In this research, nanometer size clusters of TiO2 have been successfully synthesized through sol-gel method. Further, at different concentration of Ag were further deposited on TiO2. After successful deposition of TiO2: Ag the gas sensing performance of the sample has been studied at different exposure of NH3(ammonia) gas. Analysis has been done via XRD to evaluate the grain sizes of the nanoparticles and calculated 18 nm for TiO2 and 12 nm for 5% Ag doped TiO2. EDS has been conducted, ensured that Ag has been successfully decorated on the superficial of TiO2. The formation of nano size particles has been confirmed by TEM analysis. FTlR analysis confirmed the existence of TiO2 and Ag. The surface state emission of TiO2: Ag nanoparticles can be seen in the PL spectrum at 383 nm, 450 nm, and 465 nm. As the exposure of NH3 gas increases from 50 to 250 ppm, the impedance range displayed a decrease in semicircle radius, which was then marginally increased. The variance in resistance also contributed to the gas sensing properties due to grain boundaries, in accordance to impedance spectroscopy review.

Polymer-based composites depending on natural fiber reinforcement have created wide research and designing enthusiasm for the most recent couple of decades because of their lower density, high specific strength, ease of fabrication, low cost, lightweight, corrosion resistance, recyclability, and biodegradability and has earned an exceptional classification of “green composite.” This article discusses about coconut shell powder (CSP), coir fiber (CF), and small weight percentage of aramid fiber (AF)-strengthened vinyl ester (VE) composites, prepared with various weight proportions of filler/fiber. The prepared composites are investigated for its mechanical behavior, including hardness, tensile, flexural, impact, and so on, under different testing conditions and weight proportions of filler and/or fiber weight. These specimens were also subjected for dry sliding wear and coefficient of friction measurement. Microstructure and fracture mechanisms of the hybrid composites were concentrated to examine the dispersion of the fiber and/or filler in the vinyl ester matrix and involved wear mechanisms utilizing scanning electron microscopy.

Manganese-based catalysts have attracted much attention due to their excellent performance for NO reduction with NH3 (NH3-SCR) at low temperatures. In the current study, the novel metal Sb was modified into Mn/TiO2 and Fe–Mn/TiO2, and the NO x conversion was compared with those of Mn/TiO2 and Fe–Mn/TiO2 catalysts to investigate the effect of the Sb. The NO x reduction activities of the catalysts were evaluated in the temperature range of 100–250 °C at a space velocity of 60,000 h−1. The physicochemical properties of all the catalysts were characterized by Brunauer–Emmett–Teller surface area, temperature-programmed desorption of ammonia, temperature-programmed reduction, X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy. Interestingly, the Sb-promoted Mn-based catalysts showed significantly higher NO x conversion than the other catalysts with or without 6 vol% of H2O. The high performance of the Sb-modified catalysts could be related to the increase of acid sites and redox properties.

An attempt has been made to explore the effect of hybrid reinforcement on mechanical properties and dry sliding wear behavior of vinyl ester (VE) composites. Vinyl ester reinforced with alkali treated coir fibers (CF-VE), silanated aramid fibers (AFs) leading to fibridization and inclusion of coconut shell powder (CSP) with various weight proportions has been prepared resulting in hybridization. Effectiveness of treated fibers and CSP on mechanical and wear behavior of VE and their hybrids was evaluated. The density and hardness values of CF-VE composite increased steadily with inclusion of AFs and CSP. The tensile strength increased from 52 MPa at 0 wt.% AFs inclusion to a maximum of 76 MPa at 15 and 5 wt.% of AFs and CSP content. Further, it increased to a maximum of 78 MPa at 5 and 10 wt.% of AFs and CSP in CF-VE composite. The specific wear rate decreased more rapidly with the CSP content. Hence, it is deduced that hybrid VE (15CFs+5AFs) composite with 10 wt.% CSP is more effective against sliding wear. The type, geometry and dispersion of reinforcements contribute to the increased wear resistance. These results are important for the development of new composites incorporated with surface treated reinforcing materials such as CF and CSP, which will have significant application in automotive sliding or bearing components.

