Because of the growing demand for high-quality fuels, the light cycle oil fraction improvement including cetane number improvement is important. The main way to reach this improvement is the ring opening of cyclic hydrocarbons, and a highly effective catalyst should be found. Cyclohexane ring openings are a possible option to investigate the catalyst activity. In this work, we investigated rhodium-loaded catalysts prepared using the commercially available industrial supports: single-component ones, SiO₂ and Al₂O₃; and mixed oxides CaO + MgO + Al₂O₃ and Na₂O + SiO₂ + Al₂O₃. The catalysts were prepared by incipient wetness impregnation and investigated by N₂ low-temperature adsorption-desorption, XRD, XPS, DRS UV-Vis and DRIFT spectroscopy, SEM, and TEM with EDX. The catalytic tests were performed in cyclohexane ring opening in the range of 275–325 °C. The best result was demonstrated by the sample 1Rh/CaMgAlO: the selectivity to n-hexane was about 75% while the cyclohexane conversion was about 25% at 275 °C. The space-time yield was up to 12 mmol_n-hexane g_cat⁻¹h⁻¹.

A comparative study of the activity and selectivity of monometallic Ir-containing catalysts in ring opening reactions under conditions of thermal and microwave heating is performed using the...

Lignin is an abundant raw material, but its utilization in the synthesis of high-added-value products is a great challenge. Microwave activation provides benefits compared to conventional thermal heating in a variety of processes, including catalytic reactions of oxidation and hydrogenation/hydrocracking. Herein, we utilize low-power resonant microwave radiation (5.7 GHz, ≤10 W) to activate and transform lignin, resulting in a significant decrease in the reaction temperature for the onset of catalytic processes compared to conventional thermal activation. The reaction of microwave-assisted partial oxidation of lignin on an Mo_1.0V_0.37Te_0.17Nb_0.12O₃ catalyst yields a synthesis gas product with 57.6% CO selectivity and near-complete lignin conversion at 310–340 °C. The MW-activated hydrocracking of lignin on Pt/C catalysts yields methoxyphenols, alkylated derivatives, as well as light aromatic and aliphatic C₆–C₁₀ hydrocarbon products with a high yield at 260–290 °C. The energy-efficient microwave-assisted approach significantly lowered reaction temperatures compared to conventional heating, highlighting its potential for sustainable lignin valorization.

Chromium-substituted aluminophosphate (CrAPO-5) with the AFI crystal structure was prepared for the first time by using microwave conditions at the stage of gel formation and crystallization. This approach allowed the reduction of the time required for the synthesis of CrAPO-5 from 60–70 h to 6 h. CrAPO-5 metal aluminophosphate prepared by microwave-assisted synthesis is studied by UV-visible and IR spectroscopy and X-ray photoelectron spectroscopy. The material is characterized by the presence of Cr³⁺ and Cr²⁺ ions in the framework with predominating Cr³⁺ ions introduced via isomorphous substitution, as well as some minor amounts of extra-framework Cr³⁺ species, which are present presumably in the state of α-Cr₂O₃. The latter species can be partially reduced to Cr²⁺ species in the presence of CO or H₂. XPS study of CrAPO-5 revealed the presence of Cr³⁺ ions in the framework. A TPR experiment showed that the reduction of chromium starts at about 450–500 °C.