Effect of Pore Structure on CO2 Adsorption Performance for ZnCl2/FeCl3/H2O(g) Co-Activated Walnut Shell-Based Biochar

Abstract

Walnut shell is a very potential biochar precursor because of its wide source, low cost, and easy structure modification. In this paper, the co-activation method of FeCl3, ZnCl2 and H2O(g) was adopted to prepare walnut shell-based biochar with high microporosity and the effect of pore structure on CO2 adsorption performance at different temperatures was investigated. The prepared biochar had a larger specific surface area (2647.8 m2 g−1), satisfactory micropore area (2008.7 m2 g−1) and high total pore volume (2.58 cm3 g−1). At 273 K and 298 K, its CO2 adsorption capacity was 4.79 mmol g−1 and 3.20 mmol g−1, respectively. Particularly, CO2 adsorbed uptake on biochar was strongly sensitive to their narrow micropore volume, instead of the total specific surface area, total pore volume, and micropore specific surface area. The optimal pore size beneficial for CO2 adsorption was 0.33–0.82 nm at 273 K, but the optimal pore size was 0.33–0.39 nm at 298 K. It provides theoretical guidance for future material preparation and selection, and FeCl3, ZnCl2 and H2O(g) may be effective biochar activators.

Bimetallic Copper–Cerium-Based Metal–Organic Frameworks for Selective Carbon Dioxide Capture

“…When the ratio content of Cu and Ce equaled 1:2, the material showed a higher surface area and larger pore volumes, which might suggest that higher CO 2 adsorption can be expected at an optimized Cu/Ce content of 1:2. 42 The main reason for its superior properties might be due to the introduction of two nodes into the same metal−organic frameworks generates more internal defects. 43 Among the assynthesized bimetallic MOFs, CuCe-BTC-1:2 displays the largest surface area, which may be due to a synergetic effect between two metals at particular Cu/Ce content.…”

“…Notably, the pore volumes of the frameworks manifested a specific trend with a substitution ratio of metal atoms. When the ratio content of Cu and Ce equaled 1:2, the material showed a higher surface area and larger pore volumes, which might suggest that higher CO 2 adsorption can be expected at an optimized Cu/Ce content of 1:2 . The main reason for its superior properties might be due to the introduction of two nodes into the same metal–organic frameworks generates more internal defects .…”