a methanol dehydration reactor where a methanol/dimethyl ether/ water mixture was produced, and the second reactor was a hydrocarbonforming reactor which converted this mixture over ZSM-5 catalyst to a gasoline-range hydrocarbon product. As noted earlier, the conversion of methanol... 

Cavaeanti, F., Stakheev, A., and Sacther, W., Direct synthesis of methanol, dimethyl ether, and paraffins from syngas over Pd/Zeolite Y catalysts, J. Catal., 134 226-241 (1992). 

This process operates in the aqueous phase at 250 C and 65.10 Pa absolute, in the presence of cobalt iodide as catalyst The high-pressure reactor lined with hastelloy C for corrosion resistance features internal agitation of the liquid obtained by gas injection ( air lift type). It is continuously supplied with a stream of methanol, dimethyl ether, carbon monoxide if required, and water preheated to between 40 and 80°C. The amount of water added is one-third of that of methanol by weight The arid mixture and the unreacted gases are collected at the top of the reaction tower, cooled, and brought to 1.10 Pa absolute in a flash drum. The methyl iodide and header components in, the Hashed gases are recovered by scrubbing with methanol feed. ... 

Aniline can also be alkylated in the vapor phase at temperatures of about 400°C. using methanol, dimethyl ether, ethyl alcohol, "hod diethyl ether. Alumina is reported s to be the most efficient catalyst for a continuous-flow process with aromatic amines. With other catalysts there is a greater alkylation in the ring. 

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