Microporous cokes formed in zeolite catalysts enable efficient solar evaporation

Cokes are inevitably generated during zeolite-catalyzed reactions as deleterious side products that deactivate the catalyst. In this study, we in situ converted cokes into carbons within the confined microporous zeolite structures and evaluated their performances as absorbing materials for solar-driven water evaporation. With a properly chosen zeolite, the coke-derived carbons possessed ordered interconnected pores and tunable compositions. We found that the porous structure and the oxygen content in the as-prepared carbons had important influences on their energy conversion efficiencies. Among various investigated carbon materials, the carbon derived from the methanol-to-olefin reaction over zeolite beta gave the highest conversion efficiency of 72% under simulated sunlight with an equivalent solar intensity of 2 suns. This study not only demonstrates the great potential of traditionally useless cokes for solar thermal applications but also provides new insights into the design of carbon-based absorbing materials for efficient solar evaporation.