scholarly journals Effect of additives, ball milling and isotopic exchange in porous magnesium borohydride

RSC Advances ◽  
2018 ◽  
Vol 8 (49) ◽  
pp. 27645-27653 ◽  
Author(s):  
Michael Heere ◽  
Olena Zavorotynska ◽  
Stefano Deledda ◽  
Magnus H. Sørby ◽  
David Book ◽  
...  
Keyword(s):  
Specific Surface ◽  
Ball Milling ◽  
Surface Area ◽  
Specific Surface Area ◽  
Isotopic Exchange ◽  
Porous Network ◽  
Effect Of Additives ◽  
Heat Treated ◽  
Milled Sample ◽  
Porous Magnesium

Specific surface area measurements (BET) of as received and ball milled samples showed the collapse of the porous network after milling, while a heat treated ball milled sample regained most of its porous γ-Mg(BH4)2 structure.

Effect of aging and alkali activator on the porous structure of a geopolymer

2014 ◽  
Vol 47 (1) ◽  
pp. 316-324 ◽  
Author(s):  
Prune Steins ◽  
Arnaud Poulesquen ◽  
Fabien Frizon ◽  
Olivier Diat ◽  
Jacques Jestin ◽  
...  
Keyword(s):  
Specific Surface ◽  
Porous Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Inorganic Polymers ◽  
Porous Network ◽  
X Ray ◽  
Alkali Activator ◽  
Effects Of Aging

Nitrogen sorption and small- and wide-angle X-ray and neutron scattering techniques were used to study the porous structure of geopolymers, inorganic polymers synthesized by reaction of a strongly alkaline solution and an aluminosilicate source (metakaolin). The effects of aging and the use of alkali activators (Na+, K+) of different sizes were investigated at room temperature. The influence of aging time on the microstructure of both geopolymer matrixes was verified in terms of pore volume and specific surface area. The results suggested a refinement of the porosity and therefore a reduction in the pore volume over time. Regardless of the age considered, some characteristics of the porous network such as pore size, shape and distribution depend on the alkali activator used. Whatever the technique considered, the potassium geopolymer has a greater specific surface area than the sodium geopolymer. According to the scattering results, the refinement of the porosity can be associated with, first, a densification of the solid network and, secondly, a partial closure of the porosity at the nanometre scale. The kinetics are much slower for the sodium geopolymer than for the potassium geopolymer in the six months of observation.

scholarly journals A Study on the Effect of Different Ball Milling Methods on the NH3-SCR Activity of Aluminum-Laden Bayan Obo Tailings

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 568
Author(s):  
Xinrui Bai ◽  
Jiawei Lin ◽  
Zedong Chen ◽  
Limin Hou ◽  
Wenfei Wu
Keyword(s):  
Specific Surface ◽  
Ball Milling ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Conversion Rate ◽  
Nh3 Scr ◽  
Milling Method ◽  
Bayan Obo ◽  
Active Substances

Rich in Fe, Ce, Mn, Si and other elements which have good catalytic activity, Bayan Obo rare-earth tailings are naturally advantaged as the carrier of denitrification catalysts. In this paper, pseudo boehmite (γ-Al2O3) was mixed with Bayan Obo tailings using different ball milling methods for modification to prepare NH3-SCR catalysts. The effect of different mixing methods on the SCR denitrification activity at a low temperature was investigated and the prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), temperature programed desorption (NH3-TPD), temperature programed reduction (H2-TPR) and other means. The conversion rate of NOx at 250–350 °C was above 80% and the highest conversion rate of NOx of 90% was achieved at 300 °C. SEM and XRD revealed that the tailings modified by pseudo boehmite (γ-Al2O3) using the ordinary ball milling method have loose structure and good dispersion of active substances, and specific surface area (BET) analysis shows that the tailings have the maximum specific surface area and pore volume. However, over grinding and secondary spheronization were observed in the tailings modified by pseudo boehmite (γ-Al2O3) using high energy ball milling method, leading to the decrease of specific surface area and pore volume, poor dispersion of active substances, and ultimately low denitrification rate.

scholarly journals ZnO Nanospheres Fabricated by Mechanochemical Method with Photocatalytic Properties

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 572
Author(s):  
Zhou Zhou ◽  
Jing Wang ◽  
Chul Gyu Jhun
Keyword(s):  
Specific Surface ◽  
Ball Milling ◽  
Surface Area ◽  
Specific Surface Area ◽  
Large Scale ◽  
Low Cost ◽  
Specific Area ◽  
Industrial Applications ◽  
Photocatalytic Efficiency ◽  
Mechanochemical Method

The preparation of high specific area (86.5 m2/g) ZnO nanospheres with good photocatalytic efficiency via a simple, green and efficient mechanochemical method was reported in this work. The products were characterized by XRD, SEM, TEM, BET and UV–Vis. The ball milling parameters were improved to reduce the agglomeration hazard during the ball milling process, and the specific surface area, band gap and photocatalytic efficiency were investigated in relation to ball milling time. Our study developed the opportunity for the low-cost and facile synthesis of a high specific surface area photocatalyst on a large scale for future industrial applications.

Preparation and Characterization of Monolithic Al2O3 Aerogels

2016 ◽  
Vol 852 ◽  
pp. 591-595
Author(s):  
Heng Chen ◽  
Xue Ye Sui ◽  
Chang Ling Zhou ◽  
Chong Hai Wang ◽  
Fu Tian Liu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Supercritical Drying ◽  
Aluminium Chloride ◽  
Porous Network ◽  
Drying Technology ◽  
Adsorption Desorption

Al2O3 aerogels were obtained through sol-gel process and ethanol supercritical drying technology using anhydrous aluminium chloride (AlCl3) and propylene oxide as precursor and gelation initiator respectively. Monolithic Al2O3 aerogels with porous and large specific surface area were achieved in our studies. Morphology and properties of Al2O3 aerogels were investigated by techniques of X-ray diffraction, Nitrogen adsorption/desorption analysis, Scanning electron microscopy, and Fourier transform infrared spectroscope. The results showed that the Al2O3 aerogels possessed a porous network microstructure made up of needles or rod-shaped particles and a specific surface area of 398 m2/g at 600°C. It was transformed to θ-Al2O3 after calcined at 1200°C.

Nitrogen Doping to Metatitanic Acid by NH3 Heat Treatment for Achieving Visible-Light-Responsive Photocatalytic Activity

2013 ◽  
Vol 761 ◽  
pp. 35-39
Author(s):  
Se Keun Park ◽  
Jun Ho Eun ◽  
Hyun Ho Shin
Keyword(s):  
Heat Treatment ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nitrogen Doping ◽  
High Specific Surface Area ◽  
Metatitanic Acid ◽  
Heat Treated

Nitrogen doping can be achieved by heating TiO2-based photocatalyst powders under dopant-generating atmospheres such as NH3. In the present work, metatitanic acid (MTA) powder was used as a raw material to obtain nitrogen-doped titania using heat treatment in NH3flow. MTA is an industrially available intermediate product in sulfate process for TiO2production, which is mesoporous material with high specific surface area. The MTA powder was heat-treated in flowing NH3at 400–550°C. For comparison, commercial P25 TiO2powder was heat-treated under the same conditions. The results show that nitrogen dopant can be successfully incorporated into the MTA by heating in NH3 atmosphere. This obviously results in the enhanced visible-light photocatalytic activity, especially in MTA sample heated at 400°C. Due to the fascinating properties of MTA powder such as high specific surface area, the N-doping effect on MTA powder is much higher than the P25 TiO2powder.

Sign in / Sign up

Export Citation Format

Share Document