Showing papers on "Activated alumina published in 2002"
TL;DR: A novel adsorbent, aluminum-loaded Shirasu-zeolite P1 (Al-SZP1), was prepared and employed for the adsorption and removal of arsenic(V) (As(V)) ion from aqueous system and seems to be especially suitable for removal of As (V) in low concentration.
268 citations
TL;DR: In this paper, the adsorption of fluoride ion in aqueous solution by using alumina was studied and the experimental results indicated that the removal efficiency was influenced significantly by solution pH and the optimum operating pH was found to be in the range of 5 to 7.
Abstract: The adsorption of fluoride ion in aqueous solution by using alumina was studied in this research. The experimental resultsindicated that the removal efficiency was influenced significantly by solution pH and the optimum operating pH wasfound to be in the range of 5 to 7. For neutral and acidic solutions, the adsorption capacities of fluoride by alumina wasinterfered by the presence of sulfate. The Langmuir and Freundlich isotherms can well describe the equilibrium behaviorsof the adsorption processes. The experimentally determined lowvalues of activation energy indicate nonspecific adsorption isthe predominant mechanism. The surface reaction-limiting batchkinetic model can adequately describe the removal behaviors offluoride ion by alumina adsorption in the batch system.
226 citations
TL;DR: In this article, four activated carbons of various origins were impregnated with different concentrations of sodium hydroxide and used as hydrogen sulfide adsorbents in an accelerated test.
Abstract: Four activated carbons of various origins were impregnated with different concentrations of sodium hydroxide and used as hydrogen sulfide adsorbents in an accelerated test. The materials were characterized using nitrogen sorption, thermal analysis, and standard ASTM methods. The results showed that, with increasing loading of NaOH, the H2S breakthrough capacity increases 4−5 times until maximum capacity is reached at about 10% NaOH. This capacity per unit volume of the carbon bed is the same for all carbons and insensitive to their pore structures and surface areas. The specific capacity per unit surface area is also the same for all materials studied, including activated alumina. This indicates that the amount of NaOH present on the surface is a limiting factor for the capacity. By increasing the pH value of the carbon, sodium hydroxide causes an increase in the HS- ion concentration. These ions can be further oxidized to elemental sulfur or sulfuric acid, as suggested by changes in the surface pH values...
132 citations
TL;DR: In situ IR studies of the dehydroxylation of the alumina surface, showed nu(OH) absorptions for isolated surface hydroxy groups centering at 3670, 3714, and 3765 cm(-1), which are shifted to lower frequencies than common literature values.
Abstract: Mesoporous high-surface-area alumina was prepared by a modified aerogel procedure. Specific surface areas between 530-685 m(2)g(-1) were obtained after heat treatment at 500 degrees C. Nitrogen adsorption studies have shown that surface areas and pore characteristics change upon decomposition of aluminum hydroxide to oxide as well as upon compaction of oxide powders. The surface area of aluminum hydroxide increased to a maximum, while the pore volume and diameter decreased as the hydroxide was heated to a temperature of 400 degrees C. Heating at higher temperatures resulted in sintering of the particles accompanied by a decline in the surface area. Compaction of activated alumina into pellets was accompanied by a relatively gradual change in the surface area and pore characteristics at pressures below 6.9 x 10(7) Pa, while severe changes took place at a pressure of 1.4 x 10(8) Pa. In situ IR studies of the dehydroxylation of the alumina surface, showed nu(OH) absorptions for isolated surface hydroxy groups centering at 3670, 3714, and 3765 cm(-1), which are shifted to lower frequencies than common literature values. Pyridine was found to adsorb on Al(3+) ions as well as through hydrogen bonding to relatively acidic surface OH groups, and IR spectra indicated the presence of strong Lewis acid sites.
52 citations
TL;DR: In this article, a mechanism for the conversion of H2S and SO2 over alumina is proposed in which surface thiosulfate is formed and reacts with SO2 and H 2S via a series of oxy-anions to form sulfur and H2O.
