Alumina methanol

The performance of these novel catalysts was compared with that of a conventional copper-zinc-alumina methanol synthesis catalyst under the same conditions (250°C, 40,000 h, 72 /28 CO, 5 MPa). The methanol yield was only 8.0 g mol/l/hr which was more than an order of magnitude less than that obtained with the catalyst produced from the Cu-Ce-Al alloy. The methanol yields obtained using the Cu-Ce catalysts and the 72 /28 CO syngas were comparable to those obtained using conventional catalysts with CO2 present in the feed. 

H2O + 12% methanol + phosphoric Amberlite CX acid (2.9 g/liter) + methane sulfonic acid (1 g/liter), pH 2.1 Citrate/phosphate, pH 5.8, + 4% Alumina methanol + 2 mM heptane sulfonate... 

Without going into details of the chromatographic method, a SAR separation (asphaltenes having been eliminated) can be performed in a mixed column of silica followed by alumina. The saturated hydrocarbons are eluted by heptane, the aromatics by a 2 1 volume mixture of heptane and toluene, and the resins by a 1 1 1 mixture of dichloromethane, toluene and methanol. 

This is used extensively for qualitative analysis, for it is a rapid process and requires simple apparatus. The adsorbent is usually a layer, about 0 23 mni. thick, of silica gel or alumina, with an inactive binder, e.g. calcium sulphate, to increase the strength of the layer.. A. i i slurry of the absorbent and methanol is commonly coated on glass plates (5 20 cm. or 20 x 20 cm.), but microscope... 

Anhydrous, monomeric formaldehyde is not available commercially. The pure, dry gas is relatively stable at 80—100°C but slowly polymerizes at lower temperatures. Traces of polar impurities such as acids, alkahes, and water greatly accelerate the polymerization. When Hquid formaldehyde is warmed to room temperature in a sealed ampul, it polymerizes rapidly with evolution of heat (63 kj /mol or 15.05 kcal/mol). Uncatalyzed decomposition is very slow below 300°C extrapolation of kinetic data (32) to 400°C indicates that the rate of decomposition is ca 0.44%/min at 101 kPa (1 atm). The main products ate CO and H2. Metals such as platinum (33), copper (34), and chromia and alumina (35) also catalyze the formation of methanol, methyl formate, formic acid, carbon dioxide, and methane. Trace levels of formaldehyde found in urban atmospheres are readily photo-oxidized to carbon dioxide the half-life ranges from 35—50 minutes (36). 

Reaction of formaldehyde, methanol, acetaldehyde, and ammonia over a siUca alumina catalyst at 500°C gives pyridine [110-86-1] and 3-picoline... 

The reaction of methyl propionate and formaldehyde in the gas phase proceeds with reasonable selectivity to MMA and MAA (ca 90%), but with conversions of only 30%. A variety of catalysts such as V—Sb on siUca-alumina (109), P—Zr, Al, boron oxide (110), and supported Fe—P (111) have been used. Methjial (dimethoxymethane) or methanol itself may be used in place of formaldehyde and often result in improved yields. Methyl propionate may be prepared in excellent yield by the reaction of ethylene and carbon monoxide in methanol over a mthenium acetylacetonate catalyst or by utilizing a palladium—phosphine ligand catalyst (112,113). 

Because the synthesis reactions are exothermic with a net decrease in molar volume, equiUbrium conversions of the carbon oxides to methanol by reactions 1 and 2 are favored by high pressure and low temperature, as shown for the indicated reformed natural gas composition in Figure 1. The mechanism of methanol synthesis on the copper—zinc—alumina catalyst was elucidated as recentiy as 1990 (7). For a pure H2—CO mixture, carbon monoxide is adsorbed on the copper surface where it is hydrogenated to methanol. When CO2 is added to the reacting mixture, the copper surface becomes partially covered by adsorbed oxygen by the reaction C02 CO + O (ads). This results in a change in mechanism where CO reacts with the adsorbed oxygen to form CO2, which becomes the primary source of carbon for methanol. 

Natural gas contains both organic and inorganic sulfur compounds that must be removed to protect both the reforming and downstream methanol synthesis catalysts. Hydrodesulfurization across a cobalt or nickel molybdenum—zinc oxide fixed-bed sequence is the basis for an effective purification system. For high levels of sulfur, bulk removal in a Hquid absorption—stripping system followed by fixed-bed residual clean-up is more practical (see Sulfur REMOVAL AND RECOVERY). Chlorides and mercury may also be found in natural gas, particularly from offshore reservoirs. These poisons can be removed by activated alumina or carbon beds. 

Methylphenol. This phenol, commonly known as o-cresol, is produced synthetically by the gas phase alkylation of phenol with methanol using modified alumina catalysis or it may be recovered from naturally occurring petroleum streams and coal tars. Most is produced synthetically. Reaction of phenol with methanol using modified zeoHte catalysts is a concerted dehydration of the methanol and alkylation of the aromatic ring. 2-Methylphenol [95-48-7] is available in 55-gal dmms (208-L) and in bulk quantities in tank wagons and railcars. 

