Catalytic gasification of wheat straw in hot compressed