Other Process

Processes that have been considered, or investigated include  

Some processes that have been developed and commercially operated remove the calcium from solution in a different way. These routes have not been as successful, however, as those described previously. 

The solution obtained by reaction of nitric acid with phosphate rock can be treated by the addition of a soluble sulfate to precipitate part or nearly all of the calcium as calcium sulfate (gypsum or hemihydrate). In commercial processes, ammonium sulfate, potassium sulfate, and sulfuric acid have been used. Langbeinite (K2S04 2MgS04) has been used experimentally. The calcium sulfate may be separated by filtration or allowed to remain in the product. In most plants, the calcium sulfate is removed to produce a higher grade product. Chemical reactions are  

The reaction using sulfuric acid is shown in equation 

When ammonium sulfiite is used to predpitate calcium as gypsum, the gypsum can be treated wrath ammonia and carbon dioxide to regenerate ammonium sulfiite, which is recycled, and to convert the calcium to calcium carbonate  

This is the basis for the sulfate recycle process, which was developed by TVA on a pilot-plant scale [16]. One disadvantage of this process is that the N P20s ratio in the product is fixed at about 2 1 (28-14-0 grade). 

Other Processes. Direct nonoxidative conversion of methane to higher hydrocarbons has been studied to improve the yield and selectivity of the desired products. 

Selective synthesis of acetylene ( 90%) from methane was accomplished by microwave plasma reactions.568 Conversion of methane to acetylene by using direct current pulse discharge was performed under conditions of ambient temperature and atmospheric pressure.569 The selectivity of acetylene was 95% at methane conversion levels ranging from 16 to 52%. In this case oxygen was used to effectively remove deposited carbon and stabilize the state of discharge. Similar high 

Microwave heating was also used to induce catalytic oligomerization of methane to afford C2-C4 hydrocarbons.571 Changing the catalysts and the applied power and the use of diluent gas (He) allowed significant alteration of product selectivities. Selectivity to benzene over nickel powder or activated carbon was 24 and 33%, respectively. 

Photoinduced coupling of methane was reported over Ti02 at 100-200°C in the presence of oxygen, albeit in a yield of coupling products of about 0.5%.572 Better yields (3.02-5.9%) were achieved in nonoxidative photoinduced coupling at room temperature on silica-alumina or alumina evacuated at 800°C.573 

A heterogeneous hydrogen-accumulating system containing porous Ti with 0.4 wt% Ni combined with high-purity Ti chips was tested for methane activation.588 Methane conversion to C1-C4 hydrocarbons reached a value of 20% with 50-55% of ethylene at 450° C and 10 atm. The hydrogen formed was accumulated as TiH2. 

3 Other Processes - The involvement of the upper singlet state in the photochemistry of some 1,1-diarylethenes such as (29) has been assessed. Irradiation of (30) at 365 nm in chloroform solution brings about a 1,3-hydrogen 

3 Other Processes. The photochemical behaviour of dicyanodiacetylene has been reported.Irradiation of ethyne in argon or xenon matrixes results in 

C-H bond fission and the production of ethynyl radicals. Butadiyne and vinyl acetate are formed when the T -shaped ethyne dimer is irradiated at 193 nm in argon or xenon. The dynamics of the photodissociation of propyne and allene have been studied. The H2 elimination from propyne is a minor route for propyne dissociation and the major path identified in this study is loss of the alkyne hydrogen. A study of the photodissociation dynamics of allene and propyne has been reported and this work has demonstrated that allene gives rise to a propargyl radical while propyne yields the propynyl radical. Other research has examined the photodissociation of propyne and allene by irradiation at 193 nm.  

