Synthesis of CaO/ZrO2 based catalyst by using UiO-66(Zr) and calcium acetate for biodiesel production

Ca2+ ion leaching and poor pore structure are obstacles of CaO for biodiesel production. To this end, a typical Zr-based metal organic framework, UiO-66(Zr) is adopted to support calcium acetate to prepare CaO/ZrO2 catalyst. For comparison, catalyst precursor is activated in nitrogen (UCN) and air (UCA) atmosphere, respectively. Preparation factors including calcium acetate addition and activation temperature are evaluated. Moreover, effects of transesterification parameters on oil conversion are investigated and the optimized parameters are further used to examine catalyst reusability. Meanwhile, catalysts are characterized with TG, XRD, XPS, FTIR, Hammett indicator titration, N-2 adsorption and desorption. Results reveal UCN calcined at 650 degrees C (UCN650) and UCA calcined at 700 degrees C (UCA700) separately exhibits the best catalytic performance. The maximum conversion of 96.99% is achieved by UCN650 with catalyst amount of 6 wt% and molar ratio of methanol to oil of 9 at 65 degrees C for 60 min. Even after being used 3 cycles, conversion of 92.76% is still achieved by UCN650. By contrast, UCA700 shows lower conversion of 92.94% at the first cycle with catalyst amount of 8 wt% and molar ratio of methanol to oil of 9 at 65 degrees C for 60 min. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a Zr-based metal organic framework, UiO-66 (Zr), was used as a catalyst support to prepare CaO/ZrO2 catalyst, overcoming the issues of Ca2+ ion leaching and poor pore structure of CaO in biodiesel production. The results showed that the UCN650 and UCA700 catalysts exhibited excellent catalytic performance, with UCN650 achieving the highest conversion rate and maintaining a high conversion rate even after multiple cycles of use.