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Here, we report novel lignin-poly­(ε-caprolactone)-based polyurethane bioplastics with high performance. The poly­(ε-caprolactone) (PCL) was incorporated as a biodegradable soft segment to the lignin by the bridge of hexamethylene diisocyanate (HDI) with long flexible aliphatic chains and high reactivity. The effects of -NCO/-OH molar ratio, content of lignin, and molecular weight of the PCL on the properties of the resultant polyurethane plastics were thoroughly evaluated. It is important that the polyurethane film still possessed high performance in the tensile strength, breaking elongation, and tear strength, which could reach 19.35 MPa, 188.36%, and 38.94 kN/m, respectively, when the content of lignin reached as high as 37.3%; moreover, it was very stable at 340.8 °C and presented excellent solvent-resistance. The results demonstrated that the modification of the lignin based on the urethane chemistry represents an effective strategy for developing lignin-based high-performance sustainable materials.

A series of nanosheet MgO-based sorbents promoted by mixed-alkali-metal nitrate and carbonate were prepared by a simple precipitation–deposition method and applied to CO2 capture. The structural properties of these sorbents were characterized by various techniques, and their CO2 capture performance was evaluated using a thermogravimetric analyzer. Compared to the sorbent derived from commercial MgO, the nanosheet MgO-based sorbent had faster and higher CO2 uptake, because of its thin-sheet structure. Among various alkali-metal-salt-promoted nanosheet MgO, the sorbents promoted with mixed-alkali-metal nitrates (LiNO3 and KNO3) and carbonates (Na2CO3 and K2CO3) exhibited a high total CO2 uptake at a respectable rate. In particular, the sorbent with a MgO content of 73 wt % and a nitrate/carbonate molar ratio of 2 possessed the highest total CO2 uptake and the best cyclic stability, with a total uptake of 0.52 gCO2 /gsorbent and MgO conversion of 65% after 20 cycles (60 min of absorption in 40% CO2/60% N2 at 350 °C, 15 min of regeneration in 100% N2 at 400 °C). Based on the structure–activity relationship of the sorbents, a possible mechanism consisting of three stages was presented for the CO2 absorption process, in which the dissolution of CO2 and carbonation in the molten nitrate played an important role.

As a potential candidate for precombustion CO capture at intermediate temperatures (200-400 °C), MgO-based sorbents usually suffer from low kinetics and poor cyclic stability. Herein, a general and facile approach is proposed for the fabrication of high-performance MgO-based sorbents via incorporation of CaCO into MgO followed by deposition of a mixed alkali metal salt (AMS). The AMS-promoted MgO-CaCO sorbents are capable of adsorbing CO at an ultrafast rate, high capacity, and good stability. The CO uptake of sorbent can reach as high as above 0.5 g g after only 5 min of sorption at 350 °C, accounting for vast majority of the total uptake. In addition, the sorbents are very stable even under severe but more realistic conditions (desorption in CO at 500 °C), where the CO uptake of the best sorbent is stabilized at 0.58 g g in 20 consecutive cycles. The excellent CO capture performance of the sorbent is mainly due to the promoting effect of molten AMS, the rapid formation of CaMg(CO), and the plate-like structure of sorbent. The exceptional ultrafast rate and the good stability of the AMS-promoted MgO-CaCO sorbents promise high potential for practical applications, such as precombustion CO capture from integrated gasification combined cycle plants and sorption-enhanced water gas shift process.

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