Mesostructured Silica Nanoparticles Research Articles

A comparative study of fibrous silica-based catalysts for improving methane production via CO2 methanation

The process of utilizing the greenhouse gas carbon dioxide (CO2) is crucial in addressing and reducing the impact of climate change. The CO2 methanation process, also known as the Sabatier reaction, is considered one of the appealing approaches since it provides synthetic natural gas (SNG), fulfilling the present needs. However, the CO2 methanation reaction demands an exceptionally effective catalyst capable of surpassing the energy barrier associated with eight proton-electron transfers from H2 molecules. Herein, the application of fibrous silica nanospheres along with the fibrous modification of mesostructured silica nanoparticles (MSN) towards CO2 methanation, called the Centre of Hydrogen energy silica (CHE-Si) and CHE-SM was reported. Both catalysts were successfully synthesized by utilizing micro-emulsion techniques and subsequently were characterized with x-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and N2 adsorption-desorption. FTIR results revealed that CHE-SM possessed superior Si-OH and Si-O species than CHE-Si despite displaying low surface area and pore volume. Consequently, CHE-SM achieved above 50% CO2 conversion and CH4 yield at 500 °C while CHE-Si exhibited lower performance. This discrepancy in catalytic performance was due to the fact that CHE-SM was comprised of more active sites that could adsorb and dissociate CO2 and H2 reactants.

Promoting Effects of Copper and Iron on Ni/MSN Catalysts for Methane Decomposition

Copper and iron-based bimetallic nickel catalysts supported on Mesostructured Silica Nanoparticles (MSNs) with compositions of 50% Ni–5% Cu/MSN and 50% Ni–5% Fe/MSN were prepared using an impregnation method, and they were compared with a monometallic 50% Ni–MSN catalyst for their activity and stability in methane decomposition reaction. The influence of promoters, such as Cu and Fe, at different reaction temperatures (700 °C, 800 °C and 900 °C) was investigated. The results revealed that the Cu and Fe-promoted catalysts significantly increased the hydrogen yield in methane decomposition compared with the unpromoted catalyst. This could be attributed to the formation of Ni–Cu and Ni–Fe bimetallic alloys in the catalysts, respectively, and this favored the stability of the catalysts. With increasing reaction temperature, the hydrogen yield also increased. However, the hydrogen yield and the lifetime of the nickel catalyst were enhanced upon the addition of iron compared to copper at all the reaction temperatures. The analysis conducted over the spent catalysts validated the formation of multi-walled carbon nanotubes with a bamboo-like internal channel over the catalysts along with a high crystallinity and graphitization degree of the carbon produced.

Mesostructured Silica Nanoparticles with Organic Corrosion Inhibitors to Enhance the Longevity of Anticorrosion Effect

Abstract In this study, a specific organosilane molecule (octadecyldimethyl(3-trimethoxysilylpropyl)ammonium) is used to form soft-templates that store organic corrosion inhibitors (tolytriazole), and chemically anchor to silica surface during a sol-gel process. As the anchored soft-templates in the resulting mesostructured silica are not removed, it successfully achieves an environmental-friendly synthetic method and a prolonged storage of tolyriazole. Coating of a copper substrate with the mesostructured silica embedding tolytriazole, therefore, endows a prolonged anticorrosion effect.

Hybrid multifunctionalized mesostructured stellate silica nanoparticles loaded with β-diketonate Tb3+/Eu3+ complexes as efficient ratiometric emissive thermometers working in water.

Despite the great effort made in recent years on lanthanide-based ratiometric luminescent nanothermometers able to provide temperature measurements in water, their design remains challenging. We report on the synthesis and properties of efficient ratiometric nanothermometers that are based on mesoporous stellate nanoparticles (MSN) of ca. 90 nm functionalized with an acetylacetonate (acac) derivative inside the pores and loaded with β-diketonate-Tb3+/Eu3+ complexes able to work in water, in PBS or in cells. Encapsulating a [(Tb/Eu)9(acac)16(μ3-OH)8(μ4-O)(μ4-OH)] complex (Tb/Eu ratio = 19/1 and 9/1) led to hybrid multifunctionalized nanoparticles exhibiting a Tb3+ and Eu3+ characteristic temperature-dependent luminescence with a high rate Tb3+-to-Eu3+ energy transfer. According to theoretical calculations, the modifications of photoluminescence properties and the increase in the pairwise Tb3+-to-Eu3+ energy transfer rate by about 10 times can be rationalized as a change of the coordination number of the Ln3+ sites of the complex from 7 to 8 accompanied by a symmetry evolution from Cs to C4v and a slight shortening of intramolecular Ln3+-Ln3+ distances upon the effect of encapsulation. These nanothermometers operate in the 20-70 °C range with excellent photothermal stability, cyclability and repeatability (>95%), displaying a maximum relative thermal sensitivity of 1.4% °C-1 (at 42.7 °C) in water. Furthermore, they can operate in cells with a thermal sensitivity of 8.6% °C-1 (at 40 °C), keeping in mind that adjusting the calibration for each system is necessary to ensure accurate measurements.

