The multi-step reactions for the synthesis of C8 aldehydes and alcohol from propene in a single pot using an eco-friendly multi-functional catalyst system: Kinetic performance for parametric optimization

Kinetics of multi-step reactions including hydroformylation, aldol condensation and hydrogenation was carried out in a single pot for optimization of the reaction parameters for the synthesis of C8 aldehydes and alcohol from propene using an eco-friendly multi-functional heterogeneous catalyst system [HF/HT] where [HF] = rhodium complex, HRh(CO)(PPh3)3 and [HT] = hydrotalcite, Mg1−xAlx(OH2)x+(CO32−)x/n·mH2O. The catalyst [HF/HT] was synthesized by impregnation of [HF] onto the surface of [HT]. In the typical catalytic experiments conducted in a 100 mL high pressure reactor under the employed reaction conditions: propene = 10 atm, CO = 5 atm, H2 = 15 atm, [HF/HT] = 700 mg, HT/HF ratio = 7, Mg/Al molar ratio of [HT] = 3.5, aldol temperature = 250 °C, reaction time = 12 h, agitation speed = 1000 rpm, and in 50 mL toluene as a solvent, 68.4 × 10−3 M of 2-ethylhexanol with 18% selectivity was achieved. The rates of reactions were determined by analyzing the amounts of products formed at different time using gas chromatography. Kinetics of the various reactions were performed in detail by investigating the effect of reaction parameters such as Mg/Al molar ratio of [HT] at aldol temperature 150 and 250 °C, amount of [HT] and [HF] complex, aldol temperature, partial pressure of CO and H2 on the rates of formation of products namely, 2-ethylhexanol, 2-ethylhexanal, 2-ethylhexenal, butanals and butanols. The rates of reactions were found to be influenced by all these studied parameters. On increasing these parameters, the rates of formation of the products and their further conversions in single pot were favored.

Graphical abstractKinetics of multi-step reactions including hydroformylation, aldol condensation and hydrogenation was studied for the synthesis of C8 aldehydes and alcohol from propylene in a single pot using [HF/HT] as a multi-functional heterogeneous catalyst. The rates of hydroformylation and aldol condensation with [HF/HT(3.5)] were observed to be 2.5 and ∼3 times respectively, higher than those associated with [HF+KOH].Figure optionsDownload full-size imageDownload as PowerPoint slide