The purpose of this research is to evaluate, at a molecular level, the removal of nitrogen compounds from vacuum gas oil (VGO), which is used as feedstock for fluid catalytic cracking units. Here, a VGO sample was treated with two different adsorbents: an argillaceous material specifically developed for the removal of nitrogen compounds in middle distillate cuts (kerosene and diesel) and a commercial silica adsorbent. Breakthrough curves were built on two temperature levels (80 and 150 °C), containing different rupture times (from 60 to 420 min), to determine their influence on nitrogen compound removal. All samples, produced from each condition of adsorption, were analyzed by positive and negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry [ESI(±)­FT-ICR MS]. Besides FT-ICR MS characterization, the total nitrogen content was monitored. FT-ICR MS indicated that the removal of nitrogen compounds by the clay adsorbent was enhanced when the temperature was higher (150 °C). Conversely, silica has shown a rich adsorption capacity at moderate temperatures (80 °C). This result corroborates the existence of two different adsorption mechanisms. The clay adsorption mechanism is likely a chemisorption process, while the silica adsorption mechanism is related to physisorption. Both processes displayed better performance in short rupture times, for example, at 60 min. Longer rupture times require a saturation of the adsorption process through a packed bed. FT-ICR mass spectra detected a wide range of compounds from m/z 220 to 800, with average molecular weight distributions (M w) that increase as a function of decreasing the total nitrogen content (424 → 711 Da). Class distribution showed a removal preferential of N­[H] and N2[H] compounds with low carbon numbers (

This study was designed to investigate the use of commercial adsorbent materials for the removal of nitrogen compounds from a vacuum gas oil obtained from an industrial atmospheric distillation unit. Two types of adsorbents were tested: a clay developed specifically for the removal of nitrogen compounds from middle distillates (jet fuel and diesel); and a silica used in a variety of industries. Kinetic and thermodynamic equilibrium experiments were conducted at three temperatures: 80, 100, and 120 °C. The variation in the concentration of nitrogen and aromatic compounds was monitored throughout the kinetic adsorption and thermodynamic equilibrium experiments. When an adsorbent/gas oil mass ratio of 0.75 was used, the clay removed around 70 % of the basic nitrogen compounds from the gas oil, while the silica removed 80 % of the same compounds, which are the ones that effectively hamper catalytic cracking. The silica also removed 14.2 % of the aromatic compounds, while the clay only removed 4.1 %. This study shows that it is possible to treat a viscous hydrocarbon feed using an adsorption process to remove nitrogen compounds without the need to dilute the feed. Using a fluidized bed advanced cracking evaluation (ACE) unit, which simulates a fluid catalytic cracking unit on a bench scale, the gas oil treated with silica produced 3 % more liquid petroleum gas (LPG) and 4 % more gasoline, while the gas oil treated with clay produced 2 % more LPG and 3 % more gasoline than the untreated gas oil.