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The photocatalytic degradation of carbofuran (2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate) was investigated in an aqueous solution using Degussa P-25 TiO2 and ZnO as photocatalysts. The progress of degradation was monitored using TOC analyzer, HPLC, GC–MS and UV–vis spectrophotometer. The effects of various experimental parameters such as initial concentration of carbofuran, pH of the solution, catalyst loading and light intensity were systematically studied in order to achieve maximum degradation efficiency. The complete mineralization of carbofuran was confirmed by TOC analyzer. The degradation with ZnO showed less efficiency than TiO2. The formation of NO3 − was identified and quantified using HPLC. In addition, four different intermediates formed during the degradation process were also identified and characterized by GC–MS. The mineralization rate was compared with lamps of wavelength 254 and 365nm under similar conditions. The rate with 254nm was observed to be very close to that of 365nm. [Copyright &y& Elsevier]

Abstract: The vapour phase ethylation of ethylbenzene with diethyl carbonate was studied over Al-MCM-41 and 10, 20 and 40 wt% PW loaded Al-MCM-41 catalysts. Based on the conversion 20 wt% PW/Al-MCM-41 was found to be more active than others. Diethylbenzene isomers were found to be more predominant than tri-, tetra-, penta- and hexa- alkylated products. The formation of hexaethylbenzene suggested high density of ethyl cations on the catalyst surface. The feed ratio of 2:1 (ethylbenzene:diethyl carbonate) was observed to yield 100 % selectivity of diethylbenzene isomers. Although ortho, meta and para diethylbenzene isomers were observed, the selectivity to para isomer was found to be higher than other isomers. [Copyright &y& Elsevier]

Abstract: Mesoporous Al-MCM-41 (Si/Al=20) molecular sieve was synthesized hydrothermally and characterized by X-ray diffraction (XRD), nitrogen-sorption studies and 27Al and 29Si MAS-NMR spectroscopies. 10, 20 and 40wt% phosphotungstic acid (PW) (H3PW12O40) were supported on Al-MCM-41 and the resulting catalysts were characterized by XRD, FT-IR, nitrogen-sorption, DRIFT, 1H and 31P MAS-NMR and DRS UV–vis spectral techniques. 1H MAS-NMR spectra of PW/Al-MCM-41 revealed leveling of the acidity of PW protons to Al-MCM-41. Their catalytic activities were evaluated in the esterification of succinic anhydride with ethanol in the temperature between 60 and 120°C. Monoethyl succinate (MES) and diethyl succinate (DES) were obtained as products. The effects of alcohol/anhydride molar ratio and temperature were studied. Unsymmetrical alcoholysis of succinic anhydride with methanol and 1-butanol was also carried out successfully. [Copyright &y& Elsevier]

Abstract: Hexagonal mesoporous aluminophosphate (AlPO) was synthesised at room temperature using cetyltrimethylammonium bromide (CTAB) as the structure-directing agent. The mesoporosity of the synthesised material was confirmed from low angle XRD, TGA and nitrogen physisorption studies. Its textural properties were analysed with SEM and the framework vibrations by FT-IR. 27Al and 31P MAS NMR spectra revealed tetrahedral co-ordination of Al and P. The mesoporous AlPO was then impregnated with phosphotungstic acid, H3PW12O40 (PW), of various loadings viz., 10, 20 and 40wt% of PW. The PW loaded AlPOs were characterised by XRD, FT-IR, BET, DRIFT and 31P MAS NMR techniques. XRD patterns reveal the presence of Keggin structure in 20 and 40wt% PW/AlPO. Temperature programmed desorption of pyridine by DRIFT studies indicate modified acidity values due to transfer of protons to the support AlPO. The catalytic activity of the materials was examined in the vapour phase ethylation of ethylbenzene with diethyl carbonate at temperatures between 200 and 275°C. 20wt% PW/AlPO was found to be more active than 10 and 40wt% PW/AlPO catalysts. Among the alkylated products, the most significant product is hexaethylbenzene, obtained only with 20wt% PW/AlPO. The selectivity of p-diethylbenzene is higher than for other alkylated products. The time on stream study over 20wt% PW/AlPO catalyst indicates similar activity for about 4h of stream. The effect of feed ratio and WHSV on conversion and product selectivity was also examined and the results are discussed. [Copyright &y& Elsevier]