Abstract: A mechanism for the conversion of H2S and SO2 over alumina is proposed in which surface thiosulfate is formed and reacts with SO2 and H2S via a series of oxy-anions to form sulfur and H2O. In addition to thiosulfate being a key species of the catalytic cycle, it is proposed that sulfate is also formed as part of the catalytic cycle but that its surface concentration is limited to some steady-state concentration by virtue of its reduction by H2S. The initial formation of thiosulfate and sulfate on alumina probably occurs by two mechanisms. One pathway involves interaction of either H2S or SO2 with oxide sites on the alumina surface. Such oxide sites have been suggested by Sohlberg et al. to arise as a consequence of the interaction of vacant sites in the defect spinel structure of alumina with H2O [J. Phys. Chem. 100 (1996) 7550]. The other pathway, the first step of which has been referred to numerous times in the literature, likely involves the adsorption of SO2 at Lewis acid–base sites, and reaction with H2S to form sulfur oxy-anions and eventually, sulfur and water.
43 citations
TL;DR: Seven household treatment technologies for the removal of arsenic were evaluated using water from 63 different tube wells taken from 3 different regions of Bangladesh and it became clear that such technologies can increase the risk of bacterial contamination in the treated water and this needs serious consideration.
Abstract: Seven household treatment technologies for the removal of arsenic (Alcan, BUET, DPHE/DANIDA, Garnet, Sono, Stevens, Tetrahedron) were each evaluated using water from 63 different tube wells taken from 3 different regions of Bangladesh. The technologies that were evaluated were chosen from those that appeared user friendly, readily available and whose promoters were open to participate in the study. Arsenic concentrations in feed and treated waters were analysed by the PeCo 75 arsenic field test kit, AA-hydride generation and ICP-AES. Feed water arsenic concentrations were found to be up to 600 µg l−1. The more advanced treatment methods using: activated alumina (Alcan, BUET); metallic iron (Sono); anionic exchange resin (Tetrahedron) and iron coagulation (Stevens) were found to be most easily used and efficiently reduced arsenic concentrations to below the Bangladesh drinking water standard (0.05 mg As l−1). The use of aluminium sulphate coagulants and permanganate oxidants in the DPHE/DANIDA technology i...
29 citations
TL;DR: In this paper, the role of activated alumina in catalyzing C6-alkane conversion was investigated and it was confirmed that in effect of high temperature reduction (at 600-°C) Al2O3 gains a considerable acidity which must play an important role in transformation of C6alkanes.
18 citations
TL;DR: In this paper, the catalytic performance of Pd/Al2O3 catalysts is compared to that exhibited by unsupported or silica-supported palladium, i.e., the predominance of metal-catalyzed reactions is observed with high hydrogenolysis selectivity and a bond-shift mode of isomerization.
Abstract: A comparable study of catalytic conversion of two C6-alkanes (n-hexane and 2,2-dimethybutane) has shown several analogies in the catalytic behavior of a series of differently loaded, chlorine-free Pd/Al2O3 catalysts. Different sample pretreatments have been used to modify the catalytic behavior. The catalytic performance of lowly reduced (at 573 K) samples of Pd/Al2O3 catalysts is similar to that exhibited by unsupported or silica-supported palladium, i.e. the predominance of metal-catalyzed reactions is observed with high hydrogenolysis selectivity and a bond-shift mode of isomerization. Highly reduced (at 873 K) samples experience a serious increase in overall activity, and simultaneously, big enhancement of isomerization selectivity (at ≤563 K), in agreement with previous reports [1] , [2] , [3] . At the same time, the activity is strongly correlated with the amount of activated alumina in the catalyst and only insignificantly dependent on Pd content in the catalyst. TPD of ammonia has been employed to confirm expected changes in the acidity generated by various catalyst pretreatments. It is considered that Lewis acidity of alumina, increased upon high temperature reduction (HTR), is a source of enhanced isomerization activity exhibited by Pd/Al2O3 catalysts. However, a palladium-free alumina cannot serve as efficient catalyst in alkane hydroconversion. Metallic function is needed to provide active hydrogen for a hydrogenative desorption of rearranged hydrocarbon species from acid sites of γ-Al2O3.
