Department of Chemical Engineering
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1923
Browse
29 results
Search Results
Item Review: Hydrogen adsorption and storage through a spillover mechanism in palladium-integrated metal organic frameworks(Springer, 2025-10) Kuncharam, Bhanu Vardhan Reddy; Gupta, SureshHydrogen spillover, a mechanism involving the disassociation of molecular hydrogen on a metal catalyst and subsequent diffusion of atomic hydrogen to a support material, provides an effective approach for enhancing hydrogen adsorption and storage at ambient conditions. Among porous materials, metal organic frameworks (MOFs) stand out because of their large surface area, tunable porosity, and structural versatility. This review presents a comprehensive examination of hydrogen storage via the spillover mechanism in palladium integrated MOFs. These adsorbents demonstrate synergistic interactions between metal sites and MOF, contributing to improved hydrogen chemisorption and physisorption through spillover. Particular emphasis is placed on various Pd incorporation techniques, the influence of synthesis methods on spillover efficiency, and the physicochemical factors governing hydrogen uptake. The extent of hydrogen uptake depends strongly on the Pd loading, nanoparticle size, and the nature of the MOF support. Overloading of Pd often results in particle agglomeration, reducing the active surface area and thereby diminishing storage performance. Despite these advancements, challenges remain, particularly in achieving reproducible synthesis, optimizing Pd dispersion, and understanding the kinetics of spillover. The review highlights recent progress and critical challenges in developing Pd@MOF systems for practical hydrogen storage applications.Item Metal–organic framework (MOF) as adsorbents for hydrogen separation from steam methane reforming: an in-depth review(Springer, 2025-10) Kuncharam, Bhanu Vardhan Reddy; Gupta, SureshHydrogen (H2), acknowledged as a clean and advanced fuel, has attracted research focus for its production, purification, and energy generation in accordance with the Sustainable Development Goal (UN-SDG 7). H2 is produced by both fossil fuel (such as reforming, pyrolysis, gasification) and non-fossil fuel–based technologies (such as water electrolysis). Currently, fossil fuel–based hydrogen production predominates in meeting the current demands. However, hydrogen obtained through these methods is impure and requires purification before application. Metal–organic frameworks (MOFs) are emerging novel adsorbent materials that surpass conventional adsorbents owing to their favorable physicochemical characteristics and adaptability. This review elucidates the influences and correlations between MOF adsorbents and the performance of the pressure swing adsorption (PSA) process in the separation of H2 from steam methane reforming (SMR) off-gas. The PSA performance is dictated by the adsorbent’s properties and the operational parameters. The gas separation on MOF adsorbents occurs through equilibrium, kinetic, or size exclusion mechanisms. The H2 separation is largely governed by the van-der Waals interaction of various components of SMR off-gas with the MOF, and the gases interact in the order CO2 ≫ CH4 > CO > N2 > H2. It is noted that the MOF–gas interaction can be tuned by functioning MOFs with polar (e.g., -OH, NO2, SO3H) and non-polar functional groups (e.g., ester and alkanes). The operational parameters influence PSA performance indicators, and a general trend is seen among them. This review presents the critical analysis, summary, challenges, and outlook of the MOF-based PSA hydrogen separation, providing notable examples of MOFs reported.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 Spillover technique for enhancement of hydrogen adsorption capacity of metal organic frameworks(Taylor & Francis, 2025-04) Kuncharam, Bhanu Vardhan Reddy; Gupta, SureshThis review presents an overview of the hydrogen spillover process, a viable approach to enhance H2 adsorption capabilities of metal-organic frameworks (MOFs). Three primary strategies can increase the effectiveness of spillover namely, physical mixing, carbon bridge building, and doping. Spillover by physically mixing supported noble-metal catalyst and MOF increases the proximity between the catalyst and MOF, facilitating an effective diffusion of disassociated H atoms. However, physical mixing leads to partial destruction of the MOF structure. Spillover by carbon bridge building on the other hand, ensures intimate contact between the catalyst and MOF leading to enhanced H2 adsorption. Doping is another technique to optimize spillover by efficient dispersion of metal nanoparticles. Besides dispersion, the size of nanoparticles also plays a crucial role in spillover by doping. MOFs doped with small sized and well dispersed nanoparticles are ideal candidates for an effective spillover process. The future