Multifunctionalized Mesostructured Silica Nanoparticles Containing Mn2 Complex for Improved Catalase-Mimicking Activity in Water

We report the synthesis of a hybrid nanocatalyst obtained through the immobilization of bio-inspired [{Mn(bpy)(H2O)}(µ-2-MeC6H4COO)2(µ-O){Mn(bpy)(NO3)}]NO3 compound into functionalized, monodispersed, mesoporous silica nanoparticles. The in situ dual functionalization sol–gel strategy adopted here leads to the synthesis of raspberry-shaped silica nanoparticles of ca. 72 nm with a large open porosity with preferential localization of 1,4-pyridine within the pores and sulfobetaine zwitterion on the nanoparticles’ periphery. These nano-objects exhibit improved catalase-mimicking activity in water thanks to the encapsulation/immobilization of the catalytic active complex and high colloidal stability in water, as demonstrated through the dismutation reaction of hydrogen peroxide.

Structural investigation of phosphonium-based ionic liquid impregnated mesostructured silica nanoparticles and application towards the adsorption of Pb(II)

Adsorption has been widely used in waste water treatment due to its simplicity and cost-effective process. One of the popular adsorbent was silica due to their advantageous properties. Immobilizing additive onto particular adsorbent is one of the way to enhance adsorption capacity. Immobilizing ionic liquid (IL) onto silica-based support could alleviate the drawbacks of IL and enhance the adsorption capacity. Thus, silica-based materials, silica and mesostructured silica nanoparticle (MSN), were impregnated with a phosphonium-based ionic liquid (IL), trioctyldodecylphosphonium bromide (P8,8,8,12Br), which was designated as IL@SIL and IL@MSN. The structural variation of the support greatly impact the adsorbent performance. The results showed that IL@MSN with superior surface properties exhibit a faster reaction kinetic and lower thermodynamic barrier for the adsorption of Pb(II). Both adsorbents followed a pseudo second-order kinetic and chemically adsorbed Pb(II). IL@MSN showed a higher adsorption capacity in both batch and column adsorption than that of IL@SIL. The equilibrium data of both adsorbents fitted well with the Freundlich isotherm model with maximum adsorption capacity of 256.4 and 142.9 mg g−1 for IL@MSN and IL@SIL, respectively. In agreement with the batch experiment, IL@MSN showed a higher adsorption capacity in column adsorption than that of IL@SIL (325.6 and 242.2, respectively). Column adsorption with IL@MSN was able to achieve 94% removal of Pb(II) while IL@SIL achieved 70%. Superior surface properties of IL@MSN allowed a longer duration of column exhaustion than that of IL@SIL. The column experimental data showed a good fit with the Thomas model. Immobilized IL on silica based materials has potential as an adsorbent for heavy metals and structural variation over the support material played an important role.

Investigation of palladium-mesostructured silica nanoparticles (Pd-MSN) as anode electrocatalyst for alkaline direct methanol fuel cell

The commercialization of fuel cells is hindered by the high cost of noble metal electrocatalysts, such as platinum. Mesostructured silica nanoparticles (MSNs), as a novel catalyst support, are added to active palladium nanoparticles to create a Pd-MSN electrocatalyst with low Pd content to improve catalytic efficacy and decrease costs. Wet impregnation method was used to prepare catalysts that comprise palladium nanoparticles supported on MSNs (i.e. 5 wt% Pd-MSN, 10 wt% Pd-MSN, 15 wt% Pd-MSN, 20 wt% Pd-MSN and 20 wt% Pd-C) to enhance electrocatalytic activity for methanol oxidation. The structures of the catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) and Brunauer–Emmet–Teller (BET) surface area analysis, and their electrocatalytic performance towards methanol oxidation was investigated by cyclic voltammetry (CV) and chronoamperometry (CA). Amongst the catalysts, 20 wt% Pd-MSN has the highest electrocatalytic activity (14.3 mA cm−2) and stability (3600 s) for methanol oxidation in alkaline medium at the constant potential of −0.2 V. This result indicates that 20 wt% Pd-MSN may be a promising anode material for direct methanol fuel cells. The improved electrocatalytic activity and stability of the electrocatalyst are attributed to the high specific surface area of MSN and the effective surface structure of Pd nanoparticles. Furthermore, MSN increases catalyst dispersion by producing new active sites, which results in the promotion of Pd utilization.

