No abstract

No abstract

No abstract

Biomethane generated from renewable sources can be used as a renewable fuel to achieve ambitious targets for biofuels. The development of adsorption-based technologies for purification of biogas requires knowledge of adsorption equilibria and kinetics of pure gases on a specific adsorbent material. In this work, we have measured adsorption equilibria of CO2, CH4, and N2 at (299, 323, 348, 373, and 423) K over a pressure range between (0 and 700) kPa on a carbon honeycomb monolith. The adsorption capacity of the activated carbon honeycomb monolith was CO2 > CH4 > N2. The multisite Langmuir model was employed to fit the data of the pure gases offering the possibility of direct prediction of multicomponent adsorption equilibria. The diffusion of single gases in the microporous structure of the activated carbon honeycomb monolith was studied by diluted breakthrough experiments. The experiments were performed over the same temperature range [(303 to 423) K]. A simplified 1D mathematical model was employed in the description of the adsorption phenomenon. The data reported in this work allows modeling of adsorption processes such as pressure swing adsorption (PSA) and temperature swing adsorption (TSA).

No abstract

in Wiley InterScience (www.interscience.wiley.com).The novelty of this manuscript is the study of purification of hydrogen from a mixture of H 2 /CO 2 /CH 4 /CO/N 2 saturated in water vapor. Simulations results of fixed bed behavior and of an eight steps PSA process are presented using an activated carbon as adsorbent. Several operating conditions were considered, namely different feed flow rates, humid/dry feed and adiabatic/nonadiabatic operation. Simulation with single column PSA showed that a 99.9979% purity hydrogen stream could be obtained with a recovery of 71.3% and a productivity of 63.9 mol H 2 /kg ads /day. The simulation of a four columns PSA predicted a decrease in H 2 purity to 99.8193% for the same operating conditions, due to the impurities present in the recycled stream of the continuous multicolumn process. To increase the hydrogen purity above 99.99%, the feed time was decreased 25%. Thus, the multicolumn simulation predicted a hydrogen recovery, purity, and productivity, respectively, of 62.7%, 99.9992%, and 55.2 mol H 2 /kg ads /day.

The commercial technology for the separation of off-gases from steam methane reforming is pressure swing adsorption (PSA). To improve the performance of the PSA units, materials with enhanced capacity toward contaminants are required. In this work, a commercial activated carbon (AC) was used for the preparation of a new material with enhanced capacity toward contaminants (CO2, CH4, CO, and N2). Different samples were prepared by physical activation with CO2 under different operating conditions. The conditions where the sample with the highest microporosity was obtained were reproduced to prepare a scale-up of 400 g. Carbon dioxide, hydrogen, methane, carbon monoxide, and nitrogen adsorption equilibrium and kinetics were studied on the modified AC and compared to the original AC results. An improvement of CO2 adsorption capacity of 17.5% was observed at 303 K and 7 bar. Carbon dioxide micropore diffusivity of same order of magnitude (D c/r c 2 = ∼4 × 10−2 s−1 at 303 K) was observed for both adsorbents. Finally, ternary breakthrough curves (CO2−H2−CH4) were performed for the validation of the multicomponent adsorption equilibrium.

26n-Decane is a saturated long-chain hydrocarbon, belonging to the family of the 27 volatile organic compounds (VOCs), which is persistently present in indoor air of several 28 industrial closed facilities. Due to the VOCs environmental impact, all efforts that have 29 been made during the last decades to degrade this kind of air pollutants are extremely 30 important. Accordingly, the present paper reports n-decane photooxidation studies carried 31 out in an annular photoreactor under simulated solar irradiation and employing a catalytic 32 bed made of cellulose acetate monoliths coated with a photocatalytic paint. The influence 33 of the feed flow rate, n-decane concentration, relative humidity, and incident irradiance 34 on the n-decane degradation kinetics was assessed. Within this work, n-decane 35 photodegradations higher than 90% were achieved, depending on the experimental 36 conditions. Additionally, a phenomenological reaction rate model of the n-decane 37 photocatalytic oxidation was proposed and assessed. The proposed model assumes that 38 n-decane and water molecules compete for different active sites on the catalyst surface. 39Finally, despite the high n-decane photodegradation achieved, reaction by-products were 40 identified and, based on these compounds, a reaction mechanism was formulated. 41 42