Mitsubishi process

Fig. 5. Flash smelting process and equipment, (a) The Mitsubishi process. Courtesy of the Society of Mining Engineers (23). (b) Cutaway view of an...

Later developments which have had more impact on copper smelting relate to an approach which combines roasting, smelting and converting steps in one reactor, thereby making the copper production process continuous. The three unique continuous processes tried in operation are (i) the Worcra process, (ii) the Noranda process and (iii) the Mitsubishi process. The principles of the processes are respectively shown in Figures 4.5 to 4.7. 

Manganese dioxide can be used to absorb the initially low concentration SO2 to produce the sulphate in a Mitsubishi Process (23). In this case the absorbing phase is itself the oxidising agent. Regeneration with ammonia and air simultaneously produces ammonium sulphate which can be directly marketed as a fertiliser, thus the calcium ion problem of the dry limestone process is replaced by a plant nutrient ion -... 

The homogeneous palladium-catalyzed process for acetoxylation was never commercialized because of low selectivity and the difficulty in separating the catalyst from the reaction mixture. Heterogeneous palladium catalysts applied in the gas phase, in turn, quickly lose activity caused by buildup of polybutadiene. The Mitsubishi process uses a Pd-Te-on-active-carbon catalyst in the liquid phase. Tellurium apparently prevents palladium elution to acetic acid. 

Figure 9.5 illustrates a simplified scheme of the Mitsubishi process. The process includes the recycle of unconverted propane, and the BOC-PSA technology for rejection of N2 the latter is present in the feed, which contains oxygen-enriched air, and is also generated in the reactor by ammonia combustion. The unconverted hydrocarbon is recovered and recycled to the reactor [23fig], One Mitsubishi patent claims the differentiation of ammonia along the catalytic bed [23d], This might... 

The catalyst used in the Mitsubishi-process is a silica carrier with vanadium and phosphor as active components. A catalyst with the same composition was used by Varma and Saraf (18,19) in their investigation of the kinetics of the MA-synthesis on C -feedstocks. Their experiments in fixed beds cover a range of temperatures similar to the Mitsubishi process data. Consequently the results of Varma and Saraf are used in the present investigation. Basic to the model calculations is therefore the following reaction scheme ... 

Calculated and experimental maleic anhydride yields for the three fluid bed reactors involved in the scale-up of the Mitsubishi process are shown together in Figure 7. The yield value for the 45 cm dia. reactor was used to determine the reaction rate constant k, but the calculations for the 15 cm dia. bed and for the laboratory reactor with 4 cm diameter were performed without any parameter fitting. The calculation for the 15 cm bed is surprisingly close to the measurement whereas there is some deviation between theory and experiment on the laboratory scale the reason of which ist not quite clear. It should be noted however that in the laboratory reactor 1-butene was used as feed while on the pilot scale C -fractions of the naphtha cracker i.e. mixtures of various hydrocarbons were used. 

Other catalytic reactions carried out in fluidized-bed reactors are the oxidation of naphthalene to phthalic anhydride [2, 6, 80] the ammoxidation of isobutane to mcthacrylonitrilc [2] the synthesis of maleic anhydride from the naphtha cracker C4 fraction (Mitsubishi process [81, 82]) or from n-butane (ALMA process [83], [84]) the reaction of acetylene with acetic acid to vinyl acetate [2] the oxychlorination of ethylene to 1,2-di-chloroethane [2, 6, 85, 86] the chlorination of methane [2], the reaction of phenol with methanol to cresol and 2,6-xylenol [2, 87] the reaction of methanol to gasoline... 

By employing separate furnaces for smelting and converting, the Mitsubishi process allows better control of oxygen potential, and, hence, of magnetite formation. Oxygen efficiency in the converting furnace is 85 to 90%. 

The purification is done by fractional distillation. The selectivity to toluene diisocyanates is 97% (based on diamine). In the Mitsubishi process, the overall selectivity to diisocyanates is 81% (based on toluene). In addition to pure 2,4—toluene diisocyanates, two isomeric mixtures are available commercially, with ratios of 2,4— to 2,6—isomer of 80 20 and 65 35. 

Several Japanese processes (1, 2), such as the Ishikawajima, Chiyoda, or Mitsubishi processes in which the NO in the flue gas is oxidized to NO2 by O3 and subsequently passed to a NO2/SO2 absorber, have shown that a major fraction of the absorbed N0X is in the form of nitrogen-sulfur complexes, which are the compounds produced in the reaction between nitrite and sulfite ions. 

Nippon Kokan has developed and tested an ammonia-base doublealkali scrubbing process for sinter plants (27). Both in this system and the Mitsubishi process, lime will precipitate the sulfur oxides as well as the fluoride that is probably present. 

Figure 15.17 Mitsubishi process for the manufacture of BDO from butadiene.

FIGURE 9.20. Biocatalytic production of acrylamide Mitsubishi process. 

A key feature of the Mitsubishi process, the first company to build a fluid-bed reactor for this reaction, is the preparation of the catalyst under hydrothermal conditions, thus avoiding corrosive reaction conditions and the problems of flammable waste treatment encountered in organic preparation (20) the main steps of the preparation are reported in Scheme 4. 

The Mitsubishi process described above has since been converted to -butane feedstock. Mitsubishi just recently announced piloting an enhanced process with butane recycle and catalyst regeneration using a new non-VPO catalyst formulation, which is claimed to reduce cost. 

As an example, see the flow sheet of the Ruhrchemie plant at Oberhau-sen, which is in principle the same for a number of plants constructed under license of Ruhrchemie (see table 34 on page 76/77). The flow sheets of the BASF process [340,1037] and the Mitsubishi process [789] are very similar. 

Michael addition reactions alcohols with maleates, 46 with fumarates, 63 MA with acetylacetone, 235 MA derivatives, 65, 66 in maleamic acid cyclization, 83 with maleates, 63 maleates with thiols, 506 maleic anhydride, 65, 229 maleimides with amines, 512 Mitsubishi process, MA production, 29... 

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