BITS Faculty Publications

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    Steam reforming of ethanol for hydrogen production by low-temperature steam reforming using modified Ni-Sn/CeO2 catalyst
    (Elsevier, 2023) Roy, Banasri; Srinivas, Appari
    This study focuses on the development of Ni-Sn bimetallic catalysts supported on ZrO2 modified CeO2 and their application for low temperature steam reforming of ethanol (LTSRE) at different temperature 200–400 °C. The catalyst powders are prepared by an ultrasonic-assisted solution combustion synthesis method. The ethanol conversion and selectivity of H2, CO2, CO, and CH4 has been studied with feed composition H2O:EtOH = 12: 1 mol ratio, feed flow rate 0.1 cc/min, and reaction time 20 hrs. Fresh and spent catalysts are characterized using XRD, FTIR, Raman, FESEM, XPS, and TGA-DTA. ZrO2 changes the support chemistry and enhances the activity and stability of the catalyst. At 400 °C, 100 % ethanol (EtOH) conversion, 69 % H2 selectivity with least coke deposition is observed for the catalyst with 5 wt% metal (Ni:Sn = 14:1) loading on Ce:Zr 1:2 mol ratio (NiSn5/CZ12) support.
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    Tin and lanthanum modified Ni/CeO2 catalyst systems for low temperature steam reforming of ethanol
    (Elsevier, 2024-01) Roy, Banasri
    This work examines the Ni–Sn/Ce–La–O catalyst systems for low-temperature stream reforming of ethanol. Catalysts of 5 and 20 wt% metal loading, and different Ce:La ratios are prepared by ultra-sonication assisted solution combustion synthesis method. Catalysts at total metal loading 5 wt% with 33 and 67 at. % La and optimum Sn (Ni:Sn = 14:1) demonstrate better efficiency compared to the Ni/CeO2 catalysts. At 20 wt% metal loading and Ni:Sn = 1:1 atomic ratio, catalytic activity degrades. The best activity and stability are revealed for the N14S1(5)/CL21 catalyst with 5 wt.% total metal loading, Ni:Sn = 14:1, and Ce:La = 2:1 mol ratio. Physico-chemical characterizations (XRD, H2 -TPR, NH3-TPD, Raman, FESEM, TEM, XPS, N2 adsorption-desorption, DTA/TGA, etc.) are performed to understand the role of the metal loading, Sn, and La in the catalytic activity and coke deposition behavior.
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    Study of preparation method and oxidization/reduction effect on the performance of nickel-cerium oxide catalysts for aqueous-phase reforming of ethanol
    (Elsevier, 2015-12) Roy, Banasri
    The effect of preparation method and oxidation state of the active metal on the catalytic activity of Ni–Ce–O catalysts was studied for aqueous phase reforming of ethanol. A sol-gel (SG) route and a solution combustion synthesis (SCS) method were used for the preparation of 10 wt% Ni loaded catalysts. The catalytic activity of three groups of catalysts; reduced at 425 °C (HR, metallic Ni), reduced at 1000 °C (FR, metallic Ni), and not reduced (NR, as NiO) were tested at different operating conditions. The difference in the metal particle sizes, governed by the preparation method, affects the catalytic efficiency most, not the reduced or oxidized state of Ni. The SG samples were superior for ethanol conversion and selectivity for H2 and CO2 compared to the SCS samples. The X-ray photoelectron spectroscopy (XPS) analysis of the samples demonstrated that the relative ratio of Ce2O3 to CeO2 increased inside the reactor. While Ni doping increases oxygen mobility in the Ce–O lattice, Ce3+ converts Ni2+ to metallic Ni inside the reactor. This can explain why the reduction stage for Ni–Ce–O system in APR is irrelevant. Higher oxygen mobility through the support helps oxidation of CO to CO2 leading to improved catalytic performance.
