Montmorillonite intercalated with SiO2, SiO2-Al2O3 or SiO2-TiO2 pillars by surfactant-directed method as catalytic supports for DeNOx process

2014 ◽  
Vol 68 (9) ◽  
Author(s):  
Lucjan Chmielarz ◽  
Andrzej Kowalczyk ◽  
Magdalena Wojciechowska ◽  
Paweł Boroń ◽  
Barbara Dudek ◽  
...  
Keyword(s):  
Transition Metal ◽  
Catalytic Reduction ◽  
Surface Acidity ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Performance ◽  
Pillared Clay ◽  
Metal Species ◽  
Reduction Of No ◽  
Catalytic Supports

AbstractThe intercalation of natural montmorillonite with SiO2, SiO2-Al2O3 or SiO2-TiO2 pillars by the surfactant-directed method resulted in the formation of high surface area porous materials; these were tested as catalytic supports for the process of selective catalytic reduction of NO (DeNOx). The incorporation of titanium or aluminium into the structure of the silica pillars significantly increased the surface acidity of the clay samples. Iron and copper were deposited onto the surface of the pillared clays mainly in the form of monomeric isolated cations and oligomeric metal oxide species. The contribution of the latter species was higher in the clay intercalated with SiO2-TiO2 pillars than in the samples modified with SiO2 and SiO2-Al2O3 pillars. The pillared clay-based catalysts were active in the DeNOx process but, in this group, the best results were obtained for the clay intercalated with SiO2-TiO2 pillars and doped with iron and copper. The catalytic performance of the samples is discussed in respect of their surface acidity and active forms of transition metal species deposited.

Vanadium-doped titania-pillared montmorillonite clay as a catalyst for selective catalytic reduction of NO by ammonia

Clay Minerals ◽  
1997 ◽  
Vol 32 (4) ◽  
pp. 665-672 ◽  
Author(s):  
K. Bahranowski ◽  
J. Janas ◽  
T. Machej ◽  
E. M. Serwicka ◽  
L. A. Vartikian
Keyword(s):  
Selective Catalytic Reduction ◽  
Catalytic Reduction ◽  
Catalytic Performance ◽  
Pillared Clay ◽  
Area Measurement ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Reduction Of No ◽  
Pillared Montmorillonite ◽  
Doped Titania

AbstractA series of V-doped titania-pillared clay catalysts, characterized by ICP-AES chemical analysis, X-ray diffraction, BET surface area measurement, and ESR spectroscopy, have been tested in the selective catalytic reduction of NO by NH3. An ESR analysis shows that V dopant is anchored to the titania pillars. Vanadyl species with differing degrees of in-plane V-O π-covalent bonding are produced depending on the method of sample preparation. Polymeric V species appear as the V content is increased. Catalytic performance of these systems depends on the method of preparation and on the V content. The best catalyst, converting 90-100% NO in the temperature range 523-623 K, is obtained by exchange of pillared montmorillonite with vanadyl ions, at an extent of exchange below the level where significant amounts of polymeric V species appear. The co-pillared catalyst, containing vanadyl centres characterized by a higher degree of in-plane ncovalent bonding (according to ESR), is less selective than the exchanged samples.

Selective catalytic reduction of NO by NH3 over high surface area vanadia-silica catalysts

2001 ◽  
Vol 34 (3) ◽  
pp. 191-200 ◽  
Author(s):  
R.M Caraba ◽  
S.G Masters ◽  
K.M Eriksen ◽  
V.I Pârvulescu ◽  
R Fehrmann
Keyword(s):  
Selective Catalytic Reduction ◽  
Surface Area ◽  
Catalytic Reduction ◽  
High Surface ◽  
High Surface Area ◽  
Reduction Of No

Research of Catalytic Performance over Transition Metal Modified MnOx-CeOx/ACF Catalysts

2011 ◽  
Vol 383-390 ◽  
pp. 1945-1950 ◽  
Author(s):  
Bo Xiong Shen ◽  
Ting Liu ◽  
Ning Zhao ◽  
Juan Ma ◽  
Xiao Cui Hao
Keyword(s):  
Catalytic Activity ◽  
Thermal Treatment ◽  
Transition Metal ◽  
Catalytic Reduction ◽  
Surface Acidity ◽  
Catalytic Performance ◽  
Impregnation Method ◽  
Active Components ◽  
Scr Of No ◽  
Negative Effect

The catalyst of MnOx-CeOx/ACF prepared by impregnation method was used for low-temperature selective catalytic reduction (SCR) of NO with NH3, and more than 90% NO conversion was obtained at 230°C. Fe、Cu or V was used respectively to prepare transition metal modified MnOx-CeOx/ ACF catalysts which had lower catalytic activity than that over MnOx-CeOx/ACF. SEM, N2 adsorption and NH3-TPD were used to analyze the catalysts. The results showed that transition metal modified catalysts had a reduced surface area, pore volume and surface acidity. SO2 had a negative effect on SCR performance of the catalysts. Fe modified catalyst exhibited SO2 tolerance in the first 6h in the presence of 100ppm SO2. Thermal treatment in N2 at 350°C was used to regenerate the deactivated catalysts by SO2. The decomposition of ammonium salts recovered the catalytic activity to some extent. The sulfated active components in deactivated catalysts after the thermal treatment enhanced the surface acidity of the catalysts.

