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Showing papers on "Mesoporous material published in 1991"


Journal ArticleDOI
TL;DR: In this article, secondary ion mass spectroscopy (SIMS) analysis is used for the first time to simultaneously monitor all the major impurities on a surface of a Si surface.
Abstract: Microporous and mesoporous Si layers contain a very large surface area that affects both their optical and electrical properties. Secondary ion mass spectroscopy (SIMS) analysis is used for the first time to simultaneously monitor all the major impurities on that surface. SIMS data on a microporous layer demonstrate that its chemical composition changes dramatically with time during ambient air exposure. Similar trends are observed for mesoporous layers. Extended storage in air at room temperature converts the hydride surface of freshly anodized layers to that of a contaminated native oxide. Characterization techniques need to take the metastability of the hydride surface into account since the structural, optical, and electrical properties of porous Si can consequently change with time upon exposure to ambient air. Low‐temperature photoluminescence and spectroscopic ellipsometry data on freshly anodized and ‘‘aged’’ microporous and mesoporous layers are chosen to illustrate typical changes in optical pro...

349 citations


Patent
21 Jun 1991
TL;DR: In this article, a new process for catalytic oligomerization of lower olefin component in paraffin-containing mixed aliphatic feedstock is provied for contacting the feedstock under catalytic conversion conditions with acid metallosilicate solid catalyst having the structure of MCM-41 with hexagonal honeycomb lattice structure consisting essentially of uniform pores in the range of about 20 to 100 Angstroms.
Abstract: A process for upgrading aliphatic feedstocks containing lower olefins employing new synthetic catalyst of ultra-large pore crystalline material. The new crystalline material exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of greater than about 15 grams benzene/100 grams at 50 torr and 25° C., a hexagonal electron diffraction pattern that can be indexed with a d 100 value greater than about 18 Angstrom Units and a hexagonal arrangement of uniformly sized pores with a maximum perpendicular cross section of at least about 13 Angstrom units. A new process is provied for catalytic oligomerization of lower olefin component in paraffin-containing mixed aliphatic feedstock which comprises contacting the feedstock under catalytic conversion conditions with acid metallosilicate solid catalyst having the structure of MCM-41 with hexagonal honeycomb lattice structure consisting essentially of uniform pores in the range of about 20 to 100 Angstroms. The oligomerization reaction is very selective, especially when conducted at temperature of about 40° to 250° C., yielding branched intermediate olefins. Low severity reaction permits execellent conversion of lower olefins at pressure of about 100-13,000 pKa range and moderate space velocity. Oligomers of propene produced over MCM-41, when reacted under cracking/disproportionation conditions yield a propylene-rich mixture which is separated as a C 3 stream, and C 6 + isoalkenes are recovered in good yield.

50 citations


Journal ArticleDOI
TL;DR: In this paper, the intercalation of the tridecameric polyhydroxyaluminium Keggin-type cation, formally [AlO4Al12(OH)24(OH2)12]7+, into α-Sn(HPO4)2·H2O via the colloidal tetramethylammonium-exchanged intermediate α-sn[NMe4]0.9-1.0H1.1]-1.
Abstract: The intercalation of the tridecameric polyhydroxyaluminium Keggin-type cation, formally [AlO4Al12(OH)24(OH2)12]7+, into α-Sn(HPO4)2·H2O via the colloidal tetramethylammonium-exchanged intermediate α-Sn[NMe4]0.9–1.0H1.1–1.0(PO4)2·4H2O and the alumina-pillared materials obtained after calcination are described. Two different intercalated precursor materials are obtained, depending on whether the Keggin ion inserted derives from the commercial product (‘Chlorhydrol’) or from the polyhydroxyaluminium cation generated in situ. Calcination leads to materials differing in free heights and in alumina contents. Their surface areas (B.E.T., N2, 77 K) are quite high: 190 m2 g–1[chlor-SnP (400 °C)] and 228 m2 g–1[Al13-SnP (400 °C)]. Pore-size calculations show them to be mainly mesoporous, but with some micropore contribution (> 50% of pores in width range 15–40 A). The higher microporosity of the former with respect to the latter is ascribed to lateral-order differences between the alumina pillars.High cation-exchange capacities (for Co2+, Ni2+ and Cu2+) confirm that both solids are porous and have more accessible interlayer sites than does the parent material. Optical spectra of the transition-metal ion-exchanged materials indicate that the sites available in the two solids differ, and that both differ from those present in the starting α-tin phosphate. Site geometries are suggested.

