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Regeneration has been considered as an ideal way for the post-treatment of waste FCC catalyst (ECat). In this work, the degeneration mechanism of ECat was firstly researched and attributed to the increasing of strong acid sites accessibility of ECat in contrast with fresh FCC catalyst by adsorption FTIR. Based on the proposed degeneration mechanism, ECat was successfully regenerated through suitable weakening for strong acid sites by boron modification. Characterization and evaluation results suggested that, the strong acid sites of regenerated ECat (R-ECat) were apparently decreased by boron modification which had significantly improve the heavy oil catalytic cracking performance of R-ECat. Because of the excellent performance, R-ECat in this work could successfully substitute for partial fresh FCC catalyst in FCC unit, which would provide a practicable way for the reutilization of ECat. [ABSTRACT FROM AUTHOR]

• Mg species optimized microstructure, active species dispersion and basic sites. • Mg enhanced the ability to capture CO 2 and intermediate active species. • Zr and Mg synergistically promote CO 2 conversion and methanol selectivity. • CO 2 hydrogenation to methanol conforms to the formate path with Mg modification. Optimizing the microstructure of copper-based catalysts for CO 2 hydrogenation to methanol is an attractive and widely reported strategy, but there are still certain barriers to improving both carbon dioxide conversion rate and methanol product selectivity. Herein, Cu/ZnO/ZrO 2 /MgO (CZZ 1-x M x) catalysts were synthesized by co-precipitation method for CO 2 hydrogenation to methanol. Furthermore, the structural features and reaction processes were systematically characterized by XRD, TEM, nitrogen adsorption/desorption, H 2 -TPR, CO 2 -TPD and in-situ DRIFT. The results showed that Mg species optimized the microstructure of the catalyst, increased the dispersion of active species and constructed appropriate basic sites. This further enhanced the capture of reactive species and improved the CO 2 hydrotreating to methanol reaction performance, which was accompanied by a simultaneous increase in CO 2 conversion and methanol yield. It could be convinced that the highest space time yield (STY) of methanol (305.3 g MeOH kg cat −1 h−1) was obtained at 220 °C, WHSV = 18,000 mL g cat −1 h−1 and 3 MPa (X CO2 = 7.28%, S MeOH = 71.8%) for the optimized CZZ 0.8 M 0.2 catalyst, which exhibited twice the CO 2 conversion than Cu/ZnO/ZrO 2. This work elaborated a scheme for the preparation of efficient methanol catalysts. providing reference for the research of CO 2 hydrogenation to methanol process. [Display omitted] It can effectively enhance the adsorption of CO 2 with appropriate Mg added of copper-based catalysts. Moreover, The synergistic effect between Zr and Mg can promote CO 2 conversion and methanol selectivity. [ABSTRACT FROM AUTHOR]