Methanol reactor conditions

The U.S. Department of Energy has funded a research program to develop the Hquid-phase methanol process (LPMEOH) (33). This process utilizes a catalyst such as copper—zinc oxide suspended in a hydrocarbon oil. The Hquid phase is used as a heat-transfer medium and allows the reaction to be conducted at higher conversions than conventional reactor designs. In addition, the use of the LPMEOH process allows the use of a coal-derived, CO-rich synthesis gas. Typical reactor conditions for this process are 3.5—6.3 MPa (35—60 atm) and 473—563 K (see Methanol). 

The first reaction produces methanol with a low hydrogen consumption, but evolves significantly greater amounts of heat. The second reaction evolves less heat, but consumes more hydrogen and produces the byproduct steam. Thermodynamically, low temperatures and high pressures favor methanol formation. The reactions are carried out with copper-containing catalysts with typical reactor conditions of 260°C and 5 MPa (Probstein and Hicks, 1982). 

Figure 19. Battelle s methanol specific reforming catalyst. Reactor conditions atmospheric pressure, reactant feed 50 50 by weight methanol and water mixture, 24 000— 50 000 ii GHSV. The conversion was reported as moles methanol reacted/moles methanol fed. (Reprinted with permission from ref 91. Copyright 2002 Elsevier.)...

The synthesis loop consists of a recycle compressor, feed/effluent exchanger, methanol reactor, final cooler and crude methanol separator. Uhde s methanol reactor is an isothermal tubular reactor with a copper catalyst contained in vertical tubes and boiling water on the shell side. The heat of methanol reaction is removed by partial evaporation of the boiler feedwater, thus generating 1-1.4 metric tons of MP steam per metric ton of methanol. Advantages of this reactor type are low byproduct formation due to almost isothermal reaction conditions, high level heat of reaction recovery, and easy temperature control by... 

The most selective catalysts for the oxidation of methanol to formaldehyde are molybdates. In many commercial processes, a mixture of ferric molybdate and molybdenum trioxide is used. Ferric molybdate has often been reported to be the major catalytically active phase with the excess molybdenum trioxide added to improve the physical properties of the catalyst and to maintain an adequate molybdenum concentration under reactor conditions(l,2). In some cases, a synergistic effect is claimed, with maximum catalytic activity for a mixture with an Fe/Mo ratio of l.T( 3j. A defect solid solution was also proposed( ). Aging of a commercial catalyst has been studied using a variety of analytical techniques(4) and it was concluded that deactivation can largely be account for by loss of molybdenum from the catalyst surface. 

Preliminary work reported by Kumar et al. from Argonne National Laboratory [3] showed that among several catalysts with different metals and supports the system Cu/ZnO showed the most promising results. In this work, a series of Cu-Zn and Cu-Zn-Al catalysts with different compositions have been prepared and tested under differential reactor conditions for the partial oxidation of methanol to H2. 

Figure 6 In-situ valance band data of a copper foil under methanol oxidation conditions (mixture B in Figure 5) during a temperature scan. The temperature was increased linearly with 5 K min, the acquisition of each spectrum took less than 2 min. The line indicates the occurrence of the Fermi edge. The SEM image stems from a 100 pm Cu sphere held for 24 h under methanol oxidation conditions of stoichiometric feed and 572 K reaction temperature. The flat terraces are of [111] orientation, the rough parts expose facets of [112] orientation. An oxide scale from isolation out of the reactor covers the sample...

Publications on successful application of realistic design models to commercial scale slurry processes are relatively scarce. Nevertheless, progress has been made, particularly in modelling slurry reactors for coal liquefaction, Fisher-Tropsch synthesis, methanol synthesis, oxydesulfurization of coal and selective hydrogenation where intermediates are the desired product. The result is encouraging, taking the lack of reliable mass transfer data at actual reactor conditions into account. 

Oxidation of cumene to cumene hydroperoxide is usually achieved in three to four oxidizers in series, where the fractional conversion is about the same for each reactor. Fresh cumene and recycled cumene are fed to the first reactor. Air is bubbled in at the bottom of the reactor and leaves at the top of each reactor. The oxidizers are operated at low to moderate pressure. Due to the exothermic nature of the oxidation reaction, heat is generated and must be removed by external cooling. A portion of cumene reacts to form dimethylbenzyl alcohol and acetophenone. Methanol is formed in the acetophenone reaction and is further oxidized to formaldehyde and formic acid. A small amount of water is also formed by the various reactions. The selectivity of the oxidation reaction is a function of oxidation conditions temperature, conversion level, residence time, and oxygen partial pressure. Typical commercial yield of cumene hydroperoxide is about 95 mol % in the oxidizers. The reaction effluent is stripped off unreacted cumene which is then recycled as feedstock. Spent air from the oxidizers is treated to recover 99.99% of the cumene and other volatile organic compounds. 

