Cellulose nanocrystals (CNCs) are excellent candidates for the design and development of multifunctional biomaterials systems to be used in a variety of technologically relevant applications. They may be used as the structural reinforcement phase of polymer matrices, act as catalyst support constituents, as well as drug delivery vectors. Modifying and functionalizing CNCs by introducing specific functional components can impart electronic, magnetic, catalytic, fluorescence and optical properties to the system. In this work we report the successful in situ tethering of iron oxide nanoparticles (IONPs) onto CNCs by the thermal decomposition of Fe(CO)₅ in a H₂O/DMF suspension. Following this procedure, IONPs consisting of mixtures of Fe₃O₄ and Fe₂O₃ with an average diameter of 20 nm were attached to the CNCs. The type of iron oxide species that was generated was determined by selected area electron diffraction (SAED) and energy dispersive spectroscopy (EDS), and the particle size was evaluated by transmission electron microscopy (TEM). Raman spectroscopy was used to characterize the presence and the nature of the molecular interaction between the IONPs and the CNCs.

The emphasis on climate change requires processes to be more efficient to minimize CO₂ emissions, and nanostructured materials as catalysts could play a crucial role due to their high surface area per unit volume. Herein, we report the synthesis of silica microspheres (450–600 nm) using a modified Stober process, on which iron oxide clusters were deposited by sonolysis of iron pentacarbonyl to yield a nanostructured iron material (Si-Fe). A suite of spectroscopic techniques was used to characterize the synthesized materials. The BET surface area of freshly prepared Stober silica was 8.00 m²/g, and the Si-Fe material was 24.0 m²/g. Iron is commercially used as a Fischer–Tropsch (F–T) catalyst due to its low cost. However, catalyst attrition causes catalyst loss and lower product quality. In this study, the synthesized Si-Fe materials were evaluated for F–T synthesis to address these challenges. For comparison, two commercial materials, UCI (silica-supported micron-sized iron oxide) and BASF (unsupported nanosized iron oxide), were also evaluated. All three materials were first activated by pretreatment with either CO or synthesis gas (a mixture of CO and H₂) for 24 h, then evaluated for quick screening in batch mode for F–T synthesis in a Parr batch reactor at three temperatures: 493 K, 513 K, and 533 K. The F–T data at 513 K showed that the CO-pretreated Si-Fe catalyst demonstrated lower CO₂ (<0.5%), lower CH4 (58%) C₈–C₂₀ selectivity (mol% C) to hydrocarbons, surpassing both reference catalysts. The temperature dependence data for Si-Fe: 17.4%, 58.3%, and 54.9% at 493 K, 513 K, and 533 K, respectively, showed that the hydrocarbon yield maximized at 513 K. The surface area increased to 27.9 m²/g for the CO-reduced Si-Fe catalyst after the F–T reaction at 513 K. The morphology and structural change of catalysts, before and after the F–T runs, were imaged. Of all the catalysts evaluated, the SEM–EDS data analysis showed the least carbon deposition on the CO-treated Si-Fe catalyst after the F–T reaction at 513 K and minimized CO₂, a greenhouse gas. This could pave the way for selecting nanomaterials as F–T catalysts that effectively operate at lower temperatures and produce negligible CO₂ by minimizing water-gas-shift (WGS) activity.