查找使用阿拉丁产品的科研文献

Ni2P/Al2O3 hydrodesulfurization catalysts prepared by separating the nickel compound and hypophosphite

Dapeng Liu,Anjie Wang,Chenguang Liu,Roel Prins

Bulk Ni 2 P and Al 2 O 3 -supported Ni 2 P were prepared at low phosphidation temperature (300 or 330   °C) from nickel nitrate, oxide, sulfate, chloride, and acetate as nickel source and ammonium and sodium hypophosphite as well as hypophosphoric acid as phosphorus source. The hypophosphite source was positioned up-flow of the nickel source in an oven and flowing N2 gas transported the phosphine formed in the decomposition of hypophosphite to the nickel compound. X-ray diffraction, N2 adsorption-desorption, thermogravimetry and differential scanning calorimetry, temperature-programmed reduction in H 2 , and transmission electron microscopy, field emission scanning electron microscopy, CO chemisorption, and solid-state 31 P nuclear magnetic resonance were used to study the bulk and supported Ni 2 P. Whereas unsupported nickel nitrate, sulfate, chloride, and oxide led to impure Ni 2 P, nickel acetate gave pure Ni 2 P. Ni 2 P/Al 2 O 3 catalysts were therefore prepared from nickel acetate and their activity was studied in the hydrodesulfurization of dibenzothiophene. Separating the hypophosphite from the nickel compound has the advantage that the phosphate formed in the disproportionation of hypophosphite does not reach the Al 2 O 3 -supported Ni compound and cannot block the pores of the support. Ni 2 P is formed by sequential reduction and phosphidation reactions and therefore its preparation demands careful adjustment of the synthesis conditions. Insufficient PH 3 leads to Ni and Ni 12 P 5 side products and too much PH 3 to Ni 5 P 4 , which all have a lower HDS activity than Ni 2 P.

Molecular simulation and experimental analysis of Al2O3-nanoparticle-modified insulation paper cellulose

Chao Tang,Song Zhang,Jingyu Xie,Cheng Lv

Immobilization of mercury (II) from aqueous solution using Al2O3-supported nanoscale FeS

Yue Sun,Zimo Lou,Jianbing Yu,Xiaoxin Zhou,Dan Lv,Jiasheng Zhou,Shams Ali Baig,Xinhua Xu

Iron sulfide (FeS) nanoparticles were known for their excellent ability to scavenge aqueous Hg(II). However, the aggregation and oxidizability of FeS nanoparticles greatly restricted their practical application. This study developed an Al 2 O 3 -supported nanoscale FeS (FeS/Al 2 O 3 ) which effectively optimized the material performance. Characteristic data suggested that FeS/Al 2 O 3 (mass ratio of FeS to FeS/Al 2 O 3 is 30%) with a large specific surface area (142.7   m 2   g −1 ) could evenly distribute FeS, suppressing the aggregation of FeS successfully. The maximum enrichment capacity of Hg(II) on FeS/Al 2 O 3 achieved ∼313   mg/g at pH 6 and 30   °C. The pH studies indicated that alkaline environment strongly inhibited mercury uptake, while removal rate of 1   mg/L Hg(II) maintained a high level (>97.5%) over the pH range of 3–9. However, FeS/Al 2 O 3 loss was observed at low pH due to the acid corrosion. Additionally, the rates of Hg(II) reduction were almost unaffected over the range of 0.1–100   mM NaCl, but greatly inhibited by the presence of humid acid (HA). The synthetic FeS/Al 2 O 3 remained high mercury removal efficiency (over 95% in 1   mg/L Hg(II)) and low iron dissolution rate when preserved for 30   days, showing good long-term stability and remarkable application potential.

Nature of the Active Sites of VOx/Al2O3 Catalysts for Propane Dehydrogenation

Gang Liu,Zhi-Jian Zhao,Tengfang Wu,Liang Zeng,Jinlong Gong

Supported VOx catalysts are promising for use in propane dehydrogenation (PDH) because of the relatively superior activity and stable performance upon regeneration. However, the nature of the active sites and reaction mechanism during PDH over VOx-based catalysts remains elusive. We examined active species by attaining various fractions of V5+, V4+, and V3+ ions by adjusting the surface vanadium density on an alumina support. The results reveal a close relationship between TOF and the fraction of V3+ ion, indicating that V3+ was more active for PDH. In situ diffuse reflectance infrared Fourier transform spectroscopy showed the same strong adsorbed species during both propane dehydrogenation and propylene hydrogenation. The results indicated that such an intermediate may correspond to V species containing a C═C bond, i.e., V–C3H5, and a reaction mechanism was proposed accordingly.

