Papers by Keyword: γ-Al₂O₃

Abstract: The discarded empty aluminium beverage cans can pose a serious environmental contamination issue. Recently, studies are now focusing on reducing and utilising solid wastes which have grown to be a significant environmental concern. Thus, this study focuses on producing γ-Al₂O₃ from readily available aluminium garbage cans using a Sol-gel technique and analysing its thermal properties using TGA analysis. The effect of the reaction temperatures was further investigated to comprehend the synthesis of alumina at (room temperature, 50 °C, and 70 °C) at a fixed aging duration of 12 h. Experimental findings demonstrated the potential of producing γ-Al₂O₃ from used aluminium cans, which may then be used as sustainable catalysts and catalytic supports for a variety of applications. The results showed that all the synthesised alumina had a good result with a maximum weight loss less than 5%; this reflected its strong stability. The alumina that was created at 70 °C reaction temperature recorded the lowest weight loss and the highest residue at 2.78% and 97.22%, respectively.

Abstract: This paper reports the effects of γ-Al₂O₃ and α-Al₂O₃ on the properties of lightweight insulation materials. The phase compositions, microstructure and mechanical properties of lightweight insulation materials are separately investigated by XRD, SEM and tabulate thermal conductivity apparatus methods. The results indicate that the increasing of the amount of γ-Al₂O₃ is beneficial to improving the bulk density, compressive strength and acid resistance of the fired specimens. The fact negatively impacts on the increasing of the apparent porosity; however, it has no significant effect on the thermal conductivity of specimens. Meanwhile, the studies highlight that when the content of γ-Al₂O₃ increases, the nucleation and growth of mullite is accelerated at high calcination temperature, which has positive effect on improving the physicochemical properties of lightweight insulation materials. And the γ-Al₂O₃-free SiO₂ glass phase system is guided by theoretical analysis of reaction conditions for non-catalytic system with Factsage modelling.

Abstract: The moulded Al₂O₃ materials prepared by mixing of thermochemically activated aluminum trihydroxide (TCA ATH) with wood flour were proposed to be used as promising porous catalyst support for various processes. A series of Al₂O₃ supports with different wood flour loading (0, 2 and 5 %wt.) were studied by SEM, low-temperature N₂ sorption, XRD, granule strength and water-absorbing capacity. It was shown that supports were characterized by porous structure with mesopore sizes of 2-20 nm and specific surface area of 159-186 m²/g. The increase of the amount of wood flour leads to increase of the share of pore volume with wider than 10 nm and the decrease of the strength of alumina granules. Thus, optimization of preparation conditions allows obtaining alumina materials with desired porous structure.

Abstract: In this study, the γ-Al₂O₃ nanowires were prepared by a simple surfactant assisted precipitation method using the cetyltrimethyl ammonium bromide (CTAB) as a structure-directing agent (SDAs). Homemade sodium aluminate (NaAlO₂) and H₂O₂ were used as raw materials. The influences of CTAB concentration and calcination temperature on the morphology of product were discussed. The obtained samples were investigated using transmission electron microscopy, X-ray diffraction analysis and TG-DSC. In the end, a possible formation mechanism of wire-like γ-Al₂O₃ is proposed.

Abstract: Chlorella samples were pyrolysed in a fixed bed reactor with γ-Al₂O₃ or ZSM-5 molecular sieve catalyst at 600°C. Liquid oil samples was collected from pyrolysis experiments in a condenser and characterized for water content, kinematic viscosity and heating value. In the presence of catalysts , gas yield decreased and liquid yield increased when compared with non-catalytic pyrolysis at the same temperatures. Moreover, pyrolysis oil from catalytic with γ-Al₂O₃ runs carries lower water content and lower viscosity and higher heating value. Comparison of two catalytic products, the results were showed that γ-Al₂O₃ has a higher activity than that of ZSM-5 molecular sieve. The acidity distribution in these samples has been measured by t.p.d, of ammonia, the γ-Al₂O₃ shows a lower acidity. The γ-Al₂O₃ catalyst shows promise for production of high-quality bio-oil from algae via the catalytic pyrolysis.

