Preparative continuous processing

Manufacturing processes have been improved by use of on-line computer control and statistical process control leading to more uniform final products. Production methods now include inverse (water-in-oil) suspension polymerization, inverse emulsion polymerization, and continuous aqueous solution polymerization on moving belts. Conventional azo, peroxy, redox, and gamma-ray initiators are used in batch and continuous processes. Recent patents describe processes for preparing transparent and stable microlatexes by inverse microemulsion polymerization. New methods have also been described for reducing residual acrylamide monomer in finished products. 

R. A. McKay,M Study of Selected Parameters in S olid Propellant Processing,]et Propulsion Lab, Pasadena, Calif., Aug. 1986 J. L. Brown and co-workers. Manufacturing Technologyfor SolidPropellantIngredients/Preparation Reclamation, Morton Thiokol, Inc., Brigham City, Utah, Apt. 1985 W. P. Sampson, Eow Cost Continuous Processing of Solid Rocket Propellant, Al-TR-90-008, Astronautics Laboiatoiy/TSTR, Edwards AEB, Oct. 1990. 

Nonwoven technologies that employ machinery and processing principles traditionally used to manufacture textile, paper, or extmded materials, when viewed collectively, form what may be termed the primary or basic nonwoven fabric manufacturing systems. These systems are or can be continuous processes. Common to each of these systems are four sequential phases fiber selection and preparation, web formation, bonding, and finishing. 

Nylon-11. Nylon-11 [25035-04-5] made by the polycondensation of 11-aminoundecanoic acid [2432-99-7] was first prepared by Carothers in 1935 but was first produced commercially in 1955 in France under the trade name Kilsan (167) Kilsan is a registered trademark of Elf Atochem Company. The polymer is prepared in a continuous process using phosphoric or hypophosphoric acid as a catalyst under inert atmosphere at ambient pressure. The total extractable content is low (0.5%) compared to nylon-6 (168). The polymer is hydrophobic, with a low melt point (T = 190° C), and has excellent electrical insulating properties. The effect of formic acid on the swelling behavior of nylon-11 has been studied (169), and such a treatment is claimed to produce a hard elastic fiber (170). 

Nitrile Process. Fatty nitriles are readily prepared via batch, Hquid-phase, or continuous gas-phase processes from fatty acids and ammonia. Nitrile formation is carried out at an elevated temperature (usually >250° C) with catalyst. An ammonia soap which initially forms, readily dehydrates at temperatures above 150°C to form an amide. In the presence of catalyst, zinc (ZnO) for batch and bauxite for continuous processes, and temperatures >250° C, dehydration of the amide occurs to produce nitrile. Removal of water drives the reaction to completion. 

Primary amines can be prepared from alcohols and an excess of ammonia (52—55). Either a batch or continuous process can be used. The reaction is mn at elevated temperature (50—340°C) and high pressure, 3.5 MPa (500 psig), with an ammonia-to-alcohol ratio of 5 1 to 30 1. 

Batch or continuous processes can be used to prepare tertiary amines from alcohols and ammonia or a secondary amine, such as, dimethylamine. 

Trioctylamine has been prepared, in a continuous process, using 5,200 kg of -octanol, 100 kg of copper formate catalyst, 500 kg of -octylamine, 10 kg of calcium hydroxide, and 240 kg of ammonia (58). Ammonia was added over a 10-h period while 10 m of hydrogen/h was passed through the reactor at a reaction temperature of 180—200°C. The final product was composed of 94% trioctylamine, 2% dioctylamine, 1% octylamine, and 0.5% -octanol. A... 

Acid-Gatalyzed Synthesis. The acid-catalysed reaction of alkenes with hydrogen sulfide to prepare thiols can be accompHshed using a strong acid (sulfuric or phosphoric acid) catalyst. Thiols can also be prepared continuously over a variety of soHd acid catalysts, such as seoHtes, sulfonic acid-containing resin catalysts, or aluminas (22). The continuous process is utilised commercially to manufacture the more important thiols (23,24). The acid-catalysed reaction is commonly classed as a Markownikoff addition. Examples of two important industrial processes are 2-methyl-2-propanethiol and 2-propanethiol, given in equations 1 and 2, respectively. 

A continuous process has been developed for preparing borate esters usiag transesterification (24). Another modification of this method has been reported where use of molecular sieves (qv) to absorb the low boiling alcohol is used rather than distillation (25). 

In an integrated continuous process, cellulose reacts with acetic anhydride prepared from the carbonylation of methyl acetate with carbon monoxide. The acetic acid Hberated reacts further with methanol to give methyl acetate, which is then carbonylated to give additional acetic anhydride (100,101). 