Nickel phyllosilicate derived Ni/SiO2 catalysts for CO2 methanation: Identifying effect of silanol group concentration

For the conventional Ni/SiO2 catalyst, the weak metal-support interaction usually resulted in serious Ni sintering at high temperature. To address this problem, a group of Ni-phyllosilicate-derived Ni/SiO2 catalysts were synthesized via the hydrothermal reaction of nickel nitrate and mesostructured silica nanoparticles (MSN) with three different sizes of 99 (MS), 184 (MM), and 725 (ML) nm. The Ni contents of three nickel phyllosilicate catalysts varied from 5.9 to 19.7 wt%, which exhibited a reverse order of the particle size. It was found that the concentration of silanol group (SiOH) of MSN significantly affected the construction of Ni-phyllosilicate material. The surface silanol group concentration increased with the decrease of particle size of MSN, resulting in the improved formation of nickel phyllosilicate and enhanced catalytic activity for CO2 methanation. Among all catalysts, MS/H-24 showed the highest CO2 conversion of 76.5 % at 450 °C due to the highest Ni dispersion and largest CO2 and H2 uptakes. In addition, the optimal catalyst exhibited higher anti-sintering property, long-term stability and hydrothermal stability than an impregnated catalyst (Ms/Im) with the similar Ni content in a lifetime test (450 °C, 100 h) and steam treatment test (600 °C, 6 h), owing to its strong metal-support interaction derived from nickel phyllosilicate.

Template-Free Synthesis of Hybrid Silica Nanoparticle With Functionalized Mesostructure for Efficient Methylene Blue Removal

A simple one-pot synthesis process for functionalized mesostructured silica nanoparticles (MSNP) is reported. The novel process demonstrated the possibility to achieve MSNP with a surface area up to 501 m2.g−1 using a phosphonate based nonsilane precursor such as N, N´-bis[4,6- bis(diethylphosphono)-1,3,5-triazin-yl]-1,2-diaminoethane (ED). MSNP obtained by using 20 mol% of ED achieved a surface area of 80 m2.g−1 and increasing the ED content to 30 mol% resulted in a surface area of 501 m2.g−1. Zeta potential of novel MSNPs (-65.5 and -70.0 mV) were much higher than the nanoparticle (NP) prepared from only TEOS (-49 mV), indicating the presence of a large number of –SiOH and phosphonic acid surface functional groups, as confirmed by Fouriertransform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance (NMR) analysis. The functionalized MSNPs were used as an adsorbent for the removal of cationic pollutants like methylene blue (MB). The MSNP with the highest porosity displayed favorable MB adsorption behavior with ~380 mg.g−1 of MB adsorption capacity. Facile regeneration in an acidic medium (~pH 4.5) with easy recyclability (10 cycles) confirmed the practical applicability of this novel functionalized MSNPs.

Template-free synthesis of hybrid silica nanoparticle with functionalized mesostructure for efficient methylene blue removal

A simple one-pot synthesis process for functionalized mesostructured silica nanoparticles (MSNP) is reported. The novel process demonstrated the possibility to achieve MSNP with a surface area up to 501 m2.g−1 using a phosphonate based nonsilane precursor such as N, N´-bis[4,6-bis(diethylphosphono)-1,3,5-triazin-yl]-1,2-diaminoethane (ED). MSNP obtained by using 20 mol% of ED achieved a surface area of 80 m2.g−1 and increasing the ED content to 30 mol% resulted in a surface area of 501 m2.g−1. Zeta potential of novel MSNPs (−65.5 and 70.0 mV) were much higher than the nanoparticle (NP) prepared from only TEOS (−49 mV), indicating the presence of a large number of –SiOH and phosphonic acid surface functional groups, as confirmed by Fourier-transform infrared spectroscopy (FT-IR) and Nuclear magnetic resonance (NMR) analysis. The functionalized MSNPs were used as an adsorbent for the removal of cationic pollutants like methylene blue (MB). The MSNP with the highest porosity displayed favorable MB adsorption behavior with ~380 mg.g−1 of MB adsorption capacity. Facile regeneration in an acidic medium (~pH 4.5) with easy recyclability (10 cycles) confirmed the practical applicability of this novel functionalized MSNPs.