18 citations
Patent•
28 May 2002TL;DR: In this article, an activated alumina formed body with a high bulk density and a large macro-pore volume is provided, which is usable as an adsorbent, a catalyst supporting precious metal or the like.
Abstract: An activated alumina formed body with a high bulk density and a large macro-pore volume is provided. The activated alumina formed body can be produced by a method comprising the steps of calcining a gibbsite-phase aluminum hydroxide having a median particle size of from about 10 μm to about 35 μm and a packed bulk density of from about 1.05 g/cm3 to about 1.3 g/cm3 to obtain an at least partially rehydratable alumina powder; forming the rehydratable alumina powder in the presence of water; maintaining the formed body in the presence of water to rehydrate the formed body; and calcining the rehydrated formed body to obtain an activated alumina formed body. The activated alumina formed body is usable as an adsorbent, a catalyst supporting precious metal or the like.
9 citations
Patent•
01 May 2002TL;DR: In this paper, a method to remove acid gas from a sulfur compound stream by adsorption on an adorption media adsorbent followed by regeneration of the media after reaching the ad-sorption capacity has been reached is described.
Abstract: An adsorption method is disclosed for removal of acid gas from a sulfur compound stream. The method relates to a novel process to remove acid gas from a sulfur compound stream by adsorption on an adsorption media adsorbent followed by regeneration of the adsorption media after the adsorption capacity has been reached. The adsorption media comprises an activated alumina, which has been previously treated with one or more alkali metal compounds, one or more alkaline earth metal compounds, or a mixture thereof; and then regenerating the adsorbent after the adsorption capacity has been reached.
7 citations
01 Jan 2002
TL;DR: In this article, the highly ordered mesoporous silica SBA-15 was successfully synthesized and incorporated with iron, aluminum, and zinc oxides by use of an incipient wetness impregnation technique.
Abstract: The highly ordered mesoporous silica SBA-15 was successfully synthesized and incorporated with iron, aluminum, and zinc oxides by use of an incipient wetness impregnation technique. Aluminum 10% impregnation was safely incorporated by an incipient wetness impregnation technique for SBA-15, which had 638.75 m 2 /g of BET surface area and 48 A of pore diameter, without producing clogging of pore structures. The adsorption capacities of these materials were evaluated with adsorption isotherm and kinetic studies under different batch conditions. Aluminum was the best incorporation metal compound and impregnation of aluminum 10% for SBA- 15 had greater than 2 times higher arsenate adsorption capacity and 15 times higher rate than activated alumina under the condition of 0.133 mmol/L arsenate initial concentration and 0.333 g/L of solids concentration. Al10SBA-15 showed about 2.2 ~ 2.4 times higher arsenate adsorption capacities than activated alumina in a broad range of arsenate initial concentrations, in which the Freundlich isotherm model was fitted very well. The ratecontrolling step of arsenate adsorption for all adsorbents appeared to be explained by both the exchange reaction and diffusion reaction. These results showed great advantages of Al10SBA-15 for POE/POU application due to its rapid and high adsorption capacity.
Patent•
30 Apr 2002
TL;DR: In this article, the authors proposed a catalytic catalysts for desulfurization treatment of a reaction gas and producing a hydrogen-containing gas stably for a long duration without adding steam to the reaction gas by hydrocarbon partial oxidation.