An examination of competition between homolysis and heterolysis of the C-Br bond of the haloalkenes (76) has been described. Solid-state NMR techniques have been used in a study of the photochemical behaviour of 

3 Other Processes. - 1,3-Dioxolanes are formed on SET induced ring opening of a-epoxyketones in acetone using 2,4,6-triphenylpyrylium tetrafluorobor-ate as the sensitizer. The dioxolanes are formed by CO bond cleavage while reduction products are the result of CC bond fission. Photosensitized (using 

6-triphenylpyrylium tetrafluoroborate) ring opening in acetic acid of 

Tanaka and F. Toda, Org. Solid-State React., 2002,109 Chem. Abstr., 2003,138, 254535. 

Gescheidt, D. Neshchadin. G. Rist, A. Borer, K. Dietliker and K. Misteli, Phys. Chem. Chem. Phys., 2003, 5,1071. 

Font-Sanchis, M. A. Miranda, J. Perez-Prieto and J. C. Scaiano, J. Org. Chem., 2002,67,6131. 

3 Other Processes - The unfiltered irradiation of (47) in acetonitrile solution results in isomerization into (48) in reasonable yield. The reaction is an example of a concerted 1,3-alkyl migration on an allyl moiety. The authors claim this to be the first example of a rearrangement from a cembrane to the pseudoterane 

A study of the photodissociation of chloroethene on irradiation at 193 and 210 nm has been reported. The photochemical decomposition of 1,1- and 1,2-difluoroethene has also been studied using 193 nm light. Two studies have examined the photochemical decomposition of trichloroethene. One of these has utilized in situ NMR studies for the analysis of the system.  

3 Other Processes. - The quantum yield for the release of benzoic acid from 2,5-dimethylphenacyl benzoate is temperature dependent in benzene solution. At room temperature = 0.22, while at 50°C the value rises to 0.28. A much greater effect is observed in methanol or ethanol, when there is a threefold increase in the quantum yield. The authors suggest that the reaction in heated methanol enhances the -photoenol population. Givens and Lee have reviewed the use of the j9-hydroxyphenacyl moiety as a photoprotecting group for biological substrates. 

1- and 2-Naphthoyloxyl radicals can be formed by irradiation of the 2-pyridone derivatives (47) and (48), respectively. Apparently the presence of a methoxy group in the ring prevents decarboxylation.  

Sivaguru, J. Shailaja and V. Ramamurthy, in Handbook of Zeolite Science and Technology, ed. S.M. Auerbach, K.A. Carrado and P.K. Dutta, Marcel Dekker, New York, 2003, p. 515. 

Jullian, F. Courtois, G. Bolbach and G. Chassaing, Tetrahedron Lett., 2003 44, 6437. 

Cordeiro, D.S. Natalia, E. Martinez-Nunez, A. Fernandez-Ramos and S.A. Vazquez, Chem. Phys. Lett., 2003, 375, 591. 

Several other processes that have been developed to make hydrogen are 1  

A number of other processes have become commonplace in the manufacture of fruit juices. For example, if oranges of the varieties Navel or Navellina are processed the juice becomes unpleasantly bitter because of the biochemical development of a glycoside, limonin. This substance can be partially or totally removed by the use of appropriate ion-exchange resins to yield a juice of acceptable taste. 

There has also been a range of developments leading to the removal of acidity, colour and minerals from clear juices such as apple. The product of such a combination of processes can be a clear, colourless carbohydrate syrup that can be used in a variety of food processes. There seems little doubt that the legal status of such a product is not fruit juice yet it is often, optimistically, so called. 

Enzyme and finishing treatments are widely used in the processing of fruit juices to obtain products of particular specification. 

Another contentious issue is the further processing of fruit pulp, and especially citrus pulp. The addition of water to such a pulp can give an extract containing around 5% solids, which can be concentrated to around 65% and used to dilute (more expensive) pure juice. These products are normally described as 

Byproducts of the juice industry are important but are not dealt with here. The interested reader is referred to Fruit Processing (Arthey Ashurst, 2001). 

Fluoropolymer parts can be processed by other common techniques such as encapsulation, hot stamping, and ink printing. 

Encapsulation of metal parts can be easily achieved with fluoropol3miers. Parts, such as butterfly valves, are used in applications where extreme mechanical integrity and rigidity, combined with chemical resistance, are required. 