Intercalation of First Row Transition Metals inside Covalent-Organic Frameworks (COF): a Strategy to Fine Tune the Electronic Properties of Porous Crystalline Materials

2018 ◽  
Author(s):  
Srimanta Pakhira ◽  
Jose Mendoza-Cortes
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Electronic Properties ◽  
High Surface ◽  
Electronic Devices ◽  
High Surface Area ◽  
Main Role ◽  
Covalent Organic Frameworks ◽  
Porous Network ◽  
Crystalline Materials

<div>Covalent organic frameworks (COFs) have emerged as an important class of nano-porous crystalline materials with many potential applications. They are intriguing platforms for the design of porous skeletons with special functionality at the molecular level. However, despite their extraordinary properties, it is difficult to control their electronic properties, thus hindering the potential implementation in electronic devices. A new form of nanoporous material, COFs intercalated with first row transition metal is proposed to address this fundamental drawback - the lack of electronic tunability. Using first-principles calculations, we have designed 31 new COF materials <i>in-silico</i> by intercalating all of the first row transition metals (TMs) with boroxine-linked and triazine-linked COFs: COF-TM-x (where TM=Sc-Zn and x=3-5). This is a significant addition considering that only 187 experimentally COFs structures has been reported and characterized so far. We have investigated their structure and electronic properties. Specifically, we predict that COF's band gap and density of states (DOSs) can be controlled by intercalating first row transition metal atoms (TM: Sc - Zn) and fine tuned by the concentration of TMs. We also found that the $d$-subshell electron density of the TMs plays the main role in determining the electronic properties of the COFs. Thus intercalated-COFs provide a new strategy to control the electronic properties of materials within a porous network. This work opens up new avenues for the design of TM-intercalated materials with promising future applications in nanoporous electronic devices, where a high surface area coupled with fine-tuned electronic properties are desired.</div>

Facile Synthesis of Cu2O nanoparticle-loaded Carbon Nanotubes Composite Catalysts for Reduction of 4-Nitrophenol

2020 ◽  
Vol 16 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Yao Feng ◽  
Ran Wang ◽  
Juanjuan Yin ◽  
Fangke Zhan ◽  
Kaiyue Chen ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Mechanical Stability ◽  
Catalytic Reduction ◽  
High Surface ◽  
High Surface Area ◽  
Reduction Reaction ◽  
Cycle Performance ◽  
Simple Method ◽  
Composite Catalysts ◽  
Cu2o Nanoparticles

Background: 4-nitrophenol (4-NP) is one of the pollutants in sewage and harmful to human health and the environment. Cu is a non-noble metal with catalytic reduction effect on nitro compounds, and.has the advantages of simple preparation, abundant reserves, and low price. Carbon nanotubes (CNT) are widely used for substrate due to their excellent mechanical stability and high surface area. In this study, a simple method to prepare CNT-Cu2O by controlling different reaction time was reported. The prepared nanocomposites were used to catalyze 4-NP. Methods: CNTs and CuCl2 solution were put into a beaker, and then ascorbic acid and NaOH were added while continuously stirring. The reaction was carried out for a sufficiently long period of time at 60°C. The prepared samples were dried in a vacuum at 50°C for 48 h after washing with ethyl alcohol and deionized water. Results: Nanostructures of these composites were characterized by scanning electron microscope and transmission electron microscopy techniques, and the results at a magnification of 200 nanometers showed that Cu2O was distributed on the surface of the CNTs. In addition, X-ray diffraction was performed to further confirm the formation of Cu2O nanoparticles. The results of ultraviolet spectrophotometry showed that the catalytic effect of the compound on 4-NP was obvious. Conclusions: CNTs acted as a huge template for loading Cu2O nanoparticles, which could improve the stability and cycle performance of Cu2O. The formation of nanoparticles was greatly affected by temperature and the appropriate concentration, showing great reducibility for the 4-NP reduction reaction.

