Department of Chemical Engineering
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Item High-throughput computational screening of metal organic frameworks (MOFs) for CO2 selective separations: trends, challenges, and future perspectives(Elsevier, 2026-01) Kuncharam, Bhanu Vardhan Reddy; Gupta, SureshEfficient separation of CO2 from industrial gas mixtures such as CO2/N2, CO2/CH4, CO2/H2, and CH4/H2 is central to carbon capture, clean fuel production, and hydrogen purification. While metal organic frameworks (MOFs) offer an unparalleled design space for addressing these separations, the vast chemical and structural diversity of MOFs renders experimental evaluation impractical. High-throughput computational screening (HTCS), enabled by molecular simulations, has therefore emerged as a powerful approach to systematically evaluate and rank MOFs across multiple separation targets. This review critically examines HTCS methodologies for both adsorption and membrane-based separations, with a unified analysis of four industrially important gas systems. Further, emerging structure-property relationships to extract general design principles for CO2-selective separations are also highlighted. The review emphasizes that the choice of appropriate simulation inputs such as modelling the framework, force field and charge assignment significantly influence the screening and ranking of MOFs. CO2 typically exhibits strong electrostatic interactions with MOF surfaces, resulting in higher adsorption affinity compared to other gases, whereas the smaller and lighter H2 molecule displays rapid diffusivity. In kinetic separation, mixture diffusivity data is crucial in determining membrane performance. There exists a correlation between MOF structural features and their separation performance. In general, MOFs with narrow pores (3-5 Å) and moderate porosities (0.5-.75) perform better for CO2 separation. This review details the approaches adopted in HTCS of MOFs and the screening outcomes to guide future HTCS-driven MOF discovery.Item 3D self assembled graphene based cellulose acetate mixed matrix membranes for CO2/CH4 separation: An investigation(Elsevier, 2025-03) Kuncharam, Bhanu Vardhan ReddyThis study investigates the development of three-dimensional (3D) Self-Assembled Graphene (SAG) and its potential as a filler material in mixed matrix membranes (MMMs) for efficient CO₂ separation. SAG was synthesized via a one-step hydrothermal treatment of graphene oxide (GO). Additionally, reduced graphene oxide (rGO) was synthesized via chemical reduction of GO and tested alongside SAG and GO as filler materials in cellulose acetate (CA) based MMMs. Structural and gas separation properties of SAG, rGO, and GO-based MMMs were compared to identify the superior material for CO₂ separation applications. Model biogas 40 % CO2 and 60 % CH4 is used for gas permeation testing. Characterization techniques such as X-ray Photoelectron Spectroscopy (XPS), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, and X-ray Diffraction (XRD) were employed to evaluate the structural and thermal properties of the fillers and membranes. Gas permeation studies revealed that MMMs containing SAG exhibited superior CO₂ separation performance compared to rGO and GO-based membranes. The 1 % SAG/CA MMMs showed highest CO2 permeability of 50.96 Barrers which is approximately 364 % higher than pure CA membrane, 178 % higher than GO based MMMs, and 133 % higher than rGO based MMMs.Item Asymmetric mixed matrix membranes with zeolite imidazolate frameworks (ZIF-8, ZIF-67, bimetallic ZIF-8/67) and polyethersulfone for high flux and high selective hydrogen separation(Wiley, 2025-03) Pani, Ajaya Kumar; Kuncharam, Bhanu Vardhan ReddyFor producing high-purity hydrogen (H2) from hydrocarbon reforming, membrane-based separation can be used. In this study, mixed matrix polymer membranes using metal–organic framework (MOF) nanoparticles are explored to overcome the permeability-selectivity trade-off of traditional polymeric membranes. Highly permeable and highly H2 selective MMM using ZIF-8, ZIF-67, and bimetallic ZIF-8/67 MOFs were fabricated via a non-solvent induced phase inversion method by incorporating an intermediate solvent evaporation step. MMMs with 5, 10, and 15 wt.