Jaroslav Aubrecht

Hydrodeoxygenation (HDO) of lignin-derived phenolics offers a sustainable pathway for producing sustainable aviation fuels (SAF) and value-added chemicals. In this study, anisole was employed as a model compound to investigate HDO over Ni supported on SBA-15 and AlSBA-15. AlSBA-15 supports with varying Al contents were synthesized via direct and post-synthesis methods, both of which led to the incorporation of framework and extra-framework Al species to enhance HDO. Increasing Al content in AlSBA-15 resulted in lower specific surface area, decreased NiO reducibility, and a higher density of Lewis and Brønsted acid sites. Anisole conversion was found to be directly proportional to Ni reducibility, making AlSBA-15 with lower Al content the preferred catalyst support. The presence of Brønsted acid sites in AlSBA-15 enhanced selectivity toward C₆ deoxygenation products (cyclohexane and benzene) by accelerating the demethoxylation of methoxycyclohexane. However, the catalysts with Lewis and especially Brønsted acid sites were found to lack initial stability, and Ni/SBA-15 was found to be the most stable catalyst. Nickel incorporation via the chemisorption–hydrolysis method produced smaller, more uniformly dispersed, and more readily reducible Ni particles than wet impregnation, resulting in higher anisole conversions. Product selectivity, however, was independent of Ni crystallite size and the metal incorporation method.

Two supports (ZnO, ZrO ₂ ) and four promoters (Al ₂ O ₃ , ZnO, CoO _x , NiO) were investigated to design environmentally-friendly Cu-based hydrogenolysis catalysts.

This paper is an overview of the scientific results that have been achieved during the development of a sustainable hydrogenolysis catalyst. The paper describes the effects of various synthesis methods and their parameters, as well as the effect of diverse promoters and supports on the catalyst structure, activity and selectivity in the hydrogenolysis of dimethyl adipate. From the green chemistry point of view, a suitable alternative to the Adkins catalyst was found on the laboratory scale. Tento článek je přehledem vědeckých výsledků dosažených v průběhu vývoje udržitelného hydrogenolýzního katalyzátoru. V práci jsou popsány vlivy různých metod přípravy katalyzátoru včetně jejich jednotlivých kroků a efekt různých promotorů a nosičů na strukturu, aktivitu a selektivitu katalyzátoru pro hydrogenolýzu dimethyl-adipátu. Z pohledu zelené chemie byla v laboratorním měřítku nalezena vhodná alternativa k Adkinsovu katalyzátoru.

CuZn catalysts are perspective catalysts for esters hydrogenolysis, but more knowledge is needed to optimize their catalytic performance. In this work, we consider the impact of CuZn catalysts composition on their structure, activity, selectivity, and stability in esters hydrogenolysis. Four catalysts with various Cu/Zn ratio were synthesized by a co-precipitation and characterized in as-prepared, calcined, reduced, and spent state by XRF, XRD, N₂ physisorption, CO₂-TPD, NH₃-TPD, and N₂O chemisorption. XRD data revealed the effect of the composition on the size of Cu and ZnO particles. The catalytic performance was investigated using an autoclave. All catalysts exhibited high methyl hexanoate conversion about 48–60% after 3 h but their activity and selectivity were found to be dependent on Cu/Zn ratio. The conversion of methyl hexanoate and hexyl hexanoate was compared to explain the observed product selectivity. Moreover, the catalysts stability was investigated in three consecutive reaction cycles and correlated with changes in the size of constituent particles. Moreover, when different esters were tested, a slight decrease in conversion and increase in alcohol selectivity with a growth in molecule size was observed. Obtained results allow making a conclusion about the optimal composition that provides the good performance of CuZn catalysts in ester hydrogenolysis.