Hot stamping is conducted using a stamp heated well above the melting temperature of the polymer ( 360°C for PTFE). Application of pressure to the hot stamp for a period of time will imprint the desired pattern. Temperature, pressure, and time should be determined by trial and error. 

Inks having a fluorocarbon base can be used to print stripe patterns on wire for identification. In practice a wheel coated with the desired color runs along the wire prior to the sintering step of the manufacturing process. For more than one stripe, additional wheels are needed. The ink is sintered at the same time as the insulation. PTFE and FEP dispersion have been used as the base to produce ink. Inorganic pigment that is stable under the sintering conditions of polytetrafluoroethylene must be used. 

B Formed sheet into female mold, a - Preheated, clamped sheet, b - Female mold with vacuum holes, c - Vacuum. 

Eundamentally, solvolysis of PET is separated into methanolysis, glycolysis, and hydrolysis. Recently, many processes have been developed, which combine two or three of these techniqnes, such as the neutral hydrolysis process [22], hydrolysis by reactive extrusion [23], glycolysis-hydrolysis [24], etc. 

Fossil formation, the transformation of wood to coal, and petrifaction (the transformation of matter into stone), are processes that were believed to have taken millions and perhaps billions of years. FFowever, they have since been shown to occur quite quickly. A petrified bowler hat sits in a mining museum in New Zealand. The Petrified Forest National Fhrk in Arizona is claimed by evolutionists to be older than 225 million years. It is obvious that bowler hats were not around then. In fact, we know the bowler hat was petrified only a little over a hundred years ago. So if this and other items in the same catastrophe can be petrified only recently, why does the Petrified Forest have to be dated as over 225 million years old  

Washability is a concept that exploits the differences that exist between the specific gravity of different coals and the associated minerals as a basis for predicting the yields and qualities of the products obtained for any given partition density (Mazumdar et al., 1992 Ryan, 1992). Washability 

Separation of coal and mineral matter can also be achieved by exploiting differences in the surface properties certain minerals, especially clays, have polar, hydrophilic surfaces although pyrite may exhibit markedly hydrophobic behavior and cause difficulties when present in discrete particles that are selectively floated with coal particles. Froth flotation and oil agglomeration methods (Mehrotra et al., 1983 Franzidis, 1987 Schlesinger and Muter, 1989 Vettor et al., 1989 Xiao et al., 1989 Couch, 1991 Carbini et al., 1992) are examples of how such separations can be achieved and although differences exist in the surface properties of the coal components (macerals Chapters 4 and 9), these are generally small in relation to those of the minerals present. 

Addition of small quantities of hydrocarbon oils to raw coal pulps causes preferential wetting of the coal by oil, tending to increase the surface tension forces operating at the coal/water interface. If air is admitted to the system, bubbles attach preferentially to the oil-wet coal surfaces thereby increasing the buoyancy of the coal particles, hence causing rapid separation from the heavier, unoiled mineral particles. The coal is collected as froth on the surface of the system and recovered by skimming. 

FIGURE 6.20 Relationship of specific gravity of a magnetite suspension to concentration in water. (From Meyers, R.A., Ed., Coal Handbook, Marcel Dekker, New York, 1981, p. 268.) 

Cyclone separation. (From Meyers, R.A., Ed., Coal Handbook, Marcel Dekker, New York, 

It is significant that manufacturers increasingly are seeking to incorporate containment features into the design of process equipment such that physical enclosure may not be necessary, except at the highest containment levels. Particular examples of containment design for centrifuges and cell disruptors are described elsewhere in this book (see chapter 9) but the 

The RIM process involves the high-pressure impingement mixing of two or more reactive liquid components and injection of the mixture into a closed mold at low pressures. Large and thick parts can be molded using fast cycles with relatively low-cost materials. Its low energy requirements with relatively low investment costs make RIM attractive [1-21, 664-73]. 

