Mohamed Wahab Mohamed Hisham

Dehydration studies of biomass resources for activated carbon production using bet and XRD techniques

Activated carbon is produced from high cellulose containing biomass such as filter paper (FP), bamboo waste and palm empty fruit bunches (EFB) by dehydrating agent, concentrated sulfuric acid (H2SO4). At room temperature, treatment of H2SO4 is removed all the water molecules in the biomass and leaving only porous carbon without emitting any gaseous by-products. After activation by carbon dioxide (CO2), Brunauer-Emmett-Teller (BET) and X-ray Diffractometer (XRD) analysis showed the bamboo activated carbon (BAC) has good properties with higher surface area (862.76 m2/g), micropore area (463.62 m2/g) and some crystalline (graphite) phase formation. Acid treatment of biomass has shown high carbon content for FP (85.30%), bamboo (77.72%) and EFB (76.55%), and yield obtained was 47.85 wt.% (FP), 62.4 wt.% (bamboo) and 55.4 wt.% (EFB) by using dehydration method.

Magnesium oxide nanoparticles on green activated carbon as efficient CO2 adsorbent

This study was focused on carbon dioxide (CO{sub 2}) adsorption ability using Magnesium oxide (MgO) nanoparticles and MgO nanoparticles supported activated carbon based bamboo (BAC). The suitability of MgO as a good CO{sub 2} adsorbent was clarified using Thermodynamic considerations (Gibbs-Helmholtz relationship). The ΔH and ΔG of this reaction were − 117.5 kJ⋅mol{sup −1} and − 65.4 kJ⋅mol{sup −1}, respectively, at standard condition (298 K and 1 atm). The complete characterization of these adsorbent were conducted by using BET, XRD, FTIR, TEM and TPD−CO{sub 2}. The surface areas for MgO nanoparticles and MgO nanoparticles supported BAC were 297.1 m{sup 2}/g and 702.5 m{sup 2}/g, respectively. The MgO nanoparticles supported BAC shown better physical and chemical adsorption ability with 39.8 cm{sup 3}/g and 6.5 mmol/g, respectively. The combination of MgO nanoparticle and BAC which previously prepared by chemical method can reduce CO{sub 2} emissions as well as better CO{sub 2} adsorption behavior. Overall, our results indicate that nanoparticles of MgO on BAC posses unique surface chemistry and their high surface reactivity coupled with high surface area allowed them to approach the goal as an efficient CO{sub 2} adsorbent.

Peranan spesies kromium aktif pada penyokong yang berbeza dalam tindak balas penyahhidrogenan gas propana

Dehydrogenation of propane (DHP) was studied over a series of Cr2O3–Al2O3 and Cr2O3-SiO2 catalysts, prepared by incipient wetness impregnation and sol gel (SG) method, respectively, to gain a better understanding of the nature and distribution of chromium (Cr) species and their catalytic function. To this end, the catalysts were characterized by N2-physisorption and X-ray diffraction (XRD). N2-physisorption analysis of Cr2O3-SiO2 showed the relatively higher surface area of 391.1 m /g, compared with Cr2O3-Al2O3 of 224.3 m /g. The combination method of sol gel and sonothermal also produced smaller particles size of catalyst with higher microporosity of 23.5% and smaller pores size of 6 nm. The good surface properties of Cr2O3-SiO2 enabled the high conversion of propane of 55% at 550 °C. At higher temperature of 600 °C, the Cr species might be reduced into lower oxidation state and inhibit the catalytic behavior to produce hydrogen.

Study on the reduction behavior of molybdenum oxide (MoO3) in carbon monoxide (CO) atmosphere

The reduction behavior of molybdenum trioxide (MoO3) by carbon monoxide (CO) has been studied using temperature programmed reduction (TPR) and was characterized using X-ray diffraction spectroscopy (XRD). The TPR result shows that the first reduction peak of MoO3 under 20 vol. % CO in nitrogen started at 530 °C and second reduction peaks observed was at 700 °C. The XRD technique was employed to identify the changes in the sample. It was found that after non-isothermal reduction up to 700 °C, the intermediate phases Mo4O11 were observed. Completed reduction to MoO2 achieved after continued reduction with isothermal mode at 700 °C for 60 minutes. Based on the XRD analysis, it is confirmed that the reduction of MoO3 to MoO2 in CO atmosphere consists of two reduction stages, i) Mo6+ → Mo5+ and ii) Mo5+ → Mo4+. While, CO excess have resulted the formation of molybdenum carbide (Mo2C) rather than formation of metallic molybdenum (Mo).

Studies of Fe Metal Carburization by Carbon Monoxide Using XRD and TPR Techniques

This study was undertaken to investigate the effect of carburization of metallic Fe by (20%,v/v) carbon monoxide (CO). Carburization of Fe by carbon monoxide was examined by using temperature-programmed reduction (TPR), X-Ray powder diffractometry (XRD) and Carbon Hydrogen Nitrogen Sulfur (CHNS) technique. Based on a thermodynamic calculation, the free energy Gibb’s value to produce carbon is-8.08 kcal/mol which are favorable. However, production of iron carbide from the same reaction, the free energy Gibb’s value is +9.24 kcal/mol which is not feasible. From the XRD results, shows that after carburization of Fe, the peak appears only for Fe but there is a broad peak between 20 – 30°. The peak might be indicated as carbon in amorphous form. This finding is supported by the percent of carbon content in CHNS analysis which are increasing when the temperature is increased. This shows that after carburization the carbon content is increasing with increasing in temperature due to carbon deposited on metallic iron. In this research, three different temperatures were used which are 300°C, 500°C and 700°C.

