Effects Of Pore Properties Research Articles

SBA-15 Functionalized with Amines in the Presence of Water: Applications to CO2 Capture and Natural Gas Desulfurization

Conventional and pore expanded SBA-15 were amine-grafted under dry and wet conditions using N1-(3-trimethoxysilylpropyl)diethylenetriamine. The effects of pore properties and gas hourly space velocity (GHSV) as well as the CO2 and H2S capture performance were investigated, and the results indicated that pore expanded SBA-15 displayed the best performance. Clumping and agglomeration of SBA-15 were observed for conventional SBA-15 under wet grafting conditions due to interparticle polymerization of amines after pores are completely filled. This phenomenon was not observed for pore expanded SBA-15, resulting in viable adsorbents with greater amounts of grafted amines. Pore expanded SBA-15 exhibited the highest CO2 capacity (3.27 mmol/g), which to the best of our knowledge is the largest for amine-grafted adsorbents. It also exhibited high amine efficiency (0.39 mol CO2/mol N) and faster uptake rates compared to conventional SBA-15 due to enhanced amine accessibility. For direct air capture, higher GHSV values result in lower breakthrough CO2 capacities and the breakthrough CO2 capacity of wet grafted pore expanded SBA-15 is more dependent on GHSV than that of dry grafted pore expanded SBA-15 due to diffusion resistance. Last, conventional SBA-15 displayed a marginally lower H2S adsorption capacity compared to pore expanded SBA-15, suggesting that diffusion resistance does not play a significance role during H2S adsorption. These results suggest the consideration of wet grafted pore expanded mesoporous siliceous supports for the design of promising adsorbents for the capture of CO2 and the removal of H2S from natural gas.

New Li2FeSiO4–carbon monoliths with controlled macropores: effects of pore properties on electrode performance

Monolithic Li2FeSiO4-carbon composites with well-defined macropores have been prepared from the silica-based gels containing Li, Fe, and carbon sources. The macroporous precursor gels can be fabricated by the sol-gel method accompanied by phase separation. A fine control of the macropore size in the resultant composites has been achieved by controlling the macropore size of the precursor gels simply by adjusting the starting compositions. The effects of pore properties on Li insertion-extraction capabilities have been investigated by utilizing the resultant Li2FeSiO4-carbon composites as the cathode of lithium ion batteries. The electrodes prepared from the Li2FeSiO4-carbon composites with different macropore sizes exhibit significant differences in the charge-discharge properties. The results strongly suggest that the smaller macropore size (equal to the thinner macropore skeletons) and the presence of micro- and mesopores in the macropore skeletons (hierarchically porous structure) are desirable for a better electrode in the case of Li2FeSiO4, which has extremely low ionic and electrical conductivities.

Advances in Porous Biomaterials for Dental and Orthopaedic Applications

The connective hard tissues bone and teeth are highly porous on a micrometer scale, but show high values of compression strength at a relatively low weight. The fabrication of porous materials has been actively researched and different processes have been developed that vary in preparation complexity and also in the type of porous material that they produce. Methodologies are available for determination of pore properties. The purpose of the paper is to give an overview of these methods, the role of porosity in natural porous materials and the effect of pore properties on the living tissues. The minimum pore size required to allow the ingrowth of mineralized tissue seems to be in the order of 50 µm: larger pore sizes seem to improve speed and depth of penetration of mineralized tissues into the biomaterial, but on the other hand impair the mechanical properties. The optimal pore size is therefore dependent on the application and the used material.