Chemical Engineering Program

Carbon molecular sieve (CMS) membranes, fabricated via pyrolysis, are attracting attention owing to their stability under harsh environments, including high temperatures, organic media, and extreme pH. Herein, the fabrication of composite CMS (CCMS) membranes by incorporating sphere-shaped C60(OH) and ellipsoid-shaped C70(OH) fullerenol nanomaterials into intrinsically microporous 4,4′-(hexafluoroisopropylidene) diphthalic anhydride 3,3′-dimethyl-naphthidine polyimide is reported. The encapsulation of the nanomaterials by the polymer matrix, their chemical footprint, and the variation in the local chemistry of the pyrolyzed membranes are successfully revealed via nanodomain analysis using nano-Fourier-transform infrared spectroscopy. The incorporation of fullerenol nanomaterials into CMS membranes can induce the formation of fractional free volume upon pyrolysis, which can translate into molecular sieving enhancement. The effects of the concentration and geometrical shape of the fullerenol nanomaterials are successfully correlated with the membrane separation performance. The CCMS membranes demonstrate excellent stability and pharmaceutical and dye separation performance in organic media. Herein, nanodomain control is pioneered in CCMS membranes via nanomaterial footprinting to induce porosity during pyrolysis and subsequent control molecular sieving performance.

This work presents a predictive and generally applicable approach to resin pyrolysis modeling. Resins extracted from heavy fuel oil 380 (HFO) and vacuum residue oil (VRO) were tested for elemental composition, chemical structure, thermal degradation behavior, and distribution of pyrolysis products using different state-of-the-art experimental techniques. The in-house experiments, together with extensive literature research, guided the formulation of five pseudo-components for the definition of a fuel surrogate. The atomic ratios of the surrogate molecules were defined to be able to replicate the elemental composition of all the data with their linear combination. This approach makes the model flexible and readily applicable to any resin sample just by knowing its elemental composition. The kinetics mechanism was developed by coupling each pseudo-component with a decomposition reaction pathway. The choice of the kinetics parameters was driven by the experimental information available. The model presented a satisfactory agreement with experimental data used for the validation. The kinetic model represents a step of a more comprehensive project aimed at reconstructing the chemical kinetics of heavy and residual oils as a combination of their saturate, aromatic, resin, and asphaltene (SARA) fractions.

Thirty years ago, George A. Olah proposed the concept of the methanol economy, where methanol replaces fossil fuels as a means of energy storage, ground transportation fuel, and raw material for the manufacture of other carbon-based products. Over the years, with rising global warming concerns, the concept has evolved. A special interest is devoted to the development of catalytic processes that allow the transformation of carbon dioxide, via methanol, into CO2 neutral liquid hydrocarbons. These products could replace the oil-based fuels currently used by combustion engines. The rapid depletion of such fuels would avoid a considerable amount of CO2 emissions during the current energy transition.

Over the past decade, we have focused on different key processes that should allow for maximal atom efficiency and, therefore, minimal energy consumption in a field, CO2 valorization, that can easily become a zero-sum game. In this Account, we highlight the importance of catalyst design to overcome the process challenges in the production of liquid fuels from methanol. Additionally, progress in multifunctional catalysts able to directly convert, in one single reactor, CO2 to liquid fuels is also discussed in detail. This integrated option is of particular interest since it allows an important decrease in operational units while increasing throughput by converting, in situ, a thermodynamically limited intermediate.

Zeolites have been successfully applied on a wide range of reaction processes (Methanol to Hydrocarbons, Fluid Catalytic Cracking, etc) and continue to attract academic and industrial investigations. Understanding of the reaction mechanisms involved in zeolite catalysis has been a long standing issue due to the wide range of intermediates and products involved, which has hindered the industrial implementation of these materials. Thus, in order to determine and discriminate between each type of compound involved in the complex reaction mixture, computational simulations have been applied to analyse the 13C chemical shifts of a wide range of known or proposed intermediates and products. The first part of this study focuses on calculating the 13C chemical shifts of C1-C3 compounds commonly part of the reactant feed, comparing the results of mobile versus immobile states and determining which compounds could have their 13C chemical shifts superimposed over others. The second part focuses on C4-C6 olefins, analysing the differences stemming from: position of double bond, ramified structure, mobile and chemical state. Finally, the third part translates the same approach from the olefins study on aromatic derivatives.

The increasing demand for effective oil-water separation materials has encouraged the exploration of sustainable and ecofriendly solutions. In this study, we investigate the surface engineering of a superamphiphilic, self-growing fibrous membrane derived from the Pleurotus ostreatus mycelium. A nanoporous membrane contactor facilitated the harvest of a fibrous Janus membrane by blocking the contact between the mycelium and the growth medium yet allowing nutrient transport to the mycelium. The analysis of the hydrophilicity of the membrane surface and at the mycelium-membrane interface revealed improved wettability and surface fine-tuning. The hydrophilic side was observed at the membrane-mycelium interface, whereas the hydrophobic side displayed a dense layer of closely packed fibrous hyphae. A gradient in the hypha density was revealed through Z-stack fluorescence confocal microscopy and two-dimensional segmentation analysis. The selectivity in oil-water separation was fine-tuned, which provided a sustainable and ecofriendly approach for addressing environmental challenges. The findings of this study emphasize the significance of harnessing natural compounds and self-growing fibrous mycelium as an innovative approach to surface engineering for advanced separation technologies. For the first time, we have successfully demonstrated a new application of membrane contactors for developing superamphiphilic mycelium materials.