scholarly journals Flower-like boehmite nanopowders obtained at low temperature from Bayer liquor

2020 ◽  
Vol 14 (2) ◽  
pp. 168-172
Author(s):  
Marija Milanovic ◽  
Zoran Obrenovic ◽  
Ivan Stijepovic ◽  
Ljubica Nikolic
Keyword(s):  
Low Temperature ◽  
Specific Surface ◽  
Surface Area ◽  
Industrial Production ◽  
Single Phase ◽  
Low Cost ◽  
High Specific Surface Area ◽  
Nanocrystalline Powders ◽  
Transition Alumina ◽  
Bayer Liquor

Boehmite nanocrystalline powders were obtained by neutralization of Bayer liquor at 70?C with addition of glucose. Temperature of the neutralization induced formation of the flower-like morphology of the nanopowders. XRD and FTIR results confirmed that the single phase boehmite is formed without any other impurities. Calcination at 500?C led to the formation of transition -alumina with the retention of the flower-like morphology. Both as-synthesised and calcined powders possessed high specific surface area with mesopores between 3-6 nm in diameter. Relatively low temperature of neutralization as well as the use of low cost and ecologically friendly glucose as a surfactant are very promising for the possible application in the industrial production of alumina nanopowders.

scholarly journals Obtaining of transition phases of alumina starting from sodium aluminate in Bayer process

2011 ◽  
Vol 65 (3) ◽  
pp. 271-277
Author(s):  
Zoran Obrenovic ◽  
Radislav Filipovic ◽  
Marija Milanovic ◽  
Ivan Stijepovic ◽  
Ljubica Nikolic
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ph Value ◽  
Sodium Aluminate ◽  
High Specific Surface Area ◽  
Heterogeneous Structure ◽  
Aluminate Solution ◽  
Bayer Liquor ◽  
Sodium Aluminate Solution

Transition (active) phases of alumina were synthesized starting from sodium aluminate solution prepared out of Bayer liquor. The neutralisation of sodium aluminate solution was performed by sulphuric acid. Powder X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and low-temperature nitrogen absorption studies were employed to trace the formation of the transition phases of alumina. The results show that the properties of the powders (phase composition, morphology and specific surface area) are strongly influenced by the initial pH value of the system, as well as by the duration of neutralisation step. It is possible to obtain powders with heterogeneous structure with dominant phase of bayerite, gibbsite or boehmit by tuning the pH and concentration of the starting sodium aluminate solution. The transition (active) phases of alumina (?- and ?-alumina) with high specific surface area (264-373 m2/g) are formed through the thermal dehydratation of aluminium hydroxide (bayerite and gibbsite) and aluminium oxyhydroxide (boehmite or pseudoboehmite) at the temperature of 500?C. Namely, bayerite and pseudoboehmite transforms to ?-phase of alumina upon heating, while gibbsite transforms to ?-phase, maintaining the parent morphology.

scholarly journals A Type of MOF-Derived Porous Carbon with Low Cost as an Efficient Catalyst for Phenol Hydroxylation

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Renjie Zhou ◽  
Gui Chen ◽  
Yuejun Ouyang ◽  
Hairui Ni ◽  
Nonglin Zhou ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Porous Carbon ◽  
Physical Adsorption ◽  
Low Cost ◽  
High Specific Surface Area ◽  
Phenol Hydroxylation ◽  
Efficient Catalyst

Using MOF-5 as a template, the porous carbon (MDPC-600) possessing high specific surface area was obtained after carbonization and acid washing. After MDPC-600 was loaded with Cu ions, the catalyst Cu/MDPC-600 was acquired by heat treatment under nitrogen atmosphere. The catalyst was characterized by X-ray powder diffraction (XRD), N2 physical adsorption (BET), field emission electron microscope (SEM), energy spectrum, and transmission electron microscope (TEM). The results show that the Cu/MDPC-600 catalyst prepared by using MOF-5 as the template has a very high specific surface area, and Cu is uniformly supported on the carrier. The catalytic hydrogen peroxide oxidation reaction of phenol hydroxylation was investigated and exhibits better catalytic activity and stability in the phenol hydroxylation reaction. The catalytic effect was best when the reaction temperature was 80°C, the reaction time was 2 h, and the amount of catalyst was 0.05 g. The conversion rate of phenol was 47.6%; the yield and selectivity of catechol were 37.8% and 79.4%, respectively. The activity of the catalyst changes little after three cycles of use.