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    Effects of metal loading and support modification on the low-temperature steam reforming of ethanol (LTSRE) over the Ni–Sn/CeO2 catalysts
    (Elsevier, 2023-05) Roy, Banasri; Srinivas, Appari
    This article presents the effect of metal loading and support modification with MgO on low-temperature steam reforming of ethanol (LTSRE) over Ni–Sn/CeO2 catalysts prepare by a single-pot solution combustion synthesis (SCS) method. Atmospheric pressure activity study of these catalysts (0.5 g) is performed at different temperatures (200–400 °C), H2O:EtOH = 12: 1 mol ratio, and feed flow rate 0.1 ml/min. After 10 h TOS at 400 °C, NiSn(5)/CM12 catalyst with 5 wt.% total metal loading, optimal Sn (Ni:Sn = 14:1), and Ce:Mg = 1:2 mol ratio shows EtOH conversion 100% and H2 selectivity 70% with low coke deposition. Physicochemical characterizations (XRD, Raman, FESEM, TEM, and N2 adsorption-desorption) reveal that addition of MgO in CeO2 and an optimal amount of Sn decrease both Ni and support particle sizes while oxygen storage capacity (OSC) of the support increases (by XPS). Alkaline characteristics of MgO reduces support's acidity and improves active metal-support interaction, as evaluated by NH3-TPD and H2-TPR.
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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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    Experimental analysis on the effect of hydrogen supply systems in a diesel dual fuel engine
    (ISEES, 2019) Verma, Saket
    An experimental investigation on dual fuel (DF) operation of a diesel engine with hydrogen as the main fuel and diesel as the pilot fuel has been performed. The focus has been made on gaseous fuel delivery system for performance enhancement during DF operations. Two techniques of hydrogen delivery namely, manifold port induction and manifold port injection are compared in the DF engine. In the case of manifold induction, the gas is introduced with the help of a gas mixture in the intake manifold, whereas in the case of manifold injection, the gas is introduced with the help of an injector. The injector is located close to the intake valve and its timing is controlled through an electronic control unit. It was found that hydrogen manifold injection improves the diesel substitution and thermal efficiency of the DF engine as compared to manifold induction technique. The diesel substitution was improved by 2.3% and 1.5% at low and high loads respectively. Similarly, the brake thermal efficiency was improved by 0.4% and 0.5% at low and high loads respectively.
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    Exergy Analysis of Hydrogen-Fueled Spark Ignition Engine Based on Numerical Investigations
    (Springer, 2017-02) Verma, Saket
    Hydrogen fuelled IC engines (H2ICEs) have been considered as one of the most promising systems for pollution free transportations and their performance and combustion merits have been extensively discussed in the literature. However, studies related to these discussions have largely been linked to first-law analysis. On other hand, second-law of thermodynamics coupled with first-law, also known as exergy analysis, can give better insight into the engine performances. Bearing it in mind, this work presents second-law quantification of hydrogen engine processes and sub-processes, which helps to understand its true potential to deliver the output and simultaneously estimates various losses. This study quantifies different process inefficiencies in terms of irreversibilities thereby identifying the gaps to be addressed for further improvements. A computational fluid dynamics model has been prepared to simulate hydrogen-fueled spark-ignition engine (H2SIE) operations and second-law equations have been coupled to ascertain different exergy terms. Present study shows that combustion process is the biggest source of irreversibility in IC engines. It has also been found that the level of irreversibility for a hydrogen-operated engine is substantially lesser as compared to that with gasoline engine under identical ranges of operating conditions. Combustion irreversibilities for H2SIE and gasoline engine were found to be 15% and 23.6% of the total input fuel exergy respectively. Moreover, significant increase in second-law efficiency for H2SIE as 44.4% compared to 36.8% that for gasoline engines has been found. Another important conclusion from this work includes exergy distribution for H2SIE, which is considerably diverse from gasoline engine operation. It indicates that optimization and improvements of different H2SIE processes require specific attentions; nevertheless, show much better ability to deliver.
