154 research outputs found
Effect of potassium addition on the activity of nickel based catalyst used for dry reforming of methane
No full textMethane form the largest percentage of natural gas composition , it is used now in Saudi
Arabia as raw material for petrochemical industries or as fuel for some sectors in
eastern part of Saudi Arabia . With the large discoveries of oil and gas fields more
percentage of methane will be available. One way of utilization of methane is to reform
it to synthesis gas that contains hydrogen gas and carbon monoxide gas that is
considered as feed for chemical and petrochemical industries to produce chemical or
petrochemical products that will resulted in high economic return. The produced
hydrogen gas can be used as a reducing agent or as feed in chemical industries,
ammonia synthesis or as a fuel directly or indirectly in fuel cell. The reforming of
methane can be done by either the conventional steam reforming or through dry
reforming using carbon dioxide gas. The later reaction gets more attention these days
since it considered as a way of utilization carbon dioxide gas which is considered as
one of the gases that causes green house effect and hence global warming of the earth.
So this reaction has economic and environmental benefit. The objective of this paper is
to present the results of experimental study for the effect of addition of potassium to
nickel based catalyst supported by alumina on the activity of dry reforming reaction .
The catalysts used are prepared by impregnation method .The reaction is carried out at
atmospheric condition using three temperatures that range from 773- 848 K and seven
potassium amounts that range from 0.0 to 1.2 gm . The results indicate that addition of
potassium has negative effect on the conversion of either methane or carbon dioxide as well as hydrogen yield and this effect increased as the amount of potassium increased .Corresponding Author:
Anis H. Fakeeha, Chemical Engineering Department, College of Engineering , King Saud
University P.O.Box 800, Riyadh 11421.
Email: [email protected]
Optimization of the Performance of Packed Bed Fermentor with Immobilized Zymomonas Mobilis for the Production of Fuel Alcohol
No full textHeterogeneous compartmental model is used to optimize the performance of a packed bed fer-mentor with immobilized zymomonas mobilis for the production of fuel alcohol. The results indicate that the outlet ethanol concentrations have maximum values that decreased with increasing feed sugar concentration at single bead diameter. The outlet ethanol concentrations have maximum values that increased with decreasing the dilution rate. As the dilution rate increased the ethanol production increased. As the substrate inhibition constant (K1) increased both the maximum outlet ethanol concentration and the optimum feed sugar concentration increased up to K1 value of 500 g/L above that each have constant value
Investigation of Suitable Pretreatment for Dry Reforming of Methane Over Ni/Al<sub>2</sub>O<sub>3</sub>
No full textCarbon dioxide reforming of methane to synthesis gas over an alumina-supported 1% Ni-based catalyst was investigated at atmospheric pressure. The effects of activation and calcination temperatures and the addition of calcium promoted on dry reforming catalysts supported on low surface area alumina Ni/α-Al2O3 (SA-5239) were studied experimentally. In this study, the prepared catalyst was tested in a micro tubular reactor at temperature ranges of 500, 600, 700 and 800°C, atmospheric pressure, using a total flow rate of 33 ml/min. of feed gas 3 ml/min of N2, 15 ml/min of CO2 and 15 ml/min of CH4. The calcination was carried out in the range of 500-900°C. The catalysts were activated inside the reactor at 500-800°C using hydrogen gas. It was observed that calcination enhances catalyst activity which increases as calcination and reaction temperatures were increased. It was found essential activating reforming catalysts with H2.The highest process activity was obtained at 800°C reaction temperature by using catalyst calcined and activated at 900°C and 700°C respectively. The addition of Ca promoter decreases the coke formation on catalyst, however, It initially reduces the activity. The catalyst characterization conducted supported the observed experimental result</jats:p
Optimization of the performance of packed bed fermentor with immobilized zymomonas mobilis for the production of fuel alcohol
No full textHeterogeneous compartmental model is used to optimize the performance of a packed bed fer-mentor with immobilized zymomonas mobilis for the production of fuel alcohol. The results indicate that the outlet ethanol concentrations have maximum values that decreased with increasing feed sugar concen-tration at single bead diameter. The outlet ethanol concentrations have maximum values that increased with decreasing the dilution rate. As the dilution rate increased the ethanol production increased. As the substrate inhibition constant (K1) increased both the maximum outlet ethanol concentration and the optimum feed sugar concentration increased up to Kj value of 500 g/L above that each have constant value
Simulation of Distillation of a Large Relative Volatility Mixture
No full textIn this paper, difficulties relating to the simulation of distillation columns for separating mixtures containing components with large relative volatility between the light and heavy key components are discussed. The system used for the study is ethylene o-xylene mixture. The relative volatility is not only large but its change with temperature is also large. This makes the system model equations highly non-linear. Great difficulty is met to obtain converged solution using packages like Hysis and Pro/II. Attempts have been made to obtain optimum design and a method suggested to enhanced convergence
The Interaction between Corrosion Processes and Mass Transfer at Rough Surfaces
No full textThe mass transfer role in corrosion processes was discussed and experimentally investigated. The effect of artificial surface roughness (channel parallel to flow with variable depths ranging from zero to 3 mm) on mass transfer rates was studied in a flow system. Various models describing the interaction between corrosion and mass transfer from rough surfaces were also discussed. The limiting current technique which involves the cathodic reduction of ferricyanide ion was used in the experimental study. The obtained results of the flow system covered Reynolds number range of 0 → 29456 and revealed a significant increase in mass transfer due to the surface roughness which reached a value up to 3 times more than the corresponding smooth surface value. A correlation in terms of Sherwood number and Reynolds number was developed for each electrode in the following form:sh=a Reb,where a and b are constants depending on the roughness height
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