Incorporation of flexible ionic polymers into a Lewis acid-functionalized mesoporous silica for cooperative conversion of CO2 to cyclic carbonates

A rational integration of multiple reactive centers into a combined unit to facilitate their cooperative effects is a smart approach for accelerating the catalytic activity.Here,to achieve this goal,linear imidazolium-based ionic polymers were confined into the nanopores of mesoporous silica nanospheres anchored with homogeneously distributed zinc salts.Owing to the flexible character and the reinforced cooperative effects of the ionic liquid(nucleophile)and zinc species(Lewis acid)in the confined mesoporous structure,the resultant composite exhibited dramatically improved catalytic performance in the cycloaddition of CO2 with epoxides to form cyclic carbonates.This was in contrast to that observed for the individual catalytic components.Moreover,such a solid catalyst could be easily recovered and reused four times without a significant loss of activity.

Preface to Special Issue: CO_2 capture storage and utilization

Reducing the anthropogenic COemissions from fossil resource combustion and human activities has become one of the major challenges we are facing today.Beyond those practical applications for the utilization of CO,such as the synthesis of salicylic acid,methanol,urea,NaHCO-NaCOchemicals and recently developed polycarbonate synthesis,scientists are still seeking new materials and technologies for efficient capture,

A review of carbon dioxide disposal technology in the converter steelmaking process

In last decade,the utilization of CO?resources in steelmaking has achieved certain metallurgical effects and the technology is maturing.In this review,we summarized the basic reaction theory of CO2,the CO2 conversion,and the change of energy-consumption when CO2 was introduced in converter steelmaking process.In the CO2-O2 mixed injection(COMI)process,the CO2 conversion ratio can be obtained as high as 80%or more with a control of the CO2 ratio in mixture gas and the flow rate of CO2,and the energy is saving and even the energy consumption can be reduced by 145.65 MJ/t under certain operations.In addition,a complete route of CO2 disposal technology is proposed combining the comparatively mature technologies of CO2 capture,CO2 compression,and liquid CO2 storage to improve the technology of CO2 utilization.The results are expected to form a large-scale,highly efficient,and valuable method to dispose of CO2.

Carbon dioxide conversion to valuable chemical products over composite catalytic systems

This paper reports an experimental study on catalytic conversion of carbon dioxide to methanol, ethanol and acetic acid. Satalysts having different catalytic functions were synthesized and combined in different ways to enhance the selectivity to desired products. The combined catalyst system possessed the following functions： methanol synthesis, Fischer-Tropsch synthesis, water-gas-shift and hydrogenation. Results showed that the methods of integrating these catalytic functions played an important role in achieving the desired product selectivity. We speculate that if methanol synthesis sites were located adjacent to the C--C chain growth sites, the formation rate of C2 oxygenates would be enhanced. The advantage of using a high temperature methanol catalyst PdZnA1 in the combined catalyst system was demonstrated. In the presence of PdZnA1 catalyst, the combined catalyst system was stable at 380 ~C. It was observed that, at high temperature, kinetics favored oxygenate formation. The results implied that the process can be intensified by operating at high temperature using Pd-based methanol synthesis catalyst. Steam reforming of the byproduct organics was demonstrated as a means to provide supplemental hydrogen. Preliminary process design, simulation, and economic analysis of the proposed CO2 conversion process were carded out. Economic analysis indicates how ethanol production cost was affected by the price of CO2 and hydrogen.

