scholarly journals Enhanced low-temperature NH 3 -SCR performance of Ce/TiO 2 modified by Ho catalyst

2019 ◽  
Vol 6 (3) ◽  
pp. 182120 ◽  
Author(s):  
Ting-ting Zhang ◽  
Li-min Yan
Keyword(s):  
Low Temperature ◽  
Specific Surface ◽  
Selective Catalytic Reduction ◽  
Surface Area ◽  
Specific Surface Area ◽  
Catalytic Reduction ◽  
Low Temperature Scr ◽  
Redox Ability

Holmium was used as a dopant to boost the low-temperature NH 3 -selective catalytic reduction (SCR) performance of Ce/TiO 2 catalyst. It was ascertained that certain amount of Ho-doping species could exceedingly improve the low-temperature SCR activity under 60 000 h −1 of Ce/TiO 2 , accompanied with the improvement of tolerance to H 2 O and SO 2 at 200°C. Characterization results manifested that Ho modification could not only result in inhibiting the growth of TiO 2 crystals and the enlargement of specific surface area but also lead to the enhanced redox ability and the increased amount of surface-adsorbed substances, all of which could promote the low-temperature NH 3 -SCR performance of Ce/TiO 2 .

Fe and Mn mixed oxide catalysts supported on Sn-modified TiO2 for the selective catalytic reduction of NO with NH3 at low temperature

2022 ◽  
Author(s):  
Zhitao Han ◽  
Huan Du ◽  
Duo Xu ◽  
Yu Gao ◽  
Shaolong Yang ◽  
...  
Keyword(s):  
Low Temperature ◽  
Selective Catalytic Reduction ◽  
Mixed Oxide ◽  
Catalytic Reduction ◽  
Oxide Catalysts ◽  
Reduction Of No ◽  
Sn Doping ◽  
Mixed Oxide Catalysts ◽  
Fe And Mn ◽  
Low Temperature Scr

FeMn/SnxTiO2 catalysts were synthesized by introducing Sn as an additive to modify TiO2 supports, and the Sn doping could improve the SO2 tolerance and low-temperature SCR activity significantly.

scholarly journals Low-Temperature Synthesis of Monolithic Titanium Carbide/Carbon Composite Aerogel

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2527
Author(s):  
Tingting Niu ◽  
Bin Zhou ◽  
Zehui Zhang ◽  
Xiujie Ji ◽  
Jianming Yang ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Electron Microscope ◽  
Low Temperature ◽  
Titanium Carbide ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Carbon Composite ◽  
Composite Aerogel ◽  
X Ray

Resorcinol-formaldehyde/titanium dioxide composite (RF/TiO2) gel was prepared simultaneously by acid catalysis and then dried to aerogel with supercritical fluid CO2. The carbon/titanium dioxide aerogel was obtained by carbonization and then converted to nanoporous titanium carbide/carbon composite aerogel via 800 °C magnesiothermic catalysis. Meanwhile, the evolution of the samples in different stages was characterized by X-ray diffraction (XRD), an energy-dispersive X-ray (EDX) spectrometer, a scanning electron microscope (SEM), a transmission electron microscope (TEM) and specific surface area analysis (BET). The results showed that the final product was nanoporous TiC/C composite aerogel with a low apparent density of 339.5 mg/cm3 and a high specific surface area of 459.5 m2/g. Comparing to C aerogel, it could also be considered as one type of highly potential material with efficient photothermal conversion. The idea of converting oxide–carbon composite into titanium carbide via the confining template and low-temperature magnesiothermic catalysis may provide new sight to the synthesis of novel nanoscale carbide materials.

scholarly journals Novel Catalysts for Selective Catalytic Reduction of NOx by NH3 Prepared by Atomic Layer Deposition of V and Ti Oxides on SiO2 Powder

2020 ◽  
Vol 2 (1) ◽  
pp. 33
Author(s):  
Davyd Urbanas ◽  
Pranas Baltrėnas ◽  
Saeed Saedy ◽  
Aristeidis Goulas ◽  
J. Ruud van Ommen
Keyword(s):  
Nitrogen Oxides ◽  
Atomic Layer Deposition ◽  
Specific Surface ◽  
Selective Catalytic Reduction ◽  
Surface Area ◽  
Catalytic Reduction ◽  
Atomic Layer ◽  
Nh3 Scr ◽  
Layer Deposition ◽  
Highly Porous

