Department of Chemical Engineering
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Item Steam reforming of ethanol for hydrogen production by low-temperature steam reforming using modified Ni-Sn/CeO2 catalyst(Elsevier, 2023) Roy, Banasri; Srinivas, AppariThis 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.Item Tin and lanthanum modified Ni/CeO2 catalyst systems for low temperature steam reforming of ethanol(Elsevier, 2024-01) Roy, BanasriThis 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.Item 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, BanasriThe 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.Item 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, AppariThis 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.Item Sustainable use of rice husk for the cleaner production of value-added products(Elsevier, 2022-02) Kuncharam, Bhanu Vardhan Reddy; Srinivas, AppariThis 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.Item Toward an Integrated Ceramic Micro-Membrane Network: Effect of Ethanol Reformate on Palladium Membranes(ACS, 2010) Kuncharam, Bhanu Vardhan ReddyOur research group has developed a cartridge-based, ceramic microchannel system capable of integrating multiple unique chemical processes within a single monolithic system, for rapid heat and mass transfer. In this manuscript, the authors report on the performance of palladium thin films incorporated within this ceramic microchannel system and their chemical compatibility with ethanol reforming chemistry. A dense, ∼9-μm-thick palladium membrane for hydrogen purification from ethanol reformate was developed on a cordierite extruded ceramic support coated with successive alumina layers, and its compatibility was investigated via exposure to carbon dioxide, carbon monoxide, oxygen, water, and ethanol. The hydrogen permeability was determined to be 1.73 × 10−9 mol m−1 s−1 Pa−0.5 at 350 °C with an activation energy of 7.3 kJ mol−1 over the range 350−550 °C. Exposure to carbon dioxide and oxygen had no effect on hydrogen permeation, while carbon monoxide and water exposure resulted in a 12% and 14% decrease in hydrogen flux, which was fully recovered upon the removal of contaminants. Exposure to ethanol vapor caused a 41% drop in hydrogen flux, which was restored to 91% of the initial steady-state value upon ethanol removal, indicating an irreversible surface modification of the palladium film, in addition to competitive adsorption. The hydrogen/helium selectivity of the membrane remained in excess of 1000:1 throughout all exposure tests, verifying the suitability of this system for integrated hydrogen purification and ethanol reforming.Item Process simulation of hydrogen rich gas production from producer gas using HTS catalysis(Elsiever, 2019-04-15) Sheth, P.N.In the present article, ASPEN Plus is used to develop a process model of the hydrogen-rich gas production through cleaning and catalytic conditioning of producer gas. The process includes producer gas cleaning using venturi scrubber and sand bed filter followed by compression of the gas to 0.6 MPa using compressor. The clean producer gas along with steam undergoes high temperature water gas shift reaction to produce hydrogen-rich gas. The power law kinetic model for commercial HTS catalysts reported in the literature is used in the model. Experimental results from our previous study and those reported in the literature are used to validate the developed model for the compositions of CO & H2 in the product gas. The validated model is further simulated to study the effects of parameters such as reactor temperature, catalyst bed length and steam to CO ratio on the product gas composition. The optimum operating conditions for maximizing CO conversion are found and reported. The maximum H2 composition and CO conversion predicted by the model are 27.029% 97.5479% respectively and the corresponding operating conditions are reactor; temperature of 350 °C, S/CO of 8 and GHSV 1000 h−1.Item Biomass gasification coupled with producer gas cleaning, bottling and HTS catalyst treatment for H2-rich gas production(Elsiever, 2019-05-03) Sheth, P.N.The aim of the present study is to demonstrate the production of hydrogen-rich fuel gas from J. curcas residue cake. A