Department of Chemical Engineering

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Author: search.filters.author.Kuncharam, Bhanu Vardhan ReddySubject: search.filters.subject.Chemical Engineering

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    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 Reddy
    Biogas, 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.
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    Content Contributions to the Indian Adaption of Transport Phenomena
    (Wiley, 2021) Kuncharam, Bhanu Vardhan Reddy; Sheth, P.N.
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    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 Reddy
    The 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.
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    Techniques for Overcoming Sulfur Poisoning of Catalyst Employed in Hydrocarbon Reforming
    (Springer, 2021) Kuncharam, Bhanu Vardhan Reddy
    Sulfur poisoning of catalyst is a well-known phenomenon observed during the production of syngas (CO + H2). The presence of traces of sulfur content in the feedstock can drastically reduce the catalyst activity and life. Several measures have been developed over the years to mitigate the catalyst deactivation process due to sulfur poisoning. In this paper, we review literature from 1996-present related to all the developments made for sulfur-resistant systems. The basis of poisoning being the sulfur content in the feedstock, potential fuel-containing feedstocks for syngas production were briefly discussed. The basics of sulfur poisoning mechanisms are also summarized. Then, a framework consisting of sulfur tolerance methodologies were discussed. In particular, we have discussed: (i) catalyst development by altering catalyst composition and support systems, (ii) influence of using catalyst structures, (iii) process modifications and optimization, (iv) desulfurization techniques for removal of sulfur from feed and/or product streams, and (v) effective catalyst regeneration techniques to extend the catalyst life. This review emphasizes the integration of the best set of methods to develop sulfur tolerance strategies
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    Sustainable use of rice husk for the cleaner production of value-added products
    (Elsevier, 2022-02) Kuncharam, Bhanu Vardhan Reddy; Srinivas, Appari
    This paper covers a comprehensive review of the thermochemical conversion of rice husk (RH) into value-added products. RH is an organic residue and is produced in large quantities in China, India, Indonesia, and Bangladesh and appears to be a viable source for value-added products from thermochemical processes. The RH properties and operating conditions affect the quality and yield of the bio-oil, gaseous, and biochar products. The conversion techniques such as gasification, slow and fast pyrolysis, and product distribution are systematically reviewed. The literature shows that the Ni-based catalysts demonstrated high activity towards cracking of tar compounds and hydrocarbons, upgraded gas quality, and yielded high hydrogen production. Zeolite-based systems are promising catalysts for the upgradation of bio-oils. Due to the structured porosity and higher acidity, the metal-loaded zeolites catalysts have shown high removal efficiency towards the oxygenated compounds. RH ash is also used as an alternative cementitious material in the construction sector. The optimum level of cement replacement with RH ash in concrete is 15–20%, and higher compressive strength is witnessed for RH ash used concrete than conventional cement concrete. RH ash utilization for soil remediation and blended cement production are also discussed. A sustainable framework has been proposed for the utilization of RH in the chemical and construction sectors.
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    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 Reddy
    The 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.
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    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 Reddy
    Mixed 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.
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    Multi-scale two-dimensional packed bed reactor model for industrial steam methane reforming
    (Elsevier, 2020-04) Kuncharam, Bhanu Vardhan Reddy
    A non-isothermal heterogeneous steady-state model was developed for a packed bed reactor for steam methane reforming employing a multi-scale approach. The model consists of two-dimensional fluid-phase mass and heat transport equations accounting for axial and radial dispersion in the reactor tube, as well as accounting for mass and heat transfer resistances at the fluid-solid phase boundary, calculated using empirical equations. Reaction, mass and heat transfer in the catalyst particle are directly coupled with the fluid-phase equations using a 1D pellet model, thus avoiding the use of a catalyst effectiveness factor for reaction. The performance of the packed-bed reactor is compared using three pressure drop equations: the Ergun equation which neglects wall effects and the Eisfeld-Schnitzlein and Di Felice-Gibilaro correlations which include them. This multi-scale model also accounts for the effects of temperature, pressure and molar change of gas species due to reaction on superficial velocity using a separate equation. The impact of neglecting these effects through simplified models is evaluated
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    Angular difference in human coronary artery governs endothelial cell structure and function
    (Springer, 2022-10) Majumder, Syamantak; Kuncharam, Bhanu Vardhan Reddy
    Blood vessel branch points exhibiting oscillatory/turbulent flow and lower wall shear stress (WSS) are the primary sites of atherosclerosis development. Vascular endothelial functions are essentially dependent on these tangible biomechanical forces including WSS. Herein, we explored the influence of blood vessel bifurcation angles on hemodynamic alterations and associated changes in endothelial function. We generated computer-aided design of a branched human coronary artery followed by 3D printing such designs with different bifurcation angles. Through computational fluid dynamics analysis, we observed that a larger branching angle generated more complex turbulent/oscillatory hemodynamics to impart minimum WSS at branching points. Through the detection of biochemical markers, we recorded significant alteration in eNOS, ICAM1, and monocyte attachment in EC grown in microchannel having 60o vessel branching angle which correlated with the lower WSS. The present study highlights the importance of blood vessel branching angle as one of the crucial determining factors in governing atherogenic-endothelial dysfunction.
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    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 Reddy
    Biogas 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.