CO2 capture on NiO supported imidazolium-based ionic liquid

CO2 capture on NiO supported imidazolium-based ionic liquid, NiO/[emim][HSO4]/SiO2 as an adsorbent was investigated using gas adsorption analyzer and physicochemical properties of the adsorbent were characterized using X-ray powder diffraction (XRD), surface area analyzer (BET method) and temperature-program-desorption analysis (TPD). Immobilization of ionic liquid on silica, [emim][HSO4]/SiO2 slightly decreased the surface area compared to bare silica from 266 to 256 m2/g due to the pore blocking by the confinement of IL in SiO2 pore. Interestingly, introduction of NiO on supported ionic liquid, NiO/[emim][HSO4]/SiO2 was increased the surface area as well as pore volume from 256 to 356 m2/g and 0.14 to 0.38 cm3/g, respectively. The enhancement of surface area and pore volume was significantly increased the CO2 adsorption performance with capacity of 48.8 mg CO2/g adsorbent compared to [emim][HSO4]/SiO2 27.3 mg CO2/g adsorbent).

Reduction Behaviour of WO3 to W under Carbon Monoxide Atmosphere

The reduction behaviour of tungsten oxide has been studied by using temperature programmed reduction (TPR) and X-ray diffraction (XRD). The reduction behavior were examine by nonisothermal reduction up to 900 oC then continued with isothermal reduction at 900 oC for 45 min time under (40% v/v) carbon monoxide in nitrogen (CO in N2) atmosphere. The TPR signal clearly shows one peak attributed to formation of suboxide W18O49 (more) and WO2 (less) observed at 80 min. The reduction product was investigated by varying the holding reaction time. Based on the characterization of the reduction products by using XRD, it was found that, nonisothermal reduction of WO3 at temperature 900 oC partially converted to some W18O49 and WO2 phases. However, after increased the reaction holding time for 45 min, WO3 phases disappeared and converted to WO2 and W metal phases. It is obviously shows that by hold the reduction time could improve the reducibility of the sample oxide. Furthermore, it is suggested that reduction by using CO as reducing agent follows the consecutives steps WO3 → WO2.92 → W18O49 → WO2 → W.

The Reduction Behaviour of Cerium Doped Iron Oxide in Hydrogen and Carbon Monoxide Atmosphere

The reduction behaviour of 3% cerium doped (Ce-Fe2O3) and undoped iron oxide (Fe2O3) by hydrogen in nitrogen (10%,v/v) and carbon monoxide in nitrogen (10%,v/v) atmospheres have been investigate by temperature programmed reduction (TPR). The phases formed of partially and completely reduced samples were characterized by X-ray diffraction spectroscopy (XRD). TPR results indicate that the reduction of Ce doped and undoped iron oxide in both reductants proceed in three steps reduction (Fe2O3 → Fe3O4 → FeO → Fe) with Fe3O4 and FeO were the intermediate. TPR results also suggested that by adding Ce metal into iron oxide the reduction to metallic Fe by using both reductant gaseous give better reducibility compare to the undoped Fe2O3. The reduction process of Ce and undoped Fe2O3 become faster when CO was used as a reductant instead of H2. Furthermore, in CO atmosphere, Ce-Fe2O3 give complete reduction to metallic iron at 700 0C which about 200 0C temperature lower than other samples. Meanwhile, XRD analysis indicated that Ce doped iron oxide composed better crystallite phases of Fe2O3 with higher intensity and a small amount of FeCe2O4.

Studies on Adsorption-Desorption of CO2 by Long Chain Fatty Amine Supported on SiO2

The capture of carbon dioxide (CO2) molecules was achieved by utilizing impregnated long chain fatty amine solid sorbents. The long chain fatty amine impregnated on these solid substrates was octadecylamine (ODA) to improve CO2 adsorption-desorption capacity. The amine-loaded samples were characterized using nitrogen, N2 adsorption-desorption isotherm of Brunauer-Emmet-Teller (BET) and thermogravimetry analyzer (TGA). The prepared 25 wt % ODA/SiO2 exhibit acceptable CO2 capture capacities of 2.45 wt % CO2/adsorbent at 25 °C by using CO2 adsorption-desorption isotherm. TG profile shows that the solid sorbents able to adsorb and desorb CO2 in equivalent amount.

Development of α-Fe2O3 as Adsorbent and its Effect on CO2 Capture

Iron oxide (α-Fe2O3) as adsorbent was no longer new in CO2 adsorption studies. However, its contributions in the industry still in limited wherein lack of convincing results of quantifying of adsorbed CO2. This work presents an analysis for α-Fe2O3 was prepared by simple mixing method with identified the adsorption capacity that applied in CO2 capture. The synthesized α-Fe2O3 from different concentrations of precursor were analyzed using XRD, N2 adsorption-desorption isotherms with BET and BJH method, TEM, FTIR, CO2 adsorption at 298 K, CO2-TPD and TGA-DTG. It was noted that 2M concentration of precursor (s2M) with highest crystallite peaks shows highest surface area among all samples which indicative of well generated pores. The different concentration of precursor was found generated more porosity rather than particle size according to TEM micrograph. The sphere shape crystallite particle with high surface area (50.5 m2/g) and porosity were desirable properties in CO2 adsorption. Consequently, physically adsorbed CO2 with adsorption at 298 K was highest with adsorption capacity of at 17.0 mgCO2/gadsorbent. Finally, chemically adsorbed CO2 was successfully identified from CO2–TPD analysis with adsorption capacity of 0.19 mgCO2/gadsorbent and 1.31 mgCO2/gadsorbent at maximum desorption temperature of 375 °C and 749 °C respectively.