Nano-Ru deposited on titanium oxide as effective photocatalyst for synthesis of cyclic ketals

We designed and synthesized the 1–4% Ru/TiO2 system as a cost-efficient catalyst for the acetalization of the polyol-ketone reactants without the additional acidic or organic cosolvent addition. A comprehensive characterization of the catalyst was performed by EDXRF, XPS, XRD, TEM, UV–Vis/DR and TOF-SIMS techniques. We elucidated the reaction mechanisms by analyzing the influence of Ru NP concentration on TiO2, reactants structure, and UV lamp power on the conversion rate, selectivity, yield, and TON values. The 2% Ru/TiO2 catalyst proved to be the most active in a model reaction with photoassistance, exhibiting the highest TON value of 5272. This outcome underscores the synergistic activation achieved through the combination of ruthenium and titania. More detailed analysis reveals a dual mechanism, wherein photocatalytic oxygen vacancy formation in TiO2 plays a crucial role. This mechanism involves the continuous vacancy feeding by the reactant oxygen, driving the progression of the reaction. The kinetics calculation identified a second-order process as the rate-determining region. Tests conducted on post-reaction mixtures using the pervaporation technique affirmed the potential use of PervapTM 4100 and PervapTM 4100HF polymer membranes for selective water separation. Additionally, we tested the selected cyclic ketals as the 95-octane gasoline additives, analyzing their impact on various parameters, such as octane number, motor octane number, induction period, and air pollutant CO, NOx emissions. The results suggest that the synthesized neutral gasoline fuel additives could serve as bio-additives, aligning with current legal regulations and contributing to a reduced carbon footprint.