% of nanofillers loadings were prepared and tested for single gas (H2, CO2, CH4, and N2) permeability at 1–2 bar pressures. MMMs permeability and selectivities exceeded the Robeson upper bound (2008) for H2/CO2 separation, demonstrating the potential for obtaining high-purity hydrogen at low pressures. H2/N2 selectivity of 43.4, H2/CO2 selectivity of 27.86 for and H2/CH4 selectivity of 31.36 were obtained. Analytical techniques such as XRD, FTIR, and DSC were used to explain the transport mechanism in the MMMs. The cross-sectional structure and morphology of MMMs were analyzed with field-emission scanning electron microscope (FESEM) to provide insights into the membrane's porous structure.Item Synthesis and characterization of mixed-matrix material of Zirconium based metal organic framework (MOF: UiO-66-NH2) and poly(ether-urethane-urea)(Elsevier, 2020) Kuncharam, Bhanu Vardhan ReddyThe sequestration of gases like CO2 and H2S from biogas is essential for its commercialization. Biogas being a carbon-neutral fuel has the potential to reduce our reliance on fossil-based fuels. However, the required technological advancements are yet to be achieved. Amongst the available technologies for biogas upgradation, membrane separations serves the best purpose owing to their less energy-intensive nature. Mixed matrix membranes are more appealing than commercial polymeric membranes for gas separation applications because of their enhanced performance. Also, incorporation of Metal-organic frameworks (MOFs) into a polymer suspension has been reported to improve the membrane performance. In this work, Amine functionalized Zirconium based metal-organic framework particles (UiO-66-NH2) bearing an average size of around 90–200 nm were synthesized by modulated hydrothermal technique. Characterization was done using XRD, FTIR, FESEM, and TGA. Poly (ether-urethane-urea) (PEUU) was considered based on its high H2S/CH4 respectively. PEUU was prepared using a two-step polycondensation technique. The synthesized polymers were analyzed for their chemical and thermal stability using techniques like 1H NMR, FTIR, TGA, and FESEM. After successful characterization, the MOF particles were incorporated into the polymer forming a mixed matrix membranes with particle loading in the 5–10 wt% range. The membranes were then coated on a porous support and preliminary gas permeability tests have to be carried out.Item A review of techniques to improve performance of metal organic framework (MOF) based mixed matrix membranes for CO2/CH4 separation(Springer, 2022-02) Kuncharam, Bhanu Vardhan ReddyThe separation of carbon dioxide and methane is vital for biogas upgradation and natural gas sweetening applications. Membrane separation is one of the techniques used for CO2 and CH4 separation for biogas upgradation and natural gas sweetening owing to its energy efficiency, low capital cost, portable, and ease of operation. Polymer membranes and inorganic membranes have a trade-off relationship between permeability and selectivity. A new class of membranes known as Mixed Matrix Membranes (MMMs) is being explored to overcome this trade-off by dispersing inorganic fillers in the polymer matrix. However, the addition of filler poses new interfacial morphological difficulties, such as poor dispersion, very strong interaction between filler and polymer, and formation of voids. These challenges can be tackled by suitable choice of filler and polymer, functionalization of filler and polymer, polymer blending. The hybrid membranes separation process or use of two or more strategies can lead to the formation of defect-free membranes with improved separation performance. In this review article, we provide a concise literature review and analysis of the strategies for improving the transport properties of MMMs based on MOF as filter materials for CO2/CH4 separation.Item Fabrication and testing of mixed matrix membranes of UiO-66-NH2 in cellulose acetate for CO2 separation from model biogas(Wiley, 2022-10) Kuncharam, Bhanu Vardhan ReddyMixed Matrix Membranes (MMMs) of UiO-66-NH2 nanoparticles dispersed in Cellulose Acetate (CA) were prepared with filler loading of 2–20 wt%. MMMs were tested for the upgradation of model biogas (60%–40%) mixture of CH4/CO2 at a feed pressure of 2 bar and 1.5 bar. Detailed characterization of MMMs was performed with Fourier transform infrared spectroscopy (FTIR), Thermo-gravimetric analysis (TGA), Differential scanning calorimetry (DSC), and Field emission scanning electron microscopy (FESEM) to investigate the physical and thermal properties. MMMs formed are defects-free, voids-free, and without polymer rigidification, indicating a better filler polymer interface. MMMs showed improved CO2 permeability while retaining the CO2/CH4 selectivity. The 10 wt.