Rheological behavior of Al2O3 suspensions containing polyelectrolyte complexes for direct ink writing

Yuehua Sun,Chaoqun Peng,Xiaofeng Wang,Richu Wang,Junliang Yang,Dou Zhang

Al 2 O 3 polyelectrolyte suspensions containing PAA-PEI complexes have been used for direct ink writing to fabricate complex 3D structures with micro-sized feature. Zeta potential and rheological behavior of the Al 2 O 3 polyelectrolyte suspensions were investigated. The isoelectric point of Al 2 O 3 particles shifts from alkaline region to acidic region as the [COOH]:[NH x ] ratio increases from 0.12 to 3. The rheological results reveal that the 40   vol% Al 2 O 3 suspension with [COOH]:[NH x ] ratio of 0.3 and 15   mg/mL methylcellulose at pH   10 is the optimal suspension for direct ink writing, due to its good shear thinning and viscoelastic behavior . The filament in lattice structure prepared using this polyelectrolyte suspension can maintain its original shape with little spreading. In the micrograph of sample sintered at 1600   °C for 2   h, the uniform size of grains indicates that the structure is fully sintered under this sintering condition.

An effective low-temperature strategy for sealing plasma sprayed Al2O3-based coatings

Heping Li,Zhiqiang Ke,Jing Li,Lihong Xue,Youwei Yan

Pores and cracks are usually inevitable in the coatings fabricated by plasma spraying . Herein, thermal chemical reaction technique was developed as an effective low-temperature strategy for addressing this issue. Dense α-Al 2 O 3 /AlPO 4 coating was synthesized on the surface of the plasma sprayed Al 2 O 3 -based coating by thermal chemical reaction at 500   °C. The α-Al 2 O 3 /AlPO 4 composites permeated into the coating and effectively filled up the pores and cracks inside. The sealed coating showed a uniform and dense morphology. The hydrogen permeation rate of the sealed coating sharply decreased by a factor of 15, which further confirmed its significantly improved compactness. In addition, the coating exhibited good thermal shock resistance and bond strength after sealing. Considering its low-temperature heat treatment, facile fabrication process and wide applicability, thermal chemical reaction method can be potentially used as a cost-saving strategy for sealing plasma sprayed ceramic coatings .

Sulfonic acid functionalized nano γ-Al2O3 catalyzed per-O-acetylated of carbohydrates

Liqiang Wu,Zhikui Yin

A simple and clean synthesis of per- O -acetylation carbohydrate derivatives has been accomplished by treatment of sugars with a stoichiometric quantity of acetic anhydride under solvent-free conditions in the presence of sulfonic acid functionalized nano γ-Al 2 O 3 as an efficient and environmentally benign catalyst.

Reductive amination of 1,6-hexanediol with Ru/Al2O3 catalyst in supercritical ammonia

Li Yan,Cheng Haiyang,Zhang Chao,Zhang Bin,Liu Tong,Wu Qifan,Su Xinluona,Lin Weiwei,Zhao Fengyu

Hexamethylenediamine (HMDA) is an important reagent for the synthesis of Nylon-6,6, and it is usually produced by the hydrogenation of adiponitrile using a toxic reagent of hydrocyanic acid. Herein, we developed an environmental friendly route to produce HMDA via catalytic reductive amination of 1,6-hexanediol (HDO) in the presence of hydrogen. The activities of several heterogeneous metal catalysts such as supported Ni, Co, Ru, Pt, Pd catalysts were screened for the present reaction in supercritical ammonia without any additives. Among the catalysts examined, Ru/Al 2 O 3 presented a high catalytic activity and highest selectivity for the desired product of HMDA. The high performance of Ru/Al 2 O 3 was discussed based on the Ru dispersion and the surface properties like the acid-basicity. In addition, the reaction parameters such as reaction temperature, time, H 2 and NH 3 pressure were examined, and the reaction processes were discussed in detail.

High-performance B4C-Al2O3 composite ceramics fabricated via fast hot-pressing sintering

Zhiwei Xu,Xiangxing Zhou,Ke Peng,Tiechui Yuan,Ruidi Li,Zhihui Zhou

In this study, fast hot-pressing sintering and the power of B 4 C and 1/3/5/7 wt% Al 2 O 3 were used to make B 4 C-Al 2 O 3 composite ceramics at 2000°C and 30 MPa. The toughening mechanism was thoroughly examined, and the impact of Al 2 O 3 content on the microstructures and mechanical characteristics of B 4 C-Al 2 O 3 composite ceramics was examined. The comprehensive mechanical properties of B 4 C-Al 2 O 3 composite ceramics were optimized by adding 3 wt% Al 2 O 3 , the relative density, flexural strength , fracture toughness, and Vickers hardness reached 99.38   %, 616.2 MPa, 5.45 MPa∙m 1/2 , and 35.91 GPa, respectively. The strengthening mechanism of B 4 C-Al 2 O 3 composite ceramics is that grain refinement and grain boundary movement are hindered by second-phase particles. And the toughening mechanism is crack deflection and Al 2 O 3 grain cracking.

