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Hierarchical zeolites have the potential to provide a breakthrough in transport limitation, which hinders pristine microporous zeolites and thus may broaden their range of applications. We have explored the use of Pd-doped hierarchical ZSM-5 zeolites for aerobic selective oxidation (selox) of cinnamyl alcohol and benzyl alcohol to their corresponding aldehydes. Hierarchical ZSM-5 with differing acidity (H-form and Na-form) were employed and compared with two microporous ZSM-5 equivalents. Characterization of the four catalysts by X-ray diffraction, nitrogen porosimetry, NH 3 temperature-programmed desorption, CO chemisorption, high-resolution scanning transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy allowed investigation of their porosity, acidity, as well as Pd active sites. The incorporation of complementary mesoporosity, within the hierarchical zeolites, enhances both active site dispersion and PdO active site generation. Likewise, alcohol conversion was also improved with the presence of secondary mesoporosity, while strong Brønsted acidity, present solely within the H-form systems, negatively impacted overall selectivity through undesirable self-etherification. Therefore, tuning support porosity and acidity alongside active site dispersion is paramount for optimal aldehyde production.

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The catalytic conversion of CO2 to CH4 and CO over nickel particles supported on layered-double hydroxide (MgAl) with different metal promoters was investigated under non-thermal plasma (NTP) conditions. It has been shown that lanthanum-promoted Ni catalysts significantly enhanced the CO2 conversion in comparison to the 10Ni/MgAl catalyst (33.4% vs. 89.3%). In comparison, for the potassium-promoted catalysts, CO2 conversion is similar to that of 10Ni/MgAl but the CO selectivity increased significantly (35.7% vs. 62.0%). The introduction of La and K to Ni catalysts increased the Ni dispersion and improved the reducibility of Ni species, thus affecting CO2 conversion and product selectivity. In situ DRIFTS showed similar reaction pathways for La- and K- promoted catalysts with Ni catalysts. However, the La and K promoters significantly improved the formation of formate species on the Ni surface, facilitating CO2 conversion to useful products.

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