comprehensive experimental study for the production of hydrogen rich fuel gas from J. curcas residue cake via downdraft gasification followed by high temperature water gas shift catalytic treatment has been carried out. The gasification experiments are performed at different equivalence ratios and performance of the process is reported in terms of producer gas composition & its calorific value, gas production rate and cold gas efficiency. The producer gas is cleaned of tar and particulate matters by passing it through venturi scrubber followed by sand bed filter. The clean producer gas is then compressed at 0.6 MPa and bottled into a gas cylinder. The bottled producer gas and a simulated mixture of producer gas are then subjected to high temperature shift (HTS) catalytic treatment for hydrogen enriched gas production. The effect of three different operating parameters GHSV, steam to CO ratio and reactor temperature on the product gas composition and CO conversion is reported. From the experimental study it is found that, the presence of oxygen in the bottled producer gas has affected the catalyst activity. Moreover, higher concentration of oxygen concentration in the bottled producer gas leads to the instantaneous deactivation of the HTS catalyst.Item Effect of variable conditions on steam reforming and aqueous phase reforming of n-butanol over Ni/CeO2 and Ni/Al2O3 catalysts(Elsiever, 2014-12-01) Roy, BanasriA comparison of aqueous phase reforming (APR) and steam reforming (SR) of n-butanol (n-BuOH) over Ni(20 wt%) loaded Al2O3 and CeO2 catalysts has been discussed in this paper. The BuOH conversion increases as the system pressure decreases in APR and SR. For both catalysts, the H2 and CO2 selectivity increased as the pressure increased in SR, reached a maximum at the bubble point pressure, and then decreased in the APR region. The Ni/CeO2 catalyst demonstrated higher selectivity for H2 and CO2than the Ni/Al2O3 catalyst during SR, which are consistent with the results of our previous publication on APR of n-butanol (n-BuOH) over similar catalysts. Unlike in APR, the Ni/CeO2 catalyst produced CO in SR. For both of the catalysts, the activation energies for H2 and CO2 production and BuOH conversion were lower in SR than that in APR. The proposed primary reaction pathway for reforming of BuOH on both catalysts is the same for APR and SR. The n-BuOH dehydrogenated to butaldehyde followed by decarbonylation to propane. Then the propane is steam reformed to hydrogen and carbon monoxide. The CO converts to CO2 mostly through water gas shift.Item Aqueous-phase reforming of n-BuOH over Ni/Al2O3 and Ni/CeO2 catalysts(Elsiever, 2011-12-15) Roy, BanasriThe aqueous-phase reforming (APR) of n-butanol (n-BuOH) over Ni(20 wt%) loaded Al2O3 and CeO2 catalysts has been studied in this paper. Over 100 h of run time, the Ni/Al2O3 catalyst showed significant deactivation compared to the Ni/CeO2 catalyst, both in terms of production rates and the selectivity to H2 and CO2. The Ni/CeO2 catalyst demonstrated higher selectivity for H2 and CO2, lower selectivity to alkanes, and a lower amount of C in the liquid phase compared to the Ni/Al2O3 sample. For the Ni/Al2O3 catalyst, the selectivity to CO increased with temperature, while the Ni/CeO2 catalyst produced no CO. For the Ni/CeO2 catalyst, the activation energies for H2 and CO2 production were 146 and 169 kJ mol−1, while for the Ni/Al2O3 catalyst these activation energies were 158 and 175 kJ mol−1, respectively. The difference of the active metal dispersion on Al2O3 and CeO2 supports, as measured from H2-pulse chemisorption was not significant. This indicates deposition of carbon on the catalyst as a likely cause of lower activity of the Ni/Al2O3 catalyst. It is unlikely that carbon would build up on the Ni/CeO2 catalyst due to higher oxygen mobility in the Ni doped non-stoichiometric CeO2 lattice. Based on the products formed, the proposed primary reaction pathway is the dehydrogenation of n-BuOH to butaldehyde followed by decarbonylation to propane. The propane then partially breaks down to hydrogen and carbon monoxide through steam reforming, while CO converts to CO2 mostly through water gas shift. Ethane and methane are formed via Fischer–Tropsch reactions of CO/CO2 with H2.