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Supercapacitors are progressively being utilized for storage systems in sustainable nanotechnologies. A NiCoS nanostructure was synthesized on nickel foam by an in situ one-pot hydrothermal method at different reaction temperatures (80, 100, and 120 °C) keeping other reaction parameters such as pH and reaction time constant for supercapacitor applications. The SEM report revealed a plate-like nanostructures of NiCoS on nickel foam (NiCoS/NF). The electrode prepared at 100 °C exhibits better electrochemical activities compared to electrodes prepared at 80 and 120 °C. The integrated binder-free NiCoS/NF electrode for supercapacitor, optimized at 100 °C, manifested a large specific capacitance of 3309 mF cm−2 at a current density of 1 mA cm−2 with a notable rate capability of 427 mF cm−2 even at 10 mA cm−2. The asymmetric supercapacitor fabricated with optimized NiCoS/NF prepared at 100 °C exhibited an exceptionally high energy density of 2.04 mW h cm−3 at a power density of 42.64 mW cm−3.

A series of ternary ZnO hollow sphere/carbon quantum dots/reduced graphene oxide (ZnO/CQDs/r-GO) nanocomposites were successfully prepared via solvothermal technique in the presence of the polyethylene glycol 400 (PEG 400) as a solvent. The structural details of as-prepared ZnO/CQDs/r-GO nanocomposites were characterized by powder X-ray diffraction analysis. The morphological properties of the composite were analyzed using field emission scanning microscopy (FE-SEM). The visible light absorption ability of the as-prepared pristine and ternary nanocomposites was examined using UV–visible (UV–Vis) spectrophotometry. The photocatalytic activity of ZnO, ZnO/CQDs, ZnO/r-GO, and ZnO/CQDs/r-GO nanostructures were evaluated for the degradation of organic pollutants such as methylene orange (MO), rhodamine B (RhB), and methylene blue (MB). The different composites with various amounts of reduced graphene oxide (r-GO) and carbon quantum dots (CQDs) were synthesized to enhance photocatalytic activity. The ZnO/CQDs/r-GO composites showed excellent potential for photocurrent generation compared with ZnO, ZnO/CQDs and ZnO/r-GO under-stimulated sunlight. The effect of various parameters such as the effect of reaction temperature, catalyst concentration, pH, and concentration of MB dye has been also studied. The photo-assisted catalytic degradation properties of the catalyst after five cycles exhibit high stability.

ZSM-5:CeO2 nanocomposites were prepared by two-step hydrothermal method in combination with the wet impregnation method. The synthesized nanocomposites were characterized by XRD, FESEM, TEM, EDX, elemental mapping, FTIR and UV–vis analysis. The bandgap investigations were done using tauc plot and the bandgap of ZSM-5 has been reduced from 3.90 to 3.15 eV upon CeO2 loading. The synthesized nanocomposites were tested for photocatalytic activity under a halogen lamp and the effect of CeO2 loading on ZSM5 has been examined. Among the various nanocomposites synthesized, ZSM-5:CeO2 25 wt% exhibited better methyl orange degradation of about 95.6% with an initial dye concentration of 10 mg/l, pH 7, 100 mg of photocatalyst under halogen lamp for 75 min. Additionally, the effect of various reaction parameters like dye concentration (10–25 mg/l), photocatalyst dosage (25–125 mg), and pH (3–9) was probed to get better performance. Tapping experiments were conducted with various radical scavengers to get insight into the key active species responsible for the photodegradation of methyl orange. The result portrays the importance of hydroxyl radical for the degradation of methyl orange dye. Cycle test and stability studies showed that the photocatalyst was stable even after four cycles. In summary, ZSM-5:CeO2 nanocomposites can be a suitable photocatalyst for numerous applications in the field of photodegradation of organic contaminants.

Bismuth sulfide (Bi2S3) nanorods have been prepared using a simple and low-cost reflux method. This method is easy to handle and opens up a way to manufacture photocatalytic pigment at a low cost. The Bi2S3 catalyst was subjected to X-ray diffraction (XRD), UV–Visible spectroscopy (UV–Vis), scanning electron microscope, high-resolution transmission electron microscopy, FT-IR spectroscopy, thermogravimetric analysis (TG/DTA), and X-ray photoelectron spectroscopy. The structures of the Bi2S3 nanorod have been investigated and were seen to be orthorhombic. The electron microscopic observations showed that surfactants greatly affect the morphologies of the as-prepared Bi2S3 samples. The XRD and TEM results confirmed that the Bi2S3 nanorods have a high surface area and are good crystallinity. TEM measurements revealed that the average breadth and length is 75 nm and 385 nm for Bi2S3 nanorods prepared using NaOH. The uniform one-dimensional Bi2S3 nanorods are due to the presence of NaOH which controls the nucleation and growth process of Bi2S3 nanorods. The photocatalytic activity of the Bi2S3 nanocrystallites has been estimated by the degradation of methylene blue (MB) under the irradiation of halogen light. It was noted that the absorption peak corresponding to MB reduced indicating the photocatalytic nature of the sample. In these conditions, the maximum degradation of the dye was achieved within 140 min for KOH added Bi2S3 samples and the photodegradation efficiency is 87.98%. A possible photocatalytic reaction mechanism of the Bi2S3 samples has also been proposed.

Hexagonal phase zinc oxide (ZnO) nanostructures were synthesized via hydrothermal method and annealed at different temperatures viz., 200, 400, 600, 800 and 1000 °C. The prepared nanostructures were characterized by XRD, FTIR, FESEM, HR-TEM, UV-DRS and XPS techniques. The crystallite sizes of the prepared nanomaterails were calculated by Williamson–Hall plots method. The ZnO annealed at 200 °C showed a crystallite size of 18.7 nm while the ZnO annealed at °C showed a 46.2 nm. It is observed that when increasing the annealing temperature the crystallite sizes were increased due to induced growth of crystallites during annealing process. Moreover, the band gaps of the ZnO annealed at different temperatures showed a decreasing trend with increasing annealing temperatures. The photocatalytic performances were studied by analyzing the degradation of methylene blue in an aqueous solution. ZnO annealed at 1000 °C exhibited better photocatalytic activity (94%) due to enhanced crystallinity, comparatively lower bandgap and high oxygen vacancy.