Spinel-structured Mn–Ni nanosheets for NH3-SCR of NO with good H2O and SO2 resistance at low temperature

2020 ◽  
Vol 10 (22) ◽  
pp. 7486-7501
Author(s):  
Fengyu Gao ◽  
Xiaolong Tang ◽  
Zaharaddeen Sani ◽  
Honghong Yi ◽  
Shunzheng Zhao ◽  
...  
Keyword(s):  
Low Temperature ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Specific Surface Area ◽  
Electronic Interaction ◽  
Adsorption Ability ◽  
Nh3 Scr ◽  
Scr Of No ◽  
So2 Resistance

High specific surface area, more NH3 adsorption ability and efficient electronic interaction over Mn–Ni spinel nanosheet leaded to good SCR activity, and Ni-outside with active Mn-inner spinel configuration and nanosheet morphology relieved SO2-poisoning.

scholarly journals Enhanced Visible Light Photocatalytic Reduction of Cr(VI) over a Novel Square Nanotube Poly(Triazine Imide)/TiO2 Heterojunction

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 55 ◽  
Author(s):  
Xin Yan ◽  
Guotao Ning ◽  
Peng Zhao
Keyword(s):  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Low Cost ◽  
High Specific Surface Area ◽  
Electron Hole ◽  
Graphite Phase ◽  
Reduction Efficiency ◽  
The One

Hexavalent chromium Cr(VI) pollution makes has a harmful impact on human health and the ecological environment. Photocatalysis reduction technology exhibits low energy consumption, high reduction efficiency and stable performance, and is playing an increasingly important role in chromium pollution control. Graphite-phase carbon nitride has been used to reduce Cr(VI) to the less harmful Cr(III) due to its visible light catalytic activity, chemical stability and low cost. However, it has a low specific surface area and fast recombination of electron–hole pairs, which severely restrict its practical application. In this work, a TiO2-modified poly(triazine imide) (PTI) square nanotube was prepared by the one-step molten salts method. The results showed the PTI had a square hollow nanotube morphology, with an about 100–1000 nm width and 60–70 nm thickness. During the formation of the PTI square tube, TiO2 nanoparticles adhere to the surface of the square tube wall by strong adsorption, and eventually form a PTI/TiO2 heterojunction. The PTI/TiO2-7 wt% heterojunction exhibited very good Cr(VI) reduction efficiency within 120 min. The enhanced photocatalytic activity was mainly attributed to the efficient separation and transport of photo-induced electron–hole pairs and the high specific surface area in the heterojunction structure.

scholarly journals High-Level Oxygen Reduction Catalysts Derived from the Compounds of High-Specific-Surface-Area Pine Peel Activated Carbon and Phthalocyanine Cobalt

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3429
Author(s):  
Lei Zhao ◽  
Ziwei Lan ◽  
Wenhao Mo ◽  
Junyu Su ◽  
Huazhu Liang ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Active Sites ◽  
High Performance ◽  
Low Cost ◽  
Specific Area ◽  
High Specific Surface Area ◽  
High Catalytic Activity

Non-platinum carbon-based catalysts have attracted much more attention in recent years because of their low cost and outstanding performance, and are regarded as one of the most promising alternatives to precious metal catalysts. Activated carbon (AC), which has a large specific surface area (SSA), can be used as a carrier or carbon source at the same time. In this work, stable pine peel bio-based materials were used to prepare large-surface-area activated carbon and then compound with cobalt phthalocyanine (CoPc) to obtain a high-performance cobalt/nitrogen/carbon (Co-N-C) catalyst. High catalytic activity is related to increasing the number of Co particles on the large-specific-area activated carbon, which are related with the immersing effect of CoPc into the AC and the rational decomposed temperature of the CoPc ring. The synergy with N promoting the exposure of CoNx active sites is also important. The Eonset of the catalyst treated with a composite proportion of AC and CoPc of 1 to 2 at 800 °C (AC@CoPc-800-1-2) is 1.006 V, higher than the Pt/C (20 wt%) catalyst. Apart from this, compared with other AC/CoPc series catalysts and Pt/C (20 wt%) catalyst, the stability of AC/CoPc-800-1-2 is 87.8% in 0.1 M KOH after 20,000 s testing. Considering the performance and price of the catalyst in a practical application, these composite catalysts combining biomass carbon materials with phthalocyanine series could be widely used in the area of catalysts and energy storage.

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