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The adsorption of refractory sulfur molecule 4,6-Dimethyldibenzothiophene (4,6-DMDBT) over copper supported on zirconia, using different copper loadings (2-10% w/w) and a zirconia support with a high specific surface area, was studied. The results showed that the adsorption capacity of 4,6-DMDBT over Cu/ZrO 2 increased with copper content, reaching a maximum at around 8% Cu (0.58 mmol 4,6-DMDBT per gram of adsorbent). The results of characterizations with H 2 -TPR, Electrophoretic Migration, and XRD demonstrated that this Cu loading (8%) also corresponds to a maximum copper dispersion capacity for ZrO 2 support. Also, these absorbents showed considerable selectivity toward the adsorption of 4,6-DMDBT in a feed stream also containing Quinoline, decreasing adsorption capacity of 4,6-DMDBT by only 35%, despite both molecules being present in the same concentrations. The results of this work showed that desulfurization adsorption using Cu/ZrO 2 adsorbents can be an effective method to remove this type of refractory sulfur molecules, and an excellent alternative as a complementary process for deep desulfurization in the fuel industry.

In this work we have carried out the adsorption of pyridine using three different supports (activated carbon, SiO 2 and γ-Al 2 O 3 ). After choosing the best support, due to its higher adsorption capacity, we have impregnated the support with nickel at three different concentrations (2, 4 and 6% w/w) by wet impregnation to study the adsorption of pyridine by π-complexation. All the samples (supports and adsorbents) were characterized by N 2 adsorption-desorption by the BET method and electrophoretic migration. The experimental results, for the three different supports, show that the adsorption capacity is better for γ-Al 2 O 3, due to its higher isoelectric point. With the incorporation of nickel, no better adsorption capacities are observed, due that the nickel incorporation diminish the zero point charges of the adsorbents. Adsorption, denitrogenation, nickel, pyridine. e-mail: patricio.baeza@pucv.cl Keywords: INTRODUCTIONCrude oil is the largest and most widely used source of energy in the world and projections assure that this will continue until at least 2050. Overexploitation of existing fields, has led to crude oils known as "Barrel Fund", composed of high molecular weight hydrocarbons which are of lower quality, as they are much heavier and therefore difficult to purify in the petroleum refining industry. The combustion of petroleum containing nitrogen compounds emits NOx into the atmosphere, which directly contributes to the production of acid rain and Photochemical Smog. Therefore, environmental regulations are becoming more stringent with regard to the maximum level of nitrogen molecules that petroleum may contain; this has caused refiners to seek new methods that allow them to eliminate nitrogenous molecules. These nitrogen containing molecules are more resistant to the existing process used in the refining industry to remove them. This hydrotreating process is called hydrodenitrogenation (HDN) and it operates at elevated temperatures and pressures, which are efficient in removing simple nitrogen molecules, but not for the removal of "refractory molecules". Nitrogenous compounds present in the petroleum may vary depending on the origin of the oil field. Despite this, the predominant compounds consist of substituted pyrrole and pyridine, which containing aromatic rings of 5 and 6 members, respectively 1 . At present, petroleum is composed of alkylated nitrogenous organic molecules, on some part of the aromatic ring, which are refractory to the HDN process 2,3 .It should be noted that the catalysts used in petroleum refining for the HDN reaction are Ni-Mo/γ-Al 2 O 3 or Co-Mo/γ-Al 2 O 3 catalysts, where Co and Ni promote the activity of MoS 2 , but an important point is that these catalysts are also active in the hydrodesulfurization (HDS) reaction, and furthermore, both reactions are carried out in the same reactor with an unique catalyst, and in the case of nitrogen containing compounds, their removal is highly recommended to ensure successful HDS. It is these nitrogen compounds that inhibi...

This study analyses the hydrodenitrogenation (HDN) of pyridine using a stacked bed catalyst system, composed of a first hydrogenating bed of Re/γ-Al 2 O 3 or W/γ-Al 2 O 3 , over a second bed of Ni-Re/γ-Al 2 O 3 (HDN bed). Using potentiometric methods, it can be seen that the Re/γ-Al 2 O 3 shows higher acidic strength than the W/γ-Al 2 O 3 . The results show that higher activity levels are obtained working with stacked bed systems compared to the separate catalysts. These results suggest that the incorporation of the catalyst Re/γ-Al 2 O 3 or W/γ-Al 2 O 3 beds would favour the formation of hydrogenated intermediary products, facilitating the removal of N-containing molecules via HDN on the Ni-Re/γ-Al 2 O 3 catalyst.