Rusmidah Ali

Catalytic methanation reaction over supported nickel-ruthenium oxide base for purification of simulated natural gas

The presence of carbon dioxide and water molecules as impurities in crude natural gas decreases the quality of natural gas. Recently, the catalytic treatment of this toxic and acidic gas has become a promising technique by converting CO2 to methane gas in the presence of H2S gas; thus, enhancing methane production and creating an environmentally friendly approach to the purification of natural gas. A series of catalysts based on nickel oxide were prepared using the wetness impregnation technique and aging, followed by calcination at 400 °C. Pd/Ru/Ni(2:8:90)/ Al2O3 catalyst was revealed as the most potential catalyst, and achieved 43.60% of CO2 conversion, with 6.82% of methane formation at 200 °C. This catalyst had the highest percentage of 52.95% CO2 conversion and yielded 39.73% methane at a maximum temperature of 400 °C. In the presence of H2S in the gas stream, the conversion dropped to 35.03%, with 3.64% yield of methane at a reaction temperature of 400 °C. However, this catalyst achieved 100% H2S desulfurization at 140 °C and remained constant until the reaction temperature of 300 °C. Moreover, the XRD diffractogram showed that the catalyst is highly amorphous in structure, with a BET surface area in the range of 220–270 m2 g- 1. FESEM analysis indicated a rough surface morphology and non-homogeneous spherical shape, with the smallest particles size in the range 40–115 nm.

Catalytic methanation reaction over alumina supported cobalt oxide doped noble metal oxides for the purification of simulated natural gas

A series of alumina supported cobalt oxide based catalysts doped with noble metals such as ruthenium and platinum were prepared by wet impregnation method. The variables studied were difference ratio and calcination temperatures. Pt/Co(10:90)/Al2O3 catalyst calcined at 700°C was found to be the best catalyst which able to convert 70.10% of CO2 into methane with 47% of CH4 formation at maximum temperature studied of 400°C. X-ray diffraction analysis showed that this catalyst possessed the active site Co3O4 in face-centered cubic and PtO2 in the orthorhombic phase with Al2O3 existed in the cubic phase. According to the FESEM micrographs, both fresh and spent Pt/Co(10:90)/Al2O3 catalysts displayed small particle size with undefined shape. Nitrogen Adsorption analysis showed that 5.50% reduction of the total surface area for the spent Pt/Co(10:90)/Al2O3 catalyst. Meanwhile, Energy Dispersive X-ray analysis (EDX) indicated that Co and Pt were reduced by 0.74% and 0.14% respectively on the spent Pt/Co(10:90)/Al2O3 catalyst. Characterization using FT-IR and TGA-DTA analysis revealed the existence of residual nitrate and hydroxyl compounds on the Pt/Co(10:90)/Al2O3 catalyst.

Alumina supported polymolybdate catalysts utilizing tert-butyl hydroperoxide oxidant for desulfurization of Malaysian diesel fuel

Abstractperformance of oxidative desulfurization (ODS) of commercial diesel by alumina supported polymolybdate based catalyst system was studied using tert-butyl hydroperoxide (TBHP) as an oxidizing agent. From catalytic testing, MoO3-Al2O3 calcined at 500 °C was the most potential catalyst which gave the highest sulfur removal under mild condition. The sulfur content in commercial diesel was successfully reduced from 440 ppmw to 105 ppmw followed by solvent extraction. Response surface methodology involving Box-Behnken was employed to evaluate and optimize MoO3/Al2O3 preparation parameters (calcination temperatures, molybdenum loading precursor and catalyst loading), and their optimum values were found to be 510 °C, 0.98 g and 11.18 g/L of calcination temperature, molybdenum loading precursor and catalyst loading, respectively. Based on results, the reaction mechanism for oxidation of sulfur compounds to the corresponding sulfones occur in the presence of MoO3/Al2O3 catalyst was proposed.

The Role of Molybdenum Oxide Based Catalysts on Oxidative Desulfurization of Diesel Fuel

The industrial technology, hydrodesulfurization (HDS) is incapable to meet ultra-low sulfur standard due to the limited treatment on organosulfur compound in diesel fuel. In this paper, catalytic oxidative desulfurization of thiophene, dibenzothiophene and 4,6-dimethyldibenzothiophene using molybdenum oxide based catalyst was investigated. A detailed parametric experimental study; number of coating, calcination temperature, addition of dopant was performed on sulfur removal. It was shown that 4.35% WO3/16.52% MoO3/γ-Al2O3 , calcined at 500°C was successfully removed 92.5% of thiophene, 100% of DBT and 100% of 4,6-DMDBT in model diesel at short reaction time and lower temperature.

