Hydrogen-rich syngas upgrading via CO2 adsorption by amine-functionalized Cu-BTC: the effect of different amines.

Syngas produced from supercritical water gasification typically contain a high amount of CO2 along with H2. In order to improve the quality of syngas, amine-functionalized copper benzene-1,3,5-tricarboxylate (Cu-BTC) was synthesized as an effective adsorbent for selective removal of CO2 from syngas to increase the concentration of H2. The amines used in this study included monoethanolamine (MEA), ethylenediamine (EDA), and polyethyleneimine (PEI). The fundamental physicochemical character of adsorbents, CO2 adsorption capacity, and CO2/H2 selectivity were analyzed. The physicochemical characterization indicated that the structure of amine-functionalized Cu-BTC was partially damaged, which resulted in a decrease in specific surface area and pore volume. On the other hand, the enlarged pore size was beneficial for the mass transfer of gas in the adsorbent. Among these adsorbents, Cu-BTC/PEI exhibited the maximum CO2 adsorption capacity of 3.83 mmol/g and the highest CO2/H2 selectivity of 19.74. It was found that the adsorption pressure is the most significant factor for the CO2 adsorption capacity. Lower temperature and higher pressure were favored for CO2 adsorption capacity and CO2/H2 selectivity, so physical adsorption by Cu-BTC played a dominant role. Moreover, Cu-BTC/PEI can be well-regenerated with stable adsorption efficiency after five consecutive cycles. These findings suggested that Cu-BTC/PEI could be a promising alternative adsorbent for CO2 capture from syngas.

Production of bagasse fly ash-derived CO2 adsorbent by physical activation and by nitrogen-functionalization using hydrothermal treatment.

The high cost of commercial CO2 capture material is one of the issues hindering the widespread adaptation of the technology. This study explored efficient ways of utilizing waste material in the form of bagasse fly ash (BFA) as CO2 adsorbent through thermochemical preparations of physical activation, and hydrothermal carbonization (HTC). The activation of BFA using flue gas was able to produce an adsorbent with good CO2 adsorption capacity, with similar results to the CO2 activation. The second approach using co-HTC of BFA with chicken manure (CM) optimized using Box-Behnken design of experiment was able to produce an adsorbent with CO2 adsorption capacity nearly on-par with commercial adsorbents. It was also found that the model was able to accurately predict the experiment outcome when verified with the additional experiments. Material characterizations showed that the increase of the CO2 adsorption capacity of the adsorbent might have been achieved through the formation of secondary amines deposited on the BFA. The results of this study showed that the utilization of waste in the form of BFA and CM could contribute to the advancement of circular and low-cost CO2 capture medium from waste materials, which could increase the adaptation and involvement of sugar industry and poultry farm.

Utilization of bagasse fly ash for the production of low-cost ammonia adsorbents in poultry farm.

NH3 pollution is a significant problem in the poultry farming because excess NH3 can negatively impact chicken health and stunt their growth. Therefore, this study investigated the low-cost production of bagasse fly ash (FA)-a byproduct of the sugar industry-as an NH3 adsorbent. Hydrothermal carbonization and activation were applied to enhance NH3 adsorption using FA. In the experiments, the adsorption capabilities were improved using industrial waste materials mixed with bamboo char or red mud. The experimental results indicate that bagasse FA mixed with bamboo hydrochar under 10 % loading achieved an NH3 adsorption capacity of âˆ¼ 1.02 mg-NH3/g-adsorbent, or âˆ¼ 55 % of that of the commercial adsorbent. To avoid secondary pollution and provide the spent absorbents with an added value, their use in CO2 capture applications was evaluated. The results showed that the adsorbent had a 0.28 mmol-CO2/g-adsorbent capacity.

Effect of catalysts on distribution of polycyclic-aromatic hydrocarbon (PAHs) in bio-oils from the pyrolysis of dewatered sewage sludge at high and low temperatures.

This study was aimed at investigating the effect of four types of catalysts on the distribution characteristics of 16 polycyclic-aromatic hydrocarbon (PAHs) in bio-oils from the pyrolysis of dry sewage sludge. The pyrolysis experiments of sewage sludge were conducted in a tubular reactor at the high and low temperatures of 850 °C and 450 °C, respectively. CaO, KCl, Na2CO3, and Fe2O3were selected as catalysts for the catalyzed pyrolysis. In the non-catalyzed sludge pyrolysis, PAHs concentrations in bio-oil increased with temperature, reaching a maximum value of 15.25 µg/g at 850 °C. This value was 4.5 times higher than PAHs concentration from the non-catalyzed pyrolysis at 450 °C. With the presence of catalysts at 850 °C, an evident reduction of PAHs concentration was observed for all the bio-oil samples. The added catalysts proved to effectively inhibit PAHs formation in bio-oil and reduce the toxic equivalent quantity (TEQ) of PAHs in the experiment at high temperature. The lowest observed PAHs concentration in bio-oil was 4.23 µg/g, obtained with the use of KCl catalyst. However, an opposite trend was observed for catalyzed pyrolysis at 450 °C. The added catalysts promoted PAHs formation, up to the concentration of 8.89 µg/g with the use of CaO catalyst. Catalyst loading also influenced PAHs concentration and TEQ, with the lowest output found at 20% loading for all catalysts. Bio-oil yields, mass ratio of 16 PAHs concentrated into bio-oil, the TEQ of 16 PAHs and their subtotal group classified by ring number were separately examined to analyze their effects on fractional distribution of the total PAH amount. Overall, the presence of the selected catalysts was found to have the ability to inhibit PAHs production at higher pyrolysis temperature and to promote PAHs production at lower pyrolysis temperature.