Abstract: PROBLEM TO BE SOLVED: To provide a catalyst for carrying out desulfurization treatment of a reaction gas and producing a hydrogen-containing gas stably for a long duration without adding steam to the reaction gas by hydrocarbon partial oxidation. SOLUTION: The hydrocarbon partial oxidation catalyst comprises heat- resistant inorganic oxides and a platinum-group metal carried by a monolith carrier. The catalyst contains activated alumina, cerium oxide, and zirconium oxide as the heat-resistant inorganic oxides at a weight ratio of activated alumina:cerium oxide in a range of (100:15) to (100:60) and at a weight ratio of cerium oxide:zirconium oxide in a range of (100:2) to (100:60). COPYRIGHT: (C)2004,JPO
Patent•
06 Mar 2002
TL;DR: In this article, a kind of organic carbonate solvents for secondary Li battery is prepared through flowing organic carbonates through a drying column containing drying agent which may be one or more of metal Li, metalNa, calcium sulfate, calcium chloride, potassium carbonate, activated alumina, molecular sieve and activated carbon for dewatering it, distilling in distillation tower at 50-200 deg.C and -0.05-0.1 MPa, and separating distillate.
Abstract: A kind of organic carbonate solvents for secondary Li battery is prepared through flowing organic carbonate through a drying column containing drying agent which may be one or more of metal Li, metalNa, calcium sulfate, calcium chloride, potassium carbonate, activated alumina, molecular sieve and activated carbon for dewatering it, distilling in distillation tower at 50-200 deg.C and -0.05--0.1 MPa, and separating distillate. Its advantages are high purity up to 99.9 % or more and low water content (lower than 5ppm).
TL;DR: In this article, the pore properties of the products obtained from the PHA-TPn composite gels were similar to those obtained from PHA gels without additives, giving a bimodal pore distribution and a small surface area.
Abstract: Transparent gels obtained from polyhydroxoaluminum (PHA) solutions on drying were transformed into activated alumina by heating To obtain activated alumina with uniform pore size, different amounts of tetrapropylammonium chloride (TP) or tetrapentylammonium chloride (TPn) were added to PHA solutions prior to drying to form composite gels The γ-alumina obtained from the composite gels with ≥40% TP content showed a sharp unimodal pore size distribution in the range of 3 to 4 nm, depending on the heat treatment temperature in the range of 400 to 900°C The γ-alumina thus obtained gave the largest pore volume of 030 cm 3 g -1 at 600°C On the other hand, the pore properties of the products obtained from the PHA-TPn composite gels were similar to those obtained from PHA gels without additives, giving a bimodal pore distribution and a small surface area These results indicate that the pore size of γ-alumina can be precisely controlled by the heat treatment temperature using composite gels with >40% TP content
Patent•
06 Feb 2002
TL;DR: A heavy metal resistant cracking catalyst (FCC) with novel matrix for cracking the heavy oil with high content of Ni or V contains clay (20-80 m), binder (5-40m), metal capture (such as rare-earth oxalate) (1-25m%), other oxides ( such as activated alumina) (0-30m%), and faujasite or ZSM-5 zeolite or beta-zeolite OR their mixture as mentioned in this paper.
Abstract: A heavy metal-resistant cracking catalyst (FCC) with novel matrix for cracking the heavy oil with high content of Ni or V contains clay (20-80 m%), binder (5-40m%), metal capture (such as rare-earth oxalate) (1-25m%), other oxides (such as activated alumina) (0-30m%), and faujasite or ZSM-5 zeolite or beta-zeolite or their mixture (5-40m%). It has excellent heavy metal resistance.
Patent•
27 Nov 2002
TL;DR: An activated alumina formed by complexing a dehydrated alumina with an agglomerate blocking agent and then hydrating the activated aluminates is described in this paper.
Abstract: An activated alumina formed by complexing a dehydrated alumina with an agglomerate blocking agent and then hydrating the activated alumina.
Patent•
28 May 2002TL;DR: In this paper, an activated alumina formed body with a high bulk density and a large macro-pore volume is provided, which is usable as an adsorbent, a catalyst supporting precious metal or the like.
Abstract: of EP1262458An activated alumina formed body with a high bulk density and a large macro-pore volume is provided. The activated alumina formed body can be produced by a method comprising the steps of calcining a gibbsite-phase aluminum hydroxide having a median particle size of from about 10 mu m to about 35 mu m and a packed bulk density of from about 1.05 g/cm to about 1.3 g/cm to obtain an at least partially rehydratable alumina powder; forming the rehydratable alumina powder in the presence of water; maintaining the formed body in the presence of water to rehydrate the formed body; and calcining the rehydrated formed body to obtain an activated alumina formed body. The activated alumina formed body is usable as an adsorbent, a catalyst supporting precious metal or the like.