43 citations


Patent
William A. Wachter1
30 Dec 1991
TL;DR: A catalytic cracking catalyst for converting a hydrocarbon feedstock at elevated temperature in the substantial absence of hydrogen, into lower average molecular weight, lower boiling hydrocarbons useful as transportation fuels as mentioned in this paper.
Abstract: A catalytic cracking catalyst for converting a hydrocarbon feedstock at elevated temperature in the substantial absence of hydrogen, into lower average molecular weight, lower boiling hydrocarbons useful as transportation fuels. The catalyst is a composite of a crystalline aluminosilicate zeolite in concentration ranging as high as about 80 percent, based on the total weight of the catalyst, within a mesoporous silica-alumina matrix. The matrix, preferably, is constituted of silica sols modified by alumina and clay and it is characterized as of polymodal pore size distribution, as measured by mercury porosimetry, a first mode wherein at least 75 percent, preferably about 80 percent to 90 percent, of the pore volume measured between 45 Angstroms and 2000 Angstroms is in pores greater than 160 Angstroms in diameter, and a second mode wherein up to about 20 percent of the pore diameters are greater than 100 Angstroms but less than 160 Angstroms in diameter. These catalysts are highly active, and selective in the production of olefins without high coke made. The attrition-resistance of these catalysts, as measured by the Davison Index, is quite low, ranging generally from about 1 to about 8, more generally from about 1 to about 5, or less.

34 citations


Patent
Quang N. Le1, Robert T. Thomson1
21 Jun 1991
TL;DR: In this paper, a process for naphtha cracking employing new synthetic catalyst of ultra-large pore crystalline material was proposed, which exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of greater than about 15 grams benzene/100 grams at 50 torr and 25° C.
Abstract: A process for naphtha cracking employing new synthetic catalyst of ultra-large pore crystalline material. The new crystalline material exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of greater than about 15 grams benzene/100 grams at 50 torr and 25° C., a hexagonal electron diffraction pattern that can be indexed with a d100 value greater than about 18 Angstrom Units and a hexagonal arrangement of uniformly sized pores with a maximum perpendicular cross section of at least about 13 Angstrom units. An improved cracking reaction is provided for catalytic conversion of hydrocarbon feedstock which comprises contacting the feedstock under catalytic conversion conditions with acid metallosilicate solid catalyst having the structure of MCM-41 with hexagonal honeycomb lattice structure consisting essentially of uniform pores in the range of about 20 to 100 Angstroms. The cracking reaction is very selective, especially when conducted at temperature of about 425° to 650° C.

32 citations


Patent
20 Jun 1991
TL;DR: In this paper, a method for improving the stability of a composition of matter comprising an inorganic, porous, non-layered crystalline phase exhibiting an X-ray diffraction pattern with at least one peak at a d-spacing greater than about 18 Angstrom Units and having a benzene adsorption capacity after stabilization of greater than 15 grams benzene per 100 grams of said material at 50 torr and 25° C.
Abstract: A method for improving the stability of a composition of matter comprising an inorganic, porous, non-layered crystalline phase exhibiting an X-ray diffraction pattern with at least one peak at a d-spacing greater than about 18 Angstrom Units and having a benzene adsorption capacity after stabilization of greater than 15 grams benzene per 100 grams of said material at 50 torr and 25° C. includes contacting the crystalline material with a compound M'X2 Yn wherein M' represents B, Al, Si, or Ti; X represents halides or alkoxides of C1-6 ; Y represents X or alkyls of C1-12 ; and n=1-2; said contacting occurring under sufficient contacting conditions to result in a thermally and/or hydrothermally stable crystalline product.

