Dimethyl carbonate (DMC) and propylene glycol (PG) synthesis through a methanol and propylene carbonate (PC) reaction, also referred to as a transesterification reaction, is a new and green alternative to other routes, such as phosgene methanolysis, urea methanolysis, etc. In this paper, the titanium–praseodymium-based catalyst prepared via the co-precipitation method has been used to improve the yield and selectivity of DMC production. Different combinations of catalysts were synthesized, referred to as Ti0.99Pr0.01, Ti0.97Pr0.03, Ti0.96Pr0.04, and Ti0.95Pr0.05, according to the molar ratio of Ti with respect to Pr. The catalysts have been studied and analyzed through various characterization techniques, such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The Brunauer–Emmett–Teller (BET) surface area and pore volume diameter have been studied through N2 adsorption–desorption using BET and Barrett–Joyner–Halenda (BJH) models, respectively. The basicity was determined through the carbon dioxide temperature-programmed desorption (CO2-TPD) for understanding the reaction mechanism. The reaction was carried out in the batch reactor, keeping the temperature range of 160–180 °C and the molar ratio of methanol/PC in the range of 3–10. The study has also been made on oxygen vacancy concentrations in the mixed oxide catalysts as a result of the mixing of Pr with Ti, thereby affecting the yield and selectivity of DMC. The maximum yield of DMC was obtained with the Ti0.96Pr0.04 catalyst at a temperature of 170 °C which resulted in the PC conversion of 81.7%, turnover frequency (TOF) of 0.120 h–1, and selectivity of 71.6% for DMC.
In the presence of specific catalysts made using the coprecipitation approach, methanol and propylene carbonate (PC) react to yield dimethyl carbonate (DMC) as well as propylene glycol (PG) through the transesterification process. The catalytic activity of mixed zirconium and praseodymium oxides (Zr 1−x Pr x O 2 , x = 0.01−0.05), synthesized by coprecipitation, was investigated in this work towards the formation of DMC and PG. The process involves the transesterification of methanol and propylene carbonate to occur in a batch reactor. Numerous methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and CO 2 -TPD have been used to characterize the catalysts. The goal of the study is to ascertain how the combination of praseodymium and zirconium affects the yield and selectivity of DMC. DFT calculations have been performed for the catalytic system. Becke's hybrid three-parameter nonlocal exchange functional (B3), the Lee−Yang−Parr (LYP) correlation functional (B3LYP), and the SDD basis set were all used to optimize the geometries. Zr 0.96 Pr 0.04 O 2 was found to have the best PC conversion (95.9%), while its yield and selectivity were 52.5% and 54.7%, respectively, at 165 °C, methanol/PC ratio = 6.5, and time of 3 h.
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