Maizatul Shima Shaharun

Effect of fixed carbon molecular sieve (CMS) loading and various di-ethanolamine (DEA) concentrations on the performance of a mixed matrix membrane for CO2/CH4 separation

Polyethersulfone (PES) as a polymer along with carbon molecular sieves (CMS) as an inorganic filler and di-ethanolamine (DEA) as the third component were used to fabricate amine mixed matrix membranes (A3Ms). The CMS and the developed membranes were characterized by variable pressure field emission scanning electron microscopy (VPFESEM) and thermal gravimetric analysis (TGA). FESEM micrographs showed that with the addition of DEA, uniform distribution of CMS particles in the PES matrix was achieved with good polymer-filler contact. The combined effect of DEA concentration (5–15 wt%), feed pressure (2–10 bar) and CMS loading on the CO2/CH4 transport properties of the PES–CMS–DEA membranes were studied. The results revealed that the PES–CMS–DEA (15 wt% DEA) membrane showed a CO2 permeance of 123.49 GPU at 2 bar, which is more than a threefold increment with respect to the native PES membrane. The corresponding CO2/CH4 ideal selectivity was increased from 5.40 for PES to 51.39 for PES–CMS–DEA (15 wt% DEA). The CO2 permeance of the PES–CMS–DEA (A3Ms) membranes was higher than PES membranes over the operating pressure range.

Oxidative desulfurization of dibenzothiophene from model oil using ionic liquids as extracting agent

The oxidative desulfurization of dibenzothiophene (DBT) from model oil (in n-dodecane) was carried out using ionic liquid as the extractant and catalyst, and hydrogen peroxide (H2O2) in combination with acetic acid (CH3COOH) and sulphuric acid (H2SO4) as the oxidant. The ionic liquids used were 1-butyl-3-methylimidazolium octyl sulphate ([Bmim][OcSO4]) and 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]). The effect of the amounts of H2O2 on oxidative desulphurization of model oil was first investigated without the usage of ionic liquids at room temperature. The results indicate that greater amount of H2O2 give higher desulfurization and the maximum desulfurization in this study, i.e. 34 %, was occurred when the molar ratio of H2O2 to sulfur was 5:1. With the usage of ionic liquid and the molar ratio of 5:1 (H2O2:sulfur), the efficiency of DBT removal from model oil was increased significantly in terms of percent removal and removal time. Ionic liquid of [Bmim][OcSO4] performed better than [Bmim][Ac] with...

Properties of activated carbon prepared from rice husk with chemical activation

The present work involves an investigation of the possible use of activated carbon developed from rice husk by chemical activation with zinc chloride (ZnCl2) and phosphoric acid (H3PO4) under different activation conditions for the removal of phenol from artificial wastewater. The physical and surface properties of the developed adsorbents were characterised using FTIR and SEM. A comparison between ZnCl2 and H3PO4 shows that the efficiency of phenol removal by H3PO4 activated carbon is generally lower than that of ZnCl2 activated carbon for both activation temperatures. After 24 hrs, removal efficiency of up to 90% could be achieved with 0.5 g ZnCl2 activated carbon, either prepared at 500°C or 600°C activation temperature. However, for 0.1g ZnCl2 activated carbon, an efficiency of 80% to 85% and 69% to 74% could be achieved at 500°C and 600°C activation temperatures, respectively. For H3PO4 activated carbon prepared at 500°C, the efficiency was 45% to 48% and 48% to 56% for 0.1 g and 0.5 g of adsorbent respectively. While for H3PO4 activated carbon prepared at 600°C, an efficiency of 41% to 45% and 43% to 51% could be achieved with 0.1 g and 0.5 g, respectively. The kinetics of phenol adsorption on both ZnCl2 and H3PO4 activated carbons were found to follow the pseudo-second-order kinetic model.

Study of Annealing Conditions on Particle Size of Nickel Ferrite Nanoparticles Synthesized by Wet Chemical Route

Wet chemical method has been employed for syntheses of nickel ferrite nanoparticles by using nitrate salts of iron and nickel as starting materials. Synthesized product was characterized in terms of thermal stability (TGA), phase determination (XRD) and structure elucidation (FT-IR). Thermal stability of the product was confirmed by TGA studies. Particle size was investigated as a reference of degree and duration of annealing temperature. A linear relationship was observed for size variation of the nickel ferrite nanoparticles with degree of annealing temperature, while size of nanoparticles remains almost constant for different time interval of duration of the annealing temperature.

Effects of Nb Promoter on the Properties of Cu/ZnO/SBA-15 Catalyst and Performance in Methanol Production

Hydrogenation of CO2 provides an alternative route for methanol production and attractive option for CO2 utilization. The present work investigates the synthesis of Cu-based catalyst on mesoporous silica (SBA-15) and promotion of the Cu-based catalyst with niobium (Nb). The addition of Nb promoter enhanced the reducibility and dispersion of the active sites as well as increased the BET and Cu surface areas. The performance of the synthesized catalyst in the hydrogenation of CO2 was evaluated in a fixed-bed microreactor at 523K, 22.5bar and H2/CO2 of 3. The CO2 conversion using the Cu/ZnO/SBA-15 catalyst was 14.2 % and increased to 17.1% on the Nb-promoted catalyst. The yield of methanol obtained using the un-promoted Cu-based catalyst was 51.4 g/h.gcat and it increased to 143 g/h.gcat over the Nb-promoted catalyst.