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    Analysis of metal hydride storage on the basis of thermophysical properties and its application in microgrid
    (Elsevier, 2020-10) Verma, Saket
    Present study focuses on the analysis of metal hydride hydrogen storage in renewable power generators-based microgrid (µG) system. The design of metal hydride storage unit requires parametric analysis on the basis of its thermophysical properties such as activation/deactivation energy, enthalpy of formation, equilibrium pressure, reaction kinetics and external thermal management system. This parametric analysis helps to assess suitability of the hydride storage with hydrogen generation (electrolyzer) and utilization (fuel cell) units in µG. Application of metal hydride in the µG creates a sophisticated system which requires careful analysis and operating strategy for achieving manifold benefits such as higher efficiency, durability of the components and self-sufficiency. In the present study, different hydrides are selected namely, LaNi5, TiCr1.6Mn0.2, hydroalloy C5 graphite and MgH2 for performance analysis on the basis of their thermophysical properties. The performance is evaluated in different operating modes aiming for higher efficiency, components durability and system self-sufficiency (minimum grid-dependency). A detailed mathematical modelling is performed in the MATLAB simulation tool for performance evaluation of overall µG system, which consists of 5 kW photovoltaic (PV), 1 kW fuel cell (FC), 5 L hydride storage and 0.6 kW electrolyzer. It was observed that the hydrogen charging and discharging processes in the hydride storage unit strongly depend on its thermophysical properties and hence require certain specific operating conditions for efficient working. Considering suitable discharging characteristics at low temperature and pressure, LaNi5 and C5 hydroalloy can be suitable for transient operation with proton exchange membrane fuel cell application. Overall energy efficiency of up to ≈ 95.49% is achieved in such type of storage-based µG. Grid-dependency ratio (load demand met by grid power/total load demand) was found between 0.26 and 5.83% in different operating modes.
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    A renewable pathway towards increased utilization of hydrogen in diesel engines
    (Elsevier, 2020-02) Verma, Saket
    In the present work, dual fuel operation of a diesel engine has been experimentally investigated using biodiesel and hydrogen as the test fuels. Jatropha Curcas biodiesel is used as the pilot fuel, which is directly injected in the combustion chamber using conventional diesel injector. The main fuel (hydrogen) is injected in the intake manifold using a hydrogen injector and electronic control unit. In dual fuel mode, engine operations are studied at varying engine loads at the maximum pilot fuel substitution conditions. The engine performance parameters such as maximum pilot fuel substitution, brake thermal efficiency and brake specific energy consumption are investigated. On emission side, oxides of nitrogen, hydrocarbon, carbon monoxide and smoke emissions are analysed. Based on the results, it is found that biodiesel-hydrogen dual fuel engine could utilize up to 80.7% and 24.5% hydrogen (by energy share) at low and high loads respectively along with improved brake thermal efficiency. Furthermore, hydrocarbon, carbon monoxide and smoke emissions are significantly reduced compared to single fuel diesel engine operation. Exhaust gas recirculation (EGR) has also been studied with biodiesel-hydrogen dual fuel engine operations. It is found that EGR could improve the utilization of hydrogen in dual fuel engine, especially at the high loads. The effect of EGR is also found to reduce high nitrogen oxide emissions from the dual fuel engine and brake thermal efficiency is not significantly affected.
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    An experimental investigation of exergetic performance and emission characteristics of hydrogen supplemented biogas-diesel dual fuel engi
    (Elsevier, 2018-01) Verma, Saket
    An experimental investigation of a conventional diesel engine with diesel, biogas and hydrogen as fuels has been carried out, while the engine is modified to operate in dual fuel mode using diesel as the pilot fuel and biogas as the main fuel respectively. In order to improve the biogas-diesel dual fuel engine performance and emission characteristics, small percentages of hydrogen supplementations, viz. 5%, 10%, 15% and 20%, in biogas were studied and the comparison was also made to that with the neat biogas-diesel dual fuel operation. Engine performance characterization has been done with exergy based approach, and major sources of irreversibilities in various engine processes are also investigated and compared for the above mentioned cases. The results show that hydrogen supplementations in biogas have lesser effect on the combustion characteristics at low load, while, at high load, the combustion patterns change significantly with higher heat release rates and peak combustion pressures. Furthermore, performance and emission characteristics are found nearly unaffected with 5% of hydrogen addition both at low and high loads. Nevertheless, further addition of hydrogen in biogas causes improvements in performance and emission characteristics of the dual fuel engine