Photocatalytic degradation of paraquat dichloride over CeO2-modified TiO2 nanotubes and the optimization of parameters by response surface methodology

Decontamination of water sources by one-dimensional (1D) nanostructured TiO2 holds great potential due to their unique electronic and textural properties. In this study, CeO2-modified TiO2 nanotubes (Ce–TNTs) have been prepared by impregnation of CeO2 on hydrothermally synthesized TiO2 nanotubes (TNTs). The catalysts were characterized by XRD, HRTEM, EDX, STEM, EELS, DR-UV/VIS spectroscopy and nitrogen adsorption (NA) analyses. The photocatalytic activities of the synthesized Ce–TNTs were examined on the degradation of paraquat dichloride (PQ) under UV light. The modification of TNTs with CeO2 led to an enhancement of the photocatalytic activity. Box–Behnken design (BBD) based on response surface methodology (RSM) was used to optimize three experimental parameters namely; CeO2 ratio, calcination temperature and catalyst loading. ANOVA of the generated quadratic model yielded a coefficient of determination, R2 of 0.9926 and probability, P < 0.0001, which confirms that the model is suitable for predicting the optimum degradation efficiency of PQ. Based on this model, the calcination temperature and CeO2 ratio were the most significant parameters and the interactions between these parameters and the catalyst loading were also significant. The predicted optimum conditions that would give a maximum of 80.798% degradation of PQ in 4 h were 9.01% CeO2 ratio, 760.49 °C calcination temperature and 0.38 g catalyst loading. Validation experiments were conducted in triplicate and an average of 80.27% degradation of PQ was achieved which is in agreement with 80.798% predicted. Under these optimum conditions, TOC analysis showed that 51.10% mineralization of PQ was achieved within 4 h. Therefore, this work further confirms that the photocatalytic treatment of organics-contaminated water can be designed and optimized by RSM.

Pengoptimuman dengan reka bentuk Box-Behnken untuk penukaran in-situ karbon dioksida menggunakan lantanum oksida

Lanthanum oxide based catalyst was revealed as one of potential catalyst to convert carbon dioxide to wealth product methane in simulated natural gas. To produce higher conversion of carbon dioxide, the Response Surface Methodology utilizing Box-Behnken design (BBD) was used to optimize the lanthanum oxide based catalysts by three critical parameters which were calcination temperature, based ratio and catalyst dosage. The maximum CO2 conversion was achieved at 1000oC calcination temperature using 7 g of catalyst for 60% based loading. The optimization result from BBD is in good agreement with experimental data. The optimize parameters gave 99% of CO2 conversion determined using Fourier Transformation Infrared (FTIR) and yielded about 50% of CH4 at reaction temperature of 400 °C. X-ray Diffraction (XRD) analysis showed an amorphous structure with RuO2 as active species and Field Emission Scanning Electron Microscope (FESEM) illustrated the catalyst surface was covered with small and dispersed particles with undefined shape. EDX analysis revealed that when the calcination temperature was increased, the mass ratio of Ru increased.

Synthesis and Characterization of Hollow Anatase TiO2 Spheres and its Application in the Photodegradation of γ-Lindane under Ultraviolet Light

Hollow anatase titania spheres have been synthesized using hydrothermally–prepared carbon spheres as the template. Here, the combination of hydrothermal process with sol–gel followed by calcination in air was done in order to obtain hollow anatase TiO2 spheres by utilizing fructose and tetrabutyl titanate (TBT) as the precursors. The structure and morphology of the products were characterized using various techniques, including Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermal gravimetric and differential thermal analysis (TG–DTA), scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD showed that all peaks of TiO2 correspond to anatase crystalline phase. The BET surface area of the hollow spheres was about 22 m2g-1. The photocatalytic activity of the hollow anatase TiO2 was measured under UV light using γ-lindane as the target pollutant and was compared to commercially available TiO2.

Zn/ZnO and Zn/ZnO/TiO 2 photocatalysts for degradation of Benzene-Toluene-Xylene in aqueous system

The aim of the present study is to investigate the catalytic activity of semiconductor materials on the degradation of Benzene-Toluene-Xylene (BTX) in aqueous system under UV light (6 W, λ = 354 nm). Two types of photocatalysts were prepared namely Zn/ZnO and Zn/ZnO/TiO2. Zn/ZnO film was prepared by anodic oxidation of zinc in NaOH with various concentrations. Zn/ZnO deposited with TiO2 photocatalyst was prepared by electrodeposition method. It was found that the optimum concentration for the electrolyte solution (NaOH) was 0.8 M. The pH value of the sample solution had influenced the photocatalytic activity of Zn/ZnO/TiO2 plate in degrading BTX solution. The most suitable pH for the degradation of BTX was pH 6. The most effective degradation of BTX solution using Zn/ZnO/TiO2 plate is 91.54% degradation under four hours of UV irradiation time. The Field Emission Scanning Electron Microscopy (FESEM) and Energy-dispersive X-ray spectroscopy (EDX) were applied to study the surface morphology of the Zn/ZnO plate and Zn/ZnO/TiO2 photocatalysts. The large porous surface of Zn/ZnO plate prepared by using 0.8 M NaOH contributed to large amount of TiO2 deposited onto the surface of the photocatalyst and excellent performance of Zn/ZnO/TiO2 on UV-Induced degradation of BTX solution.