Recovery and Purification. The dalbaheptides are present in both the fermentation broth and the mycelial mass, from which they can be extracted with acetone or methanol, or by raising the pH of the harvested material, eg, to a pH of 10.5—11 for A47934 (16) (44) and A41030 (41) and actaplanin (Table 2) (28). A detailed review on the isolation of dalbaheptides has been written (14). Recovery from aqueous solution is made by ion pair (avoparcin) or butanol (teicoplanin) extraction. The described isolation schemes use ion-exchange matrices such as Dowex and Amberlite IR, acidic alumina, cross-linked polymeric adsorbents such as Diaion HP and Amberlite XAD, cation-exchange dextran gel (Sephadex), and polyamides in various sequences. Reverse-phase hplc, ion-exchange, or affinity resins may be used for further purification (14,89). 

Polyethers are usually found in both the filtrate and the mycelial fraction, but in high yielding fermentations they are mosdy in the mycelium because of their low water-solubiUty (162). The high lipophilicity of both the free acid and the salt forms of the polyether antibiotics lends these compounds to efficient organic solvent extraction and chromatography (qv) on adsorbents such as siUca gel and alumina. Many of the production procedures utilize the separation of the mycelium followed by extraction using solvents such as methanol or acetone. A number of the polyethers can be readily crystallized, either as the free acid or as the sodium or potassium salt, after only minimal purification. 

In the petroleum (qv) industry hydrogen bromide can serve as an alkylation catalyst. It is claimed as a catalyst in the controlled oxidation of aHphatic and ahcycHc hydrocarbons to ketones, acids, and peroxides (7,8). AppHcations of HBr with NH Br (9) or with H2S and HCl (10) as promoters for the dehydrogenation of butene to butadiene have been described, and either HBr or HCl can be used in the vapor-phase ortho methylation of phenol with methanol over alumina (11). Various patents dealing with catalytic activity of HCl also cover the use of HBr. An important reaction of HBr in organic syntheses is the replacement of aHphatic chlorine by bromine in the presence of an aluminum catalyst (12). Small quantities of hydrobromic acid are employed in analytical chemistry. 

Carbon disulfide reacts with alkanols or diaLkyl ethers at 250—500°C over activated alumina catalyst to give diaLkyl sulfides. For example, methanol yields dimethyl sulfide [75-18-3]. 

High pressure processes P > 150 atm) are catalyzed by copper chromite catalysts. The most widely used process, however, is the low pressure methanol process that is conducted at 503—523 K, 5—10 MPa (50—100 atm), space velocities of 20, 000-60,000 h , and H2-to-CO ratios of 3. The reaction is catalyzed by a copper—zinc oxide catalyst using promoters such as alumina (31,32). This catalyst is more easily poisoned than the older copper chromite catalysts and requites the use of sulfiir-free synthesis gas. 

Gas Phase. The gas-phase methanol hydrochlorination process is used more in Europe and Japan than in the United States, though there is a considerable body of Hterature available. The process is typicaHy carried out as foHows vaporized methanol and hydrogen chloride, mixed in equimolar proportions, are preheated to 180—200°C. Reaction occurs on passage through a converter packed with 1.68—2.38 mm (8—12 mesh) alumina gel at ca 350°C. The product gas is cooled, water-scmbbed, and Hquefied. Conversions of over 95% of the methanol are commonly obtained. Garnma-alurnina has been used as a catalyst at 295—340°C to obtain 97.8% yields of methyl chloride (25). Other catalysts may be used, eg, cuprous or zinc chloride on active alumina, carbon, sHica, or pumice (26—30) sHica—aluminas (31,32) zeoHtes (33) attapulgus clay (34) or carbon (35,36). Space velocities of up to 300 h , with volumes of gas at STP per hour per volume catalyst space, are employed. 

An important publication by Kost et al. (63JGU525) on thin-layer chromatography (TLC) of pyrazoles contains a large collection of Rf values for 1 1 mixtures of petroleum ether-chloroform or benzene-chloroform as eluents and alumina as stationary phase. 1,3- and 1,5-disubstituted pyrazoles can be separated and identified by TLC (Rf l,3>i y 1,5). For another publication by the same authors on the chromatographic separation of the aminopyrazoles, see (63JGU2519). A-Unsubstituted pyrazoles move with difficulty and it is necessary to add acetone or methanol to the eluent mixture. Other convenient conditions for AH pyrazoles utilize silica gel and ethyl acetate saturated with water (a pentacyanoamine ferroate ammonium disodium salt solution can be used to visualize the pyrazoles). 

Solution Polymerization These processes may retain the polymer in solution or precipitate it. Polyethylene is made in a tubular flow reactor at supercritical conditions so the polymer stays in solution. In the Phillips process, however, after about 22 percent conversion when the desirable properties have been attained, the polymer is recovered and the monomer is flashed off and recyled (Fig. 23-23 ). In another process, a solution of ethylene in a saturated hydrocarbon is passed over a chromia-alumina catalyst, then the solvent is separated and recyled. Another example of precipitation polymerization is the copolymerization of styrene and acrylonitrile in methanol. Also, an aqueous solution of acrylonitrile makes a precipitate of polyacrylonitrile on heating to 80°C (176°F). 

