Technology drawbacks

One process that capitalizes on butadiene, synthesis gas, and methanol as raw materials is BASF s two-step hydrocarbonylation route to adipic acid(3-7). The butadiene in the C4 cut from an olefin plant steam cracker is transformed by a two-stage carbonylation with carbon monoxide and methanol into adipic acid dimethyl ester. Hydrolysis converts the diester into adipic acid. BASF is now engineering a 130 million pound per year commercial plant based on this technology(8,9). Technology drawbacks include a requirement for severe pressure (>4500 psig) in the first cobalt catalyzed carbonylation step and dimethyl adipate separation from branched diester isomers formed in the second carbonylation step. 

Several processes have been developed [41-43] to overcome the technological drawbacks of plastics incineration cited above. These include continuous rotary-kiln processes a process for glass-reinforced PET a combined system for wood fiber and PET to provide steam to power equipment and a fluidized system for pyrolysis, in combination with silver recovery from photographic film. Incineration of photographic film raises the additional problem of the formation of toxic halogenated compounds due to the presence of silver halides. 

Thin-layer chromatography (tic) (16) is frequently used. The procedure allows for rapid screening for most dmgs of abuse using simple, inexpensive technology. A drawback to tic, however, is that the technique is not especially sensitive and low levels of dmgs may be missed. 

Mitsubishi Gas Chemical Company Process. The commercial MMA manufacturing process based on sulfuric acid and acetone cyanohydrin suffers from the large quantities of ammonium sulfate produced. Because ammonium sulfate has only low value as fertili2er, regeneration of sulfuric acid from ammonium sulfate [7783-20-2] is required. Despite the drawbacks of using sulfuric acid, this technology is stiU the most widely practiced... 

A key feature of encapsulation processes (Figs. 4a and 5) is that the reagents for the interfacial polymerisation reaction responsible for shell formation are present in two mutually immiscible Hquids. They must diffuse to the interface in order to react. Once reaction is initiated, the capsule shell that forms becomes a barrier to diffusion and ultimately begins to limit the rate of the interfacial polymerisation reaction. This, in turn, influences morphology and uniformity of thickness of the capsule shell. Kinetic analyses of the process have been pubHshed (12). A drawback to the technology for some apphcations is that aggressive or highly reactive molecules must be dissolved in the core material in order to produce microcapsules. Such molecules can react with sensitive core materials. 

Synthesis Ga.s, Since petroleum prices rose abmpdy in 1974, the production of ethanol from synthesis gas, a mixture of carbon monoxide and hydrogen, has received considerable attention. The use of synthesis gas as a base raw material has the same drawback as fermentation technology low yields limited by stoichiometry. 

The popularity of EVs did not last. By the 1920s, the performance of ICE vehicles improved dramatically, and the earlier major drawbacks had been solved. Ironically, the replacement of the dangerous hand crank -with a battei y-powered electric starter was a major innovation accelerating ICE vehicle sales at the expense of EV sales. At the same time, there were no concurrent solutions to the limitations of battery technology for EVs that addressed the demand to drive faster and farther. 

Apart from economic considerations, the inherent disadvantages of biocatalysts have also limited the transformation of new technologies into industrial processes. Table 2.3 lists the major drawbacks of bioprocesses. 

The interest in this problem arises from the desire to eliminate some drawbacks typical of PAN and the materials obtained from it enhanced stiffness, poor dyeability, electrifiability, combustibility, etc., as well as from a wide range of possibilities in producing, based on PAN, new readily available materials with specific technologically valuable properties. 

We should also compare the scope of the technologies for different waste streams. With the exception of Brocat which only handles HBr, the systems can be used with HBr or metal salt streams. However, H2O2 has an advantage in terms of handling impurities in the steam such as low levels of organics. Chlorine and chlorate will suffer from reduced efficiency due to side reactions Brocat has potential problems with catalyst poisoning. H2O2 suffers no major drawbacks in this respect. 

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