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    Application of aspen plus to renewable hydrogen production from glycerol by steam reforming
    (Pergamon-Elsevier Science Ltd, 2020) Ünlü, Derya; Hilmioglu, Nilufer Durmaz
    Steam reforming is the most favored method for the production of hydrogen. Hydrogen is mostly manufactured by using steam reforming of natural gas. Due to the negative environmental impact and energy politics, alternative hydrogen production methods are being explored. Glycerol is one of the bio-based alternative feedstock for hydrogen production. This study is aimed to simulate hydrogen production from glycerol by using Aspen Plus. First of all, the convenient reactor type was determined. RPlug reactor exhibited the highest performance for the hydrogen production. A thermodynamic model was determined according to the formation of byproduct. The reaction temperature, water/glycerol molar feed ratio as reaction parameters and reactor pressure were investigated on the conversion of glycerol and yield of hydrogen. Optimum reaction parameters are determined as 500 degrees C of reaction temperature, 9:1 of water to glycerol ratio and 1 atm of pressure. Reactor design was also examined. Optimum reactor diameter and reactor length values were determined as 5 m and 50 m, respectively. Hydrogen purification was studied and 99.9% purity of H(2)was obtained at 25 bar and 40 degrees C. The obtained results were shown that Aspen Plus has been successfully applied to investigate the effects of reaction parameters and reactor sizing for hydrogen production from glycerol steam reforming. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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    Production of Fuel Bioadditive "Triacetin" Using a Phosphomolybdic-Acid-Loaded PVA Membrane in a Pervaporation Catalytic Membrane Reactor
    (Amer Chemical Soc, 2019) Ünlü, Derya; Hilmioglu, Nilufer Durmaz
    The objective of this article is to synthesize fuel bioadditive triacetin by the innovative membrane process with high yield under mild operating conditions. A phosphomolybdic-acid-loaded poly(vinyl alcohol) (PVA) membrane was prepared as a composite catalytic membrane. The composite catalytic membrane was placed in a membrane reactor cell. Water was separated continuously from the reaction medium using a pervaporation process for the improvement of glycerol conversion and triacetin selectivity. The effects of the operation conditions on glycerol conversion, triacetin selectivity, and separation performance were examined in detail. Although the glycerol conversion was 53% for 7 h using the phosphomolybdicacid-loaded PVA membrane pieces in the batch reactor, this value was 100% in 7 h using a phosphomolybdic-acid-loaded PVA membrane under the same operating conditions (reaction temperature 75 degrees C, catalyst concentration 5 wt %, and molar feed ratio 6:1) in the esterification coupled with pervaporation system. Furthermore, although triacetin selectivity was 0.6% in a batch reactor, this value was 76% in esterification coupled with a pervaporation process. As a result of the study, the esterification coupled with a pervaporation process was found to be an efficient process for the synthesis of triacetin with high selectivity.