Used alumina can be regenerated by repeated extraction, first with boiling methanol, then with boiling water, followed by drying and heating. The degree of activity of the material can be expressed conveniently in terms of the scale due to Brockmann and Schodder (Chem Ber B 74 73 1941). 

It was recrystd twice as the free base from ethanol or methanol/water by dropwise addition of NaOH (less than O.IM). The ppte was washed with water and dried under vacuum. It was dissolved in CHCI3 and chromatographed on alumina the main sharp band was collected, concentrated and cooled to -20 . The ppte was filtered, dried in air, then dried for 2h under vacuum at 70°- [Stone and Bradley J Am Chem Soc 83 3627 1961 , Blauer and Linschitz J Phys Chem 66 453 1962.]... 

Completely white material is obtained by rapid chromatography through alumina (Note 16). An analytically pure product, m.p. 116-117° (dec.), Is obtained after one crystallization from methanol. 

Note The reagent can be employed on silica gel, alumina, polyamide and cellulose layers. In the case of the latter it is to be recommended that the solutions be diluted 1+3 with methanol. The detection limit is reported to be 0.1 to 0.5 pg per chromatogram zone [5]. 

A solution of 1 g of the dione in 200 ml of methanol at 0° is treated with 75 mg of sodium borohydride and the mixture is kept for 2 hr. After addition of 0.1 ml of acetic acid the mixture is concentrated to ca. 20 ml. Dilution with water gives 0.9 g of crystals which are chromatographed on 20 g of unwashed alumina. Elution with benzene-ether (40 60) yields 0.73 g of the methyl-hydroxytestosterone, mp 245-249°, which after crystallization from acetone has mp 255-256° [a] 111° (CHCI3). 

A solution of cholest-4-en-3-one (139), 1 g, in diethylene glycol dimethyl ether (20 ml) is treated for 1 hr with a large excess of diborane at room temperature under nitrogen and then left for a further 40 min. Acetic anhydride (10 ml) is added and the solution refluxed for 1 hr. The mixture is concentrated to a small volume, diluted with water and extracted with ether. The extracts are washed with 10% sodium hydroxide solution, then with water and dried over sodium sulfate. Removal of the solvent leaves a brown oil (1.06 g) which is purified by chromatography on alumina (activity I). Hexane elutes the title compound (141), 0.68 g mp 76-77°. Successive crystallization from acetone-methanol yields material mp 78-79°, [a]p 66°. 

To a solution of 0.5 g of lithium aluminum hydride in 35 ml of ether is added 0.2 g of the A -cyanoaziridine. The mixture is heated at reflux temperature for 3.5 hr, cooled, and treated with excess saturated sodium sulfate in water. Filtration and evaporation of the ethereal filtrate gives 0.18 g of a glass which is chromatographed on 10 g of basic alumina (activity III). The benzene-petroleum ether (1 3) eluate gives 0.12 g of 2a,3a-imino-5a-choles-tane, mp 117.5-118.5°, after crystallization from methanol. 

A solution of the acylated thiocyanatohydrin in a minimal amount of 5% potassium hydroxide in diglyme (other solvents such as methanol, ethanol or tetrahydrofuran have also been used) is stirred for 2 days at room temperature. Water is added to the reaction mixture to precipitate the product which is filtered or extracted with ether (or chloroform). The ether extract is washed several times with water, dried (Na2S04), and concentrated under vacuum. The thiirane usually can be crystallized from an appropriate solvent pair. Chromatography over alumina has been used for the purification of episulfides. 

A solution of 0.7 g (18 mmoles) of potassium in 35 ml of /-butanol is added to a boiling solution of 5 g (13 mmoles) of 5a-cholestan-3-one in 50 ml of benzene and 25 ml of /-butanol. A total of 5 ml (11.4 g, 80 mmoles) of methyl iodide in 50 ml of benzene is then added and refluxing is continued for 3 min. The solution is cooled, ice is added and the product is isolated by extraction with ether. The crystalline residue in light petroleum solution is chromatographed on 300 g of alumina. Elution with light petroleum yields initially 0.55 g (10%) of 2,2-dimethyl-5a-cholestan-3-one mp 111-113° [o(]d 77° (CHCI3), after crystallization from ether-methanol. Further elution affords 1.01 g (20%) of 2a-methyl-5a-cholestan-3-one mp 119-120° [a]o 32° (CHCI3), after crystallization from ether-methanol. 

The product, isolated as above, is dissolved in pentane solution and chromatographed on 100 g of alumina. The initial fraction eluted with pentane, yields 1.02 g (48%) of 2,2-dimethyl-5a-cholestan-3-one mp 111-113°, after crystallization from ether-methanol. The subsequent fraction, eluted with pentane and pentane-benzene (9 1) gives 0.12 g (6%) of 2a-methyl-5a-cholestan-3-one mp 119-120°, after crystallization from methanol-ether. 

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