Page - 115 - in Advanced Chemical Kinetics

therebyanchoring it to the alumina support. Goldwas loaded onto the supports as described elsewhere [14]. 2.3.Catalyst testingconditions Catalyst testing forglycerol oxidationwasperformedat 90 C(with temperatureoptimisedat 60and90 C)andoxygenpressurekeptat8.5barusingaglass-linedParrreactor (model4563), in batchmode under agitationwith stirrer speed kept constant at 1000 rpm, using 0.5 g of catalyst for 10 g of glycerol dissolved in 90 g of de-ionizedwater. To this solution, NaOH pelletswere added such that themole ratio of glycerol to the basewas always 1:2. In-depth details areprovidedelsewhere [14]. 2.4.Catalyst characterisation 2.4.1.High resolution transmission electronmicroscopy (HRTEM) HRTEManalysiswasconductedonafieldemissionmicroscope, the JEM2100Felectronmicro- scope from JEOL Ltd., fittedwith energy-dispersive X-ray spectroscopy (EDX), wavelength dispersive spectroscopy (WDS)andelectronbeambackscattereddiffraction (EBSD)operating on Oxford Instruments software. The instrument was operated at an accelerating electron beamof 200kVand images captured in thebright fieldmode.TheNano-measurer 1.2 ‘Scion Imager’ softwarewasused forparticle sizeanalysis. 2.4.2.Temperatureprogrammeddesorption (TPD) Theacidityofthematerialswasqualitativelymeasuredbytemperatureprogrammeddesorption (TPD)ofNH3onamicromeriticsautomatedcatalyst characterisationsystem:modelAutoChem II2920chemisorptionanalyser.NH3-TPDstudieswereperformedbyloading0.25gcatalyst ina U-tube reactor and cleaning the sample in a gas stream of helium at 120 C for an hour at a ramping rateof 10 Cmin 1 to removemoistureandother adsorbedspecies.Amixtureof 10% NH3balanced inHewas flushedover the sample isothermally at 120 C.After adsorptionwas achieved at 120 C, the NH3 desorption measurements ensued at 120 C using the thermo- conductivitydetector (TCD)anddatacollectedupto500 Catarampingrateof15 Cmin 1. 2.5.Modelsandcomputationalmethods 2.5.1.Kinetic parameter estimation The regression analysis of the experimental datawas performed by use of Easy Regression Analysis (ERA 3.0) software [15, 16]. The software uses the sum of the square of residual deviations as the objective function. All the kinetic parameters were estimated at a 95% confidence limitusingamodifiedadaptive randomsearchalgorithm. 2.5.2.DFTmethodology Unlessotherwisestated,allelectronicenergiesofreactants,productsandtransitionstateswere determined by density functional theory (DFT) using the DMol3 code [17, 18] within the Oxidation of Glycerol to Lactic Acid by Gold on Acidified Alumina: A Kinetic and DFT Case Study http://dx.doi.org/10.5772/intechopen.70485 115