In this study, we examined the highly selective sensing of Fe3+ ions in water using metal complex-functionalized mesoporous silica materials. Metal complex-functionalized mesoporous silica materials were synthesized on the mesoporous surface of SBA-15 via complexation process between Eu3+ and aminosilane groups. Mesoporous silica, SBA-15, and the Eu3+-complex functionalized SBA-15 were characterized using X-ray diffraction (XRD), transmittance electron microscopy (TEM), nitrogen sorption behavior, and Fourier transform infrared (FTIR) spectroscopy. The sensing behavior of the Eu3+-complex functionalized SBA-15 was studied using various metal ions (Fe3+, Cu2+, Cr3+, Co2+, Hg2+, Pb2+, and Zn2+) aqueous solutions. Photoluminescence intensity (λ = 612 nm) of the Eu3+-complex functionalized SBA-15 was dependent on the different interactions between metal ions and Eu3+-complexes. Photoluminescence intensity at λ = 612 nm of the Eu3+-complex functionalized SBA-15 decreased to near zero and proved the highly selective sensing effect of Fe3+. Therefore, the Eu3+-complex functionalized SBA-15 can be considered an excellent candidate for sensing iron ions in water.

The development of efficient, scalable, and economically viable electrode materials with high specific capacitance is of great significance for supercapacitor applications. Herein, α-Fe2O3 nanoparticles, α-Fe2O3/rGO, and α-Fe2O3/SnO2/rGO nanocomposite were synthesized by a one-step hydrothermal method. Different characterization techniques were used to study the physical and chemical properties of the prepared materials. The powder XRD measurement revealed that the formation of the ternary composite without any impurities. As characterized by SEM and TEM techniques, both α-Fe2O3 and SnO2 nanoparticles were embedded on two-dimensional reduced graphene oxide sheets. The electrochemical properties of the prepared electrode materials were studied by cyclic voltammetry and galvanostatic charge/discharge, and impedance spectroscopy techniques in a 6 M KOH electrolyte solution. All the electrode materials exhibit Faradic reaction peaks in CV curves which imply the pseudocapacitive nature of the prepared materials. The ternary α-Fe2O3/SnO2/rGO nanocomposite demonstrated the enhanced specific capacitance of 821 Fg−1 at 1Ag−1 than that of α-Fe2O3 nanoparticles (373 Fg−1 at 1Ag−1), and α-Fe2O3/rGO (517 Fg−1 at 1Ag−1) nanocomposite with excellent cyclic retention (98.7%) after successive 10,000 cycles. This improved electrochemical performance of ternary α-Fe2O3/SnO2/rGOnanocomposite is mainly attributed to the surface properties of nanostructures of metal oxides and an excellent conductive network. Moreover, the asymmetric supercapacitor (ASC) device was fabricated using the ternary α-Fe2O3/SnO2/rGOnanocomposite as the anode material and rGO as the cathode material. The ASC device showed an energy density of 17 Wh Kg−1 at a power density of 3585 W kg−1 and retains 94.52% capacitance after successive 5000 cycles at a current density of 10Ag−1.

To use as the efficient solid base catalysts, alanine functionalized MCM-41 (Alanine-MCM-41), catalysts viz. 16Alanine-MCM-41 and 8Alanine-MCM-41, were successfully prepared by post-grafting method using MCM-41 synthesized by basic sol-gel method. The synthesized Alanine-MCM-41 catalysts were characterized by several instrumental techniques such as XRD, N2-sorptions and TEM to confirm the standard mesoporous nature. The CHN result shows that the alanine groups have been successfully functionalized on the surface of MCM-41 while the functionalization of alanine groups on MCM-41 were also confirmed by FTIR spectra. The total basic sites of 16Alanine-MCM-41 determined by TPD-CO2 are higher than that of 8Alanine-MCM-41 and enhance to lead the Knoevenagel condensation of furfural and acetylacetone under solvent-free condition. A variety of reaction parameters such as reaction time, temperature, mole ratio and solvents were studied to find an optimum parameter. The Alanine MCM-41 catalysts were successively recovered and reused several times without loss of catalytic activity because of strongly anchored the alanine groups on inner pore of MCM-41, as confirmed by FTIR spectra. Compared to 8Alanine-MCM-41, the 16alanine-MCM-41 gives higher catalytic activity in this reaction because its total base sites lead to produce a major product, 3-(2-furylmethylene)-2,4-pentanedione (FMP) with 100% selectivity using the best parameters like 1:1 M ratio of furfural: acetylacetone, 100 °C and 30 min.

Novel hollow sphere morphologied zinc sulphide@carbonaceous aerogel (ZnS@CA) composites with different ZnS content were fabricated using a simple hydrothermal carbonization treatment following by a facile in situ growth method. The fabricated composites were used as catalysts for chemical degradation of the methylene blue (MB) and for hydrogen evolution. Our photocatalytic studies are found, from the photocatalytic results obtained by different ZnS@CA materials, that 55 wt%ZnS@CA exhibits the excellent photocatalytic performances for MB degradation and the highest rate of hydrogen production that are correspondingly 1.7- and 8.1-fold higher than that of pure ZnS. This improved photocatalytic performance could be mainly attributed by unique 3D catenulate carbon networks, which can be highly favorable to disperse of ZnS on the surface of CA. An synergetic properties between CA and ZnS could be highly beneficial to the photo-generated electron–hole separation. The hollow microsphere structured ZnS nanoparticles allow multi-reflections of light within the interior cavity and increases the capture efficiency of visible light. A possible photocatalytic mechanism of the main active radicals has also been proposed. This work opens up the new prospects for a low-cost biomass-based sulfide photocatalysts used for the environmental purification and hydrogen generation.