Abstract: Cu-Mn/Al₂O₃, Cu-Mn/TiO₂ and Cu-Mn/SBA-15 were prepared by incipient wetness impregnation. The activity of those catalysts for selective catalytic oxidation (SCO) of ammonia to nitrogen at low temperature (100°C~250°C) is not so satisfying. 5%Cu-5%Zr/TiO₂ has the highest NH₃ conversion and highest NO, NO₂ yield. 5%Cu-5%Mn/Al₂O₃ is a promising NH₃ selective catalytic oxidation catalyst, but still needs further study. SBA-15 is a bad support for Cu-Mn. Al₂O₃-based catalysts and TiO₂-based catalysts were also prepared by incipient wetness impregnation to sure the synergistic effect between transition metal. The results find the activity on Cu-Mn/Al₂O₃ is better than Cu-Mn/TiO₂, but NH₃ conversion on Cu-Zr/TiO₂ is rather well with high yield of NO. The role of supports and transition metals play in catalyst are discussed by a series of experiments. Key ward: SCO, NH₃, transition metal, γ-Al₂O₃, TiO₂, SBA-15

Abstract: This work presents the synthesis and hydrodesulfurization performance of NiMo sulfide catalysts supported on γ-Al₂O₃ during the hydrodesulfurization (HDS) of dibenzothiophene (DBT). The catalysts were synthesized by the co-impregnation method using an atomic ratio of Ni=Ni/(Ni+Mo)=0.5. The materials were characterized by N₂ physisorption, XRD and HRTEM. This catalyst exhibited the larger pore size and high specific surface area, as well as better morphological properties. The catalytic activity was evaluated using a high-pressure batch reactor at 280 °C and 3.0 MPa. The catalytic activity during HDS-DBT indicated that the NiMoS/γ-Al₂O₃ catalyst was better than that NiMoS/γ-Al₂O₃ catalyst. the NiMoS/γ-Al₂O₃ catalyst exhibits higher DDS selectivity (3.0) than NiMo/γ-Al₂O₃ catalyst (2.55).

Abstract: Ultrasonic-assisted supported Fe/γ-Al2O3, fluoride; γ-Al2O3; adsorption Abstract: γ-Al2O3 adsorbent modified with iron (Fe/γ-Al2O3) was prepared by impregnation and ultrasonic wave-assisted oxidation. The optimum pH range for fluoride adsorption was 3.0–9.0, which is preferable for actual application. The maximum adsorption capacity of the Fe/γ-Al2O3 adsorbent was 2.51 mg g-1 and about 2 times of the plain γ-Al2O3 (γ-Al2O3). A column experiment was performed at an initial fluoride concentration of 30 mg l-1, space velocity of 1.7 h-1 and pH of 5.9, and the breakthrough time of the Fe/γ-Al2O3 was more than 210 min with the effluent fluoride under 10 mg l-l and was about 5 times of the plain one. The samples were measured by X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images.

Abstract: The active ingredient of catalysts is generally dispersed on porous supports of inert metal oxides to augment its catalytic activity. In this paper, the dispersion and topography of CeO2 supported on γ-Al2O3 was studied by means of XRD. The monolayer coverage of CeO2 was determined by internal-standard method with NiO reference material. Highly dispersed CeO2 would appear and encapsulate outside theγ-Al2O3 support surface evenly when CeO2 loading was below its monolayer coverage; above the monolayer coverage, crystalline CeO2 would appear.

Abstract: γ-Al₂O₃ namely activated alumina or alumina gel is widely used as a pigment on the inkjet paper at present. But it is easy to come out a particles agglomeration problem to restrict its application. In this paper, the γ-Al₂O₃ with coupling agents were modified to improve its dispersion in water. In the modification process, the he main modification parameters such as aluminum-zirconium complex oligomeric coupling agent TL-3A were selected to study. The parameters of addition, modification time and modification temperature were discussed. During the experiment, the best modification conditions were determined via orthogonal experiments. The polydispersity index PDI was used the target parameters to inspect via orthogonal experiments results and the affected factors. We found the best addition quantity of coupling agent, modification time and modification temperature to reach the minimum of the polydispersity index PDI introduction. The results showed that the best condition for carbonization alumina was: the best condition for export γ-Al₂O_{3Subscript text} 2.0%, modification time 30min, modification temperature 50°C。