Apparatus catalyst

By their very nature, the vapor-phase oxidation processes result in the concentration of reaction heat in the catalyst zone, from which it must be removed in large quantities at high-temperature levels. Removal of heat is essential to prevent destruction of apparatus, catalyst, or raw material, and maintenance of temperature at the proper level is necessary to ensure the correct rate and degree of oxidation. With plant-scale operation and with reactions involving deep-seated oxidation, removal of heat constitutes a major problem. With limited oxidation, however, it may become necessary to supply heat even to oxidations conducted on a plant scale. 

The TPR experiments were performed in 5% H Ar gaseous mixture at 20 cm3/min. Samples were heated at 5 K/min within the temperature range of 298-1073 K. Prior to TPR experiments, samples were treated in situ with air at 723 K for 2 h, The TPD runs were carried out in the same apparatus. Catalysts were reduced in H2 at different temperatures for 1 h. After cooling the reactor down to room temperature, samples were heated under Ar at 5 K/min from 298 up to 873 K The amounts of H2 desorbed were calculated from the integrated peaks areas measured by a heat conductivity cell, which was calibrated by injection of known volumes of H2 into the carrier gas. 

Details of the apparatus, catalyst preparation, reaction mixture and procedure employed in this study were described previotisely (refs. 1 and 5). The catalyst was CuHM (2.3 wt% copper on H-type mordenile), crushed to 20/30 mesh panicle size. H-type mordenile (Lot 75702) is obtained from Norton Co. under the designation of 900H. 

The titanium contents of the resulting catalyst samples were determined with an inductively coupled plasma-atomic emission spectrometer (ICP-AES) (Kon-tron, Germany Model S-35) after HE acid digestion of the solid. N2 adsorption/ desorption isotherms at 77 K were obtained using a Micromeritics ASAP 2020 apparatus. Catalyst crystalline structure was examined by X-ray diffraction (XRD) on a Shimadzu XRD-6000 diffractometer with Cu Ka radiation. X-ray photoelectron spectroscopy (XPS) data were acquired on a VG Microtech MT-500 spectrometer using A1 Ka X-ray radiation (1,486.6 eV). Fourier transform infrared (FUR) data were obtained on a Shimadzu IR Prestige FUR spectrophotometer. 

Fig. 2-1 Carbonylation ofl-decene in a high-pressure iR apparatus catalyst [(PPhslsCuClj/tetramethylethylenediamine, solvent THF.

In the presence of catalyst, usually platinum, ammonia is oxidised by oxygen (and air) to nitrogen oxide. NO. This reaction, used to obtain nitric acid from ammonia (p. 238), can be demonstrated in the laboratory using the apparatus shown in Figure 9.4 the oxygen rate should be slow. 

Pack the catalyst into a Pyrex combustion tube about 90 cm. long and 15 mm. bore, and place plugs of glass wool at 25 cm. intervals inseit into a tube furnace and adjust to a temperature of 330° full details of the complete apparatus are given in Section 111,72 and Fig. Ill, 72, 1. 

The complete assembly for carrying out the catalytic decomposition of acids into ketones is shown in Fig. Ill, 72, 1. The main part of the apparatus consists of a device for dropping the acid at constant rate into a combustion tube containing the catalyst (manganous oxide deposited upon pumice) and heated electrically to about 350° the reaction products are condensed by a double surface condenser and coUected in a flask (which may be cooled in ice, if necessary) a glass bubbler at the end of the apparatus indicates the rate of decomposition (evolution of carbon dioxide). The furnace may be a commercial cylindrical furnace, about 70 cm. in length, but it is excellent practice, and certainly very much cheaper, to construct it from simple materials. 

Place a solution of 10 -4 g. of benzalacetophenone, m.p. 57° (Section IV,130) in 75 ml. of pure ethyl acetate (Section 11,47,15) in the reaction bottle of the catalytic hydrogenation apparatus and add 0 2 g. of Adams platinum oxide catalyst (for full experimental details, see Section 111,150). Displace the air with hydrogen, and shake the mixture with hydrogen until 0 05 mol is absorbed (10-25 minutes). Filter oflF the platinum, and remove the ethyl acetate by distillation. RecrystaUise the residual benzylacetophenone from about 12 ml. of alcohol. The yield of pure product, m.p. 73°, is 9 g. 

Use the apparatus described in Section 111,72 and adjust the furnace for a working temperature of 400-450°. Although a manganous oxide catalyst gives satisfactory results, thoria is more convenient in practice. 

