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In the framework of research on desulfurization by adsorption, an experimental study of the adsorption selectivity between thiophene and toluene molecules in liquid n-heptane solutions onto NaY (Si/Al = 2.4) and NaX (Si/Al = 1.2) zeolites has been carried out. It investigates the possibility for these commercially available adsorbents to be used in a desulfurization process operated under ambient conditions without using H2. Dynamic adsorption experiments were performed at room temperature mainly at two concentration ranges:  25 mmol·L-1 for competitive adsorptions and 1.25 mmol·L-1 for single-solute experiments. Adsorption isotherms of thiophene and toluene on NaY and NaX sorbents have been obtained. On the NaY zeolite, toluene is favorably adsorbed (αthio/tol = 0.60) while an inverse behavior is observed with NaX sorbent (αthio/tol = 1.63). This exhibits many differences in sorbate/sorbent interactions with slight changes in the adsorbent nature. Besides, the selectivity on NaY sorbents has been found to depend significantly on the concentration range. Such a phenomenon agrees with the fact that the sorbates' adsorption over NaY zeolites cannot be described by a simple Langmuir model. Thiophene adsorption onto NaY undergoes a peculiar phenomenon, since its isotherm exhibits an inflection at a coverage of 1 molecule per α-cage.

In the framework of research considering adsorption for gasoline desulfurization purposes, dynamic adsorption experiments have been performed to study a comparison between thiophene and toluene affinities toward Y-faujasite adsorbents (Si/Al ) 2.4) exchanged with various alkali metal cations (Li + , Na + , K + , Rb + , Cs + ). These experiments have been carried out at two concentration ranges in liquid n-heptane solutions: around 25 mmol‚L -1 for competitive adsorptions and around 1.25 mmol‚L -1 for single-solute adsorptions. Complementary microcalorimetry studies have been carried out in order to investigate the interaction of nucleophilic compounds toward alkaline Y zeolites, by measuring the adsorption enthalpy of CCl 4 onto NaY and CsY sorbents. The results clearly exhibit two opposite trends for the adsorption of thiophene and toluene molecules onto alkaline Y faujasites. The thiophene affinity increases with cation electropositivity, while the toluene affinity decreases as the cations are more electropositive. Thus, from a favorable adsorption for toluene onto the LiY zeolite (R thio/tol ) 0.38 at ca. 26 mmol‚L -1 ), the selectivities shift in favor of thiophene so that the R thio/tol value reaches 3.00 with the CsY zeolite. The calorimetry measurements of CCl 4 adsorption have exhibited an increase of the adsorption enthalpy with more electropositive cations, which seems to indicate that thiophene molecules are adsorbed similarly to CCl 4 , i.e., by strong interaction between the nucleophilic S atom of thiophene and the cationic charge. However, toluene should be mainly stabilized on the adsorption sites through other interactions, as combined attractions between the H atoms of toluene and the O atoms of the zeolite framework surrounding the S II cation can be suggested.

CFD simulations have been carried out in a full three-dimensional, unsteady, Eulerian framework to simulate hydrodynamic/thermal coupling in a bubble column with internals. A first part of the study, dedicated to the hydrodynamic/thermal coupling in liquid single-phase flows, showed that assuming constant wall temperature on the internals constitutes a reasonable approximation in lieu of comprehensive simulations encompassing shell flow and coolant flow together. A second part dealing with the hydrodynamics of gas-liquid flows in a bubble column with internals showed that a RNG k-e turbulence model formulation accounting for gas-induced turbulence was a relevant choice. The last part used these conclusions to build a hydrodynamic/thermal coupling model of a gasliquid flow in a bubble column with internals. With a per-phase RNG k-e turbulence model and assuming constant wall temperature, it was possible to simulate heat transfer phenomena consistent with experimentally measured heat transfer coefficients.

Thermal cracking reactions of a variety of heavy petroleum feeds were analyzed by in situ cross-polarized microscopy using a reactor equipped with a sapphire window. Cross-polarized microscopy is a powerful technique for detecting the formation of anisotropic domains of carbonaceous material (mesophase coke). The present study, however, focused on the characterization of the chemical and physical events prior to the formation of new phases by evaluating the changes in image properties with reaction time. Results showed that changes in image brightness were strongly correlated to the conversion of 524+ °C material but could not provide much insight regarding the stability of reacting oils. Color analyses of the cross-polarized micrographs, however, revealed a consistent red-to-blue color shift around the point of instability. This color shift corresponded to either the formation of a fouling layer of isotropic material or a homogeneous color change of the reacting medium, indicating the formation of CS2-insoluble material. In both cases, the beginning of the color shift preceded the formation of mesophase, whose appearance had the effect of enhancing the blue color of the samples. The detection of the red-to-blue color shift in reacting samples under thermal cracking conditions provides an improved framework for testing the fouling propensity of feeds or for developing online sensors operating on industrial units.

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To help address production issues in refineries caused by the fouling of process units and lines, we have developed a setup as well as a method to visualize the behavior of petroleum samples under process conditions. The experimental setup relies on a custom-built micro-reactor fitted with a sapphire window at the bottom, which is placed over the objective of an inverted microscope equipped with a cross-polarizer module. Using reflection microscopy enables the visualization of opaque samples, such as petroleum vacuum residues, or asphaltenes. The combination of the sapphire window from the micro-reactor with the cross-polarizer module of the microscope on the light path allows high-contrast imaging of isotropic and anisotropic media. While observations are carried out, the micro-reactor can be heated to the temperature range of cracking reactions (up to 450 °C), can be subjected to H2 pressure relevant to hydroconversion reactions (up to 16 MPa), and can stir the sample by magnetic coupling. Observations are typically carried out by taking snapshots of the sample under cross-polarized light at regular time intervals. Image analyses may not only provide information on the temperature, pressure, and reactive conditions yielding phase separation, but may also give an estimate of the evolution of the chemical (absorption/reflection spectra) and physical (refractive index) properties of the sample before the onset of phase separation.