Coke deposited on catalytic cracking catalysts has been investigated by continuously monitoring evolved CO and CO 2 during temperature-programmed oxidation (TPO) in a 1% O 2 /N 2 mixture. Analyses were carried out on spent samples recovered from an industrial catalytic cracker and on coke prepared in the laboratory by exposure of fresh catalyst to 1-hexene and cyclohexene at 500°C. A maximum of three peaks in the rate of carbon dioxide evolution and one carbon monoxide peak are apparent in the TPO spectra. The small lowest temperature CO 2 peak, which is only observed for the TPO of the spent catalyst, is assigned to either highly reactive coke or coke in the vicinity of trace metals. Two larger overlapping CO 2 peaks occur at higher temperatures and are attributed to competing coke oxidation mechanisms. The first of these larger peaks coincides with the CO evolution, while for the final peak only CO 2 evolution prevails. This reduction in CO and increase in CO 2 are also observed for the TPO of powdered charcoal. The temperature dependence of carbon oxide evolution is attributed to changes in the combustion rate-determining steps due to different pre-exponential factors and activation energies. This indicates that the combustion reaction mechanism can affect the shape of the TPO spectra and so must be included in the interpretation of catalytic coke oxidation data.

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The rearrangement of 3-methyl-2-oxetanone (lactone) into methacrylic acid has been explored using DFT methods. Calculations were performed for (i) intramolecular, (ii) lactone-lactone and (iii) water and phosphomolybdic acid catalyzed conversions. The water and acid surface catalyzed route exhibited the lowest activation barrier (156 kJ mol -1 ) of the three reaction pathways and overall is slightly endothermic (DH f = 37 kJ mol -1 ).

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Titanium-doped indium tin oxide thin films were synthesized via a sol-gel spin coating process. Surface chemical bonding states and mechanical properties have been investigated as a function of titanium content (2 and 4 at%) and annealing temperature ranging from 400 to 600 °C with increments of 100 °C. Raman analysis was performed to study the phonon vibrations for the prepared samples and the results revealed the existence of ITO vibrational modes. The elemental compositions, bonding states and binding energies of the film materials were investigated using X-ray photoelectron spectroscopy (XPS) technique. The XPS results indicated that the ratio of the metallic elements (In, Sn, Ti) to the oxygen on the surface of the thin film coatings decreased due to the increase of the oxide layer on the surface of the thin films. Also, by increasing the annealing temperature up to 600 °C, the Ti 2p and Cl 2p signals were no longer detected for both 2 and 4 at% Ti contents, respectively, due to the thicker surface oxidation layer. Mechanical properties of the synthesized films were also evaluated using a nanoindentation process. Variations in the hardness (H) and the elastic modulus (E) were observed with different Ti at% and annealing temperatures. The hardness is within the range of 6.3–6.6 GPa and 6.7–6.8 GPa for 2 and 4 at% Ti content samples, respectively, while the elastic modulus is within the ranges of 137–143 and 139–143 GPa for 2 at% and 4 at% Ti contents samples, respectively. A combination of the highest H and E were achieved in the sample of 4% Ti content annealed at 600 °C. Furthermore, the H/E ratio ranges from 4.5 × 10−2 to 5.0 × 10−2 which reflects a reasonable level of wear resistance