Water electrolysis powered by renewable energy sources to produce green hydrogen is a very promising and sustainable alternative to fossil fuels, as well as one of the best approaches for significantly reducing carbon footprints and controlling pollution. In this study, novel hybrid non-stoichiometric nanocomposite Co3S4/Co0.85Se electrocatalyst materials were synthesized using a simple and one-pot eco-friendly hydrothermal method. The as-prepared samples were characterized using X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) for structural features. Crystalline phases of Co3S4, Co0.85Se, and mixed phases in the hybrid samples were confirmed through XRD. Uniformly distributed agglomerated nanoparticles (30-80 nm) of Co3S4, clearly distinguishable nanoaggregates (20-90 nm) of Co0.85Se, and nanoflakes covered with nanoparticles (30-150 nm) of Co3S4/Co0.85Se were confirmed by FESEM. The synergistic effects of the hybrid nanocomposite due to the combination of Co3S4 (containing two different oxidation states of cobalt) and non-stoichiometric Co0.85Se, was investigated towards the oxygen evolution reaction (OER). The electrocatalytic studies confirmed that the Co3S4/Co0.85Se electrocatalyst exhibited a low overpotential of 362 mV @ +30 mA.cm−2 towards the OER in an alkaline solution in comparison with Co3S4 and Co0.85Se electrocatalysts. Furthermore, a low overpotential of 1.59 V at a high current density and a high electrochemical active surface area (ECSA) of 210 cm2 was achieved due to the combined effects of chemical coupling between the Co3S4 and Co0.85Se. Chronoamperometric studies revealed excellent stability of the hybrid nanocomposite samples with negligible changes in the overpotential, even after 30 hours of testing. The synergetic effect of cobalt chalcogenides due to the nanoscale interaction was confirmed by the enhanced electrocatalytic activity.

NiO-supported TiO2 (nNiO/TiO2) as highly active and selective catalysts for triacetyl glyceride (TAG) biofuel additive production via acetylation of glycerol is reported. The catalysts are prepared by incorporating various amounts of Ni2+ (n = 10, 30 and 50 wt% Ni added during catalysts preparation) onto the TiO2 support using simple sol-gel approach followed by calcination. The spectroscopy and microscopy analyses reveal that the NiO nanoparticles (ca. 6 nm) are uniformly distributed on the surface of TiO2 support where octahedrally coordinated NiO as active species is formed upon calcination. Among the catalysts prepared, 30NiO/TiO2 with strongest acidity and highest accessible surface area is found to be the most active in the acetylation of glycerol with acetic acid, achieving 90.2% glycerol conversion with 65.9% selective to TAG under non-microwave instant heating conditions (170 °C, 30 min). In addition, 30NiO/TiO2 also shows better catalytic performance than previous reported catalysts. No significant deterioration in catalytic activity is shown by 30NiO/TiO2 after eight successive runs, thus offering a green pathway for synthesizing TAG vehicle fuel additives with high selectivity.

Herein, we develop an efficient and novel catalytic system, i.e. silver nanoparticles (AgNPs) incorporated mesoporous silica SBA‒15/copolymer hybrid material, for selective oxidation of different alcohols to aldehydes or ketones under ‘mild’ conditions. The copolymer of N,-N-dimethylaminoethyl methacrylate and 2-hydroxyethyl acrylate (p(DMAEMA-co-HEA)) was used to graft the surface-modified SBA‒15 (MS) using free radical polymerization method. Then AgNPs were decorated on the polymer grafted SBA‒15. The dual (thermal and pH) responsive behaviors of the AgNPs/p(DMAEMA-co-HEA)/MS catalyst were investigated using the dynamic light scattering technique. The lower critical solution temperature (LCST) of the copolymer was found to be approximately 30–35 °C. The catalytic activity of AgNPs/p(DMAEMA-co-HEA)/MS was investigated for the selective oxidation of different alcohols to aldehydes or ketones. The conversion of catalytic products and selectivity were calculated using gas chromatographic techniques, whereas the molecular structure of products was determined using 1H and 13C nuclear magnetic resonance spectroscopy. The catalyst showed improved catalytic activity toward the oxidation of alcohols to aldehydes in aqueous medium below LCST and pKa value (7–7.5) of the copolymer. The selectivity toward the corresponding aldehyde was found to be significantly high (99%). The main advantages of the hybrid catalyst as compared to existing catalysts include outstanding alcohol conversion (up to 99%), short reaction time (1 h), small necessary amount of catalyst (6 mg), and performing the catalytic conversion at room temperature using water as a solvent, which are highly beneficial for organic conversion under mild reaction conditions.

Hard donor atoms (N and O) containing macrocyclic ligand was synthesized and further functionalized with mesoporous SBA-15 materials by chemical modification method. The modification was achieved by the immobilization of 3-chloropropyltriethoxysilane (CIPTES) onto mesoporous silica surface followed by post grafting route. The resulting material (Py-Cy-SBA-15) has been characterized by low angle X-ray diffraction (XRD), nitrogen adsorption-desorption isotherm, Fourier-transform infrared (FT-IR) spectroscopy, 29Si and 13C CP MAS NMR spectroscopic analyses, Thermogravimetric analysis (TGA) and elemental analysis. The long range orders of the materials were identified by transmission electron microscopy (TEM). The functionalized material was employed to the heavy metal ions adsorption from aqueous solution containing Cu2+, Co2+, Zn2+, Cd2+ and Cr2+. The prepared hybrid material showed high selectivity and adsorption capacity for Co2+ ion at pH 8.0.