The surfaces of coir fiber (CF) and coconut shell powder (CSP) were modified by alkali and silane treatment respectively to investigate the consequent effects on reinforcement of vinyl ester (VE) composites. Mono‐composites of VE with surface treated CFs and CSP as well as their hybrid composites with as‐received aramid fibers (AFs) have been prepared by hand layup followed by compression molding methods. The effectiveness of surface treated reinforcements in improving the mechanical properties of the composites was demonstrated. Significant differences between VE mono‐composites and their hybrid reinforcements on hardness and tensile properties of VE were observed, while no improvement in the above‐mentioned properties except for Young's modulus was observed for hybrid composite with AFs. It was also observed that surface treated CFs and CSP reinforced VE composites exhibited better hardness and tensile properties. SEM imaging confirmed decreased fiber pull‐out for VE reinforced with alkali treated CFs because of the enhanced adhesion between the CFs and the VE matrix. Flexural properties of all the composites decreased. This study has proved that the mechanical properties of hybrid VE composites can be enhanced by modifying the reinforcements by alkali and silane into their formulations. These results have been explained on the basis of structure and morphology in terms of fractography of VE composites. Furthermore, this study demonstrates that alkali treatment is a promising technique for improving the mechanical properties such as hardness and tensile properties of CF reinforced hybrid polymer matrix composites. POLYM. COMPOS., 39:4542–4550, 2018. © 2017 Society of Plastics Engineers

Herein, we investigated the NOx reduction performance of Sb–V–CeO2/TiO2 (SbVCT) catalyst subjected to hydrothermal aging, where 6 vol% of H2O was fed to the SbVCT for 16 h with variable temperatures of 550–750 °C. The structural, morphological, redox, and acid properties of fresh and aged catalysts were comprehensively characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, N2-physisorption, temperature programmed reduction/desorption (H2–TPR/NH3/NO–TPD) and in situ DRIFTS. The XRD, Raman and TEM results of the fresh and the one hydrothermally aged at 550, 600 °C catalysts indicated the presence of finely dispersed polymeric vanadia, antimony, and nano-crystalline ceria species on TiO2 support. The SbVCT catalysts hydrothermally aged at the temperatures ≤ 600 °C showed better NOx conversions than the others aged > 600 °C. This was because aging at the temperatures ≤ 600 °C could help to minimize the loss of surface redox/acid properties that were originally inherent to surface vanadyl and CeO2 species that went into CeVO4 and large CeO2 aggregates. This in turn led to the loss of surface redox and acidic characters indigenous to the SbVCT and reduced its NOx reduction performance. Moreover, the NOx reduction performance of hydrothermally aged V–WO3–TiO2 catalyst, when compared with that of SbVCT catalyst, showed relatively low NOx conversions at the temperatures below 300 °C.

The Cu based zeolite NH3-SCR catalysts are well-known for after treatment of exhaust gases from light-and heavy-duty diesel engines. However, these catalysts are easily deactivated under the co-presence of H2O and SO2. In the present study, Sb–V–CeO2/TiO2 catalyst showed superior conversion for the abatement of NOx with NH3 under H2O and SO2 condition compared to commercial Cu–SAPO-34 and CuFe–ZSM-5 zeolite catalysts. The physico-chemical properties of fresh and used catalysts were examined by BET surface area, TEM (Transition electron microscopy) with EDS/EDX (Energy dispersive spectrometer/X-ray), XPS (X-ray photoelectron spectroscopy), DRIFTS (in situ diffuse reflectance infrared Fourier transformed spectroscopy) and H2-TPR (temperature programmed reduction). Higher than 95% of initial NOx conversion was obtained over Sb–V–CeO2/TiO2 catalyst at 250 °C under 14% H2O and 50 ppm SO2 conditions. The SO2 on/off test of the CuFe–ZSM-5 and Cu–SAPO-34 catalysts indicated a drastic decrease of NOx conversion when SO2 was turned on. In contrast, Sb–V–CeO2/TiO2 catalyst maintained a high NOx conversion and initial NOx conversion was completely recovered when SO2 was turned off.