Ethylene. Under the influence of pressure and a catalyst, ethylene yields a white, tough but flexible waxy sohd, known as Polythene. Polyethylene possesses excellent electric insulation properties and high water resistance it has a low specific gravity and a low softening point (about 110°). The chemical inertness oi Polythene has found application in the manufacture of many items of apparatus for the laboratory. It is a useful lubricant for ground glass connexions, particularly at relatively high temperatures. 

Alternatively, use the following procedure in which triethylamine replaces potassium acetate as the basic catalyst. Place 2 1 g. (2-0 ml.) of purified benzaldehyde, 2 0 ml. of anhydrous triethylamine and 5 0 ml. of A.R. acetic anhydride in a 200 ml. round-bottomed flask, equipped with a short reflux condenser and a calcium chloride drying tube. Boil the solution gently for 24 hours—heating may be interrupted. Incorporate a steam distillation apparatus in the flask and steam distil until the distillate is no longer cloudy (about 100 ml.) and then collect a further 50 ml. of the distillate di ard the steam distillate. Transfer the residue in the flask to a 400 ml. beaker, add water until the vplume is about 200 ml., then 0 2 g. of decolourising carbon, and boil for a few minutes. Filter the hot solution, and acidify the hot filtrate with 1 1 hydrochlorioiaoid... 

This catalyst works in a similar manner to NaBHaCN except that it does not suffer from the same potential toxicity that NaBHaCN does. It is also different in that one can synthesize the damn stuff rather easily in one s own garage, as opposed to NaBHaCN which will require a very complicated and dangerous cyanide generation apparatus as is shown in the Chemicals section of this book. The following is about all Strike has on the making of the catalyst NaBH(OAc)3 [55] ... 

This catalyst should really be purchased rather than made because its use in underground chemistry is limited and is hardly watched at all if not ever. This may change considering its potential as a precursor to the NaBHsCN in Strike s 1 method of choice. There are a lot of ways to make this catalyst, but the least involved is the one using boron trifluoride. What the method calls for is an apparatus called an autoclave. You know how using a vacuum causes the absence of pressure to make things boil at a lower temperature Well, an autoclave is a device that causes an... 

The methods in which iodine is used as a catalyst for the reaction between ceric sulfate and nitrite or arsenite (86,87) are capable of determining smaH amounts of iodine. However, these catalytic methods are deHcate and require accurate timing, carefiH temperature control, and special apparatus. 

Because of the delay in decomposition of the peroxide, oxygen evolution follows carbon dioxide sorption. A catalyst is required to obtain total decomposition of the peroxides 2 wt % nickel sulfate often is used. The temperature of the bed is the controlling variable 204°C is required to produce the best decomposition rates (18). The reaction mechanism for sodium peroxide is the same as for lithium peroxide, ie, both carbon dioxide and moisture are required to generate oxygen. Sodium peroxide has been used extensively in breathing apparatus. 

Static Pressure Synthesis. Diamond can form direcdy from graphite at pressures of about 13 GPa (130 kbar) and higher at temperatures of about 3300—4300 K (7). No catalyst is needed. The transformation is carried out in a static high pressure apparatus in which the sample is heated by the discharge current from a capacitor. Diamond forms in a few milliseconds and is recovered in the form of polycrystalline lumps. From this work, and studies of graphite vaporization/melting, the triple point of diamond, graphite, and molten carbon is estimated to He at 13 GPa and 5000 K (Fig. 1)... 

Several other catalyst systems have been suggested, including boron fluoride and both crystalline and noncrystalline siUcas and alurninosihcates. Although no commercial faciUty exists, the concept of using a crystalline siUca or alurninosihcate catalyst in an integral reaction and distillation apparatus has been proposed (9). 

The most commonly used combination of chemicals to produce a polyacrylamide gel is acrylamide, bis acrylamide, buffer, ammonium persulfate, and tetramethylenediarnine (TEMED). TEMED and ammonium persulfate are catalysts to the polymerization reaction. The TEMED causes the persulfate to produce free radicals, causing polymerization. Because this is a free-radical driven reaction, the mixture of reagents must be degassed before it is used. The mixture polymerizes quickly after TEMED addition, so it should be poured into the gel-casting apparatus as quickly as possible. Once the gel is poured into a prepared form, a comb can be appHed to the top portion of the gel before polymerization occurs. This comb sets small indentations permanently into the top portion of the gel which can be used to load samples. If the comb is used, samples are then typically mixed with a heavier solution, such as glycerol, before the sample is appHed to the gel, to prevent the sample from dispersing into the reservoir buffer. 

