From Spent Lithium-Ion Batteries to Low-Cost Li4SiO4 Sorbent for CO2 Capture.

The huge consumption of fossil fuels leads to excessive CO2 emissions, and its reduction has become an urgent worldwide concern. The combination of renewable energies with battery energy storage, and carbon capture, utilization, and storage are well acknowledged as two major paths in achieving carbon neutrality. However, the former route faces the discard problem of a large amount of lithium-ion batteries (LIBs) due to their limited lifespan, while it is costly to obtain effective CO2-capturing materials to put the latter into implementation. Herein, for the first time, we propose a route to synthesize low-cost Li4SiO4 as CO2 sorbents from spent LIBs, verify the technical feasibility, and evaluate the CO2 adsorption/desorption performance. The results show that Li4SiO4 synthesized from the cathode with self-reduction by the anode graphite of LIBs has a superior CO2 capacity and cyclic stability, which is constant at around 0.19 g/g under 15 vol % CO2 after 80 cycles. Moreover, the cost of fabricating sorbents from LIBs is only 1/20-1/3 of the conventional methods. We think this work can not only promote the recycling of spent LIBs but also greatly reduce the cost of preparing Li4SiO4 sorbents, and thus could be of great significance for the development of CO2 adsorption.

Density Functional Theory Studies on the Hydrolysis of Levoglucosenone to 5-Hydroxymethylfurfural.

Selective conversion of lignocellulosic biomass-derived chemicals is of critical significance for sustainable fine and commodity chemical industries. Cellulose-derived levoglucosenone (LGO) has a promising potential for producing 5-hydroxymethylfurfural (HMF) with a substantial yield under acid conditions, but the mechanism is unidentified. Herein, we disclose the mechanism of LGO conversion to HMF in the aqueous phase without and with H2SO4 as a catalyst by density functional theory (DFT) calculations for the first time. Results showed that LGO first forms 6,8-dioxabicyclo[3.2.1]-octane-2,4,4-triol (DH) via two sequential hydration reactions occurring at the C═C bond and then the ketone group. The use of H2SO4 as a catalyst significantly reduced the free energy barriers of LGO and DH conversion to HMF, with a free energy barrier of 115 kJ/mol for LGO → HMF compared to that of 91 kJ/mol for DH → HMF, demonstrating that DH is easier for HMF formation.

Experimental and DFT studies on oxygen release and migration mechanisms of LaAl-type perovskites as catalyst supports in biomass-to-H2 conversion.

Perovskites are potential candidates for catalyst supports in biomass gasification to produce high-purity H2 due to their excellent redox properties. However, the significant mechanism of lattice oxygen release and migration in perovskites has not been clearly understood. In this work, the characteristics of surface oxygen release and subsurface oxygen migration in various LaAl-type perovskites were investigated by experiments and density functional theory calculations. Results show that the oxygen release capacity of La0.7Sr0.3AlO3-δ is considerable and that of Ni/La0.7Sr0.3AlO3-δ decreases slightly compared to the difficult occurrence of oxygen release in LaAlO3. Moreover, the rate-limiting step of oxygen release from pure LaAlO3 is determined to be the formation of O2 complex by two opposite O atoms. Sr doping reduces the charge of the outermost O atom, making oxygen release easy, and the desorption process of O2 becomes the rate-limiting step. After Ni loading, the strength of the surrounding Al-O bond increases, which raises the energy barrier and blocks the release of oxygen to some extent.

Synthesis of CaO-based sorbents for CO(2) capture by a spray-drying technique.

Highly effective and durable CO(2) sorbents were synthesized with different calcium and support precursors using a spray-drying technique. It was found that spray-drying could be a useful technique for producing sorbents with enhanced cyclic performance, especially when d-gluconic acids of calcium and magnesium were used. Seven sorbents were synthesized with five calcium precursors and three inert solid precursors, and the sorbent made from calcium d-gluconte monohydrate and magnesium d-gluconate hydrate with 75 wt % CaO content achieved a high CO(2) sorption capacity of 0.46 g of CO(2)/g of calcined sorbent at the 44th cycle of carbonation and calcination.

Fabrication of CaO-based sorbents for CO2 capture by a mixing method.

Three types of sorbent were fabricated using various calcium and support precursors via a simple mixing method, in order to develop highly effective, durable, and cheap CaO-based sorbents suitable for CO(2) capture. The sorption performance and morphology of the sorbents were measured in a thermogravimetric analyzer and a scanning electron microscopy, respectively. The experimental results indicate that cement is a promising low-cost support precursor for contributing to the enhancement of cyclic CO(2) sorption capacity, especially when organometallic calcium precursors were used. A sorbent (with 75% CaO content) made from calcium l-lactate hydrate and cement showed the highest CO(2) sorption capacity of 0.36 g of CO(2)/g of sorbent and its capacity decreased only slightly after 70 cycles of carbonation and calcination.