Patent•
31 Oct 2002
TL;DR: In this article, a method for producing a vicinal diol compound from the corresponding epoxy compound with easy separation of the catalyst and under mild conditions with slight production of impurities is presented.
Abstract: PROBLEM TO BE SOLVED: To provide a method for producing a vicinal diol compound from the corresponding epoxy compound with easy separation of the catalyst and under mild conditions with slight production of impurities. SOLUTION: This method for producing a vicinal diol compound is characterized by comprising contacting the corresponding epoxy compound with a readily available activated alumina and water.
Patent•
27 Aug 2002
TL;DR: In this article, the authors proposed a method to provide a catalyst that has enhanced heat resistance of a HC adsorbing catalyst and which is formed in such a manner that an Ag zeolite layer 11 and a Pd catalyst layer are layered on a carrier 10 and provided a method for manufacturing the same.
Abstract: PROBLEM TO BE SOLVED: To provide a catalyst that has enhanced heat resistance of a HC adsorbing catalyst and which is formed in such a manner that an Ag zeolite layer 11 and a Pd catalyst layer are layered on a carrier 10 and to provide a method for manufacturing the same. SOLUTION: The catalyst prevents the Pd catalyst layer 12 from peeling off by using a hydrated alumina binder as a binder of the Ag zeolite layer 11, using an activated alumina as a supporting material of the Pd catalyst layer 12 and using a zirconia binder as a binder of the Pd catalyst layer 12.
Journal Article•
TL;DR: In this paper, the maximal and available fluoride removal capacity of activated alumina was analyzed with mathematical method and the proper controlling parameters for continuous-flow column were also discussed, according to the results of batch and continuous flow columns experiments.
Abstract: In this paper, according to the results of batch and continuous-flow columns experiments, analysis on the maximal and available fluoride removal capacity of activated alumina was conducted with mathematical method. The proper controlling parameters for continuous-flow column were also discussed.
Journal Article•
Journal Article•
TL;DR: In this article, a comparative study is made the fluoride absorption capacity, and the treated water quality between activated zeolite, activated alumina and bone char using batch reactor and continuous flow column.
Abstract: A comparative study is made the fluoride absorption capacity, and the treated water quality between activated zeolite,activated alumina and bone char using batch reactor and continuous flow column. The result indicated that the activated zeolite has the tendency to be good and can be used at home with fine quality and enough quantity. Activated alumina and bone char can be used in water plant for their good effect and perfect technology.
Patent•
30 Jul 2002
TL;DR: In this paper, a treating agent containing calcium hydroxide was proposed for treating waste gas discharged from urban waste incineration facilities, which has high efficiency for removing not only hydrogen chloride but also sulfur oxides, and is relatively large in particle diameter enough to lighten the load to a bag filter.
Abstract: PROBLEM TO BE SOLVED: To provide a treating agent containing calcium hydroxide as an effective component, which is utilized for treating waste gas discharged from urban waste incineration facilities, has high efficiency for removing not only hydrogen chloride but also sulfur oxides, and is relatively large in particle diameter enough to lighten the load to a bag filter, and furthermore to provide a treating agent by which dioxins in the waste gas can be effectively removed. SOLUTION: This treating agent contains calcium hydroxide of an average particle diameter of 6-25 μm, of a specific surface area of 30 m2/g or more, and of a pore surface area of 20 m2/g or more in a range of 5-40 nm in diameter in terms of the pore distribution measurement by the BJH method. The agent enhanced in the property of removing dioxins comprises compounding 70-97 pts.wt. of the calcium hydroxide and 30-3 pts.wt. of one or two kinds of activated coke and activated alumina, of which the pore surface area is 100 m2/g or more in a range of 2-5 nm in diameter in terms of the pore distribution measurement by the BJH method.
