Carbon-1 3 high-pressure process

Methanol Synthesis. Methanol has been manufactured on an industrial scale by the cataly2ed reaction of carbon monoxide and hydrogen since 1924. The high pressure processes, which utili2e 2inc oxide—chromium oxide catalysts, are operated above 20 MPa (200 atm) and temperatures of 300—400°C. The catalyst contains approximately 72 wt % 2inc oxide, 22 wt % chromium (II) oxide, 1 wt % carbon, and 0.1 wt % chromium (VI) the balance is materials lost on heating. 

KAAP [Kellogg advanced ammonia process] The first high-pressure process developed for synthesizing ammonia from its elements which does not use an iron-containing catalyst. The reformer gas for this process is provided by the KRES process. The catalyst was developed by BP it contains ruthenium supported on carbon. Developed by MW Kellogg Company in 1990 and first installed by the Ocelot Ammonia Company (now Pacific Ammonia) at Kitimat, British Columbia, from 1991 to 1992. Another plant was installed at Ampro Fertilizers in Donaldsonville, LA, in 1996. 

Mitsui-Toatsu A high-pressure process for making urea from ammonia and carbon dioxide. Invented in 1967 by Toyo Koatsu Industries. 

An industrial process to produce methanol from carbon monoxide and hydrogen was developed by BASF in 1923 using a zinc oxide-chromia catalyst.361 362 Since this catalyst exhibited relatively low specific activity, high temperature was required. The low equilibrium methanol concentration at this high temperature was compensated by using high pressures. This so-called high-pressure process was operated typically at 200 atm and 350°C. The development of the process and early results on methanol synthesis were reviewed by Natta 363... 

The co-monomers such as vinyl acetate, acrylate esters, or carbon monoxide are fed together with ethylene, or introduced by liquid pumps, into the suction of the secondary compressor. The concentration in the feed of the co-monomer which is required to achieve a certain level of the co-monomer in the resulting polymer depends on the reactivity ratios, ri and r2, which are the ratios of rate constants of chain-propagation reactions [5]. The values for the co-monomers used in the high-pressure process are presented in Table 5.1-3. In the case of vinyl acetate, both reactivity ratios are identical and therefore the composition of the copolymer is the same as that of the feed. The concentration of vinyl acetate, for example, in... 

The reaction is exothermic and may form polymer from a molecular weight of 1000 to well over 1 million. The high-pressure process, which normally produces types I and II, uses oxygen, peroxide, or other strong oxidizers as catalyst. Pressure of reaction ranges from 15.000 to 50.000 psi ( 1,020-3,400 atmospheres). The polymer formed in this process is highly branched, with side branches occurring every 15-40 carbon atoms on the. chain backbone. Ciystallinity of this polyethylene is approximately 40-60%, Amorphous content of the polymer increases as the density rs reduced,... 

Polyethylenes produced commercially via high pressure, free radical processes have densities around 0.92 g/cc and are referred to simply as "low density" polyethylenes. It has been well established from infrared measurements that these low density polyethylenes possess appreciable quantities of ethyl and butyl branches (1-3) but it was not until C-13 NMR became available that an absolute identification, both qualitatively and quantitatively, of the short branches became possible (4-8). Long chain branching is also present in high pressure process low density polyethylenes and carbon-13 NMR was useful here also in establishing the identity and relative amounts of long versus short chain branches (9-11). 

Carbon dioxide and ammonia are obtained as by-products in both the low-and high-pressure processes. These components are usually recycled to the urea process to improve process economics. With recycling, 1.5 to 2.0 pounds of urea are used to produce one pound of melamine. This corresponds to a yield of 95% (compared to a yield of only 49% without recycle)114. 

Diamonds were first synthesized through a high-temperature and high-pressure process [50]. Using diamond seeds, micrometer-sized diamonds have been grown in a hydrothermal process at 800 °C and 1.4 kbar [51]. Chemical vapor deposition (CVD) is a low-pressure technique for the preparation of polycrystalline diamonds films using CH4 or C2H2 as a carbon source [52]. 

It should be recognized that only small amounts of entrainer (up to 5%) are reasonable. Such low levels cannot change very much the polarity of carbon dioxide. If larger amounts are necessary the high pressure process is less viable and it should be replaced by direct alcoholic extraction. Even the small amounts destroy most of the advantages of the pure carbon dioxide as they leave solvent residues in the extract and raw material. Such residues would have to be removed in a second step. Additionally new problems are created in maintaining a strictly defined and constant entrainer concentration during the operation. 

The essential reaction to polymer, which occurs in the high-pressure process to polyethylene, is correctly represented by Eq. 23.1. However, careful examination of the high-pressure product by infrared spectroscopy shows that it has 20-30 methyl groups per 1,000 carbon atoms of chain, i.e., far more than can be accounted for by the 1 or 2 chain end methyl groups expected... 

Sims M, Estigarribia E. Continuous sterilization of aqueous pumpable food using high pressure carbon dioxide. 4th International Symposium on High Pressure Process Technology and Chemical Engineering, Venice, 2002. 

In the presence of catalysts such as are used for the synthesis of methanol from mixtures of hydrogen and carbon monoxide and which have been promoted by the addition of an alkali oxide, ethanol may be dehydrated to form butanol in a high pressure process. Catalyst mixtures composed of chromium and zinc oxides to which either barium hydroxide or potassium oxide has been added have been specified.6 ... 

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