Based on the 2019 report of the European Environment Agency on Air Quality in Europe nitrogen oxides (NOx) were identified as the most harmful air pollutants in terms of damage to ecosystems. Moreover, in Europe, NO2 is pinpointed as one of the most dangerous pollutants for human health. Anthropogenic emissions of NOx are mainly generated by the combustion of fossil fuels. Nitrogen oxides being emitted into the atmosphere cause environmental problems such as acid rain, acidification of soil, lakes and rivers, eutrophication and photochemical smog. The most effective and widely applicable technology to date for the purification of flue gases from NOx is selective catalytic reduction using ammonia (NH3-SCR de-NOx). Nowadays, one of the most significant research fields in NH3-SCR de-NOx is the application of unconventional reduction methods and the preparation of novel catalysts possessing high specific surface area, uniformity, dispersion of active sites, activity and selectivity. Atomic layer deposition (ALD) is an attractive technique for the deposition of uniformly distributed active catalytic layers, or nanoparticles, on highly porous substrates characterized by a complex structure. For this type of materials, conventional catalyst preparation methods (e.g., impregnation or deposition precipitation) can encounter several limitations. The significant advantage of ALD for the preparation of supported catalysts is that the process can be controlled on the atomic scale, providing the required thickness of an active layer, synthesized with a sub-nm accuracy. Moreover, ALD ensures the formation of catalytic sites from the gas phase, which enhances the possibility of active species being deposited inside pores which are very small in size. In this study, ALD was applied to the preparation of VxOy-based NH3-SCR de-NOx catalysts. Highly porous silica gel powder (63–100 μm) with a specific surface area of up to 450 m2·g−1 was used as a substrate for VxOy/SiO2 with different metal loadings (wt.%). In addition (VxOy+TiO2)/SiO2 catalysts were prepared by applying vanadium (V) tri-i-propoxy oxide (VTIP) and titanium tetrachloride (TiCl4) as precursors with deionized water as the co-reactant. Elemental analysis (ICP-OES) revealed that vanadium loadings of the VxOy/SiO2 catalysts were 0.3, 0.7, 1.1 and 1.60 wt.%, while the loadings in the TiO2-promoted VxOy/SiO2 catalyst were 1.0 and 0.2 wt.% for V and Ti, respectively. The obtained XPS spectra indicated the presence of V2O3 and V2O5 species (V2O5/V2O3 ratio was 1.6 and 6.3 for the as-synthesized and calcined samples respectively). Vanadium(V) oxide is known to be a catalytically active compound for NH3-SCR de-NOx. Additionally, TEM, XRD and N2 adsorption (BET) analyses were conducted to provide a comprehensive characterization of the species size, crystalline phase and porosity of the catalysts prepared.

Low Temperature Selective Catalytic Reduction of NO on CeO2-Fe3O4/TiO2,CeO2 /TiO2 Catalysts Prepared by Coprecipitation Method

2014 ◽  
Vol 960-961 ◽  
pp. 234-239 ◽  
Author(s):  
Wen Long Zhen ◽  
Rui Tang Guo ◽  
Wei Guo Pan
Keyword(s):  
Low Temperature ◽  
Adsorption Capacity ◽  
Selective Catalytic Reduction ◽  
Surface Area ◽  
Catalytic Reduction ◽  
Coprecipitation Method ◽  
High Concentration ◽  
Excellent Performance ◽  
Reduction Of No ◽  
Chemisorbed Oxygen

CeO2-Fe3O4/TiO2and CeO2/TiO2catalysts were prepared by coprecipitation method, and their activities for selective catalytic reduction of NO with NH3were investigated. As can be seen from the experimental results, the CeO2-Fe3O4/TiO2catalyst prepared showed the best SCR activity and SO2resistance. Based on the characterization results of BET, XRD, NH3-TPD and XPS the excellent performance of CeO2-Fe3O4/TiO2catalyst should be resulted from its large surface area, high NH3adsorption capacity and high concentration of surface chemisorbed oxygen.