Evaluation of multi-cycle performance of chemical looping dry reforming using CO_2 as an oxidant with Fe–Ni bimetallic oxides

Chemical looping dry reforming（CLDR） is an innovative technology for CO2 utilization using the chemical looping principle.The CLDR process consists of three stages,i.e.CH4 reduction,CO2 reforming,and air oxidation.Spinel nickel ferrite（NiFe2O4） was prepared and its multi-cycle performance as an oxygen carrier for CLDR was experimentally investigated.X-ray diffraction（XRD） and Laser Raman spectroscopy showed that a pure spinel crystalline phase（NiFe2O4） was obtained by a parallel flow co-precipitating method.NiFe2O4was reduced into Fe-Ni alloy and wustite（FexO） during the CH4 reduction process.Subsequent oxidation of the reduced oxygen carrier was performed with CO2 as an oxidant to form an intermediate state：a mixture of spinel Ni（1-x）Fe（2＋x）O4,Fe（2＋y）O4 and metallic Ni.And CO was generated in parallel during this stage.Approximate 185 mL of CO was generated for 1 g spinel NiFe2O4 in a single cycle.The intermediate oxygen carrier was fully oxidized in the air oxidation stage to form a mixture of Ni（1＋x）Fe（2-x）O4 and Fe2O3.Although the original state of oxygen carrier（NiFe2O4） was not fully regenerated and agglomeration was observed,a good recyclability was shown in 10 successive redox cycles.

Facile and controllable synthesis of BaCO_3 crystals superstructures using a CO_2-storage material

We here report a new CO_2 capture and storage method that converts CO_2 into a novel alkyl carbonate salt, denoted as CO_2 SM, by a system consisting of equimolar 1,4-butanediol(BDO) and 1,2-ethylenediamine(EDA). This novel CO_2 SM was then used to prepare BaCO_3 crystals through a simple and fast hydrothermal synthesis under mild conditions. The CO_2 SM was both the source of CO_2 and the modifier to regulate the nucleation and growth of BaCO_3 crystals. The morphology of the BaCO_3 crystals could be tuned from rod to shuttle by adjusting the key influencing factors, including CO_2 SM concentration, mineralization temperature, and mineralization time. A possible mechanism for the synthesis of BaCO_3 crystals from the CO_2 SM was also presented. After the BaCO_3 crystals were isolated, the filtrate of the hydrothermal reaction could be recycled to again absorb CO_2 and prepare BaCO_3 crystals of the same polymorph. This novel approach appears promising for preparing well-formed metal carbonates.

Generation of electricity from CO_2 mineralization: Principle and realization

Current CO2 reduction and utilization technologies suffer from high energy consuming. Thus, an energy favourable route is in urgent demanding. CO2 mineralization is theoretically an energy releasing process for CO2 reduction and utilization, but an approach to recovery this energy has so far remained elusive. For the first time, here we proposed the principle of harvesting electrical energy directly from CO2 mineralization, and realized an energy output strategz1 for CO2 utilization and reduction via a CO2-mineralization fuel cell （CMFC） system. In this system CO2 and industrial alkaline wastes were used as feedstock, and industrial valuable NaHCO3 was produced concomitantly during the electricity generation. The highest power density of this system reached 5.5 W/m2, higher than many microbial fuel cells. The maximum open circuit voltage reached 0.452 V. Moreo- ver, this system was demonstrated viable to low concentration CO2 （10%） and other carhonation process. Thus, the existing of an energy-generating and environmentally friendly strategy to utilize CO2 as a supplement to the current scenario of CO2 emis- sion control has been demonstrated.

An efficient technique for improving methanol yield using dual C02 feeds and dry methane reforming

Steam methane reforming(SMR)-based methanol synthesis plants utilizing a single CO2 feed represent one of the predominant technologies for improving methanol yield and CO2 utilization.However,SMR alone cannot achieve full CO2 utilization,and a high water content accumulates if CO2 is only fed into the methanol reactor.In this study,a process integrating SMR with dry methane reforming to improve the conversion of both methane and CO2 is proposed.We also propose an innovative methanol production approach in which captured CO2 is introduced into both the SMR process and the recycle gas of the methanol synthesis loop.This dual CO2 feed approach aims to optimize the stoichio-metric ratio of the reactants.Comparative evaluations are carried out from a techno-economic point of view,and the proposed process is demonstrated to be more efficient in terms of both methanol productivity and CO2 utilization than the existing stand-alone natural gas-based methanol process.