Mesoporous aluminophosphate (AlPO) has been synthesized hydrothermally using cetyltrimethylammonium bromide (CTAB) as structure-directing agent in the presence of tetramethylammonium hydroxide (TMAOH) at room temperature. Phosphotungstic acid, H3PW12O40 (PW) was supported on the synthesized mesoporous AlPO at various loadings viz., 10, 20 and 40wt.% to yield PW/AlPOs and characterized by XRD, TGA and FT-IR. XRD patterns confirm that HPA retains the Keggin structure on the AlPO surface and forms finely dispersed heteropoly acid (HPA) species. HPA crystal phase was not developed even at HPA loading as high as 40wt.%. Catalytic activities of both parent AlPO and HPA loaded AlPOs were studied by carrying out t-butylation of phenol with tert-butanol in vapour phase in the temperature range 190–250°C. The products obtained were o-tert-butyl phenol (o-t-BP), p-tert-butyl phenol (p-t-BP) and tert-butylphenyl ether (t-BPE) with high selectivity towards p-t-BP. The effects of feed ratio and WHSV towards conversion of phenol were studied and finally the time on stream studies were also carried out to compare the activities of the catalysts. PW/AlPO catalysts were found to yield higher conversion than parent AlPO due to the increase in Bronsted acid sites. Hence, PW/AlPO compositions are promising catalysts exclusively for acid type conversion of large organic molecules. [Copyright &y& Elsevier]

Abstract: Photocatalytic activity of TiO2 and zeolites supported TiO2 were investigated using propoxur as a model pollutant. Hβ, HY and H-ZSM-5 zeolites were examined as supports for TiO2. Hβ was chosen as the TiO2 support based on the adsorption capacity of propoxur on these zeolites (Hβ>HY=H-ZSM-5). TiO2/Hβ photocatalysts with different wt.% were prepared and characterized by XRD, FT-IR and BET surface area. The progress of photocatalytic degradation of aqueous propoxur solution using TiO2 (Degussa P-25) and TiO2 supported on Hβ zeolite was monitored using TOC analyzer, HPLC and UV–vis spectrophotometer. The degradation of propoxur was systematically studied by varying the experimental parameters in order to achieve maximum degradation efficiency. The initial rate of degradation with TiO2/Hβ was higher than with bare TiO2. TOC results revealed that TiO2 requires 600min for complete mineralization of propoxur whereas TiO2/Hβ requires only 480min. TiO2/Hβ showed enhanced photodegradation due to its high adsorption capacity on which the pollutant molecules are pooled closely and hence degraded effectively. [Copyright &y& Elsevier]

Abstract: One pot unsymmetrical alkylation of benzene with different alkylating agents is an interesting reaction, as the alkylated products have important commercial applications. Keeping this in view, one pot ethylation and isopropylation of benzene with diethyl carbonate and isopropyl alcohol were carried out over Hβ (Si/Al=15),HY (Si/Al=3) and HM (Si/Al=10) zeolites in the vapour phase. In addition to homo-alkylated products, unsymmetrical dialkylated products were also obtained with significant selectivity. Nearly similar trend in selectivity was obtained over all the catalysts with increase in temperature. The zeolites with high density of acid sites are suggested to be beneficial for unsymmetrical alkylation, as they could provide more probability for the formation of both the alkyl cations together. The proper control of concentration of alkylating agents based on their formation and reactivity also appears to be important in enhancing unsymmetrical alkylation. The effect of temperature, feed ratio, WHSV and time-on-stream on the selectivity to unsymmetrical alkylation was studied and the results are presented in the manuscript. [Copyright &y& Elsevier]

Abstract: Magnesium and barium doped TiO2 nanoparticles were synthesised by sol-gel technique. The materials were characterised by XRD, BET, UV-Vis, FT-IR, SEM and TEM techniques. The pure TiO2 nanoparticles gave both anatase and rutile phases together, but the presence of either Mg2+ or Ba2+ metal ion in TiO2 gave only anatase phase. The framework substitution of Mg2+ in TiO2 was established by XRD and FT-IR techniques. However, Ba2+ was retained only on the surface of TiO2 as BaCO3 and the absence of framework substitution of Ba2+ in TiO2 was evident from XRD and FT-IR analysis. The band gap values of Mg2+ and Ba2+ doped nano TiO2 were higher than the parent nano TiO2. The photocatalytic activity in the degradation of bisphenol-A was found to be higher for metal doped nano TiO2 than both pure nano TiO2 and commercial TiO2 (Degussa P-25). [Copyright &y& Elsevier]

Abstract: Zr4+ doped nano titania was prepared by sol–gel method using titanium(IV) isopropoxide and zirconium nitrate as precursors. The materials were characterized by XRD, BET, UV–vis, FT-IR, SEM-EDX and TEM techniques. The nanoparticles of pure TiO2 contained both anatase and rutile phases together but Zr4+ doped TiO2 gave anatase phase only. The framework substitution of Zr4+ in TiO2 was established by XRD, SEM-EDX and FT-IR techniques. The band gap value of Zr4+ doped TiO2 was higher than the parent nano TiO2. TEM observations confirmed the nanocrystalline nature of Zr4+ doped TiO2. The presence of dopants therefore could suppress the growth of TiO2 grains, increase the surface area, decrease the anatase–rutile phase transformation and accelerate the surface hydroxylation. These properties resulted higher photocatalytic activity for Zr4+ doped nano TiO2 than undoped nano TiO2. The presence of anatase type structure in TiO2 with high crystallinity and high phase stability, even after annealing at 800°C substantially indicated that the dopants might inhibit densification and crystallite growth by providing dissimilar boundaries. The photocatalytic activity in the degradation of 4-chlorophenol was found to be higher for Zr4+ doped TiO2 than both nano TiO2 and commercial TiO2 (Degussa P25). The experimental parameters such as initial concentration of 4-chlorophenol, catalyst loading, pH and light intensity were optimized for maximum degradation efficiency. [Copyright &y& Elsevier]

