Synthesis alumina

Texier-Boullet, F. and Foucaud, A., Synthesis of 1-hydroxyalkanephosphonic esters on alumina, Synthesis, 916, 1982. 

Kabalka, G.W., Wang, L., Pagni, R.M., Hair, C.M. and Namboodiri, V., Solventless Suzuki coupling reactions on palladium-doped potassium fluoride alumina, Synthesis, 2003, 217-222. 

Ballini, R., Marotta, E., Petrini, M., and Rosini, G. 1986. Conjugate addition of nitro derivatives to aP-unsaturated carbonyl compounds on basic alumina. Synthesis, 3 237-8. 

Figure 1. Flow sheet for alumina synthesis through sol-gel route...

This general synthesis route represents several improvements use of inexpensive, small organic chemicals as pore-forming agents instead of surfactants no micelles formed in the mesopore templating process, whereas most other mesoporous materials are synthesized based on micelle formation mesoporosity of the aluminum oxide can be easily and continuously tuned and use of inexpensive inorganic aluminum sources. While the original alumina synthesis utilized aluminum isopropoxide ( AIP ), the more recent efforts successfully used aluminum sulfate or nitrate. 

The water extraction method, as used for alumina synthesis by Liu and Mlcox [167], was also successfully used by them for mullite synthesis a mixed colloidal sol of alumina and silica was used as the water phase. 

Cejka, J. 2003. Organized mesoporous alumina Synthesis, structure and potential in catalysis. App/. Catal. A Gen 254 327-338. 

E. Santaniello, F. Ponti, and A. Manzocchi. Reduction of carbonyl compounds by sodium borohydride absorbed on alumina. Synthesis, 1978, 891. 

Bare S R, Strongin D R and Somoqai G A 1986 Ammonia synthesis over iron single crystal catalysts—the effects of alumina and potassium J. Phys. Chem. 90 4726... 

To separate the oil added an equal volume of fresh cool water (note waited until solution cooled before adding the water). The oil started to drop out perfectly, used DCM to extract all traces of the oil. This woik up is by far the cleanest, easiest and simplest to date... (This dreamer was tried all method of ketone synthesis)... Once the oil was extracted, the extracts were pooled washed with sodium bicarbonate lx, saturated solution of NaCI 1x, and two washes with fresh dHzO... Some time was required for the work up as there was a little emulsion from the use of the base wash and then with the first water wash. The JOC ref suggested using an alumina column to remove the catalyst (could be a better way to go). 

Aryl, heteroaryl, and alkenyl cyanides are prepared by the reaction of halides[656-658] or triflates[659,660] with KCN or LiCN in DMF, HMPA, and THF. Addition of crown ethers[661] and alumina[662] promotes efficient aryl and alkenyl cyanation. lodobenzene is converted into benzonitrile (794) by the reaction of trimethylsiiyl cyanide in EtiN as a solvent. No reaction takes place with aryl bromides and chlorides[663]. The reaction was employed in an estradiol synthesis. The 3-hydroxy group in 796 was derived from the iodide 795 by converting it into a cyano group[664]. 

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert siHca or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acryHc acid were prepared from bismuth, cobalt, kon, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic siHcic acids. Preferred second-stage catalysts generally are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity and productivity (39,45,46). 

Gas purifications H2O/olefin-containing cracked gas, natural gas, air, synthesis gas, etc sHica, alumina, zeoHte... 

Propylene Dimer. The synthesis of isoprene from propjiene (109,110) is a three-step process. The propjiene is dimeri2ed to 2-methyl-1-pentene, which is then isomeri2ed to 2-methyl-2-pentene in the vapor phase over siUca alumina catalyst. The last step is the pyrolysis of 2-methyi-2-pentene in a cracking furnace in the presence of (NH 2 (111,112). Isoprene is recovered from the resulting mixture by conventional distillation. 

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. 

Ethjlben ne Synthesis. The synthesis of ethylbenzene for styrene production is another process in which ZSM-5 catalysts are employed. Although some ethylbenzene is obtained direcdy from petroleum, about 90% is synthetic. In earlier processes, benzene was alkylated with high purity ethylene in liquid-phase slurry reactors with promoted AlCl catalysts or the vapor-phase reaction of benzene with a dilute ethylene-containing feedstock with a BF catalyst supported on alumina. Both of these catalysts are corrosive and their handling presents problems. 

A continuous process has been described (14) which can produce either the amide or the nitrile by adjusting the reaction conditions. Boric acid has been used as a catalyst in the amidation of fatty acid (15). Other catalysts employed include alumina (16), titanium, and 2inc alkoxides (17). The difficulty of complete reaction during synthesis has been explained by the formation of RCOOH NH RCOO , a stable intermediate acid ammonium salt (18). 

Pyrrohdine [123-75-1] (tetrahydropyrrole) (19) is a water-soluble strong base with the usual properties of a secondary amine. An important synthesis of pyrrohdines is the reaction of reduced furans with excess amine or ammonia over an alumina catalyst in the vapor phase at 400°C. However, if labde substituents are present on the tetrahydrofurans, pyrroles may form (30). 

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. 

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. 

The industrial catalysts for ammonia synthesis consist of far more than the catalyticaHy active iron (74). There are textural promoters, alumina and calcium oxide, that minimise sintering of the iron and a chemical promoter, potassium (about 1 wt % of the catalyst), and possibly present as K2O the potassium is beheved to be present on the iron surface and to donate electrons to the iron, increasing its activity for the dissociative adsorption of N2. The primary iron particles are about 30 nm in size, and the surface area is about 15 m /g. These catalysts last for years. 

Hydrogenation of Acetylenes. Complete hydrogenation of acetylenes to the corresponding alkanes, which maybe requited to remove acetylenic species from a mixture, or as a part of a multistep synthesis, may be accompHshed using <5 wt % palladium or platinum on alumina in a nonreactive solvent under very mild conditions, ie, <100°C, <1 MPa (10 atm). Platinum is preferred in those cases where it is desired to avoid isomeri2ation of the intermediate olefin. Silver on alumina also can be used in this appHcation as can unsupported platinum metal. 

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