Electrochemical strategy for grown ZnO nanoparticles deposited onto HY zeolite with enhanced photodecolorization of methylene blue: Effect of the formation of Si O Zn bonds

Nanoparticles of electrogenerated zinc-supported HY zeolite (EGZnO/HY) catalyst were prepared by a simple electrochemical method. The interaction between zinc species and HY support during the electrolysis was found to affect the EGZnO/HY structure. In addition to the formation of EGZnO nanoparticles (<30 nm in size) that distributed on the surface of HY support, an isomorphous substitution of Al with Zn also occurred in the aluminosilicate framework to result in a Si O Zn bonds. The photoactivity of EGZnO/HY was tested on the decolorization of methylene blue (MB). An amount of 0.375 g L−1 of 1 wt% EGZnO/HY was found to be the optimum dosage for 10 mg L−1 MB, which resulted in 80% of maximum decolorization after 6 h of contact time at pH 3 under fluorescent light (420 nm). Increasing the EGZnO loading led to additional formation of Si O Zn bonds and lessened the number of EGZnO nanoparticles, which then reduced the photodecolorization percentage of MB.The photocatalytic reaction was follows the first-order Langmuir–Hinshelwood model, and gives partially mineralization. The photocatalyst was still stable after five cycling runs with no Zn leaching

CO2 reforming of methane over ni supported on mesostructured silica nanoparticles (NI/MSN): effect of NI loading

A series of Ni incorporated Mesostructured Silica Nanoparticles (MSN) were prepared by physical mixing method. Electrolyzed nickel oxide was used as the Ni precursor. The N2 adsorption-desorption and X-Ray diffraction (XRD) analyses evidenced that the increase in Ni loading decreased the surface area and crystallinity, and increased Ni particle size in the catalyst, respectively. The activity of CO2 reforming of CH4 followed the order of 10Ni/MSN > 15Ni/MSN > 5Ni/MSN > MSN. The highest activity was achieved by 10Ni/MSN with the CH4 and CO2 conversion of 63.4% and 87.2 %, respectively. The results indicated that the presence of a suitable Ni amount in MSN was beneficial to achieve high catalytic activity due to its effect on the amount of active metal sites available for the reaction. Thus, the electrolyzed nickel oxide precursor and Ni/MSN catalyst prepared by electrochemical method and physical mixing synthesis has a potential to be utilized in CO2 reforming of CH4

Significant effect of ph on photocatalytic degradation of organic pollutants using semiconductor catalysts

Photocatalytic is one of the inexpensive and non-toxic techniques for degradation of organic pollutants into harmless substances such as water and carbon dioxide. In this study, simple electrolysis method was used in preparation of Ag/TiO2 and α-Fe2O3/HY catalysts. The physicochemical properties of the catalysts were studied using XRD, FTIR, FESEM-EDX and surface area analysis. The pH of solution plays an important role in the photocatalytic degradation of organic pollutants which influences the surface-charge properties of the catalysts. Ag/TiO2 and α-Fe2O3/HY were used as catalyst on degradation of 2-chlorophenol (2-CP) and methyl orange (MO), respectively. The effect of pH on degradation of 2-CP and MO were investigated over a pH range from 2 to 9. Higher degradation of 2-CP and MO were obtained at pH 5 (74%) and pH 2 (80%), respectively. This finding might be explained by the amphoteric performance of the catalyst using point zero charge (pHZPC). The pHZPC for Ag/TiO2 and α-Fe2O3/HY was found to be at pH 6.3 and pH 7.2, respectively. Hence, the activities of the catalysts may have been affected by the existence of a strong electrostatic field between the positively charged catalysts surface and negatively charged 2-CP and MO caused a pH value lower than their pHZPC give greater degradation