In this study, the NOx conversion under standard and fast SCR conditions on the Sb–V–CeO2/TiO2 catalyst has been conducted in the temperature range of 150–400 °C. The Sb–V–CeO2/TiO2 catalyst, under both fast and standard NH3-SCR conditions, showed higher NOx conversion than the commercial V2O5/WO3–TiO2 catalyst at low temperatures. In comparison to the V2O5/WO3–TiO2 catalyst, the NO oxidation to NO2 was promoted for the Sb–V–CeO2/TiO2 catalyst at the temperatures between 150 and 400 °C. The in-situ DRIFTS studies at 200 °C on the Sb–V–CeO2/TiO2 catalyst surface indicated the IR bands assigned to NO2, nitrate species and ammonia adsorbed species assigned to Brønsted and Lewis acid sites under both standard and fast SCR conditions. Furthermore, in-situ DRIFTS results of Sb–V–CeO2/TiO2 catalyst revealed that the formation of surface adsorbed NO2, bridged nitrate and bidentate nitrate species. The reduction of nitrates to nitrites is induced by NO2, which reacts with the adsorbed ammonium species forming intermediate NH4NO2. Eventually, this is converted to N2 and H2O in both SCR conditions.

In this work, the antimony promoted Vanadia-Ceria catalysts have been prepared by homogeneous precipitation method for the selective catalytic reduction of NOx with NH3. With an introduction of Sb into Vanadia-Ceria, the catalysts showed an improvement in the low temperature NOx conversion below 250 degrees C. These high activities of the Sb promoted catalysts were related to the increase of acid sites and redox properties of the catalysts, which were investigated by the NH3-TPD (temperature programmed desorption), H-2-TPR (temperature programmed reduction) and in-situ NH3-DRIFTS (diffused reflectance infrared Fourier transformed spectroscopy) spectra. In addition, structural and morphological properties of these catalysts were examined by X-ray diffraction, BET surface area and FE-SEM (Field emission scanning electron microscopy). After the addition of Sb to Vanadia-Ceria, the increase of surface area with a smaller, uniform sized particles and high dispersion of vanadia were indicated in the optimized 4wt.% V2O5-2wt.% Sb-CeO2 catalyst. Furthermore, the Lewis and Bronsted acid sites were enhanced in the 4 wt.% V2O5-2wt.% Sb-CeO2 catalyst to promote NOx conversion at a wide temperature range of 175-400 degrees C. XPS results also indicated an improvement in the active oxygen species of this catalyst due to the enhancement of surface oxidation species of V4+/V5+, Sb3+/Sb5+ and Ce3+/Ce4+. (C) 2016 Elsevier B.V. All rights reserved.

In this work, the synthesis of Sb-V/CeO2–TiO2 catalyst was modified by controlling pH with the addition of monoethanolamine solution. All the catalysts were systematically investigated for NO x reduction with NH3 at different reaction conditions and then characterized by XRD, BET-surface area, X-ray photoelectron spectroscopy, NO-TPD, NH3-TPD, and H2-TPR. This modified synthesis method for the Sb-V/CeO2–TiO2 catalyst exhibited noticeably higher NO x reduction activity at low temperatures (<250 °C). H2-TPR revealed an increase of reducible species for the modified catalyst at basic pH, followed by neutral pH and acidic pH, respectively. High activity of the catalyst synthesized at basic pH was persistent for NO x reduction with time that was confirmed by the time on stream durability test under SO2 and water. The Ce 3d XPS spectra of spent catalyst synthesized at basic pH explains the gradual decrease in activity due to the decrease of Ce4+ to Ce3+ ratio by the formation of sulfates.

In this study, catalytic activity and thermal stability of the arc plasma deposited (APD) Pt nano-particles on A12O3 and CeO2-Al2O3 were compared with that of the conventionally prepared Pt/Al2O3. All the catalysts were characterized by BET-surface area, transmission electron microscopy, X-ray photoelectron spectroscopy, CO-pulse chemisorption, H2-temperarture programmed reduction and X-ray absorption near edge spectroscopy. Through the quantum chemical calculations of different metal oxide support, CeO2 was identified as a suitable anchoring material with high energy level between the Pt species (Pt(0) and PtO(x)) on ceria. Subsequently, the results of XPS and XANES revealed the presence of abundant Pt(0) metal species in APD catalysts. The addition of ceria to Al2O3 support enhanced the dispersion of Pt nano-particles. The H2-TPR of Pt/CeO2-Al2O3 (APD) catalyst showed high-temperature reduction peaks corresponding to the interaction of Pt with ceria on alumina by Pt-O-Ce. Consequently, the Pt nano-particles deposited on CeO2-Al2O3 by APD attained strong thermal resistance at high temperatures. In addition, superior catalytic activities for CO and C3H6 oxidation and NO(x) reduction were obtained for the Pt/CeO2- Al2O3 (APD) catalyst.