To achieve a high level of heavy metal adsorption, 1,1′,1″-(1,3,5-triazine-2,4,6-triyl)tris(3-(3-(triethoxysilyl)propyl)urea) (TTPU) was synthesized as a novel melamine precursor and incorporated on the silica surface of periodic mesoporous organosilica (PMO). The melamine modified PMOs (MPMOs) were synthesized under acidic conditions using TTPU, tetraethylorthosilicate (TEOS) and Pluronic P123 as a template and the modified PMOs were characterized using the relevant instrumental techniques. The characteristic materials were used as adsorbents for the adsorption of Fe(III) ions. Fe(III) adsorption studies revealed MPMO-7.5 to be a good absorbent with higher adsorption efficiency than other MPMOs.

Mesoporous CeSBA-15 catalysts with a variety of n Si / n Ce ratios have been synthesized under pH-adjusting direct hydrothermal (pH-aDH) method using cerium (IV) sulphate tetrahydrate and Pluronic P123 as the sources of cerium and template, respectively. For comparison studies, Ce/SBA-15(10) catalyst has been synthesized by an incipient wetness impregnation (IWI) method. The hydrothermal stabilities of CeSBA-15 catalysts have been investigated in boiling water (373 K) at autogenous pressure for 168 h. The mesoporous CeSBA-15 catalysts synthesized by different methods have been characterized using the relevant techniques viz. ICP-AES, XRD, N 2 adsorption, UV–vis DRS, EPR, 29 Si MAS NMR, TEM and FE-SEM, and their characteristic results show that the CeSBA-15 catalysts synthesized by pH-aDH method have higher tetrahedral cerium-ions with two-dimensional mesostructures than the Ce/SBA-15(10) synthesized by IWI method. In addition, CeSBA-15(10) has higher hydrothermal stability than CeSBA-15(50). The CeSBA-15 catalysts have been tested in the liquid phase oxidation of cyclohexane with hydrogen peroxide (H 2 O 2 ). Based on the catalytic activities of all catalysts, CeSBA-15(10) is found to be a highly active, recycle and promising heterogeneous catalyst for the oxidation of cyclohexane.

A novel CSA-SBA-15 has been synthesized under mild reaction condition using mesoporous SBA-15 synthesized by pH-adjusting method with organic modifying reagents and copper nitrate trihydrate, and it has been characterized by XRD, FTIR, N 2 adsorption, ESR, UV–vis DRS, FE-SEM and TEM for the investigation of nature of copper species and its interaction with SA-SBA-15. The results of elemental analysis obtained by CHN and ICP-AES show that the molar ratio of N:Cu is ≈3.5, and the molar ratio of C:Cu is ≈23.8. ICP-AES result shows the number of copper-ions (ca. 0.198 wt.%) coordinated with SA-SBA-15. The FTIR results confirm the amine and azomethine groups grafted on SBA-15 while the results of ESR and UV–vis DRS confirm the Cu(II) species anchored on SA-SBA-15. The CSA-SBA-15 is found to be a highly active and recycle heterogeneous catalyst for the selective syntheses of olefin epoxides, and it has superior catalytic activity in the epoxidation of olefins than metal ions incorporated/impregnated mesoporous catalysts.

This study examined the adsorption of lysozyme using three different types of periodic mesoporous organosilicas (PMOs) produced from either bis[3-(trimethoxysilyl)propyl] amine (BTMS-amine), 1,4-bis(triethoxysilyl)benzene (BTES-benzene), or 4-bis(triethoxysilyl) biphenyl (BTES-biphenyl) as precursors. For comparison, the adsorption of lysozyme on mesoporous silica SBA-15 as an absorbent was also investigated. The mesostructure of pristine PMOs and SBA-15 were characterized by small angle X-ray scattering (SAXS), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherm curves and 29Si and 13C solid state CP MAS NMR spectroscopy. The zeta potential was measured to interpret the dispersive and adsorptive ability of the mesoporous materials. BTES-biphenyl with a more hydrophobic character showed a higher adsorption capacity at the pH near the pI of the organosilica precursor than the other two PMO’s. The maximum amount of enzyme was obtained at pH close to the pI. BTES-benzene and BTES-biphenyl showed high affinity to lysozyme and adsorbed most of the lysozymes. In addition, the adsorption rates of the hydrophobic PMOs were quite fast at pH 10.2; faster than that of SBA-15. Overall, hydrophobic PMO materials are suitable for immobilizing lysozyme at pH 10.2.

The synthesis of Fe-SBA-16 with isolated framework Fe species was achieved by simple adjustment of molar ratio of co-surfactant n-butanol, TEOS, n H 2 O / n HCl ratio, Si/Fe ratio, and aging condition, respectively. The extent of mesopore structural ordering and the coordination of iron are confirmed by X-ray diffraction, N2 physisorption, 29Si-MAS NMR, SEM, TEM, electron spin resonance (ESR), and NH3-TPD analysis. The material obtained constitutes micro- (∼316 m2/g) and mesopore surface area (∼1000 m2/g), with high-mesopore sizes (∼9.8 nm). The micropore volume present up to 0.28 cm3/g, while the total pore volume range ∼0.90 cm3/g at the maximum. Among various Si/Fe ratios synthesized, Fe-SBA-16 with Si/Fe ratio 19 exhibited good catalytic activity for the oxidation of cyclohexene at the optimized reaction condition.