31 citations


Patent
24 Jul 1991
TL;DR: Paraffins, especially paraffins in the C4 -C8 range, are isomerized to iso-paraffins over an isomerization catalyst comprising a noble metal such as platinum on a support material comprising an inorganic, non-layered, porous, crystalline phase aluminosilicate material with pores of at least 13 Å and which exhibits, after calcination, an X-ray diffraction pattern with at least one peak at a d-spacing greater than 18Å as mentioned in this paper.
Abstract: Paraffins, especially paraffins in the C4 -C8 range, are isomerized to iso-paraffins over an isomerization catalyst comprising a noble metal such as platinum on a support material comprising an inorganic, non-layered, porous, crystalline phase aluminosilicate material with pores of at least 13 Å and which exhibits, after calcination, an X-ray diffraction pattern with at least one peak at a d-spacing greater than 18 Å. These materials have a high surface area and sorption capacity marked by a benzene adsorption capacity of greater than about 15 grams benzene per 100 grams at 50 torr and 25° C. In its preferred form, the support material has a uniform, hexagonal arrangement of pores with diameters of at least about 13 Å and a hexagonal electron diffraction pattern that can be indexed with a d100 value greater than about 18 Å which corresponds to at least one peak in the X-ray diffraction pattern.

31 citations


Patent
24 Jun 1991
TL;DR: In this paper, a method for synthesizing ultra-large pore crystalline material which can be used as a sorbent or catalyst component for conversion of organic and inorganic compounds is described.
Abstract: This invention relates to a method for synthesizing ultra-large pore crystalline material which can be used as a sorbent or catalyst component for conversion of organic and inorganic compounds. A dialkoxyaluminoxytrialkoxysilane is added to the reaction mixture as a metal oxide source.

28 citations


Patent
24 Jul 1991
TL;DR: In this paper, a method for modifying a synthetic composition of ultra-large pore crystalline material, e.g., silicate, comprising an inorganic, porous, non-layered crystalline phase material exhibiting, after calcination, an X-ray diffraction pattern with at least one peak at a d-spacing greater than 18 Angstrom Units and having a benzene adsorption capacity of greater than 15 grams benzene per 100 grams of said material at 6.7 kPa (50 torr) and 25° C.
Abstract: This invention relates to a method for modifying a synthetic composition of ultra-large pore crystalline material, e.g., silicate, comprising an inorganic, porous, non-layered crystalline phase material exhibiting, after calcination, an X-ray diffraction pattern with at least one peak at a d-spacing greater than 18 Angstrom Units and having a benzene adsorption capacity of greater than 15 grams benzene per 100 grams of said material at 6.7 kPa (50 torr) and 25° C., by contacting with a treatment composition comprising an inorganic oxide of a trivalent element X, e.g., sodium aluminate, or precursor of said inorganic oxide, under sufficient conditions so that the trivalent element X is incorporated in the crystalline phase material. The composition is suited to use for catalytic conversion of organic compounds or as a sorbent.

27 citations


Patent
21 Jun 1991
TL;DR: In this paper, a process for upgrading olefins employing new synthetic catalyst of ultra-large pore crystalline material was proposed, which exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of greater than 15 grams benzene/100 grams at 50 torr and 25° C.
Abstract: A process for upgrading olefins employing new synthetic catalyst of ultra-large pore crystalline material. The new crystalline material exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of greater than about 15 grams benzene/100 grams at 50 torr and 25° C., a hexagonal electron diffraction pattern that can be indexed with a d100 value greater than about 18 Angstrom Units and a hexagonal arrangement of uniformly sized pores with a maximum perpendicular cross section of at least about 13 Angstrom units. A new process is provided for catalytic oligomerization of olefin feedstock which comprises contacting the feedstock under catalytic conversion conditions with acid metallosilicate solid catalyst having the structure of MCM-41 with hexagonal honeycomb lattice structure consisting essentially of uniform pores in the range of about 20 to 100 Angstroms. The oligomerization reaction is very selective, especially when conducted at temperature of about 40° to 250° C. Low severity reaction permits excellent conversion of lower olefins at pressure of about 100-13,000 pKa range and moderate space velocity.