Versatile nanoadsorbents based on magnetic mesostructured silica nanoparticles with tailored surface properties for organic pollutants removal

This paper addresses the development of new magnetic silica-based nanoadsorbents and evaluates their potential application in the removal of contaminants of emerging concern (CECs), polyaromatic hydrocarbons (PAHs) and aliphatic hydrocarbons. For this purpose, magnetic iron oxide nanoparticles were covered with a hybrid shell of silica and 3-(trimethoxysilyl)propyl-octadecyldimethyl-ammonium chloride (TPODAC) as structure directing agent. The as-prepared hybrid material (MMST) was further modified with trimethoxyphenylsilane, obtaining a phenyl-functionalized nanoadsorbent (MMST-Ph). Both materials were thoroughly characterized with diverse physicochemical techniques, and batch sorption tests with single-contaminant and with mixtures of contaminants were performed. MMST-Ph proved to be more efficient for the adsorption of PAHs and aliphatic hydrocarbons. The presence of TPODAC and phenyl moieties anchored on the mesostructured silica frameworks resulted to be a key factor to obtain high PAHs uptakes from aqueous media. In the case of CECs, ibuprofen (IBU), diclofenac (DCF) and carbamazepine (CBZ) were tested. These experiments demonstrated that even though MMST possesses better adsorption capacities of CECs, MMST-Ph achieved high IBU and DCF uptakes. Regeneration and reuse experiments showed that MMST-Ph can be reused in eight cycles without losing the adsorption capacity of anthracene. In the case of MMST, there was a 42% drop in the adsorption capacity of ibuprofen in the second cycle, whereas in the next seven cycles the adsorption capacity remained constant.The promising results obtained in this work strengthen the potential application of surface-modified magnetic silica nanoparticles for the removal of different types of organic pollutants from waters.

NiPd Supported on Mesostructured Silica Nanoparticle as Efficient Anode Electrocatalyst for Methanol Electrooxidation in Alkaline Media

The direct methanol fuel cell (DMFC) is a portable device and has the potential to produce 10 times higher energy density than lithium-ion rechargeable batteries. It is essential to build efficient methanol electrooxidation reaction electrocatalysts for DMFCs to achieve their practical application in future energy storage and conversion. A catalyst consisting of nickel–palladium supported onto mesostructured silica nanoparticles (NiPd–MSN) was synthesized by the wet impregnation method, while MSN was synthesized using the sol-gel method. MSN act as a catalyst support and has very good characteristics for practical support due to its large surface area (>1000 m2/g) and good chemical and mechanical stability. The microstructure and catalytic activity of the electrocatalysts were analyzed by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), Brunauer–Emmet–Teller (BET) theory, X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and chronoamperometry (CA). XRD showed that the NiPd–MSN electrocatalysts had a high crystallinity of PdO and NiO, while FESEM displayed that NiPd was dispersed homogeneously onto the high surface area of MSN. In alkaline media, the catalytic activity toward the methanol oxidation reaction (MOR) of NiPd–MSN demonstrated the highest, which was 657.03 mA mg−1 more than the other electrocatalysts. After 3600 s of CA analysis at −0.2 V (vs. Ag/AgCl), the MOR mass activity of NiPd–MSN in alkaline media was retained at a higher mass activity of 190.8 mA mg−1 while the other electrocatalyst was significantly lower than that. This electrocatalyst is a promising anode material toward MOR in alkaline media.

Immobilization of Cellulolytic Enzymes in Mesostructured Silica Materials

Mesostructured silica nanoparticles offer a unique opportunity in the field of biocatalysis thanks to their outstanding properties. The tunable pore size in the range of mesopores allows for immobilizing bulky enzyme molecules. The large surface area improves the catalytic efficiency by increasing enzyme loading and finely dispersing the biocatalyst molecules. The easily tunable pore morphology allows for creating a proper environment to host an enzyme. The confining effect of mesopores can improve the enzyme stability and its resistance to extreme pH and temperatures. Benefits also arise from other peculiarities of nanoparticles such as Brownian motion and easy dispersion. Fossil fuel depletion and environmental pollution have led to the need for alternative sustainable and renewable energy sources such as biofuels. In this context, lignocellulosic biomass has been considered as a strategic fuel source. Cellulases are a class of hydrolytic enzymes that convert cellulose into fermentable sugars. This review is intended to survey the immobilization of cellulolytic enzymes (cellulases and β-glucosidase) onto mesoporous silica nanoparticles and their catalytic performance, with the aim to give a contribution to the urgent action required against climate change and its impacts, by biorefineries’ development.