A series of highly ordered mesoporous GaSBA-15 materials have been synthesized using different Ga sources with Pluronic P123 by simply adjusting the molar ratio of water to hydrochloric acid ( n H 2 O / n HCl ) under direct hydrothermal conditions. To control the structural and textural properties with high gallium incorporation in the framework of SBA-15, the GaSBA-15 has been prepared using different crystallization temperature. The synthesised GaSBA-15 materials have been characterized by ICP-AES, XRD, N2 adsorption, 71Ga MAS NMR, and FE-SEM. Gallium(III) nitrate is found to be a good Ga-ion source for the synthesis of mesoporous GaSBA-15 material, with nSi/nGa ratio up to 11.2 successfully prepared by changing the nSi/nGa ratio in the synthesis gel at n H 2 O / n HCl of 295. By increasing the crystallization temperature from 373 to 403 K, nitrogen adsorption measurement shows that the pore diameter of GaSBA-15 can be tuned from 88.4 to 92.7 A, with an increase of pore volume from 1.08 to 1.17 cm3/g accompanied by the concomitant decrease of surface area from 981 to 783 m2/g and the decrease of pore wall thickness from 35.3 to 32.7 A. 71Ga MAS NMR results demonstrate that a large amount of tetrahedral gallium could be incorporated into the framework of SBA-15. Furthermore, the hydrothermal stability of GaSBA-15 samples has also been investigated, with hexagonal GaSBA-15(5) having better hydrothermal stability than GaSBA-15(50).

Epoxidation of styrene with t -butyl hydroperoxide (TBHP) as an oxidizing agent has been conducted under liquid phase reaction conditions over Zr–Mn-MCM-41 with different n Si /( n Zr + n Mn ) ratios and Mn-MCM-41(31) catalysts for selective synthesis of styrene oxide. The influences of various reaction parameters such as temperature, time, oxidants, and solvents, styrene to TBHP mmol ratios and acetonitrile (MeCN) to N , N -dimethylformamide (DMF) volume ratios on the conversion of styrene and the selectivity of styrene oxide have also been studied. With the decrease of the n Si /( n Zr + n Mn ) ratios of Zr–Mn-MCM-41 catalysts from 327 to 49, the conversion of styrene as well as the yield and selectivity of styrene oxide increase due to the increase of the number of Lewis acid sites on the surface of catalysts. Moreover, the conversion and selectivity in Zr–Mn-MCM-41(49) is higher as compared to that of Mn-MCM-41(31). The Zr–Mn-MCM-41(49) is found to be reusable for the epoxidation of styrene with TBHP for selective synthesis of styrene oxide.

Isopropylation of m-cresol with isopropyl alcohol (IA) as an alkylating agent has been conducted under vapor phase reaction conditions over mesoporous Zn–Al–MCM-41 catalysts with different nSi/(nZn + nAl) ratios for highly selective synthesis of thymol. The influence of reaction parameters such as reaction temperature, WHSV, mole ratio of reactants, time-on-stream and recyclability reactions, have also been investigated. With increasing the nSi/(nZn + nAl) ratios of Zn–Al–MCM-41 catalysts from 75 to 380, conversion of m-cresol and yield as well as selectivity of thymol decrease because the number of Bronsted acid sites in Zn–Al–MCM-41 catalysts are found to decrease almost linearly with increasing ratios of nSi/(nZn + nAl) from 75 to 380. The conversion of m-cresol and selectivity of thymol in Zn–Al–MCM-41(75) remain constant with each cycling of reaction because of no loss of catalytic activity on the inner side surface of pore walls. Furthermore, these catalytic results are compared with those obtained by using Al–MCM-41(with different nSi/nAl ratio = 21, 42 and 104), HY, Hβ, HM and H-ZSM-5 zeolites. Based on the comparison of catalytic results, Zn–Al–MCM-41(75) is found to be a highly active and recyclable heterogeneous catalyst for the highly selective synthesis of thymol.

Mesoporous CrSBA-15 molecular sieves with different n Si / n Cr ratios have been directly synthesized, for the first time, using Pluronic 123 triblock polymer [(EO) 20 (PO) 70 (EO) 20 ] as a structure-directing agent by NH 4 F acidic method and pH-adjusting method. The mesoporous materials have been characterized using ICP-AES, XRD, N 2 adsorption, ESR, SEM and TEM. ICP-AES studies show a higher amount of chromium incorporation on the silica pore walls in pH-adjusting method as compared to NH 4 F acidic method; however, more octahedral Cr 3+ species are oxidised using pH-adjusting method than those using NH 4 F acidic method. The structural and textural properties of calcined CrSBA-15 are characterized by XRD and N 2 adsorption. ESR results show that both octahedral Cr 3+ and tetrahedral Cr 5+ /Cr 6+ are coordinated on the silica surface of calcined CrSBA-15 prepared using NH 4 F acidic method whereas only tetrahedral Cr 5+ /Cr 6+ are coordinated on the silica surface of calcined CrSBA-15 prepared using pH-adjusting method. TEM and FE-SEM images show the uniform pore diameter and rope-like hexagonal mesoporous structure of CrSBA-15. CrSBA-15 materials have then been used as catalysts for liquid-phase oxidation of anthracene for selective synthesis of 9,10-anthraquinone under different optimal conditions using benzene as the solvent and t -BHP as the oxidant. CrSBA-15(4) gave the highest conversion of 90.6% of anthracene and 100% selectivity of anthraquinone as compared to other CrSBA-15 and CrMCM-41 catalysts.

Selective liquid-phase t -butylation of p -cresol with t -butyl alcohol ( t -BuOH) to produce 2- t -butyl- p -cresol (TBC) has been conducted over Al-MCM-41 catalysts with different Si/Al ratios. The effects of various reaction parameters such as temperature, reaction time and n t -BuOH : n p -cresol ratio on the conversion of p -cresol and the selectivity of TBC have been systematically investigated as well. When the Si/Al ratio of Al-MCM-41 catalysts is increased from 21 to 104 (respectively yielding Al-MCM-41(21), Al-MCM-41(42), Al-MCM-41(62), Al-MCM-41(83) and Al-MCM-41(104)), both the conversion of p -cresol and the yield and selectivity of TBC decrease due to the decrease of the number of Bronsted acid sites of the Al-MCM-41 catalysts. Al-MCM-41(21) catalyst is found to give the highest conversion of p -cresol (88.2%) and the highest selectivity of TBC (90.40%) under the optimal n t -BuOH : n p -cresol mole ratio of 2:1, the optimal reaction temperature of 90 °C and the optimal reaction time of 2 h. Furthermore, Al-MCM-41(21) can be recycled up to at least four times without losing its catalytic performance for butylation reaction.

