Drying alumina

The features due to adsorbed water and carbonates observed on the boehmite and y-alumina deserve further attention as they differ from results published by previous investigators. Figure 4 shows a series of difference spectra for adsorption on y-alumina. Spectra were taken after drying the y-alumina at 350 C, cooling to room temperature and carrying out room temperature adsorption. The spectra are the difference of the sample before and after adsorption. Spectrum 4e is the spectrum for the as received alumina differenced with the dried alumina. The positive band at 3400 cm" is due to adsorbed water, and the small negative feature at 3740 cm" is due to isolated hydroxyls on the dried surface. Besides the three... 

A dichloromethane solution of [Run(L 3) (CO) (EtOH)] (0.07 mmol) was added to a well-stirred dichloromethane solution of ra-chloroperoxy benzoic acid (100 mg, 0.62 mmol) in a 10 mL round-bottomed flask. After 3 to 5 minutes stirring, the mixture was poured onto a short dry alumina column. 

In this series of experiments, the catalysts were used over five repeat contacts with fresh coal liquid. Point of Ayr coal liquid was supplied by the British Coal Corporation, Coal Research Establishment (CF ) one batch of this coal liquid was used in experiments with CoMo and NiMo catalysts and a further batch was used in experiments with ZnMo and ZnW. The catalysts were prepared as extrudates by the technique of incipient wetness which requires stirring the dry alumina support with a set volume of a pre-determined concentration of an appropriate soluble salt of the metal such that the pore space is just taken up by the metals at the required concentration. The alumina support was supplied by Akzo Chemie, The Netherlands and the catalysts were made up to contain 15% WO3 or M0O3 and 3% NiO, CoO, or ZnO, expressed as a weight percentage of the weight of support... 

For the determination of vitamin D in fortified milk (96), the unsaponifiable residue was dissolved in 5 ml of hexane, and 0.1 or 0.2 ml of a tracer solution (chlorophyll-a) and 1 g of dry 8% water-deactivated alumina were added. The solvent was evaporated off, and the dried alumina containing the sample was poured on top of a prepared column packed with 15 g of alumina. Elu-... 

The choice of units and standards for the remaining variables is arbitrary. The following conventions were followed by Snyder [350] standard adsorbent (a= 1) dry alumina standard solvent (e° = 0) n-pentane standard solute area (Aj=6) benzene ... 

Our catalyst for the isomerization of alkenes is going to be HC1 absorbed on to solid alumina (aluminium oxide, AI2O3) and the isomerization is to occur during a reaction, the addition of HC1 to an alkyne, in which the alkenes are formed as products. In this reaction the oxalyl chloride is first mixed with dried alumina. The acid chloride reacts with residual water on the surface (it is impossible to remove all water from alumina) to generate HC1, which remains on the surface. 

A slightly modified synthesis of dihydrobenzo[c]furan was achieved, in which the key reaction involved the exposure of a dibromide to dry alumina and one equivalent of water in toluene instead of in hexanes <07TL3039>. Another synthesis of dihydrobenzo[c]furans was reported by Hashmi and Teles <07SL1747> and an example is depicted below. Base-promoted cycloaddition of 1-aryl- or l-aryl-7-substituted-4-oxahepta-1,6-diynes in DMSO were found to involve an anionic intramolecular Diels-Alder reaction, and also resulted in the formation of dihydrobenzo[c]furans <07JA4939>. 

An attempt was made to learn whether increased interaction of platinum with exposed A1 ions could be seen on more highly dried alumina. The population of such ions increases with temperature of dehydration of the alumina (8). A Pt/Al O catalyst was predried at various temperatures in He. The results in Figure 9 show a... 

Figure 10 also shows that the spectra obtained from the more strongly dried catalyst (the 700°C treatment) shifts in the band maxima to frequencies higher than seen on the less strongly dried catalyst (the 500°C treatment). This peak shift indicates that the Pt interacts more with the more highly dried alumina surface and therefore confirms the TPD results. 

FIGURE 12.40 Compaction of spray dried alumina at 92% relative humidity. Data from Reed [23, p. 337]. 