A process based on a nickel catalyst, either supported or Raney type, is described ia Olin Mathieson patents (26,27). The reduction is carried out ia a continuous stirred tank reactor with a concentric filter element built iato the reactor so that the catalyst remains ia the reaction 2one. Methanol is used as a solvent. Reaction conditions are 2.4—3.5 MPa (350—500 psi), 120—140°C. Keeping the catalyst iaside the reactor iacreases catalyst lifetime by maintaining a hydrogen atmosphere on its surface at all times and minimises handling losses. Periodic cleaning of the filter element is required. 

Solution Polymerization These processes may retain the polymer in solution or precipitate it. Polyethylene is made in a tubular flow reactor at supercritical conditions so the polymer stays in solution. In the Phillips process, however, after about 22 percent conversion when the desirable properties have been attained, the polymer is recovered and the monomer is flashed off and recyled (Fig. 23-23 ). In another process, a solution of ethylene in a saturated hydrocarbon is passed over a chromia-alumina catalyst, then the solvent is separated and recyled. Another example of precipitation polymerization is the copolymerization of styrene and acrylonitrile in methanol. Also, an aqueous solution of acrylonitrile makes a precipitate of polyacrylonitrile on heating to 80°C (176°F). 

The maximum attainable production was sought that did not cause thermal runaway. By gradually increasing the temperature of the water, boiling under pressure in the reactor jacket, the condition was found for the incipient onset of thermal instability. Runaway set in at 485.2 to 485.5 K for the 12 m reactor and at 435.0 to 435.5 K for the shorter, 1.2 m reactor. The smaller reactor reached its maximum operation limit at 50 K lower than the larger reactor. The large reactor produced 33 times more methanol, instead of the 10 times more expected from the sizes. This... 

This program helps calculate the rate of methanol formation in mol/m s at any specified temperature, and at different hydrogen, carbon monoxide and methanol concentrations. This simulates the working of a perfectly mixed CSTR specified at discharge condition, which is the same as these conditions are inside the reactor at steady-state operation. Corresponding feed compositions and volumetric rates can be calculated from simple material balances. 

Adesina [14] considered the four main types of reactions for variable density conditions. It was shown that if the sums of the orders of the reactants and products are the same, then the OTP path is independent of the density parameter, implying that the ideal reactor size would be the same as no change in density. The optimal rate behavior with respect to T and the optimal temperature progression (T p ) have important roles in the design and operation of reactors performing reversible, exothermic reactions. Examples include the oxidation of SO2 to SO3 and the synthesis of NH3 and methanol CH3OH. 

The gas feed and mixing system consists mainly of glass flowmeters or electronic mass flowmeters connected to gas bottles. For reactants that are in liquid state at room conditions (e. g. methanol) a saturator is normally used through which helium is sparged and then mixed with the other reactants. In this case all lines connected to the reactor are heated (e.g. at 150°C) to avoid condensation in the lines. In certain cases the gases from the bottles should be pretreated in order to avoid contamination of the catalyst. For example, a... 

In the above three processes, the catalysts are all composed of Cu-based methanol synthesis catalyst and methanol dehydration catalyst of AI2O3. The reactors used by JFE and APCI are slurry bubble column, while a circulating slurry bed reactor was used in the pilot plant in Chongqing. It can be foxmd from Table 1 that conversion of CO obtained in the circulating slurry bed reactor developed by Tsinghua University is obvious higher and the operation conditions are milder than the others. 

OS 38] [reactor and protocol given in [107]] By reaction of N,N-dimethylaniline with 4-nitrobenzenediazonium tetrafluoroborate, the corresponding azobenzene derivative is obtained at a conversion of 37% using methanol (protic solvent) or acetonitrile (aprotic solvent) under electroosmotic flow conditions [107] (see also [14]). 

OS 73] [R 4a] [P 54] The micro reactor yield (up to 42%) is comparable to that for batch Stork-enamine reactions using p-toluenesulfonic acid in methanol imder Dean and Stark conditions [11],... 

The experimental results are presented for the esterification of dodecanoic acid (C12H24O2) with 2-ethylhexanol (CgHigO) and methanol (CH4O), in presence of solid acid catalysts (SAC). Reactions were performed using a system of six parallel reactors (Omni-Reacto Station 6100). In a typical reaction 1 eq of dodecanoic acid and 1 eq of 2-ethylhexanol were reacted at 160°C in the presence of 1 wt% SAC. Reaction progress was monitored by gas chromatography (GC). GC analysis was performed using an InterScience GC-8000 with a DB-1 capillary colunm (30 m x 0.21 mm). GC conditions isotherm at 40°C (2 ntin), ramp at 20°C min to 200°C, isotherm at 200°C (4 min). Injector and detector temperatures were set at 240°C. 

This successfully demonstrated the Rh catalyzed carboi rlation of methanol in the absence of Mel. Even under the most forcing of conditions experienced in the vapor take-off reactor, the effluent contained, at most, ca. 0.3 wt% Mel which represents a >50X reduction from current commercial practice. 

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