25 citations


Journal ArticleDOI
TL;DR: In this paper, a detailed electron microscope study of porous silicon compared the different structures of macro-, meso- and microporous material. And they provided strong direct evidence that visible luminescence arises from dramatic carrier confinement in quantum-size, crystalline silicon structures.
Abstract: This detailed electron microscope study of porous silicon compares the different structures of macro-, meso- and microporous material. Mesoporous silicon of high porosity (~80%) exhibits efficient red photoluminescence at room temperature. Transmission electron microscopy provides strong direct evidence that this visible luminescence arises from dramatic carrier confinement in quantum-size, crystalline silicon structures. Images of undulating, interconnected ‘quantum wires’ of widths <3nm are shown.

Patent
25 Jun 1991
TL;DR: In this paper, a method for synthesizing an ultra-large pore crystalline material which can be used as a sorbent or catalyst component for conversion of organic and inorganic compound is improved through the addition of a strong acid to the reaction mixture.
Abstract: A method for synthesizing an ultra-large pore crystalline material which can be used as a sorbent or catalyst component for conversion of organic and inorganic compound is improved through the addition of a strong acid to the reaction mixture.

Patent
24 Jul 1991
TL;DR: The mesoporous crystalline catalyst as mentioned in this paper comprises an inorganic, non-layered, porous, crystalline phase aluminosilicate material which exhibits a benzene adsorption capacity of greater than about 15 grams benzene per 100 grams at 50 torr and 25° C.
Abstract: Emissions of nitrogen oxides (NOX) to the atmosphere are reduced by treatment of gases containing nitrogen oxides with a reducing agent such as ammonia in the presence of a catalyst containing a mesoporous crystalline catalyst. The mesoporous crystalline catalyst comprises an inorganic, non-layered, porous, crystalline phase aluminosilicate material which exhibits a benzene adsorption capacity of greater than about 15 grams benzene per 100 grams at 50 torr and 25° C. In its preferred catalytic form, the crystalline material has a uniform, hexagonal arrangement of pores with diameters of at least about 13 Å and exhibiting, after calcination, an X-ray diffraction pattern with at least on d-spacing greater than about 18 Å and a hexagonal electron diffraction pattern that can be indexed with a d100 value greater than about 18 Å which corresponds to at least one peak in the X-ray diffraction pattern.

Patent
18 Jul 1991
TL;DR: In this article, a method for synthesizing an ultra-large pore crystalline material and the use of such crystalline materials as a sorbent and in catalytic conversion of organic and inorganic compounds is described.
Abstract: This invention relates to a method for synthesizing an ultra-large pore crystalline material and the use of such crystalline material as a sorbent and in catalytic conversion of organic and inorganic compounds. The synthesis method includes hydrothermally treating the as-synthesized crystalline material in the presence or absence of a binder. In a preferred embodiment, the crystalline material contains organic directing agent and is composited in an alumina binder. The crystalline material exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of greater than about 15 grams benzene/100 grams at 50 torr and 25° C., a hexagonal electron diffraction pattern that can be indexed with a d100 value greater than about 18 Angstrom Units and a hexagonal arrangement of uniformly sized pores with a maximum perpendicular cross section of at least about 13 Angstrom units.