Abstract: Al-MCM-41 (Si/Al=20) molecular sieve was synthesized hydrothermally and phosphotungstic acid (PW) of 10, 20 and 40wt% was supported on it. Their catalytic performance was examined in the vapour phase alkylation of phenol with tert-butyl alcohol (TBA) in the temperature range 190–275°C. The major products were 2-tert-butyl phenol (2-TBP), 4-tert-butyl phenol (4-TBP), 2,4-di-tert-butyl phenol (2,4-DTBP) and small amounts of undesired products. 4-TBP was obtained as the major product with high selectivity. The results revealed that 20wt% PW supported on Al-MCM-41 is found to be more active than other catalysts. The effects of molar feed ratio, space velocity and reaction temperature on conversion and products selectivity were studied and the results are discussed. The reaction parameters were optimized to obtain high selectivity of 4-TBP at high phenol conversion. [Copyright &y& Elsevier]

Abstract: Liquid phase Claisen–Schmidt condensation between 2′-hydroxyacetophenone and benzaldehyde to form 2′-hydroxychalcone, followed by intramolecular cyclisation to form flavanone was carried out over zinc oxide supported metal oxide catalysts under solvent free condition. The reaction was carried out over ZnO supported MgO, BaO, K2O and Na2O catalysts with 0.2g of each catalyst at 140°C for 3h. Magnesium oxide impregnated zinc oxide was observed to offer higher conversion of 2′-hydroxyacetophenone than other catalysts. Further MgO impregnated with various other supports such as HZSM-5, Al2O3 and SiO2 were also used for the reaction to assess the suitability of the support. The order of activity of the support is ZnO>SiO2 >Al2O3 >HZSM-5. Various weight percentage of MgO was loaded on ZnO to optimize maximum efficiency of the catalyst system. The impregnation of MgO (wt%) in ZnO was optimized for better conversion of 2′-hydroxyacetophenone. The effect of temperature and catalyst loading was studied for the reaction. [Copyright &y& Elsevier]

Mesoporous Al-MCM-41 (Si/Al = 55 and 104) and Al,Zn-MCM-41 (Si/(Al+Zn)=52) molecular sieves were synthesized hydrothermally. The materials were characterized by XRD, TGA, TPD (pyridine), ICP-AES, nitrogen sorption, and FT-IR techniques. The catalytic performance of these materials was examined in the vapor phase alkylation of m-cresol with isopropyl acetate. The products obtained were thymol, isothymol, 2-isopropyl-5-methylphenyl acetate (2-I-5-MPA), and isopropyl-3-methylphenyl ether (I-3-MPE). The time-on-stream study was carried out over Al-MCM-41(55) at 300 °C and WHSV 1.52 h-1 wherein optimum conversion of m-cresol and selectivity to thymol were obtained. The dependence of activity and selectivity on the acid sites and hydrophobic and hydrophilic properties of the catalysts is discussed. [Copyright &y& Elsevier]

In this paper photoinduced degradation of reactive yellow 17 (RY 17) dye has been studied employing TiO[SUB2] in the form of slurry in a batch reactor. UV lamps were used as the source for irradiation. The disappearance of the dye in the solution follows approximately pseudo-first order kinetics. The apparent rate constant decreases with increase in initial concentration of the dye. The addition of oxygen, hydrogen peroxide and persulphate ion influences the degradation rate of the dye. The formation of CO[SUB2], SO[SUP2-,SUB4], NO[SUP-,SUB3] and NH[SUP+,SUB4] ions have been identified in the mineralisation process. The decolourisation and mineralisation were followed by UV-Visible spectrophotometer and high performance liquid chromatography respectively. The results reveal that photocatalytic degradation may be a useful technique in the removal of reactive dyes in wastewater from textile industries. [ABSTRACT FROM AUTHOR]

