Abstract
The impregnation of phosphotungstic acid (HPW) with porous cobalt-cerium oxide (HPW@CoCeO) has been prepared by pyrolysis of CoCe-MOF and used for the production of methyl oleate from oleic acid and methanol. FTIR, XRD, SEM, TEM, N2 adsorption/desorption, and NH3-TPD were characterized for the prepared composites. Simultaneously, the effects of reaction time, substrate molar ratio, temperature, and catalyst loading on catalytic activity were highlighted, and the conversion of 67.2% was reached after 4 h at 60°C. Importantly, HPW@CoCeO was reusabe and reused more than eight times, and the oleic acid conversion could be maintained at 61.8% without significant activity loss. Thus, the HPW@CoCeO composite could be used as acid catalysts for sustainable energy production.
Highlights
No diffraction peaks of HPW can be observed from HPW@CoCeMOF and HPW@cobalt-cerium oxide (CoCeO) samples, indicating HPW uniformly occupies the matrix frame. e result is similar to our previous reports [27]
XRD patterns of the HPW@CoCeO sample display the intensity of the CoCeMOF sample characteristic peaks decreased or even disappeared, and two strong diffraction peaks at 18.2° and 28.7° are assigned to cobaltosic oxide and cerium oxide, respectively [28], implying that the CoCe-metal-organic frameworks (MOFs) transformed to CoCeO after pyrolysis. is indicates that the HPW@ CoCeO catalyst was successfully synthesized
E FTIR spectra for the HPW and HPW@CoCeO were characterized to illustrate the HPW had been embedded in the CoCeO framework, and the results are presented in Figure 2. e strong spectra at 750 cm−1 were ascribed to the Ce-O bonds [29], and the spectra in the range of 500–580 cm−1 were assigned to the Co-O bonds [30]
Summary
After cooling to room temperature, the resultant precipitation was centrifuged and washed two times using DMF and distilled water, respectively, to get the catalyst precursor, HPW@CoCe-MOF, and dried at 100°C overnight under an air atmosphere. The HPW@CoCe-MOF was calcined in air at 350°C with 5°C min−1 heating rate and kept for 3 h to obtain the composite catalyst, which are designated as HPW@CoCeO. CoCe-MOF and cobalt-cerium oxide (CoCeO) were synthesized through a similar procedure without HPW. A mixture of oleic acid, methanol, and HPW@CoCeO catalyst was placed in a 50 mL round flat-bottom flask, heated by using oil bath equipped with a reflux condenser for several hours at an appropriate temperature and vigorously agitated by magnetic stirring. Excess methanol and water produced were evaporated from the liquid product and analyzed via the acid value to get the esterification conversion, and the acid value was determined by using the ISO 660-2009 standard
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
