Methanol condensation

Combined condensate W12 (268.7 ton/hr, 114 ppmw methanol). This stream consists of combined condensate from second, third, and fourth evaporators (Wg, 116.5 ton/hr, 20 ppmw methanol), condensate from fifth evaporator (W , 48.0 ton/hr, 233 ppmw methanol), condensate from sixth evaporator (Wjo, 52.0 ton/hr, 311 ppmw methanol), and condensate from surface condenser (W[, 52.2 ton/hr, 20 ppmw methanol). 

This cost includes air compression and methanol condensation. 

Design an exchanger to sub-cool condensate from a methanol condenser from 95°C to 40°C. Flow-rate of methanol 100,000 kg/h. Brackish water will be used as the coolant, with a temperature rise from 25° to 40°C. 

A new transition-state-searching algorithm was used to determine the mechanism for methanol condensation to form dimethyl ether within the microporous environment of the zeolite, chabazite, using periodic boundary conditions and density functional theory. An acid site in the zeolite produces MeOH2+ for nucleophilic attack by a second adsorbed MeOH molecule. 

Figure 16 Electron energy-loss spectra with 14-eV electrons incident on (a) a 5-ML film of methanol condensed on an Ar spacer after exposition to small (lower curve) and large (higher curve) electron doses and (b) a 10-ML film of CO condensed on a platinum substrate. The a H excited state of CO is characterized by a vibrational progression having a spacing of about 0.21 eV. (From Ref. 37.)...

Acid-treated clays Alcylation reactions (e.g. of benzene with benzyl chloride) Dimerization reactions (e.g. of a-methylstyrene) Etherification reactions (e.g. of ferf-butanol with methanol) Condensation reactions (e.g. of cyclohexanone) Separation of close boiling aromatic amines Separation of isomers of xylene... 

More recently phosphorus-containing zeolites developed by Union Carbide (alu-minophosphates, silicoaluminophosphates) were shown to be equally effective in methanol condensation.439-444 ZSM-5 was also shown to exhibit high activity and selectivity in the transformation of Fischer-Tropsch oxygenates to ethylene and propylene in high yields.445 Silicalite impregnated with transition-metal oxides, in turn, is selective in the production of C4 hydrocarbons (15-50% isobutane and 8-15% isobutylene).446... 

Use the information in Table 6.2 to calculate the enthalpy change that occurs when (a) 207 g of methanol condenses at its boiling point (337.8 K) ... 

The sodium salts of the hydrazones of 2-hydroxybenzaldehydes or of 2-hydroxyphenyl methyl ketones, prepared from the phenols and sodium methoxide in methanol, condensed... 

The product mixture leaving the reactor flows through heat exchangers in order to heat the reactant mixture to the desired temperature. Subsequently, the mixture is further cooled and raw methanol condenses while the unconverted synthesis gas is recycled to the reactor. The raw methanol is purified by distillation. 

Methanol synthesis section. The synthesis loop is comprised of a circulator combined with compressor (6), "MRF-Z" reactor (7), feed/effluent heat exchanger (8), methanol condenser (9) and separator (10). Currently, MRF-Z reactor is the only reactor in the world capable of producing 5,000-6,000 t/d methanol in a single-reactor vessel. The operation pressure is 5-10 MPa. The syngas enters the MRF-Z reactor (7) at 220-240°C and leaves at 260-280°C normally. 

For a first approximation to the solution, we will assume that essentially all the methanol condenses, with only trace amounts appearing in the recycle line. We will also assume that most of the water condenses and that very small amounts of carbon monoxide, carbon dioxide, hydrogen, methane, and nitrogen dissolve in the condensate. To account for methanol and water vapor in the recycle gases and the solubility of the gases in the crade methanol, we would have to include phase equilibrium relationships in the analysis. As stated earlier, several condensable byproducts, high and low-boiling compounds in the cmde methanol, are present in small amounts, as shown in Table 3.5.1. We will not consider these compounds in the synthesis-loop analysis. 

Use Table 16-6 to determine how much heat is released when 1.00 mole of gaseous methanol condenses to a liquid. 

Dimerization and codimerization reactions are widely used on an industrial scale either to provide chemicals of high added value or to upgrade by-product olefinic streams coming from various hydrocarbon cracking processes (steam or catalytic cracking) or hydrocarbon forming processes (Fischer-Tropsch synthesis or methanol condensation) (e. g., according to eq. (1)). 

