Mohd Shariff Azmi

Zeolitic Imidazolate Frameworks (ZIF): A Potential Membrane for CO2/CH4 Separation

Removal of carbon dioxide (CO2) from natural gas is of importance because the existence of CO2 in natural gas increases the cost of the sweetening process. In recent years, membrane technology has emerged as an attractive alternative in separating CO2 from CH4 due to its economical, efficient, and environmentally-friendly process. Here, we review the different types of membranes used in CO2/CH4 gas separation. Zeolitic imidazolate frameworks (ZIFs) membranes are emphasized and ZIF-8 membranes are selected for further discussion due to their remarkable properties, including high chemical and thermal stability, facile and controllable pore apertures, and high CO2 permeance. Different types of methods used for the synthesis of ZIF membranes and the challenges encountered in the growth of the membrane are summarized. Potential use of microwave technology in fabricating a continuous and low-defects ZIF membrane within a short period of time are discussed and highlighted. In conclusion, future direction and perspectives are indicated.

Study of CO2 Solubility in Aqueous Blend of Potassium Carbonate Promoted with Glycine

CO2 solubility in aqueous potassium carbonate promoted with amino acid (glycine) was measured at temperatures (303.15, 313.15, and 333.15) K over the partial pressure range from 200 to 1000 kPa. The solubility of CO2 is reported as the loading capacity of the CO2 in the solvent, defined as (moles of CO2 per mole of solvent). It was found that the loading capacity of the CO2 increases by increasing the partial pressure of the CO2, whereas, it reduces with increase in temperature. CO2 loading capacity in aqueous potassium carbonate (PC) promoted with glycine (GLY) was also compared with different solvents, which shows that the new solvent blend is considerably better than various solvents.

Membranes for Gas Separation Current Development and Challenges

—A new bang of natural gas demand has opened up the opportunities towards the utilization of membrane technology for the purification process.The advantages in terms of smaller footprint, lower weight, minimum utility requirement and low labor intensity make them appropriate for wide scale applications. Polymeric membrane is one of the greatest emerging fields in membrane material development. Nevertheless, the separation performance of the existing polymeric materials were reached a limit in the trade-off between permeability and selectivity. The development of inorganic material gives a significance improvement in membrane performance but it outrageously expensive for many applications and having complicated procedure during fabrication process have limit the application of inorganic membrane in gas separation. Thus, a rapid demand in membrane technology for gas separation and the effort toward seeking the membranes with higher permeability and selectivity has motivated the development of mixed matrix membrane. Mixed matrix membrane (MMM) which incorporating inorganic fillers in a polymer matrix is expected to overcome the limitations of the polymeric and inorganic membranes. Apart from an overview of the different membrane materials for gas separation, this paper also highlights the development of mixed matrix membrane and challenges in fabrication of mixed matrix membranes.

Fast Synthesis of Highly Crystalline ZIF-8 using Microwave-assisted Solvothermal Method

This paper presents the formation of highly crystalline ZIF-8 using microwave-assisted solvothermal method. The crystallinity of the ZIF-8 particles was characterized using X-ray diffraction. The lattice vibrations of the structure in the ZIF-8 framework were determined through Fourier transforms infrared spectroscopy. The morphology of the ZIF-8 particles was observed through scanning electron microscopy. The results showed that, 0.5 hour was sufficient for the formation of highly crystalline ZIF-8 particles using microwave-assisted solvothermal method under temperature 120 oC.

Carbon Dioxide Retention on Bentonite Clay Adsorbents Modified by Mono-, Di- and Triethanolamine Compounds

A series of organic-inorganic hybrids were developed via intercalation process of primary, secondary and tertiary ammonium cations into different alkali and alkaline earth and transition metal cation forms of bentonite clay to be used as adsorbent materials for CO2 capture under ambient temperature and slightly high pressure. The effect of the molar mass of amines on the structural characteristics, surface properties and CO2 loading capacity of bentonite clay were investigated by X-ray diffraction, Brunauer-Emmett-Teller method and Magnetic Suspension Balance equipment, respectively. X-ray diffraction results revealed that the basal spacing of bentonite clay after modification with amines was increased with the molar mass of amine used, while BET results showed an inverse effect of the molar mass of amines on the surface area of the synthesized materials. The CO2 loading capacity of the examined samples revealed that bentonite clay modified with monoethanolammonium cations retained higher CO2 amount compared to those modified with di-and triethanolammonium cations. CO2 adsorption isotherms on MEA+-Mg-MMT were conducted at 298, 323 and 348 K and different pressures. A decrease in CO2 uptake with increasing temperature was observed, suggesting the exothermic nature of the adsorption process.