Patent
29 Apr 1991
TL;DR: In this paper, a process for oligomerizing alpha olefins to produce hydrocarbon oligomers useful as lubricants and lubricant additives uses a catalyst comprising a supported reduced group VIB metal, preferably chromium, in the form of its oxide.
Abstract: A process for oligomerizing alpha olefins to produce hydrocarbon oligomers useful as lubricants and lubricant additives uses a catalyst comprising a supported reduced group VIB metal, preferably chromium, in the form of its oxide. The support is a mesoporous, inorganic, crystalline solid of unique structure, of novel pore geometry. The preferred forms of these mesoporous materials are characterized by substantially uniform hexagonal honeycomb microstructure, with uniform pores having a cell diameter greater than 13 Å, preferably in the mesoporous range of about 20-100 Å. The use of the catalysts made with the mesoporous support materials enables products of greater viscosity to be made as compared to the products from catalysts using amorphous supports. The catalyst is usually used under oligomerization conditions at a temperature of about 90° to 250° C. to produce liquid hydrocarbon oligomers in the lubricant range which have a branch ratio of less than 0.19 and high values of viscosity index.

Patent
24 Jun 1991
TL;DR: In this article, a method for purifying an ultra-large pore crystalline material by contact with an aqueous solution having a hydroxyl concentration sufficient to solubilize an impurity phase but not the material is described.
Abstract: A method is described for purifying an ultra-large pore crystalline material by contact with an aqueous solution having a hydroxyl concentration sufficient to solubilize an impurity phase but not the crystalline material. The purified crystalline material is also described, as is a hydrocarbon conversion process over the purified crystalline material.

Journal ArticleDOI
TL;DR: The presence of H3PO3 in the synthesis of zirconium diphosphonates in dimethylsulfoxide, other than the expected dilution of the pillars, which in turn gives rise to a certain degree of microporosity, may also induce the formation of a high percentag. of mesopores as mentioned in this paper.
Abstract: The presence of H3PO3 in the synthesis of zirconium diphosphonates in dimethylsulfoxide, other than the expected dilution of the pillars, which in turn gives rise to a certain degree of microporosity, may also induce the formation of a high percentag. of mesopores. E.g., compounds with high surface area(300-500 m2 /g) of which 60-70% is due to mesopores with diameters 20-40 A and the remaining is due to micropores, were obtained. It was furthermore found that the distribution of the mesopores was fairly narrow. Compounds with micropores <3 A and mesopores of 20-30 A behave in practice as pure and narrow mesoporous solids;they are therefore of great interest as new molecular inorgano-organic sieves.

Patent
Quang N. Le1, Robert T. Thomson1
07 Oct 1991
TL;DR: In this paper, a mesoporous acid metallosilicate crystalline catalyst material having Bronsted acid sites in a hexagonal lattice structure is characterized by a substantially uniform pores in hexagonal arrangement with a pore size of about 20 to 100 Angstroms units.
Abstract: In the process of olefin disproportionation, a feedstock containing predominatly mono-olefin the feedstock is charged at elevated temperature into a catalytic conversion zone in contact with mesoporous acid olefin conversion catalyst under selective olefin interconversion conditions. The improvement is characterized by a mesoporous acid metallosilicate crystalline catalyst material having Bronsted acid sites in a hexagonal lattice structure, said catalyst material having substantially uniform pores in hexagonal arrangement with a pore size of about 20 to 100 Angstroms units. In the preferred embodiments the olefinic feedstock is reacted for less than 10 seconds in contact with MCM-41 mesoporous metallosilicate catalyst under partial reaction conditions sufficient to provide increased yield of C4 alkene having a ratio of isobutene to normal butenes greater than equilibrium.

