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Applied Catalysis B, Environmental (v.64, #3-4)
Photocatalytic oxidation of low molecular weight alkanes: Observations with ZrO2–TiO2 supported thin films by Troy M. Twesme; Dean T. Tompkins; Marc A. Anderson; Thatcher W. Root (pp. 153-160).
Low molecular weight alkanes including, propane, isobutane and n-butane can be completely oxidized to carbon dioxide and water vapor using a tubular photoreactor containing supported ZrO2–TiO2 thin film photocatalyst. It is observed that efficient reactor design requires optimization of catalyst packing to minimize bypass of the contaminant gas and optimization of the reactor diameter to maximize catalyst illumination. Single gas streams of ∼1000ppmv were fed into the optimized tubular reactor and evaluated for complete oxidation at relative humidity ranging from <2 to 60% and at reactor temperatures of 35, 70, and 100°C. The magnitude of reaction rate constants for isobutane and n-butane are comparable while on average the reaction rates of propane were significantly smaller. Reaction rates of propane and n-butane respond similarly to humidity levels, but isobutane reactivity differs in response to humidity. Reaction rates increase significantly from 35 to 70°C, but not from 70 to 100°C. In a feed stream containing a tertiary mixture of these alkanes and passed through the reactor, n-butane had the highest photoconversion followed by isobutane and propane. Variations in the gases’ reactivity in single gas and tertiary experiments are attributed to differences in strength of adsorption to the catalyst and reaction pathways that led to different intermediate compounds.
Keywords: Titania; Photocatalytic oxidation; Alkanes; VOCs
Selective catalytic reduction of NO x by methane in excess oxygen over Rh based aluminium pillared clays by S. Mendioroz; A.B. Martín-Rojo; F. Rivera; J.C. Martín; A. Bahamonde; M. Yates (pp. 161-170).
Pillared clays can be tailored to give high surface areas and porosities with different degrees of acidity. These materials often show better hydrothermal stability than zeolites. Al-PILC based Rh catalysts were tested in the selective catalytic reduction of NO by methane in presence of excess oxygen. The catalysts were prepared by two methods: incipient wetness impregnation (IMP) and wet ion exchange (IEX). The Rh3+ ion exchanged PILCs showed better performances than their homologues prepared by IMP. On IEX samples the effect of temperature and O2 concentration in SCR-CH4 activity was analyzed. Different activation degrees detected in the catalysts after 25vol.% O2 and 450°C reaction conditions, were related to the various Rh species present in the catalysts as a consequence of the exchange degree of the support in contact with the active phase solutions. From the results, a reaction mechanism is proposed by which exchanged Rh3+ in the Al-PILC matrix and oxidized Rh2O x in combination with the supports acid sites contribute to form oxygenated species as the process-determining step. The results from XPS and O2 adsorption isotherms were used to support the proposed mechanism.
Keywords: Nitrogen oxides; SCR; Methane; Al-PILC; Ion exchanged Rh catalysts
Enhancement of photoinduced hydrogen production from irradiated Pt/TiO2 suspensions with simultaneous degradation of azo-dyes by Alexia Patsoura; Dimitris I. Kondarides; Xenophon E. Verykios (pp. 171-179).
The production of hydrogen from aqueous Pt/TiO2 suspensions illuminated with UV–vis light has been examined in the absence and in presence of azo-dyes in solution. The effects of operational variables, including dye concentration, solution pH and temperature, on the rate of hydrogen production were investigated. It has been found that deposition of Pt (0.5wt.%) on the semiconductor surface results in an increase of the H2 production rate, which goes through a maximum with time of irradiation and then drops to steady-state values comparable to those obtained over bare TiO2. Both, maximum and steady-state rates obtained over Pt/TiO2 suspensions were found to increase with increasing solution pH and temperature. Addition of small quantities of azo-dyes in solution results in significantly enhanced rates of H2 production for a period which depends on dye concentration, solution pH and, to a lesser extent, solution temperature. It is proposed that the dye acts as a scavenger of photogenerated oxidizing species while it is degraded toward CO2 and inorganic ions. When complete mineralization is achieved, oxygen can no longer be removed from the photocatalyst surface and the rate drops to steady-state values, comparable to those obtained in the absence of azo-dye in solution. The amount of additional H2 produced is directly proportional to the amount of dye added in the solution. The rate increases with increasing solution pH, where dye degradation is faster, indicating that the process is limited by the rate of consumption of photogenerated oxygen. It is concluded that, under certain experimental conditions, it is possible to obtain significantly enhanced rates of photoinduced hydrogen production from Pt/TiO2 suspensions with simultaneous mineralization of azo-dyes. The process could be used for combined production of fuel H2 and degradation of organic pollutants present in water.
