VO x /SBA-15 catalysts with five different vanadium loadings were prepared by a modified wet impregnation method, characterized using N 2 adsorption, XRD, EDX, SEM, Raman and UV-vis spectroscopies and H 2 -TPR techniques, and tested in the oxidative dehydrogenation of propane in the temperature range 450-600 • C. For all the catalysts the propane conversion increases with both reaction temperature and vanadium loading, while the selectivity for propene decreases mainly to the benefit of carbon oxides. Several types of VO x species coexist on the catalyst surface, with monomeric and low-polymerized ones leading mainly to propene, while V 2 O 5 crystallites at high vanadium loadings producing more carbon oxides. Propene was determined to be the only primary product irrespective of the vanadium content.

Five Cu(x)CeMgAlO mixed oxides with different copper contents (x) ranging from 6 to 18 at. % with respect to cations, but with fixed 10 at. % Ce and Mg/Al atomic ratio of 3, were prepared by thermal decomposition of LDH precursors at 750 °C. Cu(15)CeMgAlO was also calcined at 550 and 650 °C. They were characterized by XRD, SEM-EDX, nitrogen adsorption/desorption, H2-TPR, XPS and DR-UV-Vis techniques. Their catalytic properties in the total oxidation of methane were evaluated and compared with those of an industrial Pd/Al2O3 catalyst. Cu(15)CeMgAlO was the most active catalyst in this series, with a T50 value of only ca. 45 °C higher than that of Pd/Al2O3. This difference becomes as low as ca. 25 °C for the Cu(15)CeMgAlO system calcined at 550 °C. The excellent stability on stream of the Cu(15)CeMgAlO catalyst was evidenced.

Transient‐pulse experiments in temporal‐analysis‐of‐product (TAP) and conventional mode were performed to determine elementary reaction steps involved in the methane steam reforming reaction over Rh/Al2O3 and Rh/12 CeO2–Al2O3. TAP pulse experiments demonstrated that both catalysts dissociate methane at 773 K leading to hydrogen, carbon, and CHx adspecies. Conventional transient pulse experiments with alternating methane/argon and water pulses with a delay between them of 86, 73, and 5 s, respectively, showed that the reactivity of adspecies over the promoted and nonpromoted catalysts decrease with time. Ceria catalyzes the oxidation of carbon species by water.

Based on previous Computational Fluid Dynamics (CFD) design results, an 11 channel microreactor of dimensions (0.5 mm × 0.5 mm × 100 mm) (width × depth × length) and optimal manifold geometry was fabricated, coated with a newly-developed Au/SBA-15 catalyst and then integrated in an experimental rig specifically built for this research. Propane (as model volatile organic compound) oxidation experiments were conducted at three different flow velocities, 12.5, 15.4 and 17.5 m/min, respectively, at six temperatures, 150, 200, 225, 250, 275, and 300 °C, respectively. The catalyst was prepared by one-pot sol-gel synthesis of SBA-15 with MPTMS (3-mercaptopropyl-trimethoxy-silane) before loading with HAuCl4 gold precursor and then characterized by SEM/EDX, TEM and wide angle XRD. A novel catalyst coating technique was developed, using airbrush (0.3 nozzle) to spray a catalyst slurry into the microchannels that produced a thin, firm and uniform layer of Au/SBA-15 catalyst coating inside the microreactor. The experimental measurements revealed that propane conversion increased as the flow feed rates decreased and increased with increasing temperatures in the reactor. For the built microreactor and for the flows and temperatures set, the combustion of propane was possible with measurable conversions and reasonable reactor stability, the performance of the catalyst appeared to be central to the satisfactory operation of the reactor.

Gold catalysts, with different particle sizes ranging from 19 to 556 Å, and supported on SBA-15 mesoporous silica, were prepared by using deposition-precipitation, co-precipitation, and impregnation methods. All samples were characterised by TEM, EXAFS, XPS, XRD, CFR (Continuous Flow Reactor), and TPR. The sample which proved to have the highest activity was characterised by TAP (Temporal Analysis of Products) as well. XPS, wide-angle XRD, EXAFS, and H2-TPR measurements and data analysis confirmed that gold was present as Au0 only on all samples. The size of the Au nanoparticle was determined from TEM measurements and confirmed through wide-angle XRD measurements. EXAFS measurements showed that as the Au-Au coordination number decreased the Au-Au bond length decreased. TEM data analysis revealed a dispersion range from 58% (for the smallest particle size) to 2% (for the highest particle size). For Au particles’ sized lower that 60 Å, the Au dispersion was determined using a literature correlation between the dispersion and EXAFS Au-Au coordination number, and was in good agreement with the dispersion data obtained from TEM. The Au dispersion decreased as the particle size increased. CFR experiments validated the relationship between the size of the gold particles in a sample and the sample’s catalytic activity towards acetone oxidation. The lowest temperature for the acetone 100% conversion, i.e., 250 °C, was observed over the reduced catalyst sample with the smallest particle size. This sample not only showed the highest catalytic activity towards acetone conversion, but, at the same time, showed high reaction stability, as catalyst lifetime tests, performed for 25 h in a CFR at 270 °C for the as-synthesised sample, and at 220 °C for the reduced sample, have confirmed. TAP (Temporal Analysis of Products) measurements and data analysis confirmed a weak competitive adsorption of acetone and oxygen over the Au/SBA-15 sample. Based on TAP data, a combination of Eley–Rideal and Langmuir–Hinshelwood mechanisms for acetone complete oxidation was proposed.