Improving the performance of nickel catalyst supported on mesostructured silica nanoparticles in methanation of CO2-rich gas by urea–nitrate combustion

In this work, NiO supported mesostructured silica nanoparticles (MSN) were synthesized via the urea–nitrate combustion method using urea as fuel and nitrate salts as oxidants with the different urea/nitrate ratios and calcination duration. The physicochemical properties of catalysts were investigated by several techniques, including N2 physisorption measurements, powder X-ray diffraction, N2-BET isothermal adsorption, hydrogen temperature-programmed reduction, carbon dioxide temperature-programmed desorption, scanning electron microscopy and transmission electron microscopy. The obtained catalysts were employed in the methanation of CO2-rich gas at a temperature range of 225–400 °C with the CO2/H2 ratio of 1/4 and CO2 concentration of 20 mol%. The results showed that using the urea–nitrate combustion method in synthesizing catalysts led to improved physicochemical properties that increased the activity of NiO/MSN catalysts. The catalyst prepared with the urea/nitrate molar ratio of 3 and calcined at 600 °C for 3 h showed the highest catalytic performance in methanation of CO2-rich gas, reaching CO2 conversion of 96% and CH4 selectivity of 100% at 375 °C. The best catalyst has excellent stability in CO2 solo-hydrogenation at a reaction temperature of 375 °C during 30 h of reaction thanks to the resistance to coke formation. Besides, adding 1 mol% CO in the feedstock should be simultaneously conducted to surge the effectivity of CO2 methanation.

Multidimensional Nanoparticle Characterization through Ion Mobility-Mass Spectrometry.

Multidimensional techniques that combine fully or partially orthogonal characterization methods in a single setup often provide a more comprehensive description of analytes. When applied to nanoparticles, they have the potential to reveal particle properties not accessible to more conventional 1D techniques. Herein, we apply recently developed 2D characterization techniques to nanoparticles using atmospheric-pressure ion mobility-mass spectrometry (IM-MS), and we demonstrate the analytical capability of this approach using ultraporous mesostructured silica nanoparticles (UMNs). We show that IM-MS yields a 2D particle size-mass distribution function, which in turn can be used to calculate not only important 1D distributions, i.e. particle size distributions, but also nanoparticle structural property distributions not accessible by other methods, including size-dependent particle porosity and the specific pore volume distribution function. IM-MS measurement accuracy was confirmed by measurement of NIST-certified polystyrene latex particle standards. For UMNs, comparison of IM-MS results with TEM and N2 physisorption yields quantitative agreement in particle size and qualitative agreement in average specific pore volume. IM-MS uniquely shows how within a single UMN population, porosity increases with increasing particle size, consistent with the proposed UMN growth mechanism. In total, we demonstrate the potential of IM-MS as a standard approach for the characterization of structurally complex nanoparticle populations, as it yields size-specific structural distribution functions.

Catalytic decomposition of methane into hydrogen and carbon nanotubes over mesostructured silica nanoparticle-supported nickel catalysts

Hydrogen is an alternative source of renewable energy that can be produced by methane decomposition without any COx formation. In this work, an impregnation method was used to prepare a set of Ni-based catalysts (5% to 50%) supported on mesostructured silica nanoparticles (MSNs) for its application in methane decomposition. The use of MSN as an effective support for nickel in methane decomposition was reported here for the first time. The physical, chemical and structural properties of the catalysts was studied and the results indicated that NiO was the active species in the fresh catalyst that were effectively distributed on the mesoporous surface of MSN. The reduction temperature of Ni/MSN catalysts were shifted to low temperatures with increased loading of nickel. The hydrogen yield increased with the increment of Ni amount in the catalysts. The catalytic activity of the 50% Ni/MSN catalyst showed that this catalyst was highly efficient and stable compared with other catalysts. The catalyst showed the highest hydrogen yield of 68% and remained more or less the same during 360 min of reaction. Approximately 62% of hydrogen yield was observed at the end of reaction. Further analysis on the spent catalysts confirmed that carbon nanotubes was formed over Ni/MSN catalyst with high graphitization degree.