Keywords: Photocatalysis; Splitting of water; Hydrogen production; Sacrificial agent; Azo-dye; Platinum; Titanium dioxide
Selective catalytic reduction of NO x with NH3 over Cu-ZSM-5—The effect of changing the gas composition by Hanna Sjövall; Louise Olsson; Erik Fridell; Richard J. Blint (pp. 180-188).
The selective catalytic reduction of nitrogen oxides (NO x) with ammonia over ZSM-5 catalysts was studied with and without water vapor. The activity of H-, Na- and Cu-ZSM-5 was compared and the result showed that the activity was greatly enhanced by the introduction of copper ions. A comparison between Cu-ZSM-5 of different silica to alumina ratios was also performed. The highest NO conversion was observed over the sample with the lowest silica to alumina ratio and the highest copper content. Further studies were performed with the Cu-ZSM-5-27 (silica/alumina=27) sample to investigate the effect of changes in the feed gas. Oxygen improves the activity at temperatures below 250°C, but at higher temperatures O2 decreases the activity. The presence of water enhances the NO reduction, especially at high temperature. It is important to use about equal amounts of nitrogen oxides and ammonia at 175°C to avoid ammonia slip and a blocking effect, but also to have high enough concentration to reduce the NO x. At high temperature higher NH3 concentrations result in additional NO x reduction since more NH3 becomes available for the NO reduction. At these higher temperatures ammonia oxidation increases so that there is no ammonia slip. Exposing the catalyst to equimolecular amounts of NO and NO2 increases the conversion of NO x, but causes an increased formation of N2O.
Keywords: Ammonia; Ammonia oxidation; Cu-ZSM-5; Nitrogen oxide; NO reduction; Selective catalytic reduction (SCR); Water; Zeolite
Regeneration of thermally aged Pt-Rh/Ce xZr1− xO2-Al2O3 model three-way catalysts by oxychlorination treatments by J.A. Anderson; R.A. Daley; S.Y. Christou; A.M. Efstathiou (pp. 189-200).
Pt-Rh/Ce xZr1− xO2-Al2O3 with 0.6 and 1.0wt.% noble metal loadings were prepared and characterized for their metal dispersion with respect to Ce xZr1− xO2-free Pt-Rh/Al2O3 in fresh, thermally aged and oxychlorinated states. Thermal ageing at 973K led to loss of metal dispersion in all cases but to negligible effect on the dispersion of the Ce xZr1− xO2 component where present. Oxychlorination was able to fully recover metal dispersion in all cases but led to different effects on the redox properties of Ce xZr1− xO2 which appeared to be related to the metal loadings. Despite showing improved dispersion following regeneration, higher loaded catalyst showed no improvement in light-off performance for either NO reduction or CO oxidation and showed poorer oxygen storage (OSC) ability, particularly at higher temperatures. Lower loaded catalyst showed improved dispersion, improved OSC and reduced light-off temperatures for NO reduction and CO oxidation after oxychlorination compared to that in the thermally aged state.
Keywords: Pt-Rh/Ce; x; Zr; 1−; x; O; 2; -Al; 2; O; 3; Three-way catalysts; Regeneration; Redispersion; Thermal ageing; Oxychlorination
Nitrous oxide as an oxidant for ethane oxydehydrogenation by A. Held; J. Kowalska; K. Nowińska (pp. 201-208).
Waste nitrous oxide was used as an oxidant for ethane oxydehydrogenation performed at the range of temperature from 350 to 450°C over iron modified zeolite catalysts. Different zeolite matrices (zeolite ZSM-5 of different Si/Al ratio, H-Y, mordenite) modified with iron cations introduced into zeolite by means of ionic exchange were applied as catalysts for the reaction under study. Additionally, amorphous silica and alumina silica as well as silicalite of MFI structure were also used as a matrix for iron ions accommodation and they were tested for oxydehydrogenation reaction. It was found that only iron modified zeolites showed activity for reaction under study. Amorphous oxide supports and crystalline neutral silicalite modified with iron cations by means of impregnation were completely inactive for oxydehydrogenation reaction. The best catalytic performance was found on iron modified zeolites of MFI structure. The Si/Al ratio of the ZSM-5 matrix influenced the activity for ethane oxydehydrogenation reaction insignificantly. N2O oxidant was partly utilized for ethane oxidation (towards ethene or carbon oxides), while some part of the oxidant was decomposed to nitrogen and oxygen. Performing the reaction at 450°C resulted in a high ethene yield and complete N2O removal.
