Processi di desolforazione mediante l'utilizzo di adsorbenti e catalizzatori solidi

The sulfur content in fuels is an environmental concern because upon combustion sulfur is converted to SOx, which not only contributes to acid rain, with have a negative effect on human health and in the environment, but also poisons catalytic converters for the treatment of exhaust emissions, which are very expensive due to are based on noble metals Adsorption of organo-sulfur compounds present in liquid fuels on metal–organic framework (MOF) compounds is an efficient alternative to the conventional hydrodesulfurization process. Metal Organic Frameworks (MOFs) are hybrid organic/inorganic crystalline porous materials with unique characteristics with respect to other porous materials (i.e. carbons, silica and zeolites), such as the possibility of tuning the structure during the synthesis, very large surface areas, porosity and a fully accessible internal volume. The void space within these stable network structures can be available to fix guest molecules, being the number of possible MOF/guest combinations practically infinite. A huge variety of applications as “materials for energy” are currently being explored for different types of MOFs. Among these, some MOFs have shown attractive properties as adsorbent materials for organosulfur compounds present in liquid fuels. In this work, it is presented some results on the 4,6-DMDBT adsorption capacity exhibited by the Copper (II) benzene-1,3,5-tricarboxylate MOF (Cu-BTC) obtained through a ball-milling synthesis. Two different methods, called Neat Grinding (NG) and Liquid Assisted Grinding (LAG), were used to prepare NG-MOF and LAG-MOF-compounds, respectively. The chemical–physical features of both samples were analysed by X-ray powder diffraction, thermal analyses and N2 adsorption at 77K. Preliminary results on 4,6-DMDBT liquid-phase adsorption at ambient temperature have shown a higher adsorption capacity, for our ball-milled MOFs in comparison to other previously tested adsorbents. In particular, the LAG-MOF exhibits an adsorbing capacity of the S-compound about two times higher with respect to the analog commercial Basolite-C300 by BASF. It is also presented a study on Ni-Mo and Co-Mo sulphides supported on siliceous materials for the catalytic HDS reaction using thiophene as a model compound is presented here. Pure SBA-15 and silicas, as well as Al-modified SBA-15 and MAS-5, were used as supports, due to the well known structural and textural stability of such mesoporous materials under the HDS reaction conditions. Transition metal oxides were added by wetness impregnation method and alternative impregnation by two solvents techinques, using ammonium molybdate, cobalt nitrate, and nickel nitrate as precursors.