Studies on pore systems in catalysts IV. The two causes of reversible hysteresis

Boer, J. H. de; Heuvel, A. van den; Linsen, B.G.

doi:10.1016/0021-9517(64)90173-3

Cited by 50 publications

(11 citation statements)

References 3 publications

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“…This suggests that there are both cylindrical and slit-shaped pores in this sample. Slit-shaped pores give rise to Sads values in excess of SBET and equal values for So~ and S~ET (de Boer et al, 1964;Aylmore & Quirk, 1967).…”

Section: Specific Surface Areasmentioning

confidence: 99%

Characteristics of fine pores in some halloysites

et al. 1995

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Isotherms were obtained for nitrogen adsorption and desorption on seven halloysiterich samples from New Zealand and Western Australia. Calculations from these isotherms indicate that halloysites with mainly small particles (< c. 0.08 I~m in width) had abundant cylindrical pores with narrow size distributions in the 5-15 nm range. They also indicate that halloysites with mainly large particles (> c. 0.1 ~tm in width) had few if any pores in the mesopore range (2-50 nm). Transmission electron microscopy (TEM) shows that cylindrical pores originate from the central holes in tubular particles. The TEM also suggests that slit-shaped pores can originate from the shrinkage of blocks of layers upon dehydration of halloysite.

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Section: Specific Surface Areasmentioning

confidence: 99%

Characteristics of fine pores in some halloysites

et al. 1995

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“…Two commercially available gibbsite samples, different in particle size distribution, were used : medium-sized gibbsite (M-GIB) having a similar particle size distribution as commercial pseudoboehmite, and coarse gibbsite (C-GIB). These two types were chosen because the dehydration is dependent on particle size (de Boer et al, 1954a(de Boer et al, , 1954b(de Boer et al, , 1956(de Boer et al, , 1964.…”

Section: Methodsmentioning

confidence: 99%

“…In Table 1, it can be seen that the theoretical weight loss of gibbsite is attained at 700°C. In Figure 2, three peaks are observed and can be explained as follows (de Boer et al, 1954a(de Boer et al, , 1954b(de Boer et al, , 1956(de Boer et al, , 1964Rouquerol et al, 1975Rouquerol et al, , 1979. The first peak corresponds to the formation of boehrnite according to the reaction :…”

Section: Glbbsltementioning

confidence: 96%

TG/XRD/Sem Study of the Conversion of Gibbsite to (Pseudo) Boehmite

Decleer¹

1989

Bulletin des Soc Chimique

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The conversion of gibbsite to (pseudo)boehmite has been studied by thermogravimetry, X-ray diffractometry and scanning electron microscopy, supplemented by density and surface area measurements. As a reference for desired product properties, commercial pseudoboehmite, laboratory synthesized seudoboehmite and autoclaved boehmite have also been studied. Three kinds of heating processes have gee, applied : In an oven, in a steam flow and under vacuum. All experiments were carried out at 220°C.Prolonged heating under vacuum resulted in a corn lete conversion of gibbsite to (pseudo)boehmite. The product still differs too much from commercial pseucfoboehmite to be a valuable alternative. Also takin into account the manufacturing implications of vacuum heating, this process seems hardly feasible on ayarge scale.

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“…Inoue et al (1989) examined the boehmite formation from gibbsite in alcoholic media and found that in an alcohol having a carbon number > 5 (higher alcohols), the boehmite yield increased with an increase in the carbon number of the alcohol. They attributed this increase in the boehmite yield to the increase in fugacity of water formed by partial dehydration ofgibbsite and concluded that in these higher alcohols, boehmite formed by means of an intraparticle hydrothermal reaction mechanism, originally proposed by de Boer et al (1954ade Boer et al ( , 1954bde Boer et al ( , 1964 for the formation of boehmite during the thermal dehydration of gibbsite. Similarly, in the present system, the ratio of unreacted gibbsite to well-crystallized boehmite in the product can be explained by the fugacity of water, as follows.…”

Section: Xrd Profiles Of the Productsmentioning

confidence: 96%

Formation of Organic Derivatives of Boehmite by the Reaction of Gibbsite with Glycols and Aminoalcohols

Inoue

Tanino

Kondo

et al. 1991

Clays and clay miner.

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Abstract--The reaction of gibbsite in various organic solvents at 2500--300"C under spontaneous vapor pressure of the solvents was examined. Glycols and aminoalcohols afforded the organic derivatives of boehmite in which one of the oxygen atoms of the glycol molecule or the alcoholic oxygen atom of aminoalcohol was incorporated into the boehmite layers. By increasing the molecular size of the solvent, the yield of the boehmite derivative decreased, and, at the same time, the basal spacing of the boehmite derivative increased. The product had a honeycomb texture on the surface of the particle, which suggests a dissolution-recrystallization mechanism for the formation of the boehmite derivatives. A hydroxyl group and a functional group, such as hydroxyl, methoxyl, or amino group having the ability to donate its lone pair electrons, were apparently necessary for the organic solvent molecules to form the boehmite derivative by this mechanism.

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Studies on pore systems in catalysts IV. The two causes of reversible hysteresis

Cited by 50 publications

References 3 publications

Characteristics of fine pores in some halloysites

Characteristics of fine pores in some halloysites

TG/XRD/Sem Study of the Conversion of Gibbsite to (Pseudo) Boehmite

Formation of Organic Derivatives of Boehmite by the Reaction of Gibbsite with Glycols and Aminoalcohols

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