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The objective of this study is to develop a new low-cost, highly selective, and stable sorbent based pre-combustion CO 2 capture. A high surface area titanium oxide (TiO 2) prepared by a template method and amine modified TiO 2 (M-TiO 2) were investigated for CO 2 /CH 4 adsorption at conditions relevant to pre-combustion CO 2 capture. Single-component and binary CO 2 /CH 4 adsorption tests at different operating conditions were performed in a fixed bed adsorber. Experimental results show that the selectivity of TiO 2 for separation of CO 2 from CO 2 /CH 4 mixture can be significantly improved via amine modification. The selectivity of CO 2 over CH 4 for M-TiO 2 is enhanced to 22.1 at 333 K and 35 bar. Pure CO 2 or CH 4 can be obtained from the adsorber packed with M-TiO 2 through cyclic CO 2 /CH 4 mixture gas adsorption and desorption.

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The objective of this research is to study the performance of an inexpensive high-surface-area nanoporous titanium oxide (TiO 2 ) on the CO 2 /H 2 separation and resulting pre-combustion CO 2 capture. The experiments were carried out at different temperatures (25, 50, 75, 100, and 125 °C) and pressures (5, 10, 15, 20, 25, 30, and 35 bar) using a fixed-bed adsorber. The data obtained for the pure component isotherms and binary gas mixtures were correlated using Sips and Langmuir−Freundlich binary-component-expanded isotherm adsorption (LFBE) models, respectively. Also, the deactivation model was used to simulate the observed CO 2 sorption breakthrough curves. Experimental results show that the capture capacities of the sorbent for both H 2 and CO 2 were improved with the increase in the pressure and decrease in the temperature. The maximum sorption capacities for pure CO 2 and H 2 were found to be 14.4 and 5.2 mmol/g of TiO 2 at 35 bar and 25 °C, respectively. The increase in the temperature and decrease in the pressure improve the sorption selectivity of TiO 2 for CO 2 . The selectivity value of TiO 2 reached 9.87 at 125 °C and 5 bar for a CO 2 /H 2 molar ratio of 50:50. TiO 2 also shows great stability and regenerability. This study indicates that nanoporous TiO 2 is potentially a cost-effective and robust CO 2 /H 2 separation agent and provides the knowledge needed for further demonstration of the nanoporous TiO 2 -based pre-combustion CO 2 separation technology.

Since 1990s, as a result of unprecedented drought and warm winters, mountain pine beetles have devastated mature pine trees in the forests of western North America from Mexico to Canada. Especially, in the State of Wyoming, there are more than 1 million acres of dead forest now. These beetle killed trees are a source of wildfire and if left unharvested will decay and release carbon back to the atmosphere. Fast pyrolysis is a promising method to transfer the beetle killed pine trees into bio-oils. In the present study, an unsteady state mathematical model is developed to simulate the fast pyrolysis process, which converts solid pine wood pellets into char (solid), bio-oils (liquid) and gaseous products in the absence of oxidizer in a temperature range from 500°C to 1000°C within short residence time. The main goal of the study is to advance the understanding of kinetics and convective and radiative heat transfer in biomass fast pyrolysis process. Conservation equations of total mass, species, momentum, and energy, coupled with the chemical kinetics model, have been developed and solved numerically to simulate fast pyrolysis of various cylindrical beetle killed pine pellets (10 mm diameter and 3 mm thickness) in a reactor (30 mm inside diameter and 50 mm height) exposed to various radiative heating flux (0.2 MW/m2 to 0.8 MW/m2). A fast pyrolysis kinetics model for pine wood that includes competitive path ways for the formation of solid, liquid, and gaseous products plus secondary reactions of primary products has been adapted. Several heat transfer correlations and thermo property models available in the literature have been evaluated and adapted in the simulation. Finite element method is used to solve the conservation equations and a 4th order Runge-Kutta method is used to solve the chemical kinetics. Unsteady-state two dimensional temperature and product distributions throughout the entire pyrolysis process were simulated and the simulated product yields were compared to the experimental data available in the literature. This study demonstrates the importance of the secondary reactions and appropriate convective and radiative modeling in the numerical simulation of biomass fast pyrolysis.

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Since the 1990s, mountain pine beetles have infested mature pine trees in the forests of western North America. Fast pyrolysis is an encouraging method to convert the beetle killed pine trees into bio-oils. In this study, an unsteady-state mathematical model is developed to simulate fast pyrolysis under concentrated solar radiation. Conservation equations of total mass, species, and energy, coupled with the chemical kinetics model, have been developed and solved to simulate fast pyrolysis of cylindrical biomass pellets in a quartz reactor exposed to various radiant heating fluxes. This study demonstrates the importance of the secondary reactions on fast pyrolysis products.