Reformed gas is compressed to 100 barg in a 27 MW split, three-stage compressor and injected into the converter loop at the suction of the 5 MW circulating compressor. Converter circulating gas plus make-up gas is heated and fed to a six-bed converter (ZnO/CuO/Al O catalyst). Part of the gas is fed to the inlet of the reactor at 210-240°C and the balance is fed, at a lower temperature, to the lower beds as quench gas. Reactor effluent is cooled both against reactor feed and saturator water feed before passing to the methanol condensers. The crude methanol is then rundown to off-site tankage and the MTG unit. 

The thermodynamics of this process are described in detail in references (67 —72, 80,81). Let us examine a typical methanol injection system. In a typical methanol injection and recovery system for a cold-oil absorption or turboexpander plant, feed gas passes through a free-water knockout drum and into a gas-gas exchanger with methanol being sprayed on exchanger tube-sheets. Methanol inhibits hydrate formation and aqueous methanol condenses in the exchanger (and the chiller following it) and is pumped to a primary separator. The methanol-water solution is then flashed in a flash drum and filtered into a methanol still to recover methanol. Normally, methanol dissolves in the hydrocarbon liquids and is distilled as a mixture of propane and methanol. Some of the methanol is recovered as the overhead product to recover the methanol dissolved in the heavier solution, the bottoms of the methanol still (propane product or hydrocarbon liquids from the demethanizer)... 

Wilkinson s catalyst mediates a Cannizzaro-like process with benzaldehyde in ethanol the aldehyde serves as a dihydrogen source to reduce itself, and the benzoic acid formed is esterified by the solvent (eq 8). Pyrrolidine is IV-methylated by methanol in the presence of RhCl(PPh3)3, a reaction that presumably occurs via hydrogen transfer from methanol, condensation of the formaldehyde formed with pyrrolidine, then hydrogen transfer to the iminium intermediate (eq 9). ... 

An important problem is the research of change of the initial drop spectrum described by distribution (21.3) under the influence of mass-exchange (evaporation of methanol, condensation of water vapor), coagulation, breakup and deposition of drops at the pipe wall. As of now, it is not possible to take into account the flux of drops from the wall (ablation), because at the present time there are no reliable relevant data in literature. 

Bogorad, I.W. et al (2014) Building carbon-carbon bonds using a biocatalytic methanol condensation cycle. Proc. Natl Acad. Sci. 

Unlike the raw methanol produced at high pressures over a zinc-oxide/chro-mium-oxide catalyst in the past, the reaction of copper catalysts produces hardly any aldehydes or ketones. Although the fact that methyl formiate or methyl acetate can be detected, suggests that minor quantities of formic acid and acetic acid are formed as well, corrosion by formic acid in the raw methanol condensation section, which had been so much dreaded in the high-pressure synthesis processes, has not been described for low-pressure syntheses. 

The second key component in this system is methyl formiate. Acetone occurs in the raw methanol only in the order of a few ppm, and dimethyl ether is much more volatile than methyl formiate and can therefore be separated more easily from the raw methanol. Essentially, only the prerun column is a pure stripping column, the heat supply to the colunrn bottoms and the number of trays being designed to ensure that methyl formiate is, for all practical purposes, removed completely from the bottom product, the so-called stabilized methanol. Refluxing the methanol condensed in the ovahead condensers is inevitable to keep overhead methanol losses to a minimum. 

The preferred process consists of mixing sulfuric acid, methanol, and the fluori-nated emulsifier liquid resulting in a strongly acidic mixture containing the methyl ester of the perfluorinated emulsifier acid, that is, methyl perfluorooctanoate (Me-PFOA). Distillation of Me-PFOA yields a ternary mixture containing Me-PFOA along with water and methanol. Condensation of the vapor results in two phases. The lower phase is more or less pure ester while the upper phase consists of water... 

Figure 6.3 The main components of a DMFC. Not all the components will always be present. However, larger systems may have additional components, such as heat exchangers in the fuel system for cooling, air pumps, and methanol condensers in the carbon dioxide outlet pipe. See text, especially Section 6.2.4. Note that the electrode connections are shown at the edge for simplicity normally the current will be taken off the whole face of the electrode, as in Figure 1.8. 

---