TL;DR: In this paper, the application of the molten salt technique is considered as a feasible technique to be applied for the removal of radionuclides from the spent fillers, such as sodium fluoride (NaF), magnesium fluoride (CaF2), or activated alumina (A12O3) from the chemical traps.
Abstract: Various kinds of chemical traps are used for the removal of gaseous radionuclides, fluorine, etc in the process-off gas of uranium conversion facility or similar facilities. The spent fillers such as sodium fluoride (NaF), magnesium fluoride (CaF2), or activated alumina (A12O3) from the chemical traps should be reused as useful materials, or converted into general industrial wastes so as to reduce the amount of radioactive waste, wherever possible.Molten salt technique can be considered as a feasible technique to be applied for the removal of radionuclides from the spent fillers. The mixed salt, NaF with sodium chloride (NaCl) was used in this experiment. The uranium concentration in the molten salt, pre-treatment condition, electrolytic temperature, current density, etc was used as parameters. Several fundamental experiments were carried out, and the obtained results were analyzed and evaluated. They indicate that the application of the molten salt technique is one of the potential methods for th...
Patent•
29 Jun 2002
TL;DR: In this article, a process of preparing a composite absorbent by dispersing fine active alumina uniformly, spinning the thus produced pitch and then stabilizing is provided, where by the product has a crystal structure of active alumina and its porous structure is not damaged to be used as an absorbent.
Abstract: PURPOSE: A process of preparing a composite absorbent by dispersing fine active alumina uniformly, spinning the thus produced pitch and then stabilizing is provided. Whereby, the product has a crystal structure of active alumina and its porous structure is not damaged to be used as an absorbent. CONSTITUTION: About 0.01 to 50 parts by weight of active alumina is dispersed uniformly in 100 parts by weight of pitch at a temperature of 20 to 80deg.C higher than the pitch softening point, spun at a temperature of 5 to 80deg.C higher than the pitch softening point, and heat-stabilized at 200 to 350deg.C in an air atmosphere, and the stabilized pitch fiber is activated at 700 to 850deg.C for 10min to 10hr.
Patent•
12 Sep 2002
TL;DR: In this article, a deodorizer consisting of an adsorption material having titanium oxide(IV) and porous material; another adsorization material(B) containing porous material carrying metallic oxides including one or more of iron, chromium, nickel, cobalt, manganese, copper, magnesium and calcium; UV enhancer to promote light oxidation of the titanium oxide by using activated molecules; at least one component selected from a group consisting of lighttransmission ceramic and ceramic and light-transmission plastic.
Abstract: PURPOSE: Provided are a deodorizer and a method for deodorizing using the deodorizer in a light-regeneration mode to decompose and remove bad odor generating materials by adsorption and/or using catalyst and to recover original deodorizing performance by radiation of visual or near-UV light. CONSTITUTION: The deodorizer comprises an adsorption material(A) having titanium oxide(IV) and porous material; another adsorption material(B) containing porous material carrying metallic oxides including one or more of iron, chromium, nickel, cobalt, manganese, copper, magnesium and calcium; UV enhancer to promote light oxidation of the titanium oxide by using activated molecules; at least one component selected from a group consisting of light-transmission ceramic and ceramic and light-transmission plastic. The adsorption agents(A,B) may be activated carbon, silica, activated alumina and/or zeolite.
Patent•
17 Sep 2002
TL;DR: In this article, a method for removing a phosphoric acid ion in water efficiently at a low cost was proposed by using an adsorbing material being a particle of activated alumina deposited with aluminum sulfate.
Abstract: PROBLEM TO BE SOLVED: To provide a method for removing a phosphoric acid ion in water efficiently at a low cost. SOLUTION: This method for removing the phosphoric acid ion in water is carried out by using an adsorbing material being a particle of activated alumina deposited with aluminum sulfate so that the deposited aluminum sulfate has the concentration distribution uniform from the surface to the inside and adjusting the pH of the water to 5-8 before the adsorbing material is brought into contact with the water.