Study of synthesis parameters of MIL-53(Al) using experimental design methodology for CO/CH separation

In this study hydrothermal method was used to synthesize MIL-53(Al) (MIL stands for Materials Institute of Lavoisier). Plackett–Burman (P–B) as an experimental design method was applied to investigate the effect of synthesis and activation conditions on specific surface area, relative crystallinity, and production yield of MIL-53(Al) synthesis. Some parameters such as ligand-to-metal molar ratio, synthesis time, synthesis temperature, calcination temperature, and calcination time were selected as the variables. The Brunauer–Emmett–Teller (BET) technique was used in order to estimate the specific surface area of samples while the relative crystallinity of the samples was estimated by comparing their X-Ray Diffraction (XRD) pattern. The morphology of the samples was investigated by field emission scanning electron microscopy. The yield of final products was determined based on organic ligands. The results revealed the significant effect of synthesis temperature on BET surface area, particle size, yield, and crystallinity. The calcination temperature has significant positive effect on BET and crystallinity. Also, the negative significant effect of molar ratio on yield was concluded from the results. However, negligible effect of synthesis and calcination time on the properties of prepared materials were observed. Furthermore, separation capability of a selected sample for carbon dioxide (CO 2 ) and methane (CH 4 ) was measured. Pure gas adsorption data were successfully fitted to Langmuir, Sips, and Toth models. The selected sample provided high adsorption capacity for both gases. The binary adsorption of gases was also investigated based on extended Langmuir equations and the ideal adsorbed solution theory (IAST) models. Comparing the experimental and models data indicated good agreement between the IAST model and experiments. Finally, high CO 2 /CH 4 selectivity of 7.6 was obtained experimentally for the CO 2 /CH 4 molar ratio of 0.2/0.8

Treatment effect of titanosilicate ETS-10 on heavy hydrocarbon adsorption

Heavy hydrocarbons must be separated from natural gas for various reasons, including two-phase formation in transportation pipelines. One of the most important methods for this purpose is the adsorption method. However, there is a lack of studies on heavy hydrocarbons’ adsorption on titanosilicates as an early-developed adsorbent. In this work, titanosilicate ETS-10 was evaluated for the adsorption of heptane, as a representative of heavy hydrocarbons. To study the effect of ETS-10 treatment on its properties and consequently heavy hydrocarbon adsorption, the synthesized samples were treated by different methods such as using an organic template, changing the solvent, fluorination and ion exchanging. All samples were characterized by combined analyses and their heptane adsorption was studied by volumetric method. Results showed that ETS-10 treatment leads to an increase in the mesoporosity of ETS-10. Also, using organic directing agents and isopropanol solvents resulted in better crystallization and higher adsorption capacity for the prepared ETS-10. It was observed that in a 3-h degassing at 300 °C, the HF-ETS-10 sample had the highest heptane uptake (1.84 mmol/g) which is more than twice that of ETS-10. Further evaluation confirmed that adsorption capacity of this sample remained constant after being used for 5 cycles of adsorption-desorption. It was concluded that ETS-10 can be suggested as an attractive adsorbent for heavy hydrocarbon removal

Synthesis, characterization, and CO2 adsorption properties of pure ETS-10

Synthesis of titanosilicate ETS-10 with high purity and crystallinity is a big challenge due to its limited crystallization region. ETS-10 was synthesized and characterized by SEM, EDX, BET, and TGA/DTA methods. The effect of synthesis parameters including pH of the gel, crystallization temperature and time, and the potassium source, were studied using the one-at-a-time (OFAT) approach. The results showed that the ETS-10 with the highest purity was achieved considering the gel pH of 11.3, and the crystallization time and temperature of 72 h and 230 °C. It was also revealed that there was considerable interaction between the potassium source with other synthesis parameters. Afterward, CO2 adsorption of the pure synthesized sample was obtained at 298 K using a volumetric setup. The Dual-site Langmuir, Toth, and UNILAN isotherms were applied to model the obtained equilibrium adsorption data. The CO2 adsorption capacity of the synthesized pure ETS-10 was obtained equal to 3.37 mmol/g. Finally, the adsorption kinetics data were modeled using the PNO model with n = 3.5. The results showed that about 90% of the equilibrium absorption was achieved in only 25 s, which indicates the remarkable capability of using pure ETS-10 for CO2 capture by the PSA method