Patent
21 Jun 1991
TL;DR: In this article, a multistage process is provided for catalytic oligomerization of lower olefin which comprises contacting ole finetextraction feedstock under catalytic conversion conditions with acid metallosilicate solid catalyst having the structure of MCM-41 with hexagonal honeycomb lattice structure consisting essentially of uniform pores in the range of about 20 to 100 Angstroms.
Abstract: A process for upgrading olefinic feedstocks containing lower olefins employing new synthetic catalyst of ultra-large pore crystalline material. The new crystalline material exhibits unusually large sorption capacity demonstrated by its benzene adsorption capacity of greater than about 15 grams benzene/100 grams at 50 torr and 25° C., a hexagonal electron diffraction pattern that can be indexed with a d100 value greater than about 18 Angstrom Units and a hexagonal arrangement of uniformly sized pores with a maximum perpendicular cross section of at least about 13 Angstrom units. A multistage process is provided for catalytic oligomerization of lower olefin which comprises contacting olefinic feedstock under catalytic conversion conditions with acid metallosilicate solid catalyst having the structure of MCM-41 with hexagonal honeycomb lattice structure consisting essentially of uniform pores in the range of about 20 to 100 Angstroms. The oligomerization reaction is very selective, especially when conducted at temperature of about 40° to 250° C., yielding branched intermediate olefins. Low severity reaction permits excellent conversio of lower olefins at pressure of about 100-13,000 pKa range and moderate space velocity. Intermediate oligomers produced over MCM-41, when reacted under cracking/disproportionation conditions yield etherifiable C4 + isoalkenese in good yield.

Journal ArticleDOI
TL;DR: In this paper, it was shown that increasing the pH of preparation leads to an increase in exchange capacities of the hydroxide precipitated gels that are characterized to be mesoporous, whereas an increase is not observed in the case of carbonate precipitated microporous gels.
Abstract: In the case of gels precipitated by ammonium carbonate, oxygen gas was used as the oxidizing agent whereas with ammonium hydroxide as precipitant, oxidation was performed with hydrogen peroxide. Ion exchange capacities were determined by visible spectrophotometry. Increasing the pH of preparation lead to an increase in exchange capacities of the hydroxide precipitated gels that are characterized to be mesoporous. Such an increase is not observed in the case of carbonate precipitated microporous gels. It is shown that in the latter case the NH,~ ions generated by the initial interaction of (NH4)2C03 with the acidic titanous chloride lead to the formation of titania exchangers that are predominantly in the, ammonium form. The textural characteristics of the exchanger resulting from different conditions of preparation is a significant contributing parameter to the resulting data. Ageing of the microporous titania samples markedly reduces the exchanger capacity of the smaller Ni 2+ ions but increases that of the bulkier Cr 3§ as a result of the presence of some wide pores that appear upon agglomeration. The presence of Cr 3§ ions in the hydroxo form in solution seems to inhibit its exchange with the appropriate surface species. Studies on the kinetics of exchange with respect to the Ni 2+ ions seem to indicate that a particle diffusion mechanism is partly or completely responsible for the rate of exchange.

Book ChapterDOI
TL;DR: In this paper, the mesoporous material from a precursory hectorite synthesized at 150°C has a total specific surface area of 848 m 2 g − 1, a pore volume of 0.98 cm 3 g −1 and an pore average diameter of 46 A, values which are significantly higher than those of conventional pillared clays.
Abstract: Novel mesoporous materials having exceptionally large pores were produced from hydrothermally synthesized silicate-bearing hectorites. Experiments suggest that interlayer anisotropic silicates act as larger pillars. Method of preparing such materials is described, together with their porous properties. The mesoporous material from a precursory hectorite synthesized at 150°C has a total specific surface area of 848 m 2 g −1 , a pore volume of 0.98 cm 3 g −1 and an pore average diameter of 46 A, values which are significantly higher than those of conventional pillared clays.