Keywords: Nitrous oxide (N; 2; O); Ethane oxidation; Iron modified zeolite
Thermal and catalytic conversion of used tyre rubber and its polymeric constituents using Py-GC/MS by G. San Miguel; J. Aguado; D.P. Serrano; J.M. Escola (pp. 209-219).
This paper investigates the effect of various acid catalysts in the conversion of tyre rubber into hydrocarbon products. A used tyre rubber and three pure elastomers ( cis-1,4-polyisoprene, polystyrene-co-butadiene and cis-polybutadiene) were characterised for their chemical composition and thermal behaviour in order to determine the main constituent of the waste material. Five acid solids of comparable aluminium contents but varying textural and/or acid characteristics were used as catalysts, including three zeolites (standard ZSM-5, nanocrystalline n-ZSM-5 and beta) and two mesostructured materials (Al-MCM-41 and Al-SBA-15). The presence of catalysts did not affect the degradation temperature of waste tyre rubber, although significant differences were observed in the nature of the resulting hydrocarbons. All zeolitic materials showed a marked selectivity towards the formation of aromatic species, particularly toluene (up to 19.82%), m/ p-xylene (up to 16.91%) and benzene (up to 10.28%). This behaviour was slightly more marked in zeolites with stronger acid properties and reduced steric impediments, like nanocrystalline n-ZSM-5. Mesostructured catalysts (Al-MCM-41 and Al-SBA-15) not only exhibited strong aromatisation properties but also a marked benzene alkylation capacity, which resulted in the formation of a wider range of alkylaromatic products. This behaviour was associated with their weaker Lewis type acid character and also to their larger pore sizes, which posed no impediment to the formation of larger molecular size products.
Keywords: Polyisoprene; Waste tyres; Catalysis; Pyrolysis
Catalytic reduction of NO by propene over LaCo1− xCu xO3 perovskites synthesized by reactive grinding by Runduo Zhang; Adrian Villanueva; Houshang Alamdari; Serge Kaliaguine (pp. 220-233).
One series of LaCo1− xCu xO3 perovskites with high specific surface area was prepared by the new method designated as reactive grinding. These solids were characterized by N2 adsorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), H2-temperature programmed reduction (TPR), O2-temperature programmed desorption (TPD), NO+O2-TPD, C3H6-TPD, NO+O2-temperature programmed surface reaction (TPSR) under C3H6/He flow as well as catalytic reduction of NO activity tests. The catalytic performance of unsubstituted sample is poor with a maximum conversion to N2 of 19% at 500°C at a space velocity of 55,000h−1 (3000ppm NO, 3000ppm C3H6, 1% O2 in helium) but it is improved by incorporation of Cu into the lattice. A maximal N2 yield of 46% was observed over LaCo0.8Cu0.2O3 under the same conditions. Not only the abundance of α-oxygen but also the mobility of β-oxygen of lanthanum cobaltite was remarkably enhanced by Cu substitution according to O2-TPD and H2-TPR studies. The better performance of Cu-substituted samples is likely to correspond to the essential nature of Cu and facility to form nitrate species in NO transformation conditions. In the absence of O2, the reduction of NO by C3H6 was performed over LaCo0.8Cu0.2O3, leading to a maximal conversion to N2 of 73% accompanied with the appearance of some organo nitrogen compounds (identified as mainly C3H7NO2). Subsequently, a mechanism involving the formation of an organic nitro intermediate, which further converts into N2, CO2 and H2O via isocyanate, was proposed. Gaseous oxygen acts rather as an inhibitor in the reaction of NO and C3H6 over highly oxidative LaCo0.8Cu0.2O3 due to the heavily unselective combustion of C3H6 by O2.
Keywords: SCR of NO; Propene; Reactive grinding; High surface area; Co-based; Perovskite; TPR; TPD
Catalytic decomposition of N2O over monolithic supported noble metal-transition metal oxides by Viviane Boissel; Saad Tahir; Carolyn Ann Koh (pp. 234-242).