The role of support morphology on the performance of Cu/ZnO-catalyst for hydrogenation of CO2 to methanol

The effects of SBA-15 support morphology on the activity of Cu/ZnO catalyst in the hydrogenation of CO2 to methanol was investigated. In the hydrogenation of CO2 to methanol at 210°C, 2.25 MPa, H2/CO2 ratio of three remarkable difference was obtained using Cu/ZnO catalyst supported on SBA-15 with different morphology. The catalysts were characterized using N2-adsorption, field emission scanning microscopy (FESEM/EDX), transmission electron microscopy (HRTEM), and temperature-programmed reduction (TPR). Characterization of the catalyst showed that support morphology, surface area, metals dispersion, and reducibility influenced the catalytic performance. On the fiber-shaped SBA-15, copper dispersion was 29 % whereas on the spherical-shaped SBA-15, the dispersion was 20 %. The experimental results showed that the catalyst supported over fiber-shaped SBA-15 exhibit higher CO2 conversion (13.96 %) and methanol selectivity (91.32 %) compare to catalyst supported over spherical-shaped SBA-15.

Synthesis and Characterization of Multiwalled Carbon Nanotubes Using Ferrocene and Aluminum Oxide/Iron Nitrate Catalysts

Large scale production of impurity-free carbon nanotubes is a current challenge. For the bulk production of carbon nanotubes, the selection of an appropriate catalyst is also an important task. In this study, an aluminum oxide/iron nitrate catalyst was prepared by using a co-precipitation method. The surface morphology and composition of the catalyst were studied by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results were compared with a commercially available ferrocene catalyst. Multiwalled carbon nanotubes were grown by catalytic decomposition of ethylene over the catalyst via floating catalytic chemical vapor deposition. The yield of nanotubes increased with an increase in the mass of aluminum oxide/iron nitrate but remained unchanged with an increase in ferrocene mass. The yield of carbon nanotubes remained between 68% and 93%, which was much higher than obtained with only ferrocene (4%). In case of ferrocene, rather affecting the product yield, the catalyst mass affected the diameter of the nanotubes. The tube diameters were between 20 nm and 34 nm for aluminum oxide/iron nitrate and between 39 nm and 71 nm for ferrocene.

Physicochemical investigations of carbon nanofiber supported Cu/ZrO2 catalyst

Zirconia-promoted copper/carbon nanofiber catalysts (Cu‐ZrO2/CNF) were prepared by the sequential deposition precipitation method. The Herringbone type of carbon nanofiber GNF-100 (Graphite nanofiber) was used as a catalyst support. Carbon nanofiber was oxidized to (CNF-O) with 5% and 65 % concentration of nitric acid (HNO3). The CNF activated with 5% HNO3 produced higher surface area which is 155 m2/g. The catalyst was characterized by X-ray Diffraction (XRD), Fourier Transform Infra-Red (FTIR) and N2 adsorption-desorption. The results showed that increase of HNO3 concentration reduced the surface area and porosity of the catalyst.

Removal of Ni(II), Zn(II) and Pb(II) ions from single metal aqueous solution using rice husk-based activated carbon

An attempt was made to investigate the potential of rice husk-based activated carbon as an alternative low-cost adsorbent for the removal of Ni(II), Zn(II) and Pb(II) ions from single aqueous solution. Rice husk-based activated carbon was prepared via treatment of rice husk with NaOH followed by the carbonization process at 400°C for 2 hours. Three samples, i.e. raw rice husk, rice husk treated with NaOH and rice husk-based activated carbon, were analyzed for their morphological characteristics using field-emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX). These samples were also analyzed for their carbon, hydrogen, nitrogen, oxygen and silica contents using CHN elemental analyzer and FESEM/EDX. The porous properties of rice husk-based activated carbon were determined by Brunauer-Emmett-Teller (BET) surface area analyzer, and its surface area and pore volume were 255 m2/g and 0.17 cm2/g, respectively. The adsorption studies for the removal of Ni(II), Zn(II) and Pb(II) ions from sin...

Homogeneous Deposition Precipitation Method for Synthesis of Carbon Nanofibre Based Cu-ZrO2 Catalyst for Hydrogenation of CO2 to Methanol

Deposition precipitation method was employed to synthesize carbon nanofiber based Cu-ZrO2 catalyst (Cu-ZrO2/CNF). Carbon nanofibre of herringbone type was used as a catalyst support. Prior deposition of catalyst particles, carbon nanofibre was oxidized to (CNF-O) with nitric acid solution. Catalyst was characterized by X-ray diffraction (XRD), Fourier Transmission Infrared (FTIR), Transmission Electron Microscopy (TEM) and Temperature-Programmed Reduction (TPR). Highly loaded, well-dispersed and thermally stable catalyst particles with average size of 4 nm were obtained by deposition precipitation method. Reaction studies confirmed the activity of the catalyst towards methanol formation.