Accumulation of greenhouse gases especially CO2 in the atmosphere leading to global warming with undesirable climate changes has been a serious global concern. Major power generation in the world is from coal based power plants. Carbon capture through pre- and post- combustion technologies with various technical options like adsorption, absorption, membrane separations, and chemical looping combustion with and without oxygen uncoupling have received considerable attention of researchers, environmentalists and the stake holders. Carbon capture from flue gases can be achieved with micro and meso porous adsorbents. This review covers carbonaceous (organic and metal organic frameworks) and noncarbonaceous (inorganic) porous adsorbents for CO2 adsorption at different process conditions and pore sizes. Focus is also given to noncarbonaceous micro and meso porous adsorbents in chemical looping combustion involving insitu CO2 capture at high temperature (>400 °C). Adsorption mechanisms, material characteristics, and synthesis methods are discussed. Attention is given to isosteric heats and characterization techniques. The options to enhance the techno-economic viability of carbon capture techniques by integrating with CO2 utilization to produce industrially important chemicals like ammonia and urea are analyzed. From the reader's perspective, for different classes of materials, each section has been summarized in the form of tables or figures to get a quick glance of the developments.
The paper presents an attempt to find the possibility of measuring high temperature properties of mould powder slags such as viscosity, break temperature, liquidus temperature during heating as well as solidification start and solidification end temperatures during cooing using ultrasonics. These powders are used in continuous casting of steel and the abnormality in their properties can impact the productivity and quality of the steel products. These properties are in general measured by high temperature rotational viscometers, hot stage microscopes and DTA instruments. Here, the fundamental flexural guided wave mode F(1,1) in a ceramic buffer rod was employed in experiments. The results show the possibility of measuring all the above properties in single experiment by measuring ultrasonic reflection factors during continuous heating and cooling of the mould powders. The advantage of the ultrasonic system is that it can be installed in the plant for online monitoring of these properties. The ultrasonically measured properties of the mould powders supplied by five different suppliers were compared with those measured by rotational viscometers and estimated by mathematical models.
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