Efficient Selective Catalytic Fixation of CO₂ into Epoxide to Form Cyclic Carbonates Using Sodium Aluminate Engineered Gamma Alumina Catalyst

Abstract

The anthropogenic carbon dioxide (CO 2 ) fixation and various engineering strategies are gaining very significant attention because of the expansion of the net‐zero carbon environment in the atmosphere. Herein, we designed a sodium aluminate@γ‐alumina (NaAlO 2 @γ‐Al 2 O 3 ) catalyst by a simple and facile precipitation and impregnation tactics. A series of different weight percentage NaAlO 2 @γ‐Al 2 O 3 materials were successfully synthesized and well characterized by using advanced analytical and spectroscopic techniques such as TGA, XRD, FE‐SEM, TEM/HR‐TEM, FT‐IR, Raman, TPD, and XPS analysis. The NaAlO 2 @γ‐Al 2 O 3 catalyst was employed as a competent catalyst for the CO 2 fixation under atmospheric pressure reaction conditions. The catalytic activity results evidently revealed that the cycloaddition reaction successfully achieved 94% styrene oxide conversion and 93% selectivity, along with an 87% yield of the styrene carbonate at 120 °C for 6 h. Furthermore, we comprehensively examined the effect of different reaction parameters such as the effect of sodium aluminate amount, co‐catalyst amount, temperature, and time for CO 2 fixation reaction. Additionally, different terminal and internal epoxides were tested under optimized reaction conditions and achieved moderate to excellent yield of the desired cyclic carbonate products. Interestingly, a plausible reaction mechanism was proposed for the styrene carbonate synthesis using NaAlO 2 @γ‐Al 2 O 3 catalyst surface with the support of characterization and experimental results. Remarkably, the NaAlO 2 @γ‐Al 2 O 3 catalyst could be easily recoverable and successfully recyclable up to six consecutive cycles without declining its initial catalytic activity along with stable structural and physicochemical properties.

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