A diamine functionalized cubic mesostructured KIT-6 (N-KIT-6) has been prepared by post-synthetic method using calcined mesoporous KIT-6 with a diamine source, i.e., N-'[3-(tri methoxysilyl)- propyl]'ethylenediamine. The KIT-6 mesoporous silica used for N-KIT-6 was synthesized under weak acidic hydrothermal method using bitemplates, viz., Pluronic P123 and 1-butanol. The synthesized mesoporous materials, KIT-6 and N-KIT-6, have been characterized by the relevant instrumental techniques such as SAXS, N2 sorption isotherm, FT-IR, SEM, TEM and TGA to prove the standard mesoporous materials with the identification of diamine groups. The characterized mesoporous materials, KIT-6 and N-KIT-6, have been extensively used in the potential application of controlled drug delivery, where ibuprofen (IBU) employed as a model drug. The rate of IBU adsorption and release was monitored by UV vis-spectrometer. On the basis of the experimental results of controlled drug delivery system, the results of IBU adsorption and releasing rate in N-KIT-6 are higher than those of KIT-6 because of the higher hydrophobic nature as well as rich basic sites on the surface of inner pore wall silica.

Mesoporous V-Mo-MCM-41 with Si/(V + Mo) ratio equal to 46, 92, 184 and 230 were synthesized using cetyltrimethylammonium bromide surfactant as template under hydrothermal conditions while the mesoporous materials were characterized using several techniques e.g., ICP-AES, XRD, N 2 -adsorption, FTIR, TG/DTA, 51 V-MAS-NMR, 95 Mo-MCM-41, 29 Si-MAS-NMR, SEM and TEM. The d -spacing value and unitcell parameter in the V-Mo-MCM-41 increases by increasing the metal ions content. FTIR studies showed that V- and Mo-ions were incorporated into the hexagonal mesoporous MCM-41 materials, however, the wavenumber of the anti-symmetric Si–O–Si vibration bands (1097 cm −1 ) in V-Mo-MCM-41 are higher than those in Si-MCM-41 (1081 cm −1 ). These bands should be due to the increase of the mean Si–O distance in the wall caused by the substitution of the small ionic radii of silicon by the larger ionic radii of vanadium and molybdenum. The surface area, pore diameter, pore volume, hydrothermal stability and acid sites in the V-Mo-MCM-41 decreases by increasing the metal ions content. The incorporated metal ions as V 5+ and Mo 6+ in V-Mo-MCM-41 are coordinated to Si(IV) by tetrahedral environments. The synthesized V-Mo-MCM-41 materials were found to be effective as catalysts in the oxidation of alkyl aromatics, e.g., in the oxidation of o -xylene using O 2 gas as the oxidizing agent for the production of phthalic anhydride. The effect of reaction temperature, feed flow rate ratio ( o -xylene:O 2 gas), contact time and recyclability on the selectivity of phthalic anhydride were studied. Thus, the selectivity of phthalic anhydride in the presence of V-Mo-MCM-41(46) catalyst was higher than that of other V-Mo-MCM-41 catalysts due to increasing the catalytic activity on the inner side pores of silica surface.

Aminocyclization reaction of 4-methyl acetophenone (4-MAP) with formaldehyde and ammonia was contacted under vapor phase reaction conditions over novel mesoporous Zn–Al–MCM-41 catalysts with different Si/(Zn + Al) ratios for highly selective synthesis of 2,6-BP (2,6-bis(4-methylphenyl)pyridine). For the reactions, the influences of various reaction parameters such as different catalysts, reaction temperature, reactant molar ratio, WHSV, TOS and recyclability are discussed. With increasing the Si/(Zn + Al) ratios of Zn–Al–MCM-41 catalysts from 75 to 380, the conversion of 4-methyl acetophenone (4-MAP), and the yield and selectivity of 2,6-BP decreased because the number of Bronsted acid sites in Zn–Al–MCM-41 catalysts is found to decrease almost linearly with increasing ratios of Si/(Zn + Al). Further the catalytic results were compared with those obtained by using Al–MCM-41, HY, Hβ, HM and H-ZSM-5 zeolites. The conversion and selectivity is increased in Zn–Al–MCM-41(21) with each cycling of reaction because its catalytic activity does not change. The Si/(Zn + Al) ratio of 21 is found to be more suitable for the aminocyclization reaction of 4-MAP to highly selective synthesis of 2,6-BP. Thus the selectivity of 2,6-BP is higher in Zn–Al–MCM-41(21) than that in other Zn–Al–MCM-41, Al–MCM-41, HY, Hβ, HM and H-ZSM-5.

Mesoporous Zn–Al–MCM-41 molecular sieves with Si/(Zn + Al) ratio equal to 75, 151, 228, 304 and 380 were synthesized using cetyltrimethylammonium (CTMA+) surfactants as template under hydrothermal conditions while the mesoporous materials were characterized using several instrumental techniques. The unitcell parameter, surface area, pore size, hydrothermal and thermal stability of Zn–Al–MCM-41 decreases with increasing metal-ions content. The acid sites in the Zn–Al–MCM-41 are higher than that of Al–MCM-41 [M. Selvaraj, A. Pandurangan, K.S. Seshadri, P.K. Sinha, K.B. Lal, Appl. Catal. A: Gen. 242 (2003) 347.] due to the aluminum ions non-framework by the introduction of zinc ions. The effect of reaction temperature, reaction time, t-butyl alcohol to toluene ratios and recyclability on the selectivity of 4-t-butyltoluene was studied. The Zn–Al–MCM-41(75) catalyst containing higher number of Bronsted acid sites was found to be more effective in the alkylation of alkyl aromatics, for example, in the production of 4-t-butyltoluene from toluene, using t-butyl alcohol as the alkylating reagent. The selectivity of 4-t-butyltoluene was obtained under varying experimental condition, viz. effect of reaction temperature, time and ratio of t-butyl alcohol to toluene for the various catalysts to follow the sequence Zn–Al–MCM-41(75) > Zn–Al–MCM-41(151) > Zn–Al–MCM-41(228) > Zn–Al-MCM-41(304) > Zn–Al–MCM-41(380).

