Adsorption and Electrothermal Desorption of Volatile Organic Compounds and Siloxanes onto an Activated Carbon Fiber Cloth for Biogas Purification

Abstract

Although biogases mainly consist of a mixture of carbon dioxide and methane, traces of volatile organic compounds are present, and these undesirable compounds must be removed during the purification process. Adsorption onto an activated carbon fiber cloth (ACFC) was investigated and, in particular, the feasibility of electrothermal desorption. Five compounds were chosen, and their desorption was assessed by monitoring the electric resistance of the material as a function of the temperature. The results were confirmed by thermogravimetric analysis. Toluene, dichloromethane, and isopropanol were entirely desorbed at 420 K, whereas siloxane D4 and ethyl mercaptan (ethanethiol) were partially removed. These conclusions were confirmed by dynamic adsorption measurements. Cycles of adsorption followed by electrothermal desorption were first carried out for a single component (toluene). Although there was a loss of adsorption capacity between the first and second cycles, a steady performance was reached, shedding light on the complete reversibility of the adsorption of toluene. On the contrary, for the mixture of five organic compounds, a constant loss of adsorption capacity was measured after 3 cycles, which was attributed to the incomplete regeneration at 420 K of two organic compounds (ethanethiol and siloxane D4) from the ACFC from one cycle to another. The electrical consumption for the electrothermal desorption was highest at the beginning of the desorption and rapidly decreased as the temperature within the filter reached its set point. An average consumption was estimated at 1500 W kg −1 of activated carbon fiber cloth.

Siloxane removal for biogas purification by low cost mineral adsorbent

“…Note that the activated carbon is included in all comparisons because this adsorbent is the most used in the biogas purification process (Cabrera-Codony et al, 2018). The adsorption process with activated carbon still has some drawbacks associated with the high regeneration temperatures (400-1000 °C), incomplete desorption (Giraudet et al, 2014) and, consequently, a high cost (Santos-Clotas et al, 2019). This study aims to evaluate a low-cost mineral as a new material for siloxane removal, which has a silicon dioxide composition similar to silica gel, approximately 80 % (Alkan et al, 2005), and it is three times cheaper than activated carbon.…”

Relationships between PEMFC Cathode Kinetic Losses and Contaminants’ Dipole Moment and Adsorption Energy on Pt

“…[47][48][49][50] With regard to mass transfer performance losses, their cause in the presence of contaminants is not yet clear, and several possibilities exist including localized higher current densities (catalyst active area is reduced owing to contaminant adsorption, a situation equivalent to a catalyst loading decrease), [50][51][52][53] the potential dependence of contaminant adsorbates coverage leading to an additional capacitive or inductive loop in the frequency range usually ascribed to mass transfer [54][55][56][57] and contaminant adsorption on C (liquid water management). 58,59 Therefore, several physicochemical parameters may be necessary to correlate mass transfer performance losses.…”

1H NMR Investigations of Activated Carbon Loaded with Volatile Organic Compounds: Quantification, Mechanisms, and Diffusivity Determination

“…This specificity leads to a decrease of the intra-particular mass transfer resistance and then to a 2 to 20 times faster adsorption kinetics. Moreover, fast adsorption/desorption cycles using the Joule effect could be easily implemented 38 . BET analysis gave a specific surface area of 1768 m 2 .g -1 for THC515.…”