The decomposition of nitrous oxide to nitrogen and oxygen using a series of monolithic (ceria-alumina washcoated cordierite) supported transition metal (Cu, Fe, Co, Ni, Mn) and noble metal (Ir, Rh) oxide catalysts has been studied using gas chromatography. The effect of combining a transition metal with a noble metal has also been investigated. A synergetic effect was observed between transition metal and noble metal oxides in the presence of a small amount of water for some of the catalysts. The synergy between Fe-Ir and Ni-Ir was also verified under dry conditions. X-ray photoelectron spectroscopic measurements on these catalysts indicate that Fe, Rh and Ir are present predominantly as Fe2O3, RhO2 and IrO2, while significant amounts of Co and Ni ions may migrate inside the support to form cobalt and nickel aluminate. Only the Fe-Ir catalyst showed a significant interaction between the noble metal and the transition metal. The effect of water, oxygen and carbon monoxide on the catalytic behaviour of the five most active catalysts (Ni-Ir, Ni-Rh, Fe-Ir, Co-Ir, Ir) has also been investigated. Oxygen and water were found to inhibit the catalytic activity, although the extent of oxygen inhibition is limited, presumably due to the presence of ceria in the monolith washcoat support. Conversely, carbon monoxide greatly enhances catalytic activity.
Keywords: Nitrous oxide; Transition metals; Rhodium; Iridium; Monolith; Catalytic decomposition; X-ray photoelectron spectroscopy
Rhodium deposits on pyrolytic graphite substrate: Physico-chemical properties and electrocatalytic activity towards nitrate reduction in neutral medium by Oleg Brylev; Mathieu Sarrazin; Daniel Bélanger; Lionel Roué (pp. 243-253).
The electrodeposition of metallic rhodium on pyrolytic graphite from 10mM Na3RhCl6+0.5M NaCl aqueous solution was studied by potentiostatic method with the use of a double-pulse technique involving nucleation and growth pulses. Physico-chemical properties of Rh deposits were investigated by electrochemical methods and scanning electron microscopy. The activity of Rh-modified graphite electrodes towards nitrate reduction in neutral medium was demonstrated, the activation energy of nitrate reduction and NO3− Langmuir adsorption constant on Rh deposits were determined.The use of double-pulse technique resulted in enhanced surface coverage in comparison with usual potentiostatic deposition and in decreasing the mean particle size down to 30nm, while the specific catalyst surface area attains 32m2g−1. The increase in the nucleation pulse duration from 20 to 100ms enhances the mass catalytic activity towards NO3− reduction, which reaches 175Ag−1 for the best samples. Irrespectively of electrodeposition parameters, only NH3 and NO2− were detected as nitrate reduction products. The rate of NO3− destruction was equal to5.4molgRh−1h−1 which is much higher than that of most of Pd/Cu-based nitrate hydrogenation systems and Ag/TiO2 photocatalysts.
Keywords: Rhodium; Electrodeposition; Double-pulse technique; Nitrate reduction; Electrocatalysis
Kinetics and mechanism of liquid-phase alkylation of 3-methylthiophene with 2-methyl-2-butene over a solid phosphoric acid by Virginie Bellière; Chantal Lorentz; Christophe Geantet; Yuji Yoshimura; Dorothée Laurenti; Michel Vrinat (pp. 254-261).
Drastic regulations concerning sulfur content in fuels require the development of new processes in the refineries. In the case of gasoline, AOTS process based on the alkylation of thiophene by butenes was proposed. In the present work, we attempted to describe the mechanism of such a reaction with model molecules. Liquid-phase alkylation of 3-methylthiophene with 2-methyl-2-butene was performed on supported phosphoric acid. It is shown that this reaction is mainly selective to monoalkylation products. The kinetics is following an Eley–Rideal law and the reaction intermediate seems to be an ester of phosphoric acid or polyphosphate.
Keywords: Heterogeneous catalysis; Solid phosphoric acid; Alkylation; Kinetics; Desulfurization; Gasoline; In situ NMR
Performance of alumina-supported noble metal catalysts for the combustion of trichloroethene at dry and wet conditions by Beatriz Miranda; Eva Díaz; Salvador Ordóñez; Aurelio Vega; Fernando V. Díez (pp. 262-271).
