Scalable preparation of high-strength hierarchically porous carbon beads with bicontinuous macroporous network by solvent induced phase separation technique for NOx removal

Abstract

The potential of hierarchically porous carbons is drastically limited by their intrinsic fragility, tedious preparation, high cost, and poor processability. Here we develop a novel solvent-induced phase separation technique for fast and continuous preparation of hierarchically macro-/microporous carbon beads (MMCBs). The as-prepared MMCBs show spherical shape with millimeter size, which give the carbons many value-added physical properties such as regular geometry, good mechanical properties, low dust, and good flowability. The MMCBs have a high BET surface area of 1099 m 2 g −1 , and percolating macroporous superstructure with axial-oriented macrovoid channel and sponge-like bicontinuous network issued from solvent-induced macrophase separation and microphase separation, respectively. In addition, the MMCBs have a high nitrogen doing of 4–5 wt% originated from their nitrogen-rich polyacrylonitrile precursor. The MMCBs could directly sever as the metal-free carbon catalysts for room-temperature oxidation of NO to NO 2 with over 80% conversion, and the urea-loaded MMCBs could use for selective catalytic reduction of NO to N 2 with long-time NO x removal. This convenient synthesis to porous carbons with the engineered morphology and percolating macropores has great potential in practical applications where both rapid mass transport and high surface areas are required. Scalable preparation of high-strength porous carbon beads with hierarchically macroporous network by solvent induced phase separation for NOx removal. • Macro/microporous carbon beads with bicontinuous macroporous network were prepared. • The MMCBs have highly spherical shape and millimeter size. • The MMCBs have high strength, high wear resistance, low dust, and good flowability. • The MMCBs could sever as the metal-free catalysts for room-temperature oxidation of NO to NO 2 . • The urea-loaded MMCBs could use for selective catalytic reduction of NO to N 2 .