Patent
01 Aug 1991
TL;DR: In this article, a diphosphonate/phosphite of a tetravalent metal is described in the form of a crystalline solid with an alpha-type lamellar structure with a distance between layers of 7.4 to 20Å (depending on the dimensions of radical R).
Abstract: The present invention discloses a compound comprising a diphosphonate/phosphite of a tetravalent metal: M[(O.sub.3 P--R--PO.sub.3).sub.1-(x+y) (HPO.sub.3).sub.2X (O.sub.3 P--R--PO 3 H 2 ) 2y ] (where M, R, x and y have the meaning given in the description), in the form of a crystalline solid with an alpha-type lamellar structure with a distance between layers of 7.4 to 20Å (depending on the dimensions of radical R), a BET surface area of 250 to 400m 2 /g, and porosity within the mesopore range, with at least 50% of the pores measuring 20 to 30Å. The compound, depending on the radical R used, may or may not have microporosity in the region between layers. Such a diphosphonate/phosphite of a tetravalent metal is obtained by reaction between diphosphonic acid, phosphorous acid and an oxyhalide of a tetravalent metal, in a solvent comprising dimethyl-sulphoxide/water containing hydrofluoric acid.

Patent
30 Jul 1991
TL;DR: In this article, a compound comprising a diphosphonate/phosphite of a tetravalent metal is described, in the form of a crystalline solid with an alpha-type lamellar structure with a distance between layers of 7.4 to 20A, a surface area of 250 to 400m2/g, and porosity within the mesopore range.
Abstract: The present invention discloses a compound comprising a diphosphonate/phosphite of a tetravalent metal: (where M, R, x and y have the meaning given in the description), in the form of a crystalline solid with an alpha-type lamellar structure with a distance between layers of 7.4 to 20A (depending on the dimensions of radical R), a BET surface area of 250 to 400m2/g, and porosity within the mesopore range, with at least 50% of the pores measuring 20 to 30A. The compound, depending on the radical R used, may or may not have microporosity in the region between layers. Such a diphosphonate/phosphite of a tetravalent metal is obtained by reaction between diphosphonic acid, phosphorous acid and an oxyhalide of a tetravalent metal, in a solvent comprising dimethyl-sulphoxide/water containing hydrofluoric acid.

Book ChapterDOI
TL;DR: In this paper, a model of porous adsorbent gels (silica, ceria) composed of regular packings of spherical oxide sol particles have been prepared and the pore size in the gels was controlled by the diameter of the sol particles.
Abstract: Summary Model porous adsorbent gels (silica, ceria) composed of regular packings of spherical oxide sol particles have been prepared. The pore size in the gels was controlled by the diameter of the sol particles. The mechanisms of adsorption and capillary condensation of water in the gels was investigated by small angle neutron scattering using H 2 O/D 2 O mixtures which had a composition which gave a contrast match with the solid oxide. Behaviour of mesoporous silicas is in accord with previous theoretical models based on multilayer and capillary condensation whereas for microporous ceria there is clear evidence of a volume filling mechanism where the sorbed water has a density significantly less than in the bulk.

Journal ArticleDOI
TL;DR: In this article, a study of the sorption of bull serum albumin (BSA) on carbon adsorbents with different porous structures has shown that the size of the adsorbent particles depends on the amount of BSA absorbed.
Abstract: A study of the sorption of bull serum albumin (BSA) on carbon adsorbents with different porous structures has shown that, for adsorbents with globular structures, sorption depends on the size of the adsorbent particles. An assumption has been made concerning the nonequilibrium nature of BSA sorption on mesoporous adsorbents associated with irreversible adsorption of the protein and the nonuniform distribution of the adsorbed protein within the adsorbent particles.


Journal ArticleDOI
TL;DR: In this article, photothermal spectroscopy experiments have been used for the first time to study non-radiative processes in mesoporous silicon layers of varying porosity, which can be explained by a model which involves interference between thermal waves reflected at the porous silicon film-silicon substrate interface.
Abstract: Photothermal spectroscopy experiments have been used for the first time to study non-radiative processes in mesoporous silicon layers of varying porosity. Data on low porosity material can be explained by a model which involves interference between thermal waves reflected at the porous silicon film-silicon substrate interface. High porosity material, which exhibits strong red photoluminescence, cannot be fitted to this model. These materials seem to indicate the existence of another critically damped wave-like excitation in addition to the thermal waves.