Selective Reduction of NO with CO Over Titania Supported Transition Metal Oxide Catalysts

A series of transition metal oxides promoted titania catalysts (MO _x /TiO₂; M = Cr, Mn, Fe, Ni, Cu) were prepared by wet impregnation method using dilute solutions of metal nitrate precursors. The catalytic activity of these materials was evaluated for the selective catalytic reduction (SCR) of NO with CO as reductant in the presence of excess oxygen (2 vol.%). Among various promoted oxides, the MnO _x /TiO₂ system showed very promising catalytic activity for NO + CO reaction, giving higher than 90% NO conversion over a wide temperature window and at high space velocity (GHSV) of 50,000 h⁻¹. It is remarkable to note that the catalytic activity increased with oxygen, up to 4 vol.%, under these conditions leading primarily to nitrogen. Our TPR studies revealed the presence of mixed oxidation states of manganese on the catalyst surface. Characterization results indicated that the surface manganese oxide phase and the redox properties of the catalyst play an important role in final catalytic activity.     

Numerical analysis of convective heat transport in a porous semi‐trapezoidal enclosure with radiation effect

A theoretical and numerical study of natural convection of two‐dimensional laminar incompressible flow in a semi‐trapezoidal porous enclosure in the presence of thermal radiation is conducted. The semi‐trapezoidal enclosure has an inclined left wall that in addition to the right vertical wall is maintained at a constant temperature, whereas the remaining (horizontal) walls are adiabatic. The Darcy‐Brinkman isotropic model is utilized. The governing partial differential equations are transformed using a vorticity stream function and nondimensional quantities and the resulting governing nonlinear dimensionless equations are solved using the finite difference method with incremental steps. The impacts of the different model parameters (Rayleigh number [Ra], Darcy number [Da], and radiation parameter [Rd]) on the thermofluid characteristics are studied in detail. The computations show that convective heat transfer is enhanced with the greater Darcy parameter (permeability). The flow is accelerated with the increasing buoyancy effect (Rayleigh number) and heat transfer is also increased with a greater radiative flux. The present numerical simulations are more relevant to hybrid porous media solar collectors.     

Effect of replacement of castor oil and polychloroprene by chlorinated paraffin in butyl compounds of tyre‐curing bladder

Ways are explored to increase the life and to reduce the cost of tyre‐curing bladders by improving their mechanical and ageing properties. Nine formulations have been designed which involve the partial replacement of polychloroprene (PC) and castor oil (CO), both individually and simultaneously, by chlorinated paraffin (CP) in the butyl bladder compound. The compounds have been tested for various cure properties such as initial torque, minimum torque, scorch time, optimum cure time, cure rate, maximum torque and reversion time. The vulcanized samples have been tested for mechanical properties such as tensile stress at 300 % elongation, tensile strength at break, ultimate elongation, rubber deterioration by dynamic fatigue test and Shore‐A hardness before and after ageing. The results show that tensile strength at break and ultimate elongation decrease, while tensile stress at 300 % elongation increase except in one case (when PC was partially replaced by CP). Simultaneous and individual replacement of CO by CP results in a decrease in hardness of up to 3 phr (base recipe CO 5 phr), whereas further replacement of CO by CP results in an increase in hardness. Tensile stress at 300 % elongation and Shore‐A hardness increase up to a limit while tensile strength at break and ultimate elongation decrease with ageing. © 2000 Society of Chemical Industry     

Effect of system optimizing conditions on biohydrogen production from herbal wastewater by slaughterhouse sludge

The study evaluates the biohydrogen production from herbal wastewater as the substrate by the enriched mixed slaughterhouse sludge as the seed source. In the following experiments, batch-fermentations are carried out with the optimum substrate concentrations, fermentation pH and fermentation temperature to observe the effects of H₂ production, hydrogen yield and other fermentation end products at different conditions. The hydrogen production is increased as substrate concentration increased up to 8 g COD/L WW, but drastically decreased at 10 g COD/L WW. When the pH of fermentation is controlled to 6.5, a maximum amount of hydrogen yield could be obtained. The hydrogen production is maximum at 50 °C (930 ± 30 mL/L WW) compared to 30 °C (436 ± 16 mL/L WW). Acid-forming pathway with butyric acid as a major metabolite dominated the metabolic flow during the hydrogen production. The experimental results indicated that effective hydrogen production from the herbal wastewater could be obtained by thermophilic acidogenesis at proper operational conditions.     

Clean development mechanism as a solution to the present world energy problems and a new world order: a review

One of the important responses of Kyoto Protocol towards mitigation of global warming is the clean development mechanism (CDM) that has garnered large emphasis amidst the global carbon market in terms of certified emission reduction (CER). CERs are the carbon credits issued by the CDM executive board for emission reductions achieved by CDM projects and verified by designated operational entity (DOE) under the rules of the Kyoto Protocol. While CDM aims to achieve sustainable development in energy production and consumption in developing countries, the results achieved through its implementation are still uncertain. More than 400 studies have been undertaken since 1997 on the CDM. Albeit, hitherto no compilations of key issues pertaining to the CDM and different points of views on its implementation and achievement have been attempted. This paper envisages to assess the contributions of the CDM towards sustainable development and its impact in various sectors.     

Bismuth Sulfonate Immobilized on Silica Gel for Allylation of Aldehydes and Synthesis of Homoallylic Amines

Catalytic allylation of aldehydes and the synthesis of homoallylic amines using bismuth sulfonate immobilized on silica gel in presence of allyltributylstannane are reported for the first time. The reaction proceeds smoothly with the aid of benzoic acid as an additive and provides corresponding homoallylic alcohols and homoallylic amines in good yields. The catalyst can be reused five times without significant loss of the catalytic activity. Bismuth Sulfonate Immobilized on Silica gel for Allylation of Aldehydes and Synthesis of Homoallylic Amines.     

Transient Thermal Behavior and Stress Development within a Cylindrical Wooden Disk during Drying in a Fluidized Bed Dryer

Thermal behavior and stresses developed in a wood particle are predicted using a mathematical model formulated for drying in fluidized bed. Drying experiments have been carried out on 10 mm long and 30 mm diameter cylindrical disks at a bed temperature of 403 K (130°C). Drying time, mass reduction, and shrinkage during drying have been measured and used to validate the thermal model. The stress model is validated with an analytical solution available in literature. The drying time is experimentally found to be 630 s. The wood particle shrinks by 4.6% in the radial direction and by 1.0% in the longitudinal direction. The model indicates splitting failure at the circumference, which was also noticed during experiments.     

Comparative Evaluation of Genetic Programming and Neural Network as Potential Surrogate Models for Coastal Aquifer Management

Determining the optimal rates of groundwater extraction for the sustainable use of coastal aquifers is a complex water resources management problem. It necessitates the application of a 3D simulation model for coupled flow and transport simulation together with an optimization algorithm in a linked simulation-optimization framework. The use of numerical models for aquifer simulation within optimization models is constrained by the huge computational burden involved. Approximation surrogates are widely used to replace the numerical simulation model, the widely used surrogate model being Artificial Neural Networks (ANN). This study evaluates genetic programming (GP) as a potential surrogate modeling tool and compares the advantages and disadvantages with the neural network based surrogate modeling approach. Two linked simulation optimization models based on ANN and GP surrogate models are developed to determine the optimal groundwater extraction rates for an illustrative coastal aquifer. The surrogate models are linked to a genetic algorithm for optimization. The optimal solutions obtained using the two approaches are compared and the advantages of GP over the ANN surrogates evaluated.