Gas adsoprtion phenomenon in microporous zeolite adsorbent

Gas adsorption on zeolites gains remarkable attention in this new era of nanotechnology since it has industrial importance in many process industries. Efforts of chemists during the past few decades have advanced the field of synthesis and accelerated the development of zeolites with different physicochemical properties for specific application. New technologies involving gas separation, gas purification, gas storage, high temperature gas sensor, semiconductor material hold a great promise for industrial applications. In order to develop and design an efficient and economically feasible industrial adsorption process, it is important to understand the adsorption phenomena between solid and gas phases. The presence of metal cations in the extra-framework structure determines the accessibility of gas molecules into the zeolite framework. In addition, the selectivity and capacity of adsorption is also being influenced by the adsorbate-adsorbent interactions. The molecules may interact through dispersion, induction, field-quadrapole and/or repulsion forces. Hence, information on physicochemical properties of zeolites as well as the properties of adsorbent is equally important in order to understand gas adsorption phenomena in zeolite microstructures. Results of this study show that structural properties and adsorbate-adsorbent interactions affect gas adsorptive characteristics of zeolites

Hydrodynamics study of the modified rotating disc contactor for CO2 absorption from natural gas using emulsion liquid membrane

This study modified the rotating disc contactor (RDC) structure to optimize its performance for CO2 separation from natural gas feed using stable emulsion liquid membrane (ELM). Based on parametric study of absorption of CO2 from natural gas feed into ELM, the mass transfer behavior in the RDC system was optimized. Rotor diameter, stator inner diameter, and minimum free area of RDC were modified to achieve maximum contact between dispersed liquid phase and gas feed phase, which was necessary to achieve maximum mass transfer. The problem of rupture of the emulsion droplet due to pressure created by direct dispersion of gas at the bottom of conventional RDC extraction system was addressed by adding an impeller at the bottom compartment of RDC. The impeller provided continuous mixing of emulsion and a gas sparger was fitted along the impeller's side that maintained the dispersed aqueous phase miscible in system. The hydrodynamic behavior of a modified RDC was optimized for CO2 absorption from natural gas in ELM, which indicated that modified design dimensions can provide a maximum liquid-gas contact. Beside the concentration of CO2 in natural gas feed, it was observed that the speed of RDC and run time significantly influence CO2 absorption from natural gas using ELM. When all the parameters optimized for CO2 absorption from natural gas feed this study is useful in extending the application of RDC in liquid-gas system. In this study, the use of ELM in RDC can be effective for CO2 when applied under proper conditions

Innovative method to prepare a stable emulsion liquid membrane for high CO2 absorption and its performance evaluation for a natural gas feed in a rotating disk contactor

This paper presents an innovative method to prepare a stable emulsion liquid membrane (ELM) for high CO2 absorption in a natural gas feed. This new method achieved high throughput at low power consumption. The ELM prepared using this new method was characterized by determining the effects of the concentration of the ELM constituents, emulsification time, and speed on the emulsion droplet size (EDS) and stability. This was followed by a parametric study of the process parameters for CO2 separation from natural gas in a rotating disk contactor (RDC)-based setup to evaluate the performance of a stable ELM. The results suggest that the retention time of the stable ELM in a RDC increases with increasing amount of absorbed CO2. The results support the fundamental development of the ELM process to achieve a high overall separation efficiency of CO2 removal from natural gas with a relatively small contact time. This is the first parametric study of CO2 absorption from a gas stream in ELM using a RDC as the contracting equipment. The results of the parametric study suggested that the factors of time, TEA concentration and RDC speed have significant effect on the CO2 absorption from natural gas feed. It was identified that 4% TEA in ELM, 30 min operational time and 700 rpm speed of modified RDC system is suitable for maximum CO2 absorption from gas mixture of CO2/CH4. Furthermore, the study suggested that the ELM containing 4% TEA can absorb 5.6 kmol/m3 CO2

Emulsion liquid membrane extraction of polyphenols compound from palm oil mill effluent

Polyphenols possess many health attributes, as they are powerful antioxidants. Recovery of value-added compounds from industrial waste is a new approach in order to promote sustainability. In this study, the extraction of polyphenols from palm oil mill sterilization condensate by emulsion liquid membrane (ELM) process is proposed. The sterilization condensate was first characterized to determine the total phenolic content (TPC) in the sample. For the extraction, liquid membrane was formulated to choose the best diluent, carrier, and stripping agent. Once the formulation was successfully attempted, the extraction of polyphenols to recover polyphenols was performed. The results show that 2627.3 mg GAE/L of TPC was obtained in the condensate. During the liquid membrane formulation, palm oil was chosen as a green diluent, TBP and n-Octanol were selected as the most appropriate carriers for synergize in a composition of 8:2 by volume, while sodium hydroxide was selected as the most appropriate stripping agents to best facilitate the extraction process. The extraction and recovery performance of polyphenols showed performance of 96.5% and 31%, respectively. The findings of this study show that ELM is a potential technology to extract and recover polyphenols from palm oil mill sterilization condensate