The performance of four different alumina-supported noble metal catalysts (0.5% of Pd, Pt, Rh and Ru, respectively) for the deep oxidation of trichloroethene (1000–2500ppmV, WHSV=55h−1) in air was studied in this work. Experiments were carried out at both dry and wet (20,000ppm of H2O) conditions. Catalysts were compared in terms of activity, selectivity for the different reaction products (CO2, HCl, Cl2, C2Cl4, CCl4 and CHCl3), and stability at reaction conditions.As general trend, the activity of the catalysts decreases in the order Ru≫Pd>Rh>Pt. Concerning to the effect of the water addition, no important effect on the catalyst activity was observed, except in the case of Pt, for which an increase of the catalytic activity was observed. Reaction mechanism (and hence product distribution) is very similar for Rh, Pd and Pt, being in these cases C2Cl4 the only organochlorinated by-product detected. In the case of Ru, the reaction mechanism seems to be quite different, CCl4 and CHCl3 being the main organic by-products.Simple power-law kinetic expressions (first order on trichloroethene concentration for Pd, Rh and Ru, and zeroth order for Pt) provide fairly good fits for catalytic performance of the studied catalysts.Finally, deactivation studies show that both formation of active metal chlorides (especially in the case of Rh) and fouling (especially for Pd and Pt) are the main deactivation causes.
Keywords: Catalytic oxidation; Trichloroethene; Pd; Ru; Pt; Rh; Adsorption
Degradation of pesticides in water using solar advanced oxidation processes by Margarita Hincapié Pérez; Gustavo Peñuela; Manuel I. Maldonado; Octavio Malato; Pilar Fernández-Ibáñez; Isabel Oller; Wolfgang Gernjak; Sixto Malato (pp. 272-281).
Alachlor, atrazine and diuron dissolved in water at 50, 25 and 30mg/L, respectively were photodegraded by Fe2+/H2O2, Fe3+/H2O2, TiO2 and TiO2/Na2S2O8 treatments driven by solar energy at pilot-plant scale using a compound parabolic collector (CPC) photoreactor. All the advanced oxidation processes (AOPs) employed mainly compared the TOC mineralisation rate to evaluate treatment effectiveness. Parent compound disappearance, anion release and oxidant consumption are discussed as a function of treatment time. The use of Fe2+ or Fe3+ showed no influence on the reaction rate under illumination and the reaction using 10 or 55mg/L of iron was quite similar. TiO2/Na2S2O8 showed a quicker reaction rate than TiO2 and a similar rate compared to photo-Fenton. The main difference found was between TiO2/Na2S2O8 and photo-Fenton, detected during atrazine degradation, where pesticide transformation into cyanuric acid was confirmed only for TiO2/Na2S2O8.
Keywords: Alachlor; Atrazine; Diuron; Photodegradation; Photocatalysis; Photo-Fenton
One-electron reducibility of isolated copper oxide on alumina for selective NO–CO reaction by Fumiaki Amano; Sosuke Suzuki; Takashi Yamamoto; Tsunehiro Tanaka (pp. 282-289).
The H2-TPR (temperature-programmed reduction) study was performed for supported copper oxide catalysts with low loading (0.5wt% as copper). Among the various kinds of support materials (γ-Al2O3, TiO2, ZrO2, SiO2, ZSM-5), alumina-supported copper oxide indicated a one-electron reduction behavior of Cu2+ into Cu+ ions in the presence of H2. The reduction of the isolated Cu2+ species in a tetragonally distorted octahedral symmetry into the low coordinated Cu+ ions was identified by means of X-ray absorption spectroscopy (XANES and EXAFS). The isolated Cu+ ions hosted by γ-Al2O3 surface were prevented from further reduction into metallic Cu0 state under reducing condition with H2 at 773K. Less dispersed supported copper oxide species were easily reduced to Cu0 metal particles with H2 at 573K regardless of the kinds of support materials. It is suggested that the one-electron redox behavior of the isolated copper oxide species over γ-Al2O3 promotes the catalytic reduction of NO with CO in the presence of oxygen on the basis of redox-type mechanism between Cu2+ and Cu+ in atomically dispersed state.
Keywords: Cu; Al; 2; O; 3; NO reduction with CO; Oxygen; Selective catalytic reduction; XAFS
Photocatalytic degradation of model organic pollutants on an immobilized particulate TiO2 layer by Josef Krýsa; Georg Waldner; Hana Měšt’ánková; Jaromír Jirkovský; Gottfried Grabner (pp. 290-301).
