Accumulation of greenhouse gases in the atmosphere is responsible for increased global warming of our planet. The increasing concentration of carbon dioxide mainly from flue gas, automobile and landfill gas (LFG) emissions are major contributors to this problem. In this work, CO2, CH4 and N2 adsorption was studied on Ceca 13X zeolite by determining pure and binary mixture isotherms using a constant volume method and a concentration pulse chromatographic technique at 40 and 100°C. The experimental data were then compared to the predicted binary behaviour by extended Langmuir model. Results showed that the extended Langmuir theoretical adsorption model can only be applied as an approximation to predict the experimental binary behaviour for the systems studied. Equilibrium phase diagrams were obtained from the experimental binary isotherms. For these systems, the integral thermodynamic consistency tests were also conducted. It was found that Ceca 13X exhibits large CO2/CH4 and CO2/N2 selectivity and could find application in landfill gas purification, CO2 removal from natural gas and CO2 removal from ambient air or flue gas streams. © 2011 Canadian Society for Chemical Engineering

Separation of methane and nitrogen gases is critical in the upgrading of LFG (Landfill gas), natural gas and coal bed gas in order to have a commercial heating value for methane. From an environmental point of view, methane capture from landfill gas is essential to prevent greenhouse gas emissions. Adsorption could be a beneficial process to capture low purity methane from a landfill site that is nearing the end of its lifecycle and produce high purity methane. In this work, Ceca 13X zeolite and Alcan Activated Alumina AA 320-AP have been studied for their potential for this separation and compared with Silicalite in literature. Pure and mixture adsorption isotherms were determined at 40 and 100°C for these adsorbents by constant volume method and concentration pulse chromatographic technique, respectively. Mixture adsorption isotherms for the binary system of methane and nitrogen gases at 40 and 100°C and 1 atmosphere total pressure have been determined by VV-CPM (Van der Vlist and Van der Meijden Concentration Pulse Method). The application of Extended Langmuir model for this binary system have also been discussed and compared to the experimental results. Results show that equilibrium separation factor for silicalite is larger than zeolite Ceca 13X and Alcan activated alumina AA320-AP. Both Silicalite and Ceca 13X find application in the bulk separation of methane from nitrogen when y CH4 [ 0.4, especially in LFG, coal bed gas and natural gas.

Power stations and industrial processes burning fossil fuels account for the largest percentage of carbon dioxide emissions. Carbon capture and sequestration has received enormous global attention to reduce the carbon footprint and combat global warming. Adsorption has become an alternative technique to the conventional absorption process for capturing carbon dioxide due to its low operating and capital costs.In this study, Pressure Swing Adsorption (PSA) process has been compared with Thermal Pressure Swing Adsorption (TPSA) process for CO 2 recovery from a flue gas composition of 10% CO 2 (by vol) in N 2 using Ceca 13X adsorbent. A factorial design set of experiments was performed to optimise the carbon dioxide recovery and study the effects and interaction of four control parameters namely, purge/feed flow ratio, purge time, purge gas temperature and adsorption column pressure.Results indicated that better regeneration conditions used in a TPSA cycle was essential over a PSA cycle for regaining maximum adsorption capacity of the used Ceca 13X adsorbent. It was found that Purge time had a significant effect on the CO 2 recovery followed by Column pressure, purge/feed flow ratio and purge temperature. A Minitab® statistical software was used to analyse the data. It was found that the test of significance for lack of fit showed the fitted model to be an adequate representation of the experimental data. The results showed that to maximise the CO 2 recovery, highest values of the control parameters have to be used.

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A one-dimensional, plug-flow, trickle-bed reactor model was developed to simulate a steady-state, adiabatic hydrotreating reactor with consideration of vapor−liquid equilibrium (VLE) effects. VLE calculations were simultaneously performed at each integration step of the model simulation. The thermophysical properties and mass flow rates of each fluid phase were updated as functions of local variables along the catalyst bed. Substantial differences in hydrodearomatization (HDA) and hydrodesulfurization (HDS) conversions were observed when the simulation was conducted with and without accounting for VLE, indicating the significance of VLE in the hydrotreater simulation. It was found that an increased inlet temperature increases HDS conversion but reduces HDA conversion. Increased pressure increases the reactor temperature and HDS and HDA conversions. Increased gas/oil ratio increases HDA conversion slightly, but does not change HDS conversion significantly. Polyaromatics are the most reactive for hydrogenation, and monoaromatics are the least reactive. Under the operating conditions investigated, both plug-flow and full catalyst wetting criteria are met, although significant vaporization of the liquid oil occurs in the commercial hydrotreating reactor.