Cell-penetrating peptide together with PEG-modified mesostructured silica nanoparticles promotes mucous permeation and oral delivery of therapeutic proteins and peptides.

Poor permeation across intestinal mucous barriers often limits the oral delivery of prospective therapeutic proteins and peptides (TPPs). In order to address this issue, cell penetrating peptide (CPP) together with PEG modified and pore-enlarged mesostructured silica nanoparticle (NP) were constructed to form the mucus-penetrating electrostatic particle-complexes, CPP/TPP/NP. Alone, CPP and TPP often present with poor stability, and their traditional electrostatic complex shows reduced pharmacodynamics. To provide satisfactory protection, silica NPs were loaded with CPP and TPP (CPP@NP and TPP@NP), respectively, and then CPP@NP and TPP@NP could together form CPP/TPP/NP via electrostatic interaction. As a result, CPP involvement with PEG modification showed an 8.45-, 1.62- and 5.09-fold increase in cellular uptake, exocytosis and final transcellular permeation in mucous conditions, respectively. It was found that CPP involvement mainly affected transport and exocytosis, and the PEG polymer significantly influenced mucous penetration and cellular uptake, which could further promote CPP ability for uptake and exocytosis. Additionally, NP-mediated CPP/TPP/NP showed a similar uptake mechanism with supporting carriers (clathrin-mediated endocytosis), and could strengthen transcellular routes (the endoplasmic reticulum-Golgi apparatus pathway and the lysosome route). Utilizing recombinant growth hormone (RGH) as a model TPP, oral administration of the RGH-loaded CPP/TPP/LMSN-PEG10k with hydrophilic and electroneutral properties induced 5.41- and 4.91-fold increases in pharmacodynamics in vitro and in vivo, respectively. Thus, CPP/TPP/NP significantly promoted mucous permeation and shows promising potential for oral delivery of TPPs.

Ni-based Catalyst Supported on Mesostructured Silica Nanoparticles (MSN) for Methanol Oxidation Reaction (MOR)

Ni-based Catalyst Supported on Mesostructured Silica Nanoparticles (MSN) for Methanol Oxidation Reaction (MOR)

Zirconium-Loaded Mesostructured Silica Nanoparticles Adsorbent for Removal of Hexavalent Chromium from Aqueous Solution

Zirconium-loaded mesostructured silica nanoparticles (Zr/MSN) were developed for the removal of hexavalent chromium (Cr(VI)) from aqueous solutions. X-ray diffraction, transmission electron microscopy, and Brunauer–Emmett–Teller results revealed that both MSN and Zr/MSN showed a characteristic highly ordered hexagonal pore structure with a high specific area of 821–1219 m2 g–1. Fourier transform infrared analysis showed that the presence of Zr diminished the absorbance band that was assigned to silanol groups of the structural defect sites, while XPS analysis of the binding energy of Si–O–Zr indicated interactions between the silanol groups and zirconium. The interaction of zirconium and silanol groups from the structural defect sites generated bidentate zirconium, which acted as an active site for the adsorption. The experimental results showed that the modification of MSN with zirconium significantly enhanced the adsorption capacity for Cr(VI). The equilibrium isotherm data showed that the adsorption pr...

Platinum and Molybdenum Oxide Supported on Mesostructured Silica Nanoparticles for n-Pentane and Cyclohexane Isomerization

Alkane isomerization into its equivalent branched isomers has gained numerous attention as a reaction to obtain high quality fuel. In this study, platinum and molybdenum oxide supported on mesostructured silica nanoparticles (Pt/MoO3/MSN) was prepared via impregnation method and tested for n-pentane and cyclohexane isomerization. The catalyst was characterized by using X-ray diffraction (XRD), nitrogen (N2) physisorption, and pyridine Fourier-transform infrared (pyridine-FTIR) spectroscopy. The IR result revealed that the addition of Pt and MoO3 into MSN formed different strength of Lewis and Brönsted acid sites. It was observed that the catalyst possessed strong acid sites and several numbers of relatively weak Lewis and Brönsted acid sites. Pt/MoO3/MSN was catalytically active towards n-pentane and cyclohexane isomerization with conversion of 63 and 87%, respectively, at 300 °C. It was proposed that the addition of Pt might assist the generation of active protonic acid sites from molecular hydrogen via the mechanism of hydrogen spillover and hence improve isomerization reaction.