The kinetics of photocatalytic degradation of four different model organic compounds, formic acid (FA), oxalic acid (OA), 4-chlorophenol (4-CP) and the herbicide monuron (3-(4-chlorophenyl)-1,1-dimethylurea) in a self-constructed batch-mode plate photoreactor with a thin flow of contaminated aqueous solution circulating over an illuminated particulate layer of TiO2 P25 (Degussa) was compared. Both OA and FA were adsorbed on TiO2 surface; their mineralization, induced by direct transfer of photogenerated holes, proceeded in a single step, without observable intermediates, following approximately zero order kinetics. Numerical simulations were performed using a newly proposed kinetic model based on the photostationary state assumption. The model allowed an explanation of the observed reaction order as well as the comparison of independent with competitive adsorption of organic compound and oxygen on the photocatalyst surface, yielding a better fit for the case of competition. 4-CP and monuron, which were not adsorbed under the conditions used, were degraded through the action of photogenerated hydroxyl radicals. Their degradation proceeded with lower photoefficiency than for the adsorbed compounds (FA and OA). While the mineralization of both 4-CP and monuron followed zero order kinetics, their degradation was close to first order. The different reaction orders were consistently explained using the photostationary state approach.
Keywords: Photocatalysis; Degradation; TiO; 2; Immobilization; Oxalic acid; Formic acid; 4-Chlorophenol; Monuron
Development of a new Rh/TiO2–sepiolite monolithic catalyst for N2O decomposition by S. Suárez; M. Yates; A.L. Petre; J.A. Martín; P. Avila; J. Blanco (pp. 302-311).
Monolithic catalysts based on Rh/TiO2–sepiolite were developed and tested in the decomposition of N2O traces. Several effects such as the presence of NO, O2 and NO+O2 in the gas mixture, the catalysts pre-treatment and the metal loading were evaluated. The system was extremely sensitive to the amount of rhodium, passing through a maximum in the catalytic activity at a Rh content of 0.2wt.%. It has been demonstrated that both NO and O2 compete for the same adsorption sites as N2O; however, this effect was not as severe as for other previously reported Rh systems. For NO+O2 gas mixtures the inhibition effect was stronger than when only NO or O2 was present. Analysis of the pre-reduced sample by XPS showed Rh mainly in the metal state, even after treatment with N2O+O2 mixtures, suggesting that the oxygen consumption observed in the Temperature Programmed Reaction experiments was related to the oxygen uptake by vacancies in the support. The presence of sepiolite in the support preparation and its role as a matrix over which TiO2 particles were distributed, seems to play an important effect in the migration process of oxygen species through the support vacancies. The Rh/TiO2 monolithic system is an attractive alternative for the elimination of N2O traces from stationary sources due to the combination of high catalytic activity with a low pressure drop and optimum textural/mechanical properties.
Keywords: N; 2; O decomposition; Monolithic catalyst; Rh catalyst; Rh/TiO; 2; Sepiolite
Photocatalytic effect of carbon-modified n-TiO2 nanoparticles under visible light illumination by Chengkun Xu; Richard Killmeyer; McMahan L. Gray; Shahed U.M. Khan (pp. 312-317).
The present research focused on wet process synthesis of visible light active carbon-modified (CM)- n-TiO2 nanoparticles and their photocatalytic activity. The CM- n-TiO2 was synthesized by hydrolysis of TiCl4 in the presence of tetrabutylammonium hydroxide and also in the presence of glucose and sodium hydroxide. UV–vis spectra, X-ray diffraction (XRD), and FT-IR were used to characterize these photocatalysts. It was found that the CM- n-TiO2 nanoparticles synthesized by hydrolysis with tetrabutylammonium hydroxide or with sodium hydroxide and glucose when subjected to extended aging and subsequent calcinations absorb well into the visible to near infrared region up to 800nm and exhibit enhanced visible light photocatalytic activity on degradation of 4-chlorophenol. CM- n-TiO2 synthesized using glucose as the carbon source generated 13-fold increase in the initial rate of photodegradation of 4-chlorophenol compared to those by regular n-TiO2, whereas, it increased only eight-fold when tetrabutylammonium hydroxide was used as the carbon source.
Keywords: Photocatalyst; Titanium dioxide; Photodegradation; Carbon-modified; Visible light active photocatalyst