The mesoporous molecular sieves Al-MCM-41 with Si/Al ratio equal to 16, was synthesized under hydrothermal conditions using cetyltrimethylammonium bromide (CTMA+Br−) as surfactant. The SO 4 2 - /Al-MCM-41(Si/Al = 16) material was synthesized using sulfuric acid under impregnation method, and the resulting material is sulfated Al-MCM-41 ( SO 4 2 - /Al-MCM-41). The mesoporous materials viz. Al-MCM-41 and SO 4 2 - /Al-MCM-41 were characterized using several techniques e.g. ICP-AES, Nephelometer, XRD, FT-IR, TG/DTA, N2-adsorption, solid-state-NMR, SEM, TEM and TPD-pyridine. By impregnating of sulfuric acid on silica surface, crystallinity, surface area, pore diameter and pore volume of SO 4 2 - /Al-MCM-41 decreased except wall thickness. While the Lewis acidity is increased because of the expelling aluminum from the Al-MCM-41 framework by impregnating sulfuric acid. The SO 4 2 - /Al-MCM-41 has been used for synthesis of 2-acetyl-6-methoxynaphthalene using 2-methoxynaphthalene with acetic anhydride as acylating agent and 1,2-dichloroethane as solvent. The catalytic results were compared with those obtained using 0.8 N sulfuric acid, amorphous silica–alumina, H-β, USY and H-ZSM-5 zeolites. From the catalytic results it was concluded that the conversion of 2-methoxynaphthalene and selectivity of 2-acetyl-6-methoxynaphthalene in the SO 4 2 - /Al-MCM-41 is higher than that in other catalysts due to higher number of Lewis acid sites. Thus the SO 4 2 - /Al-MCM-41 is found to be a highly active and recyclable heterogeneous catalyst while the catalyst is a very suitable for the synthesis of 2-acetyl-6-methoxynaphthalene.

trans -Stilbene oxide have been synthesized under liquid phase reaction conditions using trans -stilbene in the presence of different oxidants and different solvents over synthesized and characterized Zr–Mn-MCM-41 and Mn-MCM-41 as catalysts. On increasing the Si/(Zr + Mn) ratios of Zr–Mn-MCM-41 and Si/Mn ratios of Mn-MCM-41 catalysts from 49 to 327 and 15 to 102, respectively, the conversion of trans -stilbene, yield and selectivity of trans -stilbene oxide decreased. This may be due to the number of Lewis acid sites in Zr–Mn-MCM-41 and Mn-MCM-41 are found to decrease almost linearly with increasing ratios of Si/(Zr + Mn) and Si/Mn, respectively. Both the Zr–Mn-MCM-41(49) and Mn-MCM-41(31) possesses stronger affinity with trans -stilbene and TBHP, but, the conversion of trans -stilbene, yield and selectivity of trans-stilbene oxide decreased in only recyclable Mn-MCM-41. This may be due to decreasing the catalytic activity on the surface of catalysts. In the context, the Si/(Zr + Mn) ratio of 49 is found to be more suitable for the epoxidation of trans -stilbene to highly selective synthesis of trans -stilbene oxide. Thus the yield (76.3%) and selectivity of trans -stilbene oxide (84.58%) are higher in Zr–Mn-MCM-41(49) than that in other Zr–Mn-MCM-41 and Mn-MCM-41 catalysts.

Mesoporous silica molecular sieves MCM-41 containing zirconium and manganese ions (Zr–Mn-MCM-41) with Si/(Zr+Mn) ratio equal to 49, 98, 147, 196, 262 and 327 and only manganese ions with Si/Mn ratio equal to 15, 31, 46, 61, 82 and 102 respectively, were synthesized under hydrothermal conditions using cetyltrimethylammonium (CTMA + ) surfactants as template in the absence of auxiliary organics. The mesoporous materials, viz. Zr–Mn-MCM-41 and Mn-MCM-41 were characterized using several techniques, e.g. ICP-AES, XRD, FTIR, Nitrogen adsorption, TG/DTA, ESR, UV–Vis/DRS, SEM and TEM. ICP-AES studies indicated the content of zirconium and manganese in the mesoporous materials. XRD studies indicated that the materials had the standard MCM-41 structure. FTIR studies showed that zirconium and manganese ions were incorporated into the hexagonal mesoporous structure of Zr–Mn-MCM-41 and Mn-MCM-41. The thermal stability of the as-synthesized materials was studied using TG/DTA. Nitrogen adsorption was used to determine specific surface area, pore diameter, pore volume and wall thickness in the calcined Zr–Mn-MCM-41 and Mn-MCM-41 mesoporous molecular sieves. The incorporated of zirconium and manganese ions oxidation state was determined by ESR and UV–Vis/DRS. The morphology of Zr–Mn-MCM-41 and Mn-MCM-41 materials was determined by SEM. The inference that the Zr–Mn-MCM-41 and Mn-MCM-41 mesoporous materials had uniform pore size was obtained by TEM studies. The incorporated metal ions as Zr 4+ , Mn 2+ and Mn 3+ in Zr–Mn-MCM-41 are coordinated to Si(IV) by tetrahedral, disordered octahedral and tetrahedral environments respectively. The zirconium and manganese ions are homogenously dispersed on the inside silica surface of the Zr–Mn-MCM-41, but only the manganese ion is not homogenously dispersed on the inside surface of the Mn-MCM-41 under hydrothermal conditions. Thus the Zr–Mn-MCM-41 mesoporous molecular sieves are more useful for oxidation of olefin reaction with TBHP, e.g., in the epoxidation of trans -stilbene, trans -stilbene-oxide (84.58%) was found to be the highest in the presence of Zr–Mn-MCM-41(49).