Several modifications of the preparation of neutral Ca(OCl)2 2H20 do not involve intermediates. In a continuous process, lime slurry containing caustic and Ca(OCl)2 mother Hquor is chlorinated under reduced pressure to remove the heat of reaction, and the resulting slurry is separated in a classifier into Ca(OCl)2— and NaCl-rich regions from which slurry is withdrawn to obtain Ca(OCl)2 filter cake and soHd salt (204). 

Adsorbent drying systems are typicaHy operated in a regenerative mode with an adsorption half-cycle to remove water from the process stream and a desorption half-cycle to remove water from the adsorbent and to prepare it for another adsorption half-cycle (8,30,31). UsuaHy, two beds are employed to aHow for continuous processing. In most cases, some residual water remains on the adsorbent after the desorption half-cycle because complete removal is not economically practical. The difference between the amount of water removed during the adsorption and desorption half-cycle is termed the differential loading, which is the working capacity available for dehydration. 

The EBDCs are prepared by reaction of EDA with carbon disulfide in the presence of sodium or ammonium hydroxide initially, then with 2inc and/or manganese salts, as appropriate (156—160). A continuous process has recendy been reported (161). The common names of these salts are nabam [142-59-6] (Na salt), amobam (ammonium salt), 2ineb [12122-67-7] (Zn salt), maneb [12427-38-2] (Mn salt), andmanco2eb. 

In this way, a continuous process for the preparation of benzene hexachloride resulted. 

CE is generally more suited to analytical separations than to preparative-scale separations. However, given the success of CE methods for chiral separations, it seems reasonable to explore the utility of preparative electrophoretic methods to chiral separations. Thus, the purpose of this work is to highlight some of the developments in the application of preparative electrophoresis to chiral separations. Both batch and continuous processes will be examined. 

Ultimately, however, it should be noted that these examples of classical gel electrophoretic separations are batch processes and therefore limited in sample throughput. To achieve true preparative-scale separations by electrophoresis, it becomes necessary to convert to continuous processes. 

The oldest technology involved in the elastomer blending and vulcanization process is essentially a temperature controlled two roll mill as well as internal mixers followed by an optimum degree of crosslinking in autoclave molds (compression, injection, etc.) in a batch process or in a continuous process such as continuously heated tube or radiated tubes. A few examples of laboratory scale preparation of special purpose elastomeric blends is cited here. 

To develop a continuous process, the immobilisation of aminoacylase of Aspergillus oryzae by a variety of methods was studied, for example ionic binding to DEAE-Sephadex, covalent binding to iodo-acetyl cellulose and entrapment in polyacrylamide gel. Ionic binding to DEAE-Sephadex was chosen because the method of preparation was easy, activity was high and stable, and regeneration was possible. 

Both stress-induced crystallization and orientational crystallization can be used for the preparation of polymer materials with mechanical property values (e.g. tenacities and elastic moduli) much higher than those for polymer films and fibers obtained by conventional processing. We believe that the advantage of orientational crystallization over more complex methods consists in the possibility of obtaining samples of elastic moduli and tenacities in a one-step continuous process. 

Preparation. A continuous process is described in Ref 26 for its prepn from nitric acid and acetylene. Other prepns on both lab and industrial scales are by the action on Tetranitro-methane (TeNMe) of K hydroxide in aq glycerol (Ref 16), aq HOCHjSOaNa, or 30% aq H peroxide (Ref 19a) to give the K salt which is treated with sulfuric acid (Ref 16), syrupy phosphoric acid (Ref 20), or best by passing gaseous HC1 thru a suspension of the K salt in anhyd eth (Ref 19a). It has also been prepd by the action of nitric acid on malonamide,... 

A three-step nitration process of toluene is described. The advantages of the modified process are reduced waste, less hazardous operation, reduced oleum requirement, partial replacement of coned HN03 with dil HN03, and higher rate of toluene flow into the reactor (Ref 86) The continuous process of H.C. Prime (Ref 73) for preparing TNT was studied by thin-layer chromatography on silica gel with a starch binder and a fluorescent indicator. The nitration... 

This study relates to a continuous process for the preparation of perfluoroalkyl iodides over nanosized metal catalysts in gas phase. The water-alcohol method provided more dispersed catalysts than the impregnation method. The Cu particles of about 20 nm showed enhanced stability and higher activity than the particles larger than 40 nm. This was correlated with the distribution of copper particle sizes shown by XRD and TEM. Compared with silver and zinc, copper is better active and stable metal. 

Industrially, the perfluoroalkyl iodides by telomerization are mostly made by a batch system using peroxide initiators. However, the difficulty of mass production, and the production of hydrogen-containing byproducts in the process are disadvantageous [4]. In this study, a continuous process for the preparation of perfluoroalkyl iodides over nanosized metal catalysts in gas phase and the effects of the particle size on the catalytic activities of different the preparation methods and active metals were considered. 

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