Optimization of the Performance of Packed Bed Fermentor with Immobilized Zymomonas Mobilis for the Production of Fuel Alcohol

Heterogeneous 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

Simulation of Distillation of a Large Relative Volatility Mixture

In 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

The 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

Factors Affecting Enrichment of Natural Gas by Polymeric Membranes

Enrichment of natural gas by polymeric membranes is an innovative technique. The membrane separation process versus conventional chemical absorption methods has proved to be energy efficient with a high selectivity. This study concerns mathematical modelling and analysis of factors which affect the membrane separation process. The model simulates the separation of a ternary gas mixture of CH4, C02 and N, by cellulose acetate membrane. Factors considered in the analysis include, the flow configuration, the gas law. the permeability function, and other operating and design parameters, e.g., feed pressure, flow rate, feed composition, and membrane area. The flow configurations considered in the analysis are the complete mixing and plug flow patterns. Also, two gas laws are used to determine the partial pressures of gaseous species, these are, the ideal gas law and the ideal solution assumption. In addition, separation behavior using either constant gaseous permeabilities or permeability functions which are pressure and composition dependent are included in the analysis

Flow of Oil Emulsion Through Porous Media

The flow through porous media of oil emulsion is reported in this paper. Base oil, water and Triton X-100 were used to produce O/W and W/O type emulsions. Shear stress, shear rate, and yield stress were measured for the emulsions at different temperatures and oil concentrations.Results show that at low oil concentration (10% to 40%), the emulsion was oil in water type and a Newtonian behavior was observed with viscosity ranging from 1.5 to 7.7 cP. Medium oil concentration (50% to 60%) data were interpreted in terms of the power law model relationship for non-Newtonian fluid. While at high oil concentrations (70% to 90%) data were interpreted in terms of the Hershel- Bulkley model relationship for a non-Newtonian fluid with yield stress. At high oil concentration of 50 – 90% oil, the emulsion was water in oil type.Data for porous packed bed of glass beads are presented using friction factor and a general Reynolds number for the flow through porous media, which includes a fluid yield stress

CATALYST PREPARATION FOR CO2 Utilization IN REFORMING OF METHANE

The effect of using different supports, additives and changing residence time on conversion of carbon dioxide and hydrogen yield through dry reforming reaction was explored experimentally. The supports used are alumina, silica, titania and zirconia . Cerium and Cobalt were used as additives. Two F/W values were used 3.33 and 33.33 ml./min.gm.cat. The catalysts were prepared by impregnation method and tested at atmospheric pressure, total feed rate of 10 ml/ min. of equimolar feed gases and temperature range of 773- 848 K. The results showed that high surface area alumina was the best support in terms of both activity and stability . Both additives promoted the performance of the catalysts , Cerium gave much higher promotion in carbon dioxide conversion and hydrogen yield than Cobalt

Effect of potassium addition on the activity of nickel based catalyst used for dry reforming of methane

Methane 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]

Production of carbon nanomaterials and syngas from biogas reforming and decomposition on one-pot mesoporous nickel alumina catalysts

Biogas, a renewable energy source, is primarily composed of CH4 and CO2. It is a promising alternative to fossil fuels and can be used directly for electricity production as well as heat generation via combustion. Concerns about climate change and a greater emphasis on renewable energy sources have recently increased interest in biogas utilization. In this context, biogas reforming and decomposition (BRD) into synthesis gas and carbon nanofibers (CNFs) is viewed as a new and attractive way of efficiently valorising biogas. In this study, Ni-loaded (i.e., 20, 50 wt%) mesoporous alumina materials were prepared using one-pot evaporation-induced self-assembly method for BRD. Synthesized materials were characterized by various techniques: N2-physisorption, X-ray diffraction, temperature-programmed reduction, scanning electron microscopy, and thermal gravimetric analysis. Results showed that textural and structural properties of synthesised materials differed with Ni loading. High Ni-loaded catalyst displayed higher surface area, pore volume, pore size distribution, and average particle size which is the result of deposition of Ni species outside alumina grains creating thus, surface defects. BRD results were greatly influenced by Ni content with Ni50%Al2O3 reflecting catalytic behaviour similar to those expected for pure methane decomposition. Most importantly, this catalyst was also capable of generating, selectively, interesting carbon nanofibers

Performance Study of Methane Dry Reforming on Ni/ZrO₂ Catalyst

Dry reforming of methane (DRM) has important and positive environmental and industrial impacts, as it consumes two of the top greenhouse gases in order to produce syngas (H2 and CO) and thus hydrogen (H2). The performance of DRM of conversions of CH4 and CO2 was investigated over Ni/ZrO2 catalysts. The catalytic performance of all prepared catalysts for DRM was assessed in a micro-tubular fixed bed reactor under similar reaction conditions (i.e., activation and reaction temperatures at 700 °C, a feed flow rate of 70 mL/min, reaction temperature, and a 440 min reaction time). Various characterization techniques, such as BET, CO2-TPD, TGA, XRD, EDX, and TEM, were employed. The zirconia support was modified with MgO or Y2O3. The yttria-stabilized zirconia catalyst (5Ni15YZr) provided the optimum activity performance of CH4 and CO2 conversions of 56.1 and 64.3%, respectively, at 700 °C and a 70 mL/min flow rate; this catalyst also had the highest basicity. The Ni-based catalyst was promoted with Cs, Ga, and Sr. The Sr-promoted catalyst produced the highest enhancement of activity. The influence of the reaction temperature and the feed flow rate on 5Ni15YZr and 5NiSr15YZr indicated that the activity increased with the increase in the reaction temperature and lower feed flow rate. For 5Ni3Sr15YZr, at a reaction temperature of 800 °C, the CH4 and CO2 conversions were 76.3 and 79.9%, respectively, whereas at 700 °C, the conversions of CH4 and CO2 were 66.6 and 79.6% respectively