ABSTRACT Aqueous amine solutions are benchmark solvents for CO2 capture and their operational drawbacks are well-known. In order to overcome these problems, the support of amines on solid materials appears as an option for CO2 capture. Cellulose is a versatile and low-cost material that can be used as a support. This study reports chemical modification of cellulose fibers extracted from rice husk with different amines and their potential for CO2 capture. The obtained compounds were characterized by different techniques. The CO2 sorption capacity was gravimetrically assessed in a Magnetic Suspension Balance. Quantum mechanical simulations and experimental results revealed that -NH- and -NH2 represent major working sites of the employed compounds. The best result for CO2 sorption was attained for the amine-modified cellulose CL-D-400 with a sorption capacity of 409 µmol CO2/g at 1 bar and 1091 µmol CO2/g at 10 bar with amine concentrations as low as 2 × 10- 6 mol/mg.

The study of environmentally friendly CO2 sorption agents are growing due to the need of mitigate this gas from atmosphere. Ionic Liquids (ILs) present the advantage of having low vapor pressures and being chemically and thermally stable. Besides, their properties can be designed by varying the groups of the cation or anion. Yet, these compounds present a lower desorption energy when compared to amines based chemical solvents. These characteristics make ILs potentially important for the development of new processes focused on the mitigation of global warming. However, ILs have high viscosity and high cost, making them economically unfeasible. To minimize these problems, bubble glass can be used as an additive in ionic liquids to reduce cost and viscosity. Bubble glass has several applications in industry, presenting low cost and high chemical and mechanical resistance. This work evaluated the CO2 solubility in [bmim][BF4] and [mbmim][Tf2N] pure and mixed with boron silicate bubble glass in volumetric concentrations of 5% to 50%. Data are reported at 27 bar of pressure and temperatures of 303 and 323 K. Mixed systems with 50% concentration of bubble glass showed the best sorption results for both ionic liquids.

Embora tecnologias de captura e armazenamento de carbono (CCS) estejam recebendo grande atenção para a mitigação do efeito estufa, ainda existem muitas desvantagens, tais como o aumento dos custos e gastos de energia associados à sua implementação. No entanto, o uso de CO2 como bloco de construção C1 em síntese orgânica pode ser muito atraente para o desenho de processos ecológicos. Neste trabalho, foram estudados a sorção de CO2 e atividades catalíticas de alguns líquidos iônicos (ILs) base imidazólio para síntese de carbonato cíclico. O trabalho demonstra que a presença de um grupo nucleófilo no sistema catalítico pode melhorar seu desempenho, através da utilização de um IL com ânion halogenado ou por mistura de co-catalisador halogenado com ILs. A última abordagem permitiu a obtenção de um sistema de captura de CO2 eficaz, constituída por IL fluorado mais ZnBr2 que realiza a síntese de carbonato cíclico com 90% de rendimento e 82% de seletividade.

Although the carbon capture and storage (CCS) technologies are receiving great attention for mitigation of greenhouse gas effect, the increasing costs and energy penalties associated to its implementation are still major drawbacks. However, the use of CO2 as a C1 building block in organic synthesis can be very attractive for the design of environmentally friendly processes. In this work, we have studied both the CO2 sorption and catalytic activities of some imidazolium based ionic liquids (ILs) for cyclic carbonate synthesis. The work demonstrates that the presence of a nucleophilic group in the catalytic system can enhance its performance by the use of an IL with a halide anion or by mixing a halide co-catalyst with ILs. The latter approach allowed to obtain an effective system for CO2 capture constituted by a fluorinated IL plus ZnBr2 that performs cyclic carbonate synthesis with 90% yield and 82% of selectivity.