CVD Synthesis of Multi-Walled Carbon Nanotubes onto Different Catalysts at Low Temperature

NANO ◽  
2018 ◽  
Vol 13 (04) ◽  
pp. 1850036 ◽  
Author(s):  
Guiqiang Diao ◽  
Hao Li ◽  
Hao Liang ◽  
Iryna Ivanenko ◽  
Tetiana Dontsova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
Low Temperature ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Lithium Ion ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs) were synthesized onto a series of individual and bimetallic catalysts by the chemical vapor deposition (CVD) of acetylene at low temperature (600[Formula: see text]C). The catalysts were prepared by two methods, i.e., precipitation and sol–gel, with two different carriers – MgO and Al2O3. The catalysts were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermal gravimetric (TG) analysis, low-temperature adsorption of nitrogen. The yield of the MWCNTs was calculated in two ways, while the highest yield of 800% was achieved onto the two-component NiO/Co2O3/MgO catalyst, SEM and transmission electron microscopy (TEM) results confirm that uniform tube-like structure MWCNTs with the yield of 410% were obtained onto Co2O3/Al2O3 catalyst. These MWCNTs are smooth and pointing in the same direction. Their tube diameter is about 20[Formula: see text]nm, which is the smallest around all observed MWCNTs. Moreover, nonuniform curved bamboo-like MWCNTs with nozzles in the yield of 760% were obtained onto NiO/V2O3/MgO catalyst. Their diameter ranges from 25[Formula: see text]nm to 50[Formula: see text]nm. Results show that single-component catalyst promotes the growth of uniform and smaller nanotubes. Among the as-grown nanotubes, their specific surface area increases and average pores diameter reduces after the treatment with concentrated nitric acid at reflux and washing condition. The largest specific surface area (305[Formula: see text]m2/g) and average pores diameter (26[Formula: see text]m2/g) are processed to MWCNTs grown onto the NiO/Co2O3/MgO catalyst. MWCNTs with such large structural adsorption characteristics and purity of more than 99% obtained with yield 800% show potential use for preparation of nanocomposites as anode materials in lithium ion batteries.

scholarly journals Carbonate-Based Lanthanum Strontium Cobalt Ferrite (LSCF)–Samarium-Doped Ceria (SDC) Composite Cathode for Low-Temperature Solid Oxide Fuel Cells

2020 ◽  
Vol 10 (11) ◽  
pp. 3761
Author(s):  
Muhammed Ali S.A. ◽  
Jarot Raharjo ◽  
Mustafa Anwar ◽  
Deni Shidqi Khaerudini ◽  
Andanastuti Muchtar ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Low Temperature ◽  
Solid Oxide Fuel Cells ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Composite Cathode ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Composite Electrolyte

Perovskite-based composite cathodes, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF)–Ce0.8Sm0.2O1.9-carbonate (SDCC), were investigated as cathode materials for low-temperature solid-oxide fuel cells. The LSCF was mixed with the SDC–carbonate (SDCC) composite electrolyte at different weight percentages (i.e., 30, 40, and 50 wt %) to prepare the LSCF–SDCC composite cathode. The effect of SDCC composite electrolyte content on the diffraction pattern, microstructure, specific surface area, and electrochemical performances of the LSCF–SDCC composite cathode were evaluated. The XRD pattern revealed that the SDCC phase diffraction peaks vary according to its increasing addition to the system. The introduction of SDCCs within the composite cathode did not change the LSCF phase structure and its specific surface area. However, the electrical performance of the realized cell drastically changed with the increase of the SDCC content in the LSCF microstructure. This drastic change can be ascribed to the poor in-plane electronic conduction at the surface of the LSCF cathode layer due to the presence of the insulating phase of SDC and molten carbonate. Among the cathodes investigated, LSCF–30SDCC showed the best cell performance, exhibiting a power density value of 60.3–75.4 mW/cm2 at 600 °C to 650 °C.

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