The catalyst is previously prepared in an apparatus for catalytic hydrogenation, in which are placed 0.5 g. of palladous chloride, 3.0 g. of Norite, and 20 ml. of distilled water. The bottle is swept out with hydrogen and then shaken with hydrogen for 2-3 hours at 2-3 atmospheres (40 lb.) pressure. The palladium on carbon is collected on a Biichner funnel, washed with five 50-ml. portions of distilled water, then with five 50-ml. portions of 95% ethanol, and finally twice with ether. Upon drying, about 3 g. of the catalyst is obtained. It is stored in a vacuum desiccator over solid sodium hydroxide. If the reduction of the chloro-lepidine does not proceed normally, the used catalyst should be removed by suction filtration and a fresh 3-g. portion of catalyst added. Failure of the reduction step is usually due to an inactive catalyst or to impurities in the acetic acid or chlorolepidine. The palladium catalysts, prepared as described elsewhere in this volume, are presumably also satisfactory for the reduction of 2-chlorolepidine (p. 77). 

Of the alkyl esters, methyl esters are the most useful because of their rapid hydrolysis. The acid is refluxed with one or two equivalents of methanol in excess alcohol-free chloroform (or dichloromethane) containing about O.lg of p-toluenesulfonic acid (as catalyst), using a Dean-Stark apparatus. (The water formed by the... 

A solution of 4,4-dimethyl-5a-androst-l-en-3-one (128, 14 mg) in cyclohexane (3 ml) is stirred in a microhydrogenation apparatus in the presence of 10 % palladium-on-charcoal (15 mg) at atmospheric pressure and room temperature. The uptake of one eq of deuterium (1.15 ml) is complete in about 1 min and no more deuterium is consumed. After 5 min the catalyst is removed by filtration, and the solvent evaporated under reduced pressure. The resulting l<, 2< -d2-4,4-dimethyl-5a-androstan-3-one (129, 13 mg, 93%), mp 120-122°, exhibits 87% isotopic purity and 13% d species. ... 

The rhodium catalyst (46 mg) is dissolved in acetone (10 ml) in a microhydrogenation apparatus which is then flushed three times with deuterium gas. After stirring the solution in an atmosphere of deuterium for about 1 hr the deuterium uptake ceases and constant pressure is attained. 5a-Cholest-2-ene (136, 19.5 mg) is added and the stirring continued until deuterium uptake ceases (about 3/4 hr). The solvent is evaporated to dryness and the residue is extracted with hexane and the resulting solution filtered through a small alumina column (3 g, activity 111). Evaporation of the hexane gives 2, 3 -d2-5oc-cholestane (137) 18 mg, 92% mp 78-79° isotope composition 94%d2,5%d, andl%do. ... 

The phenol is reduced with hydrogen in presence of finely divided metallic nickel which acts as a catalyst. The apparatus is shown in Fig. 79. 

The non-ferrous alloys include the misleadingly named nickel silver (or German silver) which contains 10-30% Ni, 55-65% Cu and the rest Zn when electroplated with silver (electroplated nickel silver) it is familiar as EPNS tableware. Monel (68% Ni, 32% Cu, traces of Mn and Fe) is used in apparatus for handling corrosive materials such as F2 cupro-nickels (up to 80% Cu) are used for silver coinage Nichrome (60% Ni, 40% Cr), which has a very small temperature coefficient of electrical resistance, and Invar, which has a very small coefficient of expansion are other well-known Ni alloys. Electroplated nickel is an ideal undercoat for electroplated chromium, and smaller amounts of nickel are used as catalysts in the hydrogenation of unsaturated vegetable oils and in storage batteries such as the Ni/Fe batteries. 

B. Methyl indole-4-carboxylate (30). A mixture of 7.0 g (28 mmol) of methyl trans-2-[ -(dimethylamino)vinyl]-3-nitrobenzoate(29) in 140 mL of dry benzene which contained 1.4 g of 10% Pd/C was shaken in a Parr apparatus under Hj (50 psi) for 1.5 h. The catalyst was removed by filtration, and the benzene solution was washed with 30 mL of 5% aq. HCl, brine and dried over MgS04. After removal of the solvent under reduced pressure, the residue was purified via chromatography on silica gel to furnish 6.9 g (82%) of methyl indole-4-carboxylate (30). 

The technique of catalytic hydrogenation can be applied almost universally to unsaturated systems, and therein lies its chief advantage (7). By appropriate selection of catalyst, pressure, and temperature, a remarkable variety of substrates can be made to undergo hydrogenation, many of them under hydrogen pressure not exceeding 50 psi (see Appendix 3 for description and use of low-pressure hydrogenation apparatus). 

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