Design of Transition Metal Oxide and Hybrid Mesoporous Materials

2002 ◽  
Vol 728 ◽  
Author(s):  
Clément Sanchez ◽  
Eduardo L. Crepaldi ◽  
Anne Bouchara ◽  
Florence Cagnol ◽  
David Grosso ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Oxide ◽  
High Surface ◽  
High Surface Area ◽  
Directed Assembly ◽  
Optical Quality ◽  
Hybrid Thin Films ◽  
Poly Ethylene ◽  
Inorganic Framework ◽  
Hybrid Mesoporous Materials

AbstractMesostructured transition metal (Ti, Zr, V, Al and Ce-Zr) oxide-based hybrid thin films, templated by poly(ethylene oxide)-based surfactants or block copolymers, have been prepared reproducibly, displaying 2D-hexagonal (p6m) or 2D-centred rectangular (c2m) structure. By carefully adjusting the variables involved it is possible to combine both high organisation and excellent optical quality. TiO2 and ZrO2-based materials show thermal stability up to 400-550°C. The elimination of the template can be conducted efficiently and gives rise to high surface area mesoporous films. For the other metal oxide hybrids the inorganic framework is much more fragile, and requires a precise sequence of post-treatments to be stabilised. In addition, original and homogeneous macrotextures shaped with coral-like, helical or macroporous sieves morphologies have been obtained following a nanotectonic approach based on the template-directed assembly by poly-γ-benzyl-L-glutamate (PBLG) of organically functionalised CeO2 crystalline nanoparticles.

Efficient and Reusable Silica Gel Supported Metal Ionic Liquid Catalysts for Palmitic Acid Esterification to Biodiesel

2021 ◽  
Vol 43 (1) ◽  
pp. 1-1
Author(s):  
Guo Yingwei Guo Yingwei ◽  
Chen Xuedan Chen Xuedan ◽  
Yan Shiting Yan Shiting ◽  
Zhang Zhengliang Zhang Zhengliang ◽  
Chen Yuqin Chen Yuqin ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Palmitic Acid ◽  
Silica Gel ◽  
High Surface ◽  
High Surface Area ◽  
Kinetic Studies ◽  
Catalytic Performance ◽  
Reaction Conditions ◽  
Acid Esterification ◽  
Supported Metal

A series of silica gel (SG) supported metal ionic liquid catalysts (x[Bmim]Cl-CrCl3/SG) were synthesized and exploited for the esterification of palmitic acid (PA) with methanol (ML) to produce biodiesel efficiently. The 10%[Bmim]Cl-CrCl3/SG catalyst with high surface area and desirable acidity exhibited the best catalytic performance and reusability after six consecutive running cycles. Based on the response surface analysis, the optimal reaction conditions were obtained as follows: methanol/acid mole ratio = 11:1 mol/mol, catalyst amount = 5.3 wt%, reaction time = 65 min, as well as reaction temperature = 373 K, reaching to a biodiesel yield of 96.1%. Further kinetic studies demonstrated that the esterification of PA with ML obeyed 1.41 order kinetics for acid concentration with the activation energy of 16.88 kJ/mol

Engineering Modified Mesoporous Silica Catalysts through Porosity and Surface Acidity Control for Selective Production of DME

2021 ◽  
Vol 894 ◽  
pp. 45-49
Author(s):  
Rosanna Viscardi ◽  
Vincenzo Barbarossa ◽  
Raimondo Maggi ◽  
Francesco Pancrazzi
Keyword(s):  
Mesoporous Silica ◽  
Dimethyl Ether ◽  
Sulfonic Acid ◽  
Pore Diameter ◽  
Solid Acid ◽  
Surface Acidity ◽  
High Surface ◽  
High Surface Area ◽  
Bifunctional Catalysts ◽  
Scanning Electronic Microscopy

DME has been received the attention as a renewable energy due to its thermal efficiencies equivalent to diesel fuel, lower NOx emission, near-zero smoke and non-toxic. DME can be obtained by methanol dehydration over solid acid catalysts or directly from syngas over bifunctional catalysts. The catalytic dehydration of methanol to DME has been widely studied in the literature over pure or modified γ -aluminas (γ-Al2O3) and zeolites. Mesoporous silica has obtained much consideration due to its well-defined structural order, high surface area, and tunable pore diameter. In this work, sulfonic acid and aluminium modified mesoporous silica were synthesized and tested as catalysts for production of dimethyl ether from methanol. The modified silicas were studied utilizing XRD, N2 physisorption, pyridine adsorption, and scanning electronic microscopy. The effects of reaction temperature and water deactivation on the methanol selectivity and conversion to dimethyl ether were investigated. Sulfonic acid modified mesoporous silica showed higher selectivity and stability of DME than that of aluminosilicate. The grafting of mesoporous silica with sulfonic groups displayed much more enhanced hydrothermal stability than Al-MCM-41 and γ-Al2O3.

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