Modelling of Bubble Growth in Supersaturated Solution Using Computational Fluid Dynamics - Population Balance Model (CFD-PBM) Approach

The bubble growth modelling in a supersaturated solution is difficult to be accomplished as it requires coupling of many interrelated hydrodynamics and mass transfer parameters which include pressure drop, supersaturation ratio, bubble size, etc. In the current work, all these factors have been taken into consideration to predict bubble growth in a supersaturated solution using Computational Fluid Dynamics (CFD) – Population Balance Model (PBM) approach. A classical bubble growth model has been used in the simulation. The bubble growth rate was successfully validated with experimental data in terms of bubble size. The attempt to simulate the bubble growth phenomenon of more than a single bubble condition has also been presented. The outcome of this approach is expected to be applied in many engineering areas.

Modelling of High Pressure, High Concentration Carbon Dioxide Capture in Absorption Column

With the depletion of low carbon dioxide (CO2) content natural gas reserves, there is a pressing need to explore the vastly undeveloped high CO2 content natural gas reserves and reduce the release of greenhouse gas CO2 into environment. Our previous investigation on the absorption performance of CO2 at high concentration level of 50% from mixture of CO2-natural gas stream for 20wt% monoethanolamine (MEA) solution in countercurrent packed column indicated efficient removal at high pressure condition. In this present work, a combination mass transfer, chemical reaction of MEA as well as mass conservation equation was developed to model the removal behavior of the high pressure, high concentration CO2 capture along the absorption column. The model developed in this study had satisfactorily represented the mass transfer behavior for high pressure and high CO2 concentration gas removal along the absorption column.

Effect of Liquid Flow Rate and Amine Concentration on CO2 Removal from Natural Gas at High Pressure Operation in Packed Absorption Column

Greenhouse gas (GHG) emissions such as carbon dioxide (CO2) and methane (CH4) from oil and natural gas operation at offshore platforms have significant contribution to global warming. The reduction of these GHG emissions is possible through CO2 capture technology. This study reports the absorption performance of monoethanolamine (MEA) for the removal of CO2 from natural gas (NG) at high pressure conditions. The absorption experiments were performed in an absorption column packed with Sulzer Metal Gauze Packing at 5.0 MPa operating pressure. The absorption performance was evaluated in terms of CO2 removal (%) with liquid flow rate ranging from 1.81 to 4.51 m3/m2.h and MEA concentration of 1.0 - 4.0 kmol/m3. It was found that CO2 removal (%) had increased with increasing liquid flow rate and MEA concentration.

Optimization of Temperature Rise during CO2 Absorption Process Using Response Surface Methodology

This study aims to optimize the temperature rise during CO2 absorption process using response surface methodology (RSM). Verification experiments were performed using a pilot scale experimental set up to validate the optimization condition generated from RSM analysis. The magnitude of temperature rise was observed to increase with increase of pressure and it was especially significant with the increase of CO2 inlet concentration. However, the increase of temperature with higher CO2 inlet concentration was not very obvious after 60% of CO2 inlet concentration. The predicted values of the optimized temperature rise were generally in good agreement with the actual experimental results and this indicated that the empirical correlation generated was well suited with the experimental results.

Three-Tier Inherent Safety Quantification (3-TISQ) for Toxic Release at Preliminary Design Stage

This paper proposes a new technique to evaluate the level of inherent safety of process plant during the preliminary design stage by using the combined assessment of process routes, streams and inherent risk for toxic release accidents. This technique is known as 3-Tier Inherent Safety Quantification (3-TISQ). The first tier is to screen the process routes and to select the ‘best’ route that is inherently less hazardous. Next, the inherent safety level of the streams within the selected process route can be prioritized using Toxic Release Stream Index (TRSI) as the second tier. Afterwards, the inherent safety level of the selected streams can be determined using toxic release inherent risk assessment (TRIRA) as the third tier. The acceptability level of the inherent risk for the selected streams can be obtained using a two-region risk matrix concept. If the inherent risk level is not acceptable, the improvement of the design can be done using the inherent safety principle until the level of the inherent risk is at the tolerable or acceptable region. 3-TISQ can also be extended to evaluate the inherent safety level of fire and explosion accidents.