Structural and gas adsorption characteristics of zeolite adsorbents

Gas adsorption on zeolites gains remarkable attention in this new era of nanotechnology since it has industrial importance in many process industries. New technologies involving catalysis, gas separation, gas purification, gas storage, and high temperature gas sensor hold a great promise for industrial applications. In order to develop and design an efficient and economically feasible process, it is important to understand the adsorption characteristics of gas on zeolite. At present, there are many studies have been carried out in the area of gas adsorption, but the data is fragmented and still far from complete. Therefore, the aim of this study is to address some fundamental aspects of gas adsorption by investigating the structural properties and gas adsorption characteristics of different zeolite structures and cations in the extra-framework zeolites. Commercial zeolites representing channel types (ZSM-5, zeolite beta, mordenite, and ferrierite) and cage types (NaX, NaY, and zeolite A) were used in order to study the effect of structural arrangement on gas adsorption. Synthesized zeolite Y (Na-SZ18) was also used as comparison to NaY commercial, and for modification study. Modification using cation exchange method was carried out on the cage-type zeolite (Na-SZ18) by exchanging Na+ with other cations namely Li+, K+, and Rb+ (alkali metals), Mg2+, Ca2+, and Ba2+ (alkaline earth metals), and Mn2+, Ni2+, and Zn2+ (transition metals). Methane and carbon dioxide, the main components of natural gas, were used as adsorbates. The physical and chemical properties of zeolite adsorbents were determined using x-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier Transform infra-red (FTIR) spectroscopy techniques, and nitrogen adsorption at 77 K. Gas adsorption measurements were carried out using volumetric and gravimetric methods. Gas adsorption characteristics of zeolites were evaluated based on the adsorption capacity, adsorption isotherms, heat of adsorption, uptake rate of the adsorbates, and FTIR spectra of gas-zeolite interactions. It was found that cage-type zeolites are better adsorbents than channel-type zeolites. The adsorption of methane on Na-SZ18 is 5 times higher while the adsorption of carbon dioxide is 4 times higher than ferrierite. The gas adsorption measurements also revealed that exchanging Na+ with some metal cations enhanced the adsorption capacity of methane (19.8 %) and carbon dioxide (7.48 %) on modified zeolites. In addition, FTIR spectroscopy results also suggested that the extra-framework cation influenced the interaction between adsorbates and the zeolite surface. Finally, the mechanisms of gas adsorption were proposed based on zeolite of different structures and metal cations. All these results suggests that structural properties and the cations that present in extra-framework zeolites affect the adsorption characteristics of methane and carbon dioxide on zeolites

Synthesis and modification of micro and mesoporous materials as CO2 adsorbent

Carbon dioxide (CO2) removal from natural gas attracts more attention than other impurities due to its corrosiveness and inert property. Amine based chemical absorption has been used commercially for CO2 separation. However, the liquid amine based processes pose operating difficulties due to high regeneration energy, large equipment size, solvent leakage and corrosion problem. Therefore, recent studies have introduced a promising approach which is the incorporation of organic amines into porous supports for CO2 adsorption. This research studies the modification of porous materials by grafting amine functional groups directly to the surface of a solid sorbents. Amines (MEA, DEA, TEA, MDEA, and PEI) have been chosen as modification agents for mesoporous supports (MCM-41 and SBA-15) and microporous supports (zeolites NaY and 13X). The structures of the modified adsorbents were characterized by powder X-Ray Diffraction (XRD), nitrogen adsorption at 77K and Fourier Transform Infrared (FTIR) spectroscopy. Gas adsorption measurements were carried out using Thermal Gravimetric Analyzer (TGA). Investigation on the physicochemical properties and gas CO2 adsorption characteristics of the amines modified adsorbents were thoroughly studied. Results revealed that types of amines and supports, amine loading concentration, metals loading, adsorption and heating temperatures significantly affect both structural and gas adsorption characteristics of the amine modified adsorbents. MEA modified MCM-41 shows the highest CO2 adsorption capacity (40.91 mg/g sorbent) which is 2.2 times higher than MCM-41 support itself (18.58 mg/g sorbent). Although zeolites NaY and 13X show high adsorption but after modification, the adsorption capacity was reduced by 50 %. Cu modified MCM-41 also shows moderate adsorption (25.11 mg/g sorbent) but not much increment can be observed after grafting of MEA. As of operating temperatures of the adsorption process, the adsorption temperature at 25°C and heating temperature at 100°C show the highest adsorption capacity. Furthermore, adsorption bands observed in FTIR spectra demonstrated that the CO2 interact strongly with the amine modified adsorbents

Structural synthesis and modification of zeolite as methane adsorbent

Improvements in the technologies for the synthesis of zeolites and development of zeolite with different pore sizes hold a great promise in the chemical and petrochemical industries. Adsorption of methane in porous materials such as zeolite offers a possibility of storing methane at low pressure with high capacity. In this research, zeolite X (Y) have been hydrothermally synthesized in the laboratory with different composition (6.4Na2O: Al2O3: xSiO: 180H2O, 2 < x <20) followed by characterization procedure using XRD method and BET surface analyser. Post synthesis or modification using cation exchange technique has been carried out to observe the effect different cation (Li, K, Ca, Mg) on zeolite’s properties. Zeolites with faujasite type of framework were produced with different relative crystallinity and surface area. The surface area of exchanged zeolite varied depending on cation types and groups. Molecular simulation was also carried out to determine surface area of zeolites and followed by methane adsorption at 273K and 100kPa. Result shows that cation exchange modification can increase the surface area, hence increase methane adsorption