Hydrocracking of long paraffins over Pt-Pd/WO3-ZrO2 in the presence of sulfur and aromatic impurities

The hydrocracking of long paraffins in the presence of sulfur and aromatic impurities using Pt–Pd/WO3–ZrO2 was assessed. The catalysts were tested for n-hexadecane hydrocraking in the presence and absence of several poisons, benzothiophene, quinolein, carbon disulfide, benzene, and naphthalene. At small impurity levels, aromatics are beneficial for the hydrocracking of long paraffins because they increase the liquid yield and reduce the cracking to light gases. Sulfur compounds were strong poisons of the activity. Benzothiophene was the strongest, producing the highest decline in activity and being more strongly chemisorbed than basic quinolein. Sulfur poisoning drastically affected the hydrocracking activity, indicating that acid isomerization cracking on WO3–ZrO2 follows a bifunctional mechanism with a big influence of the metal function. Incorporation of Pd to Pt/WO3–ZrO2 reduced the sulfur poisoning, with Pt–Pd (3:1)/WO3–ZrO2 being the best catalyst for stable hydrocracking of long paraffins in the presence of sulfur. This catalyst retained most of the activity of the Pt/WO3–ZrO2 parent material while being less affected by sulfur.Fil: Busto, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Grau, Javier Mario. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Sepulveda, Jorge H.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; ArgentinaFil: Tsendra, Oksana. National Academy of Sciences. Chuiko Institute of Surface Chemistry; UcraniaFil: Vera, Carlos Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentin

Influence of the iron content on the arsenic adsorption capacity of Fe/GAC adsorbents

Adsorbents of granular activated carbon doped with iron (Fe/GAC) were synthesized in the laboratory and their capacity for removal of arsenic species was measured by means of techniques of equilibrium adsorption and breakthrough curves. These data were obtained at room temperature and normal pH conditions. The materials were further characterized to determine their chemical composition and texture (specific surface, pore volume distribution). It was found that the adsorbents with 10%, 20% and 30% Fe had a great capacity for arsenic adsorption, showing uptake values of 2000-3500 μg of As per gram of Fe/GAC filter material. Doping with Fe increases the As adsorption capacity of granular activated carbon and the maximum capacity of adsorption is obtained with 10% Fe loading. Higher Fe contents decrease the capacity for arsenic removal. This was related to the decreased pore volume and pore size of the adsorbents with high Fe content. A decrease of surface accessibility due to pore plugging and a higher intraparticle diffusion resistance in the high loaded adsorbents would shift the point of bed breakthrough to lower values of eluted volume.Fil: Sigrist, Mirna Edit. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Investigación y Análisis de Residuos y Contaminantes Químicos; ArgentinaFil: Brusa, Lucila. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Investigación y Análisis de Residuos y Contaminantes Químicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Beldomenico, Horacio Ramon. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Investigación y Análisis de Residuos y Contaminantes Químicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Dosso, Liza Ainalen. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Tsendra, Oksana. National Academy of Sciences. Chuiko Institute of Surface Chemistry; UcraniaFil: Gonzalez, Monica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Pieck, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; ArgentinaFil: Vera, Carlos Roman. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica ; Argentin

Adsorption of Nitrogen-Containing Compounds on the (100) α‑Quartz Surface: Ab Initio Cluster Approach

A cluster approach extended to the ONIOM methodology has been applied using several density functionals and Møller–Plesset perturbation theory (MP2) to simulate the adsorption of selected nitrogen-containing compounds [NCCs, 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4-dinitroanisole (DNAN), and 3-nitro-1,2,4-triazole-5-one (NTO)] on the hydroxyated (100) surface of α-quartz. The structural properties were calculated using the M06-2X functional and 6-31G­(d,p) basis set. The M06-2X-D3, PBE-D3, and MP2 methods were used to calculate the adsorption energies. Results have been compared with the data from other studies of adsorption of compounds of similar nature on silica. Effect of deformation of the silica surface and adsorbates on the binding energy values was also studied. The atoms in molecules (AIM) analysis was employed to characterize the adsorbate–adsorbent binding and to calculate the bond energies. The silica surface shows different sorption affinity toward the chemicals considered depending on their electronic structure. All target NCCs are physisorbed on the modeled silica surface. Adsorption occurs due to the formation of multiple hydrogen bonds between the functional groups of NCCs and surface silanol groups. Parallel orientation of NCCs interacting with the silica surface was found to be favorable when compared with perpendicularly oriented NCCs. NTO was found to be the most strongly adsorbed on the silica surface among all of the considered compounds. Dispersion correction was shown to play an important role in the DFT calculations of the adsorption energies of silica–NCC systems