Utilização de estruturas metalorgânicas como adsorventes de contaminantes sulfurados

Abstract

In this work, new composites of five Metal-organic Frameworks (UiO-66(Zr), MIL-53- TDC(Al), MIL-125-(Ti), MOF-808(Zr) and MIL-101(Cr)) has already described in the literature, were synthesized and applied in adsorptive desulfurization of sulfur compounds present in the acid gas lines of natural gas processing plants. The limitations for application in separation beds of materials originally obtained in a powder form were overcome by adjusting the particle size without compromising the textural properties. The adsorbents were shaped into cylindrical granules about 2−3 mm long, through extrusion, which is a simple and low-cost technique. Compressive strength tests were carried out and, with the exception of the MOF-808(Zr) composite, the shaped materials showed satisfactory mechanical strength values. With the aim of improving the performance in the capture of sulfur compounds (ethanethiol, 2-propanethiol and dimethyldisulfide) present in gaseous streams of carbon dioxide saturated in water, post-synthetic modification techniques of copper impregnation and increase of hydrophobic character were tested. UiO-66(Zr) composites doped with copper through postsynthetic modification were investigated for adsorptive desulfurization, observing an increase of ~330% in the adsorptive capacity of total sulfur for the sample doped with CuO (UiO-66( Zr).CuO-MC) in relation to the undoped sample (UiO-66(Zr)-MC). The regeneration of adsorbents for reuse in adsorption/desorption cycles was investigated for all materials tested for the adsorption of sulfur compounds, with the maintenance of crystallinity after the first cycle being observed in all cases. The MIL-53-TDC(Al) sample could be evaluated in two adsorptive desulfurization cycles, showing a lower adsorption capacity for ethanethiol and 2-propanethiol, but greater performance in the capture of dimethyldisulfide. Throughout this work, attempts were also made to obtain new Metal-Organic Frameworks for adsorptive desulfurization, making it possible to synthesize two metal complexes of magnesium with the ligand 2,5-thiophenedicarbarkoxylate (Mg-TDC.1 and Mg-TDC.6)) using single-crystal X-ray diffraction.