Different materials can be used such as nylon, polyester (TS), and epoxy, but TS polyurethane (PUR) is predominantly used. Almost no other plastic has the range of properties of PUR—a modulus of elasticity in bending of 200 to 1,400 MPa (29,000-203,000 psi) and heat resistance from 90 to over 200°C (122-392°F), the higher values are for chopped glass-fiber-reinforced RIM, or RRIM. 

LIM has been in use longer than RIM, but the two processes are practically similar. The advantages it offers in the automated low-pressure processing of (usually) thermoset 

Sink marks around metal inserts Practically none Distinct 

MfMi Wilh Nirrow Ribbon nd Medium or Hish An it 

Light exposure (initiation), tempering/heat treatment, and etching (development, structuring, fixation). 

When a reactor is being manufactured, both, cavities and through-holes, are required. In the case of photosensitive glass, it is difficult to make troughs. 

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The thermal profile through the reactor will in most circumstances be carefully optimized to maximize selectivity, extend catalyst life, etc. Because of this, direct heat integration with other process streams is almost never carried out. The heat transfer to or from the reactor is instead usually carried out by a heat transfer intermediate. For example, in exothermic reactions, cooling might occur by boiling water to raise steam, which, in turn, can be used to heat cold streams elsewhere in the process. 

If the reactor can be matched with other process streams (which is unlikely), then the reactor profile should be included in the heat integration problem. This would be a hot stream in the case of an exothermic reaction or a cold stream in the case of an endothermic reaction. 

Establish the heat integration potential of simple columns. Introduce heat recovery between reboilers, intermediate reboilers, condensers, intermediate condensers, and other process streams. Shift the distillation column pressures to allow integration, where possible, using the grand composite curve to assess the heat integration potential. 

Like distillation, evaporation can be represented as a box. This again assumes that any heating or cooling required by the feed and concentrate will be included with the other process streams in the grand composite curve. 

Feedstocks for this very flexible process are usually vacuum distillates, deasphalted oils, residues (hydrotreated or not), as well as by-products from other processes such as extracts, paraffinic slack waxes, distillates from visbreaking and coking, residues from hydrocracking, converted in mixtures with the main feedstock. 

Condensable hydrocarbon components are usually removed from gas to avoid liquid drop out in pipelines, or to recover valuable natural gas liquids where there is no facility for gas export. Cooling to ambient conditions can be achieved by air or water heat exchange, or to sub zero temperatures by gas expansion or refrigeration. Many other processes such as compression and absorption also work more efficiently at low temperatures. 

Were we can give these equations for the heat transfer process along radius R. The other processes of heat transfer can be simulated analogously by changing formula for heat transfer area and distances between centers of cells. For Dirichlet cells, bordering a gas medium, an equation of heat balance can be written in the form ... 

If there are no competing processes the experimental lifetime x should equal Tq. Most connnonly, other processes such as non-radiative decay to lower electronic states, quenching, photochemical reactions or... 

As one goes to higher orders, there are many other processes that can and do occur. Some are true fifth or seventh order processes and others are cascaded events arising from the sequential actions of lower order process [135]. Many of these cascaded sources of polarization interfere with the echo and quasi-echo signal and must be handled theoretically and experimentally. 

Even if the homogeneous line shape can be extracted, many other processes can contribute. Every decay process contributes to the finite lifetime of an excited species. A, with an individual decay constant k ... 

The ideal way to simulate reactions (and indeed many other processes where we might wish to derive properties dependent upon the electronic distribution) would of course be to use a fully quantum mechanical approach. 

Metallic cerium is prepared by metahothermic reduction techniques, such as reducing cerous fluoride with calcium, or using electrolysis of molten cerous chloride or others processes. The metahothermic technique produces high-purity cerium. 

By far the best method I have tried to produce benzodioxole in terms of yields and simplicity. In comparison to other processes, this is in fact quite fun and I ll explain It in a fashion that can be followed by a complete novice, like I was when I started a while ago. What we do is react and reflux the ingredients first, then use a simple distillation procedure to extract the product with water as an azeotrope. Once extracted we wash until the product is clear, and then separate. From start to finish it will take about six hours. 