of spillover depends on enhancing bridge building techniques, creating smaller catalysts, and improving their dispersion on the MOF surface. A thorough study of spillover technique is critically analyzed and frameworks for further improvements are provided.Item Investigation of mixed matrix membranes of graphene and acid-treated graphene fillers in cellulose acetate and polyetherimide polymers for CO2 separation from biogas(Wiley, 2024-10) Kuncharam, Bhanu Vardhan ReddyGas separation membranes are crucial for upgrading biogas by separating carbon dioxide (CO2) from biogas, thereby enhancing its calorific value and reducing greenhouse gas emissions. This study aims to improve CO2/CH4 separation using mixed-matrix membranes (MMMs) by incorporating graphene (Gr) and acid-treated graphene (AGr) fillers in a cellulose acetate (CA) polymer matrix. Similarly, polyetherimide (PEI) MMMs were also prepared with Gr and AGr fillers to draw a comparison. Various characterization techniques, including Fourier transform infrared spectroscopy, differential scanning calorimetry, field emission scanning electron microscopy, Raman spectroscopy, and X-ray diffraction, were employed to investigate the structural and morphological properties of the membranes and fillers. Gas permeation tests using a model biogas mixture (40% CO2 and 60% CH4) revealed that the 0.1%AGr/CA membrane achieved the highest CO2 permeability of 43 Barrers, which is approximately 307% more than that of the pure CA membrane, and showed a CO2/CH4 selectivity of 14.80. The 0.5%Gr/PEI membrane demonstrated the best performance among PEI-based MMMs, with a CO2 permeability of 17.48 Barrers and a CO2/CH4 selectivity of 8.96. These results indicate that the incorporation of Gr and AGr significantly enhances the gas separation performance over pure CA and PEI membranes.Item Novel mixed matrix membranes with indium-based 2D and 3D MOFs as fillers and polysulfone for CO2/CH4 mixed gas separation(RSC, 2025-01) Kuncharam, Bhanu Vardhan ReddyTo address the limitations of polymeric membranes, mixed matrix membranes for CO2 separation from biogas mixtures (CO2 and CH4) have been investigated utilizing various fillers. In this study, we investigated novel MMMs using 3D and 2D indium-based MOFs, MIL-68(In)–NH2 and In(aip)2, in a polysulfone polymer matrix. To confirm synthesis, both fillers were subjected to XRD and FTIR analysis, as well as FESEM characterization to assess their 2D and 3D structures. BET analysis revealed the pore size of MOFs. MMMs were characterized using XRD, FTIR, FESEM, and DSC to determine various membrane characteristics. MMMs were tested with CO2 : CH4 of 60 : 40 vol% to mimic the biogas mixture, and the CO2 permeability of 144 Barrer and 79.2 Barrer was obtained for 20 wt% In(aip)2/PSF membrane and 15 wt% MIL-68(In)–NH2/PSF membrane. The highest CO2/CH4 selectivities of 19.8 and 24.4 were obtained for 15 wt% MIL-68(In)–NH2/PSF MMM and 10 wt% In(aip)2/PSF MMM, respectively. The gas permeation findings of this study were compared with existing literature and long-term stability analysis was done to assess the performance of membranes for commercial standards.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 Study of mixed matrix membranes with in situ synthesized zeolite imidazolate frameworks (ZIF-8, ZIF-67) in polyethersulfone polymer for CO2/CH4 separation(RSC, 2024-08) Kuncharam, Bhanu Vardhan ReddyBiogas, produced from anaerobic digestion, is a sustainable and renewable energy source. To upgrade biogas to Bio-CNG, CO2 must be removed from the raw mixture. Membrane separation is an economical process for the removal of CO2, and mixed matrix membranes (MMMs) are being explored for CO2/CH4 separation. MMMs are fabricated using techniques such as in situ techniques to overcome research gaps, such as in filler agglomeration and filler–polymer interfaces. In this work, MMMs were fabricated using the in situ growth of ZIF-8 and ZIF-67 in polyethersulfone (PES) and compared with traditional filler dispersion of ZIF-8 and ZIF-67. The fabricated MMMs were characterized and tested for gas permeation using a model biogas. Fourier-transform infrared (FTIR) spectroscopy and Field Emission Scanning Electron Microscopy (FESEM) analysis were conducted to confirm in situ synthesis of ZIF-8 and ZIF-67. CO2 permeability of in situ ZIF-8 and ZIF-67-based MMMs have enhanced to 84.5 Barrer and 78.8 Barrer, respectively, compared to pure PES membrane, which is around 25 Barrer. Similarly, ZIF-8 and ZIF-67-based traditional MMMs have shown an increase in the CO2 permeability of 75.6 Barrer and 68 Barrer, respectively. Additionally, the selectivity for CO2/CH4 separation increased for some of the prepared MMMs, demonstrating the effectiveness of the in situ fabrication method.Item Content Contributions to the Indian Adaption of Transport Phenomena(Wiley, 2021) Kuncharam, Bhanu Vardhan Reddy; Sheth, P.N.
- «
- 1 (current)
- 2
- 3
- »