Effect of interparticle forces on the fluidization of fine particles

Report studies elucidation and description of effect of interparticle forces on feasibility of gaseous fluidization of particles below 50 microns in diameter. Interparticle forces are determined by inclined-plane method. Study indicated that fluidizability is related to the interparticle adhesive force

Kinetics of ammonia oxidation over Pt foil studied in a micro-structured quartz-reactor

The kinetics of Pt-catalyzed ammonia oxidation on polycrystalline Pt were investigated at partial pressures of ammonia and oxygen up to 6 kPa and temperatures between 286 and 385 °C, applying a micro-structured reactor that ascertained temperature control of the exothermic reaction. Using literature-based mechanistic models, a micro-kinetic model was derived based on parameter optimization and a model discrimination procedure. The model described the rates of formation of all nitrogen-containing products, i.e. N2, N2O and NO. Catalyst characterization of platinum samples by electron microscopy indicated that reaction-induced restructuring of the Pt surface limited the accuracy of derived kinetic parameters already at the low temperature applied in this work. Despite of necessary simplifications, the best-fitting kinetic model predicted reasonable product selectivities for the reaction conditions of an industrial ammonia burner

Computing the correlation between catalyst composition and its performance in the catalysed process

The methodology for computing correlations between continuous descriptors of catalytic materials and their performance in the catalysed process is addressed. Continuous descriptors are typically molar fractions of individual components of the catalyst, whereas the performance is represented most frequently by yield or selectivity of reaction products or conversion of key feed components. Measures of various kinds of correlation are recalled, and their descriptor-wise application to catalytic data for computing correlations between the composition and performance of catalysts is presented. The paper also compares the application of correlation measures to catalytic data on the one hand with the analysis of variance, on the other hand with the application of regression trees. As a case study, the presented approaches are applied to data from high-temperature synthesis of hydrocyanic acid

Economic Assessment of the Hydrogenation of CO₂ to Liquid Fuels and Petrochemical Feedstock

To remove high concentrations of CO2 from the off-gas of coal-driven power plants, a new process was proposed. The catalytic hydrogenation of the CO2 leads to the production of C2 – C4 (petrochemical feedstock) and liquid C5+ hydrocarbons (fuel). Thus, environmentally harmful CO2 may be converted sustainably to useful products. On the basis of a process flow sheet, the costs for processing the CO2 are estimated for different plant sizes. The price of hydrogen contributes significantly to the overall production costs. Further price reductions may be achieved by final engineering optimization of the process as a whole and specific unit operations

Effects of low pressure exhaust gas recirculation on regulated and unregulated gaseous emissions during NEDC in a light-duty diesel engine

Regulated and unregulated gaseous emissions with high pressure and low pressure EGR (exhaust gas recirculation) system were tested in a 4-cylinder, light-duty diesel EURO IV engine typically used in European vehicles. Four different engine calibrations with the low pressure EGR system were studied. Regulated emissions of NOX, CO, HC and CO2 were measured for each configuration. Unburned Hydrocarbon Speciation, HCHO (formaldehyde), HCOOH (formic acid) and N2O (nitrous oxide) were also measured in order to determine the MIR (maximum incremental reactivity) of the gaseous emissions. Pollutants were measured without the DOC (diesel oxidation catalyst) to gather data about raw emissions. When the low pressure EGR system was used, decreases in NOX, N2O and fuel consumption were observed and significant increases HC, CO and unregulated emissions; this is the result of a lower intake manifold temperature, which provides a higher gas density which modifies the combustion process. The potential of tropospheric ozone production was higher in all cases when the low pressure EGR was used. © 2011 Elsevier Ltd.Bermúdez, V.; Luján, JM.; Pla Moreno, B.; Linares Rodríguez, WG. (2011). Effects of low pressure exhaust gas recirculation on regulated and unregulated gaseous emissions during NEDC in a light-duty diesel engine. Energy. 36(9):5655-5665. doi:10.1016/j.energy.2011.06.061S5655566536

Basic solids as catalysts for the oxidative coupling of CH4. (To be published) (38p.)

The effects of basicity and acidity of various solid materials when applied as catalysts for the oxidative coupling of CH4 to C2+ hydrocarbons are described and discussed. The solids used consisted of PbO carried on various support materials partly doped with sodium oxide, alkaline earths, alkali/alkaline earths compound mixtures, and La2O3-CaO. Surface acidity is detrimental to C2+ selectivity while basicity is a requirement for promoting the formation of C2+ hydrocarbons. There appears, however, to exist a cooperative effect between strong basic sites and the acidic sites simultaneously present favoring C2+ selectivity. Supplementary to the relationship between C2+ selectivity and basicity/acidity the corresponding relevance of the electrone-activity of binary oxides applied as catalysts is discussed.