Of course, these schemes indicate only that the overall reactions may be classified as nucleophilic 1,3-substitutions and, in the last case, as electrophilic 1,3-substitut ions. The reactions often proceed only in the presence of catalytic or stoichiometric amounts of transition metal salts, while in their absence 1,1--substitutions or other processes are observed. The 1,1-substitutions are also catalyzed by salts of transition metals, and it is not yet well understood, which factors influence the 1,1 to 1,3-ratio. In a number of 1,3-Substitutions there is... 

Again, it is noteworthy that 4-substituted 5-hydrdxythiazoles (24) react like 5-hydroxy-THISs with alkynes to give pyrroles and sometimes with alkenes to give exo-cycloadducts (Scheme 22). In the latter case other processes compete with the cycloaddition, becoming dominant when 24 is treated with azo-compounds, enamines, or heterocumulenes (31). 

The other process is a nucleophilic acyl substitution triggered by hydroxide attack at the carbonyl group... 

Once formed cholesterol undergoes a number of biochemical transformations A very common one is acylation of its C 3 hydroxyl group by reaction with coenzyme A derivatives of fatty acids Other processes convert cholesterol to the biologically impor tant steroids described m the following sections... 

Other Processes. Flow sheets for typical partial-recycle process and typical once-through urea process are given in Figures 9 and 10, respectively. 

The first industrial hardboard was developed by W. Mason in the mid-1920s he found that a mat of wet fiber pressed in a hot press would produce a self-bonded flat panel with good strength, durabiUty, and stabiUty. The product was patented in 1928, trademarked as Masonite, and commercial production began. Over time several other processes for producing hardboards have been developed from modifications of the original process. Brief descriptions of these processes foUow and a flow chart of the process is shown in Figure 5. 

Butanediol. 1,4-Butanediol [110-63-4] tetramethylene glycol, 1,4-butylene glycol, was first prepared in 1890 by acid hydrolysis of N,]S3-dinitro-l,4-butanediamine (117). Other early preparations were by reduction of succinaldehyde (118) or succinic esters (119) and by saponification of the diacetate prepared from 1,4-dihalobutanes (120). Catalytic hydrogenation of butynediol, now the principal commercial route, was first described in 1910 (121). Other processes used for commercial manufacture are described in the section on Manufacture. Physical properties of butanediol are Hsted in Table 2. 

The propylene-based process developed by Sohio was able to displace all other commercial production technologies because of its substantial advantage in overall production costs, primarily due to lower raw material costs. Raw material costs less by-product credits account for about 60% of the total acrylonitrile production cost for a world-scale plant. The process has remained economically advantaged over other process technologies since the first commercial plant in 1960 because of the higher acrylonitrile yields resulting from the introduction of improved commercial catalysts. Reported per-pass conversions of propylene to acrylonitrile have increased from about 65% to over 80% (28,68—70). 

Other processes explored, but not commercialized, include the direct nitric acid oxidation of cyclohexane to adipic acid (140—143), carbonylation of 1,4-butanediol [110-63-4] (144), and oxidation of cyclohexane with ozone [10028-15-5] (145—148) or hydrogen peroxide [7722-84-1] (149—150). Production of adipic acid as a by-product of biological reactions has been explored in recent years (151—156). 

Under constant pattern conditions the LUB is independent of column length although, of course, it depends on other process variables. The procedure is therefore to determine the LUB in a small laboratory or pilot-scale column packed with the same adsorbent and operated under the same flow conditions. The length of column needed can then be found simply by adding the LUB to the length calculated from equiUbrium considerations, assuming a shock concentration front. 

Limestone slurry scmbs flue gas. SO2 absorbed, reacted to CaSO. Further ak-oxidized to CaSO settled/removed as sludge. Lower cost and simpler than other processes. Disadvantages abrasive/corrosive, plugging and scaling, poor dewatering of... 

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