Methanol conversion reactions

Basch, H., Mogi, K., Musaev, D. G., Morokuma, K., 1999, Mechanism of the Methane —> Methanol Conversion Reaction Catalyzed by Methane Monooxygenase A Density Functional Study , J. Am. Chem. Soc., 121, 7249. 

Catalytic reaction nethod. The methanol-conversion reaction was carried out in a ordinary flow reactor under atmospheric pressure. A 0.5 ml portion of the catalyst was packed into a Pyrex tubular reactor of 6 mm inner diameter. The reaction gas, composed of 20 100% MeOH balanced with N2, was then allowed to flow through the catalyst bed at a temperature in the range 24-0 360°C and a space velocity (SV) in the range 4-00 4-000 liter"liter 1,h 1. The olefin-conversion reaction was carried out in a flow reactor of 8 mm inner diameter. The reaction gas, composed of an olefin (CgH, C3H6 or C,Hg) and N2 mixed at various ratios, was then allowed to flow through the catalyst bed at a temperature in the range 260 360°C and a space velocity in the range 900 4500 h-1. 

Basch, H., Musaev, D.G., Mogi, K. and Morokuma, K. (2001 a) Theoretical studies on the mechanism of the methane —> methanol conversion reaction catalyzed by methane monooxygenase O-side vs N-side... 

A stream of methanol is joined by a recycle stream, also methanol, and the combined stream is fed. o the conversion reactor. Also entering the reactor are air (to oxidize some of the hydrogen produced in the methanol conversion reaction) and steam (to control the reactor temperature). The product... 

A mechanistic study of in.itial C-C bond formation in the methanol conversion reaction is reported. Reaction of methanol with added hydrogen using W0,/A1203 and H-ZSM-5 catalysts does not significantly alter the product distribution from that of normal methanol conversion. This is considered to be clear evidence against the involvement of a gas phase methylene intermediate. In addition the behaviour of the methoxymethyl radical in the gas phase has been studied and the results demonstrate that this species is also not involved as an intermediate in initial C-C bond formation. 

For washcoat preparation silicalite zeolite powder (S-115 from Union Carbide Corp.) was dried at 100°C in an oven overnight. Prehydrolyzed ethyl-orthosilicate containing 19.52 silica (Silbond H-5 from Stauffer Chemical Co.) was the source of the silica binder. Absolute ethanol (from U.S. Industrial Chemicals Co.) and absolute methanol (reagent grade from J. T. Baker Company) were used without further purification for the liquid portion of the washcoat slurry and for the methanol conversion reaction, respectively. Reagent grade ammonium nitrate (from J. T. Baker) was used for ion-exchange purposes. 

The methanol conversion reaction was carried out over these H-silicalite/honeycomb samples in a reactor set up as shown in Figure 1. Absolute methanol was injected into an evaporator at the rate of 0.49 ml/hour. Dry helium, a diluent gas, was passed into the evaporator at a rate of 45 ml/minute. Gaseous products were directly passed via a heated line through a six port Valeo valve with a 0.25 ml sample loop. The products were analyzed by a Varian 6000 GC with a Chromosorb-102 column. For each sample, reaction runs were made for at least 50 hours and steady state conversion data were collected. Methanol conversion was monitored at different catalytic reaction temperatures 100°C, 150°C, and 250°C. However, percent methanol conversions were calculated only for the 100°C and 150°C runs. Methanol conversion, calculated per gram of zeolite in the washcoat, was plotted (Figure 2) vs. percentage binder content. 

Methanol Conversion. Methanol conversion reactions based on borosilicate catalysts have been studied extensively (10.15,24,28.33.52-54). During the conversion of methanol, the reaction proceeds through a number of steps, to yield dimethylether, then olefins, followed by paraffins and aromatics. The weaker acid sites of borosilicate molecular sieves relative to those of aluminosilicates require higher reaction temperatures to yield aromatics. The use of less forceful process conditions leads to the formation of olefins selectively, instead of a mixture of paraffins, olefins, and aromatics (10.28.53.54). 

The conversion of methanol to hydrocarbons is the most studied reaction of oxygenates over microporous solids, for both commercial and academic reasons. Methanol can be generated from syngas over copper- and zinc-based catalysts using the ICI process, and syngas can be prepared from methane, which is a readily available resource. Under the correct economic conditions, methanol conversion reactions can provide an important route to higher... 

Bleken et al. (2011) have compared the methanol conversion of four kinds of catalysts with 10-membered ring three-dimensional pore structure (i.e., IMF, TUN, MEL, and MFI). They found that although aU catalysts have 10-ring cross channel, but there are differences between them in terms of life time and coke compositions. Since the cross channels in IMF and TUN structure have wide space near the cross, which allows the formation of heavy coke species, the zeolites (IM-5 and TUN-9) having IMF and TUN structure appear rapid deactivation in methanol conversion reaction. On the contrary, zeolites with MEL and MFI structure (such as ZSM-11 and ZSM-5), in which the space near the cross is relatively narrow and Hmits the formation of coke compositions, have a long Hfe time in the methanol conversion reaction. In this case, there are no heavy coke compositions in the channels, and the deactivation is mainly caused by the coke formation on external surface of zeolites. 

Yuan et al. (2012) investigated methanol conversion reaction and coke deposition over SAPO-34 catalyst in a microscale fluidized bed reactor, which presented some interesting results in their temperature-programmed experiments (Yuan et al., 2012). As shown in Fig. 14, methanol was fed to the reactor at 250 °C, but the hydrocarbon products generated in the temperature range of 250-300 °C is negligible. The conversion of methanol increased from temperature of 300 °C, and reached a peak conversion at 325 °C and then dropped until 350 °C. When the temperature further rose from 350 °C, the conversion of methanol increased continuously. In order... 

Hunter R, Hutchings GJ, Pickl W. Mechanism studies on initial C-C bond formation in the zeohte ZSM-5 catalyzed methanol conversion reaction—evidence against a radical pathway. J Chem Soc Chem Commun 1987 843. 

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