Department of Chemical Engineering

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

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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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    Toward an Integrated Ceramic Micro-Membrane Network: Effect of Ethanol Reformate on Palladium Membranes
    (ACS, 2010) Kuncharam, Bhanu Vardhan Reddy
    Our 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.