FIGURE 13.29 (a) Compaction of spray-dried alumina at 92% relative humidity, (b) Cumulative pore size distributions by Hg porosimetry for spray dried AI2O3 (Alcoa A-17-1) for different pressing pressures. Data taken from Reed [6, p. 337]. 

The checker esterified hematoporphyrin by refluxing it in methanol with trifluoroacetic acid for 24 hr. The crude ester was then chromatographed on dry alumina and eluted with 1 1 CHCls-methanol. 

Ni/a-Al2p3 (Type A) and Ni-AI/a-Al203 (Type C) catalysts were prepared by impregnation of the dry alumina support (a-Al20j from YPF) with an aqueous solution of Ni(N03)2.6 H2O, and Ni(N03)2 6 H2O plus Al(N03)3-9 H2O (Al/Ni = 0.5) respectively. A detailed description of the procedure has been given by Ferrelti el al. (ref 6). After the impregnation step the... 

Sodium on alumina. This high-surface sodium catalyst, prepared by adding sodium to dry alumina with stirring at 150° under nitrogen, is effective for isomerization of butenes and pentene-1. In contrast to acid-catalyzed isomerization, no skeletal rearrangement occurs. The results indicate some stereoselectivity. Thus butene-1 is isomerized initially to about equal amounts of cis- and trani-butene-2 eventually the thermodynamic equilibrium mixture rich in the trans-isomti is obtained. The catalyst was used to effect almost quantitative conversion of methylenecyclobutane into 1-methylcyclobutene. ... 

As an example a dried alumina carrier is used, which should be calcined to the highest possible surface area, but the temperature must reach at least 500°C and the use of a rotary kiln with countercurrent flow of air is considered. The kiln is heated indirectly. 

Aldehyde (1 mmol), NH2OH HC1 (0.3 g, 0.4 mmol), MeS02Cl (0.075 ml, 1 mmol) and dry alumina (0.5 g, 4.9 mmol, Fluka type 405 acidic, dried in an oven for 5 h) were thoroughly mixed with a mechanical stirrer. The resulting fine powder was transferred to a round-bottom flask (5 mL) and heated in an oil bath at 100 °C for an appropriate time. Then diethyl ether (10 mL) was added to the reaction mixture and alumina was removed by filtration. The filtrate was extracted with water (2 10 mL), dried over Na2S04 and the solvent evaporated in vacuo to give the crude product. If solid this was purified by recrystallization from EtOH and if liquid then by distillation. 

Horner and Kaps have used chlorinated y-Al203 in combination with a small amount of Al(Oz-Pr)3 as the catalyst for the reduction of benzaldehyde, cyclohexanone, and acetophenone by z-PrOH [4]. In the absence of Al(Oi-Pr)3, no reaction occurred. The addition of a small amount of strong base was found to enhance the reaction rate. Analogous phenomena have been observed in the Oppenauer oxidation of several secondary alcohols. Strong bases presumably assist the deprotonation of alumina-surface co-ordinated i-PrOH, thereby forming the required alkoxide surface species. The modified alumina, which contained ca 85 mmol chloride/ 100 g alumina, was obtained by heating dry alumina in thionyl chloride for 24 h. The chloride at the surface increases the Lewis acidity of the aluminum ions and the addition of the base facilitates the deprotonation of z-PrOH. 

Water absorptivity was measured by adding demineralised water to 5g of dried alumina until the mixture just became fluid. The amount of water required was measured and the percentage solids calculated. Reproducibility was 1%. 

Commercial native tapioca and com starches from Thailand (Tesco) were purchased and used as received. Alumina powder (99.5% purity, Amarin, Thailand), wherein the particle size distribution is shown in Figure 1, was used as the ceramic raw material. Ceramic suspensions were prepared to different % solid loadings with sodium silicate (Amarin, Thailand) as a dispersant, having a fixed concentration of 3 wt.% on a dry alumina basis. The wt.% starch powders were added in different quantities 5 wt.%, 10 wt. %, 15 wt.% and 20 wt.% on a dry alumina basis, which corresponded to 69%, 66%, 63% and 60% solid loadings, respectively. Homogenization was carried out by ball... 

Chem. Descrip. Spray-dried alumina trihydrate Chem. Analysis Al203(65%)... 

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