Abstract: Hydrothermal synthesized Al-MCM-41 with different Si/Al ratios (30, 54, 78 and 107) were characterized by XRD, ICP-AES, BET, acidity measurement by pyridine adsorbed FT-IR spectroscopy, 29Si and 27Al MAS NMR techniques. The catalytic activity of these materials was tested in the vapour phase alkylation of tert-butylbenzene (TBB) with tert-butyl acetate (TBA) in the temperature range 200–400°C. The products were found to be 1,4-di-tert-butylbenzene (1,4-DTBB), 1,3-di-tert-butylbenzene (1,3-DTBB), 4-acetyl-tert-butylbenzene (4A-TBB), 3-acetyl-tert-butylbenzene (3A-TBB), 2-acetyl-tert-butylbenzene (2A-TBB) and 2-acetyl-1,4-di-tert-butylbenzene (2A-1,4-DTBB). The selectivity towards 1,3-DTBB increased with increase in temperature, conversely the selectivity of 1,4-DTBB decreased. The selectivity to 4A-TBB, which is higher than that of other compounds, also increased with increase in temperature. The effect of temperature, flow rate and feed ratio was also studied over all the catalysts to arrive optimum conditions for higher conversion with product selectivity. The effect of time-on-stream was studied over all the catalysts and the results are discussed. [Copyright &y& Elsevier]

Abstract: Electrophilic substitution of indoles with carbonyl compounds was carried out over HY, Hβ and H-ZSM-5 zeolites as effective heterogeneous catalysts. These zeolites afford good to excellent yield of bis(indolyl)methanes at room temperature. Vibrindole A, a novel beneficial compound, has been successfully synthesised for the first time in the presence of zeolite in good yield. The yield of bis(indolyl)methanes increases in the order H-ZSM-5<Hβ<HY, which is in accordance with the acid site density of the catalyst. The catalysts can be reused five times without any loss in catalytic activity. [Copyright &y& Elsevier]

The vapour phase reaction of phenol with ethyl acetate was investigated over Al-MCM-41 with Si/Al = 55 and 80, and (Al, Zn)-MCM-41 with Si/(Al + Zn) = 52 at 200, 250, 300, 350 and 400°C. The products were phenyl acetate (PA), 2-ethylphenol (2-EP), 2-acetylphenol (2-AP) and 4-ethylphenol (4-EP). Phenol conversion increases by increasing temperature up to 350°C and then decreases at 400°C. There is no correlation between the acidity and activity of the catalysts. The low activity of (Al, Zn)-MCM-41(52) is due to its high hydrophilicity, which reduces the chemisorption of ethyl acetate on its surface. The low conversion of phenol at low ethyl acetate/phenol feed ratios is attributed to the preferential chemisorption of phenol on the catalyst surface. The decrease in conversion at higher temperature is due to blocking of active sites by coke. This study has revealed that ethyl acetate is an active alkylating reagent for phenol in the vapour phase. [Copyright &y& Elsevier]

Al-MCM-41 molecular sieves (Si/Al=50, 100, and 150) were synthesized hydro-thermally and characterized by XRD, FTIR, BET (surface area) and Si, Al MAS-NMR techniques. The catalytic activities of these molecular sieves and of Hβ-zeolite were tested for esterification of maleic anhydride in the liquid phase at 80, 100 and 150 °C. The reaction was observed to yield monomethylmaleate even in the absence of catalyst, as the product is strain-free, whereas the formation of dimethylmaleate required the presence of a catalyst. Among the catalysts, Hβ was found to be more active than Al-MCM-41 molecular sieves. The lower activity of Al-MCM-41 catalyst was due to pore blocking by reactants as well as by products. An interesting observation in this study is that dimethylmaleate isomerisation to dimethylfumarate is not favored. At 80 °C this isomerisation was completely absent over Al-MCM-41 molecular sieves, and was less than 1% over Hβ. The complete conversion of maleic anhydride with methanol to monomethylmaleate stands as a discovery that will help to design new routes to synthesize a wide variety of new heteroesters. [Copyright &y& Elsevier]

Pt, Au and Pd deposited TiO2 have been prepared and characterised by surface analytical methods such as surface area, XRD, and scanning electron micrograph and photophysical characterisation by diffuse reflectance spectroscopy. The photocatalytic activity of the doped catalysts was ascertained by the photo-oxidation of leather dye, acid green 16 in aqueous solution illuminated with low-pressure mercury lamp (∼254 nm). The effect of metal contents on the photocatalytic activity was investigated. The highest photonic efficiency was observed with metal deposition level of less than 1 wt%. [Copyright &y& Elsevier]

Reports on the solar/ultraviolet-induced photocatalytic degradation of three commercial textile dyes. Chemical oxygen demand; Solar and ultraviolet light intensity measurements; Ultraviolet source photocatalytic reactor; Thin-film coated photocatalytic device.

Discusses the removal of phenol from aqueous solution and resin manufacturing industry wastewater using the activated carbon prepared from rubber seed coat (RSCC), an agricultural waste by-product. Preparation of activated carbon; Characterization of the activated carbon; Effect of carbon dosage and contact time; Desorption of phenol.