Esterification of Benzyl Alcohol with Acetic Acid over Mesoporous H-ZSM-5

In this study, the performance of mesoporous ZSM-5 has been studied on the esterification of acetic acid (AA) with benzyl alcohol (BA). The mesoporous ZSM-5 catalyst has been synthesized with the variation of aging time i.e. 6, 12, and 24 hours at the same temperature, 70 degrees C. The cation exchange of Na-ZSM-5 to H-ZSM-5 was performed before the catalytic activity test. The acidity type and amount of solids were determined by FT-IR spectroscopy using pyridine as a probe molecule. The characterization by pyridine adsorption showed that at a higher mesoporous surface area, the number of Lewis acid was increased. The highest mesoporous surface area, Lewis, and Bronsted acid sites were obtained by sample which has the lowest crystallinity, i.e. 255.78 m(2)/g, 0.2732 mmol/g, and 0.20612 mmol/g, respectively. Influence of mesoporous volume was studied on the catalytic activity of the mesoporous ZSM-5 in the esterification reaction. Conversion of acetic acid in the esterification reaction for samples of HZ-6, HZ-12, and HZ-24 were obtained by titration methods, i.e. 39.59, 36.39, and 32.90 %, respectively. Hence, the reaction temperature of 393 K, molar ratio 1:4 (AA: BA) and catalyst loading 5 % were selected as an optimum reaction parameters. Copyright (C) 2017 BCREC Group. All rights reserved

Amine modified mesostructured silica nano particles enhanced adsorption of phenol

Mesoporous silica nanoparticles (MSN) were synthesized and modified with (3-aminopropyl) triethoxysilane (APTES) using co-condensation (co-MSN) and post-grafting (post-MSN) methods. Both modification methods seem to alter the crystallinity, surface area, and pore volume as compared to the unmodified MSN. The activity of all MSNs was tested for the adsorptive removal of phenol. Co-MSN showed significantly good adsorptivity towards 10 mg L-1 of phenols, followed by post-MSN and MSN. It was found that the highest activity of co-MSN was resulted from the additional higher adsorption energy from the quaternary alkylammonium groups (Si–C–C–C–[N+–(CH3)3]) of cationic template and also from the amine group of the APTES functionalization, which showed more advantages as compared to post-MSN and MS

Conversion of cellulose to short chain polyols over metal loaded on KCC-1 catalyst

The production of short chain polyols from cellulose over metal (Ce, Ni or Ru) loaded on fibrous mesoporous silica KCC-1 catalysts was studied at temperature range of 150-240 °C. The KCC-1 was prepared by microwave assisted hydrothermal method. Then it was modified with Ce, Ni or Ru by incipient wetness impregnation method. The KCC-1, Ce/KCC-1, Ni/KCC-1 and Ru/KCC-1 were characterized with XRD, FESEM, FTIR and nitrogen-phy-sisorption analyzer. The XRD analysis showed that the introduction of metals did not change much of the XRD pattern for KCC-1. The FESEM and EDX results showed the presence of Ce, Ni and Ru metals on the uniform spherical shape of fibrous silica particle. The surface area of KCC-1, Ce/KCC-1, Ni/KCC-1 and Ru/KCC-1 was 393.81, 371.56, 314.22 and 351.97 m2/g, respectively. At 220 °C, 5 bars of nitrogen, and 2 h of reaction, the con-version of cellulose reached 95 % over Ce/KCC-1 with the product distribution of 3-buten-1-ol (S=63.30%), diiso-propyl ether (S=2.86%) and cyclopropane carboxylic acid (S=33.70%). While, bare KCC-1, Ni/KCC-1 and Ru/KCC-1 showed less activity than that of Ce/KCC-1. The high activity of Ce/KCC-1 may be due to the presence of Ce metal and fibrous silica which provided large surface area and average pore diameter

Effect of carbon-interaction on structure-photoactivity of Cu doped amorphous TiO2 catalysts for visible-light-oriented oxidative desulphurization of dibenzothiophene

Amorphous TiO2 (AT) was successfully prepared via the sol-gel technique, using different titanium sources followed by incorporation of copper via the electrochemical method to give CuO/TiO2 (CAT) catalysts. The catalysts were characterized via XRD, N2 physisorption, FTIR, TEM, EDX, XPS, ESR and UV–Vis DRS. The results verified that the use of different titanium precursors have profound effect on the physicochemical properties of the AT catalysts. Further one-pot self-doping carbon from titanium precursor during the addition of copper could greatly enhanced the photocatalytic activity of CAT on the oxidative desulphurization of dibenzothiophene (DBT). 15 CATTBOT exhibited the best performance mainly due to the narrowest band gap and higher numbers of O–Ti–C and Ti–O–C bonds, as well as appropriate amount of Ti3+ surface defects (TSD). These abovementioned properties offered good mobility of electron-hole pairs and/or trap the electrons for enhancement of photoactivity under irradiation of visible light. Kinetic studies showed that the photocatalytic oxidative desulphurization of DBT followed the pseudo-first order Langmuir-Hinshelwood model, where the adsorption was the controlling step. It is believed that these results could contribute to the synthesis of various supported catalysts for numerous applications specifically in removal of sulphur containing compounds in fuel oils