% UiO-66-NH2/CA MMM showed optimum gas separation performance with CO2 permeability of 11 Barrer and CO2/CH4 selectivity of 10. The UiO-66-NH2/CA MMMs performed better when compared to the pure CA membrane. The experimental permeability and selectivity data were compared with the predicted data using Maxwell, Lewis–Nielsen, Higuchi, and Bruggeman's model.Item Study of dual Filler Mixed Matrix Membranes with acid-functionalized MWCNTs and Metal-Organic Framework (UiO-66-NH2) in Cellulose Acetate for CO2 Separation(Springer, 2023-03) Kuncharam, Bhanu Vardhan ReddyBiogas upgradation is vital for enhancing its calorific value and reducing corrosion. Membrane-based CO2 separation is an alternative to conventional separation techniques. Polymer membranes such as cellulose acetate have low CO2 permeability. Mixed matrix membranes (MMMs), incorporating nanofillers, either single or dual, in a polymer matrix, are explored to enhance CO2 separation. This work investigates the CO2 separation from model biogas employing dual filler MMMs prepared using acid-functionalized multi-walled carbon nano-tubes (f-MWCNTs) and amine-functionalized metal-organic framework (UiO-66-NH2) as nanofillers and cellulose acetate (CA) as the polymer matrix. MMMs were fabricated by varying the f-MWCNTs loading from 0.01 wt% to 1 wt% with a constant loading of 10 wt% UiO-66-NH2. The morphology, chemical structure, and thermal stability were analyzed using scanning electron microscopy (FESEM), X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermo gravimetric analysis (TGA). The MMMs 0.01wt% f-MWCNTs@10wt%UiO-66-NH2/CA showed enhanced gas separation performance with CO2 permeability of 31.65 Barrer and CO2/CH4 selectivity of 16.78, compared to the base polymer (CO2 permeability of 6.44 Barrer and CO2/CH4 selectivity of 20.72) and single filler UiO-66-NH2 MMM (CO2 permeability of 10.18 Barrer and CO2/CH4 selectivity of 10.43). The permeability of 0.01wt% f-MWCNTs@10wt%UiO-66-NH2/CA is enhanced by 391% compared to the pure CA membrane and 210% compared to UiO-66-NH2/CA MMMs. A comparison was made with dual filler MMMs fabricated with non-functionalized MWCNTs and UiO-66-NH2, and it was observed that the acid-functionalized MWCNTs-based dual filler MMMs performed better.Item Investigation of ZIF-8, amine-modified ZIF-8 and polysulfone based mixed matrix membranes for CO2/CH4 separation(Wiley, 2023-09) Kuncharam, Bhanu Vardhan ReddyMembrane separation is one of the techniques used for biogas upgradation. Mixed matrix membranes (MMMs) are currently being explored to overcome the trade-off of selectivity-permeability inherent in polymer membranes used for gas separation. A significant challenge associated with MMMs is the poor polymer-metal–organic framework (MOF) filler interfacial compatibility, reducing the selectivity or permeability of gas. To address this issue, the present study focuses on the effect of the amine functionalization of ZIF-8 to enhance the CO2 gas permeation without reducing the CO2/CH4 selectivity. MMMs were fabricated using unmodified ZIF-8 and amine-modified ZIF-8 nanofillers dispersed in polysulfone at 5, 10, and 15 wt% loadings. MMMs were characterized by FTIR, DSC, TGA, and FESEM. X-ray diffraction and FTIR analysis was conducted to verify the amine modification of ZIF-8. Further, the performance of MMMs was tested with pure gasses (CO2 and CH4) and a model mixture of CO2 and CH4. In the mixed gas permeation test, the 10 wt% ZIF-8 MMM exhibited the highest CO2 permeability of 25.4 Barrers, while 15 wt% NH2-ZIF-8 MMM exhibited the highest selectivity of 13.5. Notably, the ZIF-8 MMMs demonstrated a 148% increase in CO2/CH4 selectivity, whereas the NH2-ZIF-8 MMMs exhibited a 155% increase compared to the pure polysulfone membrane.