Mesoporous silica molecular sieves MCM-41 containing zinc and aluminum ions (Zn–Al-MCM-41) with Si/(Zn + Al) ratio equal to 75, 151, 228, 304 and 380 and only aluminum ions (Al-MCM-41) with Si/Al ratio equal to 21, 42, 62, 83 and 104 respectively, were synthesized under hydrothermal conditions using cetyltrimethylammonium (CTMA + ) surfactants as template in the absence of auxiliary organics. The mesoporous materials viz. Zn–Al-MCM-41 and Al-MCM-41 were characterized using several techniques. e.g. ICP-AES, XRD, FTIR, TG/DTA, Nitrogen adsorption, 27 Al-MAS-NMR, SEM, TEM, XPS and pyridine acidity (TPD and FTIR) measurements. The d -spacing value and unitcell parameter in the Zn–Al-MCM-41 and Al-MCM-41 decreases by increasing the metal ions content. FT-IR studies showed that zinc ion was incorporated into the hexagonal mesoporous Al-MCM-41 materials, however, the wavenumber of the anti-symmetric Si–O–Si vibration bands (1096 cm −1 ) in Zn–Al-MCM-41 are higher than those in Al-MCM-41 (1083 cm −1 ). These bands should be due to the increase of the mean Si–O distance in the wall caused by the substitution of the small ionic radii of silicon by the larger ionic radii of zinc. The surface area, pore diameter, pore volume of Zn–Al-MCM-41 is smaller than that of Al-MCM-41 while the hydrothermal stability and acid sites in the Zn–Al-MCM-41 are higher than that of Al-MCM-41 due to increasing protons with the aluminum ions non-framework by the introduction of zinc ions. Thus Bronsted and Lewis acid sites in Zn–Al-MCM-41 are same, but its acid sites are higher than Al-MCM-41.

The mesoporous molecular sieves Al-MCM-41 with Si/Al ratio equal to 16, was synthesized under hydrothermal conditions using cetyltrimethylammonium bromide (CTMA + Br − ) as surfactant. The same ratio of Al-MCM-41 materials was impregnated using sulfuric acid, the materials as sulfated Al-MCM-41 (SO 4 2− /Al-MCM-41). The mesoporous materials viz Al-MCM-41 and SO 4 2− /Al-MCM-41 were characterized using several techniques e.g. ICP-AES, Nephelometer, XRD, FT-IR, TG/DTA, N 2 -adsorption, solid-state-NMR, SEM and TPD-pyridine. ICP-AES studies indicated the presence of Al in the mesoporous materials. Nephelometer studies indicated the SO 4 2− presence of the SO 4 2− /Al-MCM-41. XRD studies indicated that the calcined materials of Al-MCM-41 and SO 4 2− /Al-MCM-41 had the standard MCM-41 structure. The surface area, pore diameter, pore volume and wall thickness of the mesoporous materials were calculated by BET and BJH equations, respectively. Crystallinity, surface area, pore diameter and pore volume of SO 4 2− /Al-MCM-41 decreased except wall thickness and the expelling aluminum from the Al-MCM-41 framework increased the Lewis acidity. FT-IR studies indicated that Al-ions were incorporated in the hexagonal mesoporous structure of Al-MCM-41 and sulfuric acid was impregnated into hexagonal Al-MCM-41 materials. The thermal stability of as-synthesized Al-MCM-41 materials and SO 4 2− /Al-MCM-41 materials were studied using TG/DTA. The environments of the Al-ions coordinated in the silica matrix were determined by 27 Al-MAS-NMR. The morphology of Al-MCM-41 and SO 4 2− /Al-MCM-41 was determined by SEM. The total acidity of Al-MCM-41 and SO 4 2− /Al-MCM-41 materials was determined by TPD-pyridine. The catalytic results were compared with those obtained by using sulfuric acid, amorphous silica–alumina, H-β, USY and H-ZSM-5 zeolites. The SO 4 2− /Al-MCM-41 catalyst exclusively forms the product of dypnone from self-condensation of acetophenone molecules due to higher number of Lewis acid sites and has much higher yields than other catalysts except USY.

An attempt has been made to synthesize ceramic titania and zirconia membranes by sol-gel process by filtering respective viscous colloidal sol through microporous alumina support and gelling followed by sintering at 400°C and 470°C respectively. The static charge on the pores of the so formed membranes and the pore size distribution determine the applicability in filtering colloidal solution. The mean pore size from SEM were found to be 0.65 μm and 0.54 μm for titania and zirconia membranes respectively with 1.47 × 107/cm2 as pore density for both. The filtration characteristics during membrane layer formation showed that the membrane layer formation started after 35 minutes in the case of titania membrane and 40 minutes in the case of zirconia membrane. From the gravimetric estimation of water content of the membranes the thickness of the membrane was found out to be 3 μm and the porosity was found out to be 0.30 for both the cases. The particle charge density was estimated from the zeta potential and the particle size. The pore charge density was estimated from the particle charge density, pore density, pore diameter and the thickness of the membrane layer. The membrane pore charge density was found to vary between 3 to −1 μ Coulombs/cm2 in the case of titania membrane and 7 to −0.5 μ Coulombs/cm2 in the case of zirconia membrane in the pH range 1–12.