Effects of Modifying Acidity and Reducibility on the Activity of NaY Zeolite in the Oxidative Dehydrogenation of n-Octane

Abstract

Non-coking stable alkaline earth metal (M = Mg, Sr, and Ba) modified Ga-NaY catalysts were prepared by ionic-exchange and tested in oxidative dehydrogenation (ODH) of n-octane using air as the source of oxygen. The role of the alkaline earth metals in NaY was to poison the acid sites while enhancing the basic sites responsible for ODH. The exception was the calcium modified NaY, which was more acidic than the parent NaY, coking and unstable under the ODH conditions used in this study. The role of gallium was to enhance the dehydrogenation pathway and improve the stability of NaY. The sequence of increasing selectivity to octenes followed the order: CaGa-NaY < Ga-NaY< MgGa-NaY < SrGa-NaY < BaGa-NaY. The highest octene selectivity obtained was 37% at iso-conversion of 6 ± 1% when BaGa-NaY was used at a temperature of 450 °C. The activity of the catalysts was directly proportional to the reducibility of the catalysts, which is in agreement with expectations.

Effects of Framework Disruption of Ga and Ba Containing Zeolitic Materials by Thermal Treatment

“…The IR assignments for the two prepared catalysts are similar to previously reported faujasite type zeolitic materials (Figure S2) [12]. The shifts of the IR bands observed between the two spectra obtained can be attributed to change in lattice parameters induced by the substitution of aluminum with gallium.…”

“…n-Octane was chosen as the representative medium to long chain alkane, which are very abundant and of low value. The ODH reaction was studied because it offers an interesting and less energy-intensive route for the production of olefins from paraffins by rendering the reaction exothermic as a result of the insertion of an oxygen source into the reaction, thus suppressing the thermodynamic constraints [12].…”

Influence of Composition of Nickel‐Iron Nanoparticles for Abiotic CO2 Conversion to Early Prebiotic Organics

“…As seen in Figure 4, TPD profiles of Ni and Ni 3 Fe show a large amount of desorbed CO 2 at temperature values of around 200 °C, which indicates the existence of moderate interactions. [66] CO 2 binding strengths on the Ni and Ni 3 Fe look very similar, whereby a small shift to higher temperatures in the desorption signal of Ni 3 Fe was observed, which hints an increase of binding strength of CO 2 . No noticeable CO 2 desorption signal was observed above 200 °C for Ni and Ni 3 Fe samples.…”

“…CO 2 temperature‐programmed desorption (TPD) analysis can provide some insights about the interactions of CO 2 with the surface of solid catalysts, as well as temperature induced desorption profile of the CO 2 molecule. As seen in Figure 4, TPD profiles of Ni and Ni 3 Fe show a large amount of desorbed CO 2 at temperature values of around 200 °C, which indicates the existence of moderate interactions [66] . CO 2 binding strengths on the Ni and Ni 3 Fe look very similar, whereby a small shift to higher temperatures in the desorption signal of Ni 3 Fe was observed, which hints an increase of binding strength of CO 2 .…”

Enhanced Catalytic Oxidation of Toluene over Hierarchical Pt/Y Zeolite

“…The adsorption of toluene increases with the number of acidic sites, thereby increasing the surface coverage of toluene on the catalyst and facilitating the catalytic oxidation reaction [38]. The low temperature (100-250 • C) ammonia desorption peak in the NH 3 -TPD curve corresponds to the weak acid sites, the high temperature (400-600 • C) peak corresponds to the strong acid sites, and the intermediate temperature (250-400 • C) peak corresponds to the medium acid sites [39]. Table 3 presents the number of acidic sites represented by each peak.…”