Results 1 - 10 of 19076
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[en] Huge quantities of waste cooking oils are produced all over the world every day, especially in the developed countries with 0.5 million ton per year waste cooking oil are being generated in Malaysia alone. Such large amount of waste cooking oil production can create disposal problems and contamination to water and land resources if not disposed properly. The use of waste cooking oil as feedstock for bio diesel production will not only avoid the competition of the same oil resources for food and fuel but will also overcome the waste cooking oil disposal problems. However, waste cooking oil has high acid value, thus would require the oil to undergo esterification with an acid catalyst prior to transesterification with a base catalyst. Therefore, in this study, bifunctional catalyst supports were developed for one-step esterification-transesterification of waste cooking oil by varying the CeO2 loading on γ-Al2O3. The bifunctional supports were then impregnated with 5 wt % Mo and characterized using N2 adsorption-desorption isotherm to determine the surface area of the catalysts while temperature programmed desorption with NH3 and CO2 as adsorbents were used to determine the acidity and basicity of the catalysts. Results show that the γ-Al2O3-CeO2 supported Mo catalysts are active for the one-step esterification-transesterification of waste cooking oil to produce bio diesel with the Mo/ γ-Al2O3-20 wt% CeO2 as the most active catalyst. Optimization of process parameters for the production of bio diesel from waste cooking oil in the presence of this catalyst show that 81.1 % bio diesel yield was produced at 110 degree Celsius with catalyst loading of 7 wt %, agitation speed of 600 rpm, methanol to oil ratio of 30:1 and reaction period of 270 minutes. (author)
[en] Efficiency of various compositions of demetallization catalysts was studied in hydrodesulfurization of heavy crude oil. It was shown that the highest activity is observed for trimetallic NiCoMo systems, including those prepared with the use of heteropoly compounds. The influence exerted by introduction of up to 3 wt % ultrastable zeolite Y into the demetallization catalyst support on the activity in hydrodesulfurization reactions was examined. It was shown that addition of this zeolite makes it possible to reduce the content of sulfur in the reaction products, compared with the alumina support, and to preserve a high activity on raising the space velocity of feed.
[en] Palm oil (PO) mainly constitutes of 90-98 % of triacylglycerol, 2-6 % of diacylglycerol (DAG) and 2-5 % of monoacylglycerol. This study was carried out to produce PO that is high in DAG through direct esterification using 1,3 positional specific lipase from Rhizomucor miehei (RM IM) and Thermomyces lanuginose (TL IM) as catalysts. Palm olein oil has been hydrolysed by water and 4 % enzyme in a controlled water bath at 300 rpm for 48 hours at a temperature of 60±2 degree Celsius while the esterification process was carried out in a same condition except it was run for 24 hours only. Samples DAG A1 and DAG B1 were synthesized products of the first replication using 10 % enzyme TL IM and 10 % enzyme RM IM respectively while samples DAG A2 and DAG B2 were synthesized products of second replication. DAG spots found on the thin layer chromatography (TLC) plates of samples DAG A1, A2, B1 and B2 bigger than the spot of the control sample. Based on high performance liquid chromatography chromatogram peak area, the total DAG accumulation showed significant differences (p<0.05) between the usage of enzymes TL IM and RM IM which were 34.28 % and 45.67 % respectively. The esterification method has clearly increased the DAG content of the control sample which was only 3.17 %. Significant differences (p<0.05) also existed in the iodine value (IV), melting and crystallization temperature of all the samples. IV of control sample, DAG A and B were respectively 56.00, 35.00 and 30.50. Differential scanning calorimetry curves showed the melting and crystallization temperature were respectively -3.73 and -5.72 degree Celsius for samples using TL IM while -4.92 and -6.56 respectively for RM IM. The results concluded that the usage of enzyme RM IM is more effective in the production of PO high in DAG and efficiency of direct esterification process has been proved. (author)
[en] Various kinds of active alumina supports were obtained by the Institute of Nuclear Chemistry and Technology (INCT) sol-gel process in the following steps: (1) preparation of alumina sols by extraction of nitrates with Primene JMT from aluminium nitrate solution; (2) gelation to spherical particles (with diameter < 100 μm) by extraction of water from sol emulsion in 2-ethyl-1-hexanol; (3) sometimes conversion of NO3-. stabilized gel to OH-. form by reaction with ammonia; (4) calcination of gels to γ-Al2O3 with specific surface area > 100 m2/g at 500oC. The powders were then impregnated with chloroplatinic acid and re-calcined at 500oC. Catalysts were also prepared by direct gelation of alumina sol containing hydroplatinic acid followed by steps (3) and (4). Pt/Al2O3 catalysts were used for the reduction of 1 M UO2(NO3)2 - 0.5 M HCOOH solution with hydrogen at atmospheric pressure. The course of the reduction was controlled analytically and by measuring the U(VI)/U(IV) redox potential. It was concluded that the catalysts obtained by impregnation of the supports prepared from nitrate stabilized gels exhibit the best activity and stability. (author)
[en] Mixed noble metal catalyst based on Pt+Pd deposited on stainless steel wire gauze support has been developed for mitigation of hydrogen in nuclear reactor containment under severe accident conditions. The catalyst is required to function passively in presence of various contaminants like carbon dioxide, hydrocarbons, steam etc. Another likely contaminant is carbon monoxide which is produced from core-concrete interaction due to fuel meltdown. While Pt based catalyst exhibited delay in light-off initiation for H2O2 reaction, in presence of 50 ppm, catalyst with Pd deposited in sequential manner over platinum showed no activity. Compared to these, catalyst with simultaneous Pt+Pd deposition exhibited undeterred activity upto presence of 100 ppm CO. This difference is attributed to nature of interaction of Pt and palladium with CO and change in surface morphology. When palladium was replaced by Ruthenium, Pt+Ru based catalysts were found to exhibit catalytic activity for CO concentration upto 400 ppm. This has been attributed to efficient co-oxidation of CO by ruthenium and also to the enrichment of ruthenium concentration on surface during deposition process. Another role explored is for the particle size of the deposited noble metal. For this purpose, cordierite supported catalysts were prepared with the noble metal particles in sub 10 nm dimensions. Noble metals in these dimensions are reported to oxidise CO at room temperature itself. The Pt+Pd on cordierite catalysts with noble metal dimensions of 5-9 nm exhibited catalytic activity for H2+O2 reaction for carbon monoxide concentrations as high as 2000 ppm. (author)