Catalytic dehydrogenation of perhydro-monobenzyltoluene over Pt/Al2O3 for continuous hydrogen release

Changgui Wu,Mengke Xu,Feifei Song,Biao Ma,Fuling Li,Chengxiang Shi,Zhen-Feng Huang,Ruijie Gao,Xiangwen Zhang,Lun Pan,Ji-Jun Zou

Monobenzyltoluene (H0-BT) is a promising liquid organic hydrogen carrier (LOHC), and continuous reaction process represents a more favorable approach in the large-scale hydrogen storage. In this work, the impacts of Pt loading and reaction conditions on the dehydrogenation performance of perhydro-monobenzyltoluene (H12-BT) over Pt/Al 2 O 3 were conducted in a fixed-bed reactor. The results indicate that the dehydrogenation activity of catalyst shows a volcano type as increasing Pt loading, reaching a maximum at 3 wt%. 1 wt% Pt loading is the most appropriate in consideration of the dehydrogenation activity and hydrogen purity. High reaction temperature and low pressure can facilitate dehydrogenation kinetics but result in the undesired byproducts, therefore, the optimal reaction conditions are 320 °C and 0.7 MPa. Additionally, the dehydrogenation performance of H12-BT and perhydro-dibenzyltoluene (H18-DBT) were compared under the similar conditions, revealing that H12-BT may be a superior hydrogen storage carrier.

Preparation and flame retardancy of an Al2O3 infiltration layer on polycarbonate surface

Shibo Ren,Jianlin Xu,Lei Niu,Penghui Yang

In this study, the surface flame retardancy of polycarbonate (PC) was improved and the impact of flame retardants on the substrate were minimized by pre-mixing Al2O3 particles with dichloromethane, an infiltration promoter, to form a suspension, and then treating PC with the suspension to form an Al2O3 infiltration layer. For this layer, its structure and composition were characterized, its flame retardancy was evaluated, and its flame retardancy mechanism was investigated. The characterization results confirmed that an Al2O3 infiltration layer was successfully prepared on the PC surface under the aid of dichloromethane and that the involvement of dichloromethane induced certain microscopic pores and voids in the PC, with some dichloromethane remaining within the surface infiltration layer. The surface Al2O3 infiltration layer mainly served as a condensed-phase flame retardant. The infiltration layer prepared using a suspension with a dichloromethane-to-Al2O3 mass ratio of 24:1 not only exhibited a good overall performance but also achieved the best improvement in the PC flame retardancy, such as an increase in the vertical burning rating from HB to V-0, as well as the LOI increased from 24 to 31.3, and a 35% reduction in the peak heat release rate compared to those of pure PC.

Preparation and Photocatalytic Properties of Al2O3–SiO2–TiO2 Porous Composite Semiconductor Ceramics

Kaihui Hua,Zhijing Wu,Weijie Chen,Xiuan Xi,Xiaobing Chen,Shuyan Yang,Pinhai Gao,Yu Zheng

Titanium dioxide (TiO2) is widely employed in the catalytic degradation of wastewater, owing to its robust stability, superior photocatalytic efficiency, and cost-effectiveness. Nonetheless, isolating the fine particulate photocatalysts from the solution post-reaction poses a significant challenge in practical photocatalytic processes. Furthermore, these particles have a tendency to agglomerate into larger clusters, which diminishes their stability. To address this issue, the present study has developed Al2O3–SiO2–TiO2composite semiconductor porous ceramics and has systematically explored the influence of Al2O3and SiO2on the structure and properties of TiO2porous ceramics. The findings reveal that the incorporation of Al2O3augments the open porosity of the ceramics and inhibits the aggregation of TiO2, thereby increasing the catalytic site and improving the light absorption capacity. On the other hand, the addition of SiO2enhances the bending strength of the ceramics and inhibits the conversion of anatase to rutile, thereby further enhancing its photocatalytic activity. Consequently, at an optimal composition of 55 wt.% Al2O3, 40 wt.% TiO2, and 5 wt.% SiO2, the resulting porous ceramics exhibit a methylene blue removal rate of 91.50%, and even after undergoing five cycles of testing, their catalytic efficiency remains approximately 83.82%. These outcomes underscore the exceptional photocatalytic degradation efficiency, recyclability, and reusability of the Al2O3–SiO2–TiO2porous ceramics, suggesting their substantial potential for application in the treatment of dye wastewater, especially for the removal of methylene blue.