Novel amine impregnated ZSM-5/KIT-6 composites exhibited excellent CO2 adsorption performance.

CO2 adsorption curves of A-BK-TEPA-50 at 40, 60, 75, 80 and 90 °C.

No abstract

Mesoporous silica pore-expanded KIT-6 was synthesized using tetraethoxysilane (TEOS) as the silica source, tri-block copolymer (P123) as a structure-directing agent and 1,3,5-trimethylbenzene (TMB) as swelling agents by a hydrothermal method. Then, pore-expanded KIT-6 (PE-KIT-6) was modified with different amounts of amines including triethylenetetramine (TETA) and tetraethylenepentamine (TEPA) by a post-synthetic impregnation method. The samples were characterized by small-angle X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption, elemental analysis and thermal gravimetric analysis (TGA). Experimental results revealed that the modifiers were introduced into the samples and the CO2 adsorption capacity increased first and then decreased with the increase of TETA/TEPA loadings. Under the same loadings of TETA/TEPA, the samples modified by TEPA exhibited better CO2 adsorption capacities than the samples modified by TETA because TEPA has one more amine group than TETA in the molecule. The results also indicated that the samples had good adsorption capacities at the loadings ranging from 30% to 35%. Among them, the sample modified by TEPA with the loading of 35% had the maximum adsorption capacity of 2.9[Formula: see text]mmol/g. After five cycles of adsorption/desorption, the adsorption capacity only dropped 4.59%, indicating that the adsorbent of PE-KIT-6 modified by TEPA has good cyclic stability.

An amine double functionalized composite strategy is used to fabricate grafted‐impregnated micro‐/mesoporous composites for CO2 capture. The micro‐/mesoporous three‐dimensional cross straight zeolite and cubic silica structural ZSM‐5/KIT‐6 composite is used as a support, N1‐(3‐trimethoxysilylpropyl)diethylenetriamine (TMPTA) is used as the grafted component, and tetraethylenepentamine (TEPA) or branched polyethyleneimine (PEI) is used as the impregnated component. The amine efficiency, adsorption kinetics, enthalpy of adsorption, thermal stability, regeneration performance, the effects of types of impregnated amines (TEPA or PEI) and loadings (30–60 %), and temperatures (60–90 °C) on CO2 adsorption performance are investigated using thermal gravimetric analyzer (TGA) in the mixed gases (15 % CO2 and the balance is N2). At 75 °C, the double functionalized sample with TEPA impregnation displays the highest CO2 adsorption capacity of 6.28 mmol g−1 even at high TEPA loading of 60 %, while that of 4.69 mmol g−1 is obtained for the PEI‐impregnated compound at PEI loading of 50 %. The former has higher amine efficiency and faster kinetics as well as higher enthalpy. The composites demonstrate excellent CO2 adsorption performance compared to other amine double functionalized silicas, indicating the prospect of these adsorbents for CO2 capture from actual flue gas after desulfurization (60–85 °C).