The Sb–CeO2/TiO2 (SCT) catalytic system with different vanadia loading (0–3 % w/w) was systematically investigated for removal of NO by NH3. A series of catalysts prepared by impregnation and deposition precipitation methods were thoroughly characterized physically, by BET surface area, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), and chemically, by temperature-programmed desorption (NH3 and SO2-TPD), temperature programmed reduction (H2-TPR), and in-situ DRIFT study. NH3-TPD and H2-TPR results for 2 and 3 % vanadia-loaded Sb–CeO2/TiO2 catalysts revealed high total acidity and reducibility. As a result, both catalysts had high activity at low temperatures. At 240 °C for 20 h the 2 % vanadia-loaded Sb–CeO2/TiO2 catalyst was more resistant to SO2 than the 3 % vanadia catalyst. In addition, in-situ SO2 DRIFT study revealed the existence of more surface sulfate species on Sb–CeO2/TiO2 than on vanadia-loaded Sb–CeO2/TiO2 catalysts.

A study of structural and mechanistic investigation of the Sb/V/Ce/Ti catalysts sulfated at different temperatures was carried out by X-ray absorption near edge spectroscopy (XANES) and diffused reflectance infrared Fourier transformed spectroscopy (DRIFTS). The high temperature sulfated catalyst, especially Sb/V/Ce/Ti-S500 (sulfated at 500 °C temperatures), exhibited superior NOx conversion at low temperatures (150–200 °C) compared to Sb/V/Ce/Ti-S400 and Sb/V/Ce/Ti-S300 (sulfated at 400 and 300 °C) catalysts. The Ce L3 edge XANES spectra of Sb/V/Ce/Ti-S500 catalyst showed the formation of Ce(III) dominant sulfate species, resulting in the enhancement of Lewis and Brønsted acid strength. The formation of Ce(III) sulfate species on Sb/V/Ce/Ti-S500 catalyst was clearly indicated by Ce M4,5 and S K edge XANES spectra peaks at 881.9 eV attributed to Ce3+ oxidation state and 2481 eV assigned to S6+ oxidation state of sulfate species. Furthermore, the in situ DRIFTS results revealed that the Lewis and Brønsted acid sites of Sb/V/Ce/Ti-S500 catalysts increased significantly, followed by Sb/V/Ce/Ti-S400 and Sb/V/Ce/Ti-S300. At 200 °C, the reaction between the pre-adsorbed NH3 species with NO + O2 on sulfated catalysts exhibited the formation of mono-dentate, bi-dentate, bridging nitrates and NO2 species. Meanwhile, the subsequent formation of NO2 via NO oxidation was promoted on Sb/V/Ce/Ti-S400 and Sb/V/Ce/Ti-S500 catalysts, followed by surface interaction with adsorbed NH3 to produce N2 and H2O at low temperatures (<220 °C).

The dual-walled characteristic mesoporous hollow structures of Co3O4 are explored as an efficient catalytic material for CO oxidation. The hollow structures with exposed (111) facets and a high surface area are attractive for efficient catalytic performance. As a result, complete CO conversion was achieved at 70 °C and a conversion of about 90 % was maintained at 60 °C for more than 600 min.

Pt supported on iron hydroxyphosphate catalysts has been synthesized and characterized by various adsorption and spectroscopic methods. X-ray diffraction patterns of the supported and unsupported catalysts indicate a very weak diffraction line due to the Fe-5(PO4)(3)(OH)(5) phase. The X-ray photoelectron spectroscopic studies reveal a surface composition attributed to Fe-5(PO4)(3)(OH)(5) species. The temperature programmed sequential reduction-oxidation-reduction of lwt.% Pt/Fe-5(PO4)(3)(OH)(5) indicates the absence of H-2 spillover due to Pt on the Fe-5(PO4)(3)(OH)(5) support. The temperature programmed reduction studies also show the non-reducible behavior of Fe-5(PO4)(3)(OH)(5) phase.

Iron hydroxyphosphate as support for Pt catalysts is explored for preferential oxidation of CO using simulated reformate gas mixture in the temperature range 40-240 °C. The CO oxidation activity and selectivity at low reaction temperatures are enhanced on addition of H2O but decrease at high temperatures due to the reverse water gas shift reaction. X-ray diffraction patterns of the supported and unsupported catalysts show very weak diffraction lines due to the Fe5(PO4)3(OH)5 phase. The chemical composition of this phase on the catalyst surface has been confirmed by X-ray photoelectron spectroscopy results.