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Decomposition Study of Praseodymium Oxalate as a Precursor for Praseodymium Oxide in the Microwave Field.

ABSTRACT: Micron-sized praseodymium oxide powders are prepared successfully from the praseodymium oxalate in a microwave field at 750 °C for 2 h in the present study. X-ray diffraction (XRD) analysis demonstrates that the presence of cubic structured crystalline Pr6O11 and complete decomposition of the precursor are confirmed by Fourier transform infrared (FT-IR) analysis. The scanning electron microscopy (SEM) results show yield powders with the desired particle size and uniform morphologies. Particle size analysis demonstrates that the median diameter (D 50) becomes stable at 750 °C. The D 50, average surface area, pore diameter, and pore volume calculated by Brunauer -Emmett-Teller (BET) are 4.32 ?m, 6.628 m2/g, 1.86 nm, and 0.026 cm3/g at 750 °C for 2 h, respectively. Moreover, loss on ignition (L.O.I.) analysis indicates that the L.O.I. is as low as 0.39%, meeting the enterprise requirement (<1%). In comparison, conventional calcination experiments are carried out in the electric furnace. Both XRD and FT-IR analyses are in consistence with thermogravimetry-differential scanning calorimetry, which indicates that the temperature required for the decomposition of praseodymium oxalate hydrate is higher than that of microwave heating. Furthermore, SEM, particle size distribution, and BET analysis indicate that agglomeration generates, particle size enlarges, and average surface area increases. In all, it is confirmed that preparing rare-earth oxides from rare-earth oxalates is feasible using microwave heating to replace conventional heating.

SUBMITTER: Lv P

PROVIDER: S-EPMC7469113 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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Decomposition Study of Praseodymium Oxalate as a Precursor for Praseodymium Oxide in the Microwave Field.

Lv Peng P Zhang Liangjing L Koppala Sivasankar S Chen Kaihua K He Yuan Y Li Shiwei S Yin Shaohua S

ACS omega 20200821 34

Micron-sized praseodymium oxide powders are prepared successfully from the praseodymium oxalate in a microwave field at 750 °C for 2 h in the present study. X-ray diffraction (XRD) analysis demonstrates that the presence of cubic structured crystalline Pr<sub>6</sub>O<sub>11</sub> and complete decomposition of the precursor are confirmed by Fourier transform infrared (FT-IR) analysis. The scanning electron microscopy (SEM) results show yield powders with the desired particle size and uniform mor ...[more]

PMID: 32905250

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Project description:The terpolymerization of carbon dioxide (CO?), propylene oxide (PO), and cyclohexene oxide (CHO) were performed by both random polymerization and block polymerization to synthesize the random poly (propylene cyclohexene carbonate) (PPCHC), di-block polymers of poly (propylene carbonate?cyclohexyl carbonate) (PPC-PCHC), and tri-block polymers of poly (cyclohexyl carbonate?propylene carbonate?cyclohexyl carbonate) (PCHC-PPC-PCHC). The kinetics of the thermal degradation of the terpolymers was investigated by the multiple heating rate method (Kissinger-Akahira-Sunose (KAS) method), the single heating rate method (Coats-Redfern method), and the Isoconversional kinetic analysis method proposed by Vyazovkin with the data from thermogravimetric analysis under dynamic conditions. The values of ln k vs. T-1 for the thermal decomposition of four polymers demonstrate the thermal stability of PPC and PPC-PCHC are poorer than PPCHC and PCHC-PPC-PCHC. In addition, for PPCHC and PCHC-PPC-PCHC, there is an intersection between the two rate constant lines, which means that, for thermal stability of PPCHC, it is more stable than PCHC-PPC-PCHC at the temperature less than 309 °C and less stable when the decomposed temperature is more than 309 °C. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and thermogravimetric analysis/infrared spectrometry (TG/FTIR) techniques were applied to investigate the thermal degradation behavior of the polymers. The results showed that unzipping was the main degradation mechanism of all polymers so the final pyrolysates were cyclic propylene carbonate and cyclic cyclohexene carbonate. For the block copolymers, the main chain scission reaction first occurs at PC-PC linkages initiating an unzipping reaction of PPC chain and then, at CHC?CHC linkages, initiating an unzipping reaction of the PCHC chain. That is why the T-5% of di-block and tri-block polymers were not much higher than that of PPC while two maximum decomposition temperatures were observed for both the block copolymer and the second one were much higher than that of PPC. For PPCHC, the random arranged bulky cyclohexane groups in the polymer chain can effectively suppress the backbiting process and retard the unzipping reaction. Thus, it exhibited much higher T-5% than that of PPC and block copolymers.

Dataset Information

Decomposition Study of Praseodymium Oxalate as a Precursor for Praseodymium Oxide in the Microwave Field.

Publications

Decomposition Study of Praseodymium Oxalate as a Precursor for Praseodymium Oxide in the Microwave Field.

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