Directing the amount of CNTs in CuO–CNT catalysts for enhanced adsorption-oriented visible-light-responsive photodegradation of p-chloroaniline

Copper oxide (CuO, 10–90 wt%) was loaded onto carbon nanotubes (CNTs) by electrosynthesis method. The catalysts (CuO/CNT) were characterized by XRD, nitrogen adsorption–desorption, ESR, FTIR, Raman, and XPS spectroscopy. The results indicated that a lower amount of CuO was dispersed well on the CNT, while higher loading was agglomerated, producing large-size crystallites, hence resulting in lower specific surface area. Adsorption studies revealed that the isotherms are fitted well with the Langmuir model. Moreover, the n value that was obtained from Freundlich model indicated that adsorption process is chemisorption. Photodegradation of p-chloroaniline (PCA) under visible light irradiation demonstrated that the 50 wt% CuO/CNT catalyst gave the highest degradation (97%). It was concluded that C–N moieties of PCA were chemisorbed on the catalyst prior to photodegradation, while the Cu–O–C bonds, surface defects and oxygen vacancies were the main active site in enhancing the subsequent photodegradation. The kinetics of photodegradation were correlated with pseudo-first-order model, verifying the surface reaction was the controlling step. Remarkable mineralization results of PCA were attained by TOC (89.1%) and BOD5 (50.7%). It was also evidenced that the catalyst has a good potential toward degradation of various endocrine disruption compounds

Effect of iridium loading on the formation of protonic acid sites over Ir/PtHZSM5

The Ir/Pt-HZSM5 with different iridium loading (0.3-1.0 wt%) was prepared by impregnation of iridium on Pt-HZSM5. The acidic properties of Ir/Pt- HZSM5 were studied by FTIR spectroscopy, while the activity of the catalysts was tested for n-pentane isomerization in a microcatalytic pulse reactor. The IR results of adsorbed 2,6-lutidine showed that all catalysts possessed strong Brönsted and Lewis acid sites in the outgassing at 473 K and below. When Ir/Pt-HZSM5 was heated in hydrogen, protonic acid sites were formed with concomitant decrease of Lewis acid sites. An increase in iridium loading continuously decreased the Lewis and Brönsted acid sites and inhibited the formation of protonic acid sites induced by hydrogen. The formation of protonic acid sites induced by hydrogen was also confirmed by the formation of electron detected by ESR spectroscopy. Additionally for n-pentane isomerization, an increase in iridium loading decreased the yield of isopentane due to the inhibition in the formation of protonic acid sites via hydrogen spillover phenomenon

Recovery of gold(III) from an aqueous solution onto a durio zibethinus husk

The recovery of gold(III) ions from an aqueous solution onto a durio zibethinus husk (DZH) was examined after varying pH, contact time, adsorbent dosage, initial Au(III) concentration, and temperature. The functional groups of DZH were analyzed by FTIR and Au(III) recovery onto DZH was verified by FESEM–EDX and XRD analysis. Adsorption equilibrium isotherms and kinetics of the DZH were studied using Freundlich and Langmuir models, as well as pseudo first-order, second-order kinetic and intraparticle diffusion equations. The experimental data obtained with DZH fitted best to the Langmuir isotherm model and exhibited a maximum adsorption capacity (qmax) of 1724 µmol g-1. The data followed the pseudo second-order equation. The activation energy of the adsorption (Ea) was estimated to be 38.5 kJ mol-1. Thermodynamic parameters, such as changes in enthalpy, entropy and Gibbs free energy, showed that the adsorption is exothermic, spontaneous at low temperature, and is a chemisorption process. These results indicate that DZH adsorbs efficiently and could be used as a low-cost alternative for the adsorption of Au(III) in wastewater treatment