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Carbon dioxide capture and utilization has been considered as one of the solutions to the current climate change challenge. Swing adsorption processes can be used to capture carbon dioxide from industrial gases. Developing a selective high-performance adsorbent is key in this process. Cost-effective bio-based adsorbents, such as biochar, have shown a promising performance in recent decades and have been extensively studied. In this work, dynamic modeling and mass transfer study of carbon dioxide capture using biochar and MgO-impregnated activated carbon adsorbents were performed to provide insights on the adsorption mechanisms and improve the process. The results suggested that CO2 adsorption was physisorption and diffusion in the micropore was the controlling step. However, MgO impregnation enhanced the crystalline structure of the sample and increased the diffusion flux in macropores, which resulted in a higher adsorption capacity. The effects of various biochar activation methods and MgO impregnation techniques on the macro- and micropore mass transfer coefficients were reported as well. ASPEN Adsim was used to simulate temperature swing adsorption (TSA) and vacuum swing adsorption (VSA) processes to investigate their feasibility based on the experimental data obtained. The TSA process was not feasible as a result of high heating and cooling duties and the long time required for these cycle steps; however, the VSA process worked well, and product purity and recovery of 99.9 mol % and 90% were achieved, respectively. The VSA process operates at room temperature and atmospheric pressure and has potential for industrial application, especially in biofuel plants, where biochar is already available as a waste material.

To lower the sulphur content below 500 ppm and to increase the quality of bitumen derived heavy oil, a combination of hydrotreating followed by oxidative desulfurization (ODS) and oxidative denitrogenation (ODN) is proposed in this work. NiMo/γ-Al2O3 catalyst was synthesized and used to hydrotreat heavy gas oil (HGO) and light gas oil (LGO) at typical operating conditions of 370–390 °C, 9 MPa, 1–1.5 h−1 space velocity and 600:1 H2 to oil ratio. γ-Alumina and alumina-titania supported Mo, P, Mn and W catalysts were synthesized and characterized using X-ray diffractions, N2 adsorption-desorption using Brunauer–Emmett–Teller (BET) method, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). All catalysts were tested for the oxidation of sulphur and nitrogen aromatic compounds present in LGO and HGO using tert-butyl hydroperoxide (TBHP) as oxidant. The oxidized sulphur and nitrogen compounds were extracted using adsorption on activated carbon and liquid-liquid extraction using methanol. The determination of oxidation states of each metal using XPS confirmed the structure of metal oxides in the catalyst. Thus, the catalytic activity determined in terms of sulphur and nitrogen removal is related to their physico-chemical properties. In agreement with literature, a simplistic mechanism for the oxidative desulfurization is also presented. Mo was found to be more active in comparison to W. Presence of Ti in the support has shown 8–12% increase in ODS and ODN. The MnPMo/γ-Al2O3-TiO2 catalyst showed the best activity for sulphur and nitrogen removal. The role of Mn and P as promoters to molybdenum was also discussed. Further three-stage ODS and ODN was performed to achieve less than 500 ppm in HGO and LGO. The combination of hydrotreatment, ODS and ODN has resulted in removal of 98.8 wt.% sulphur and 94.7 wt.% nitrogen from HGO and removal of 98.5 wt.% sulphur and 97.8 wt.% nitrogen from LGO.

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Metallosilicates (metal = Al, Ti, Zr, V and Ce) and silica supports were synthesized by a one-pot surfactant-free process for use in cobalt-based Fischer–Tropsch catalysts. The in-depth physical, chemical, and textural properties of all supports were determined by several characterization techniques. The introduction of metal precursors to the synthesis gel reduced the pore size of the support by 24–60%, but the use of Al, Ti, and Zr increased the surface area by 5–35%. Cobalt (15 wt %) was loaded on the supports; hydrogen chemisorption and X-ray diffraction revealed that the dispersion and cobalt crystallite sizes in all catalysts were comparable. X-ray photoelectron spectroscopy and temperature-programmed reduction techniques revealed a greater interaction between Co and metallosilicates, necessitating a higher reduction temperature for these catalysts. The Fischer–Tropsch activities of all the catalysts were determined under industrially relevant conditions (220 °C, 1.83 MPa and 2000 mLsyngas/mLcatalyst/h) after in situ reduction. The addition of metal oxides (Ti and Zr) to the supports enhanced the CO conversion by 6–10% but reduced the formation of waxes in the liquid product. The addition of zirconia to the support suppressed the formation of CO2 and CH4 while improving the olefin to paraffin ratio from 0.46 to 1.19 compared to silica-supported catalyst. The addition of titania improved the cobalt-time yield (11 × 10–5 molCO/gCo/s compared to 9.6 × 10–5 molCO/gCo/s for silica). The Fischer–Tropsch activity was retained by titania and zirconia-based metallosilicate supports for over 100 h time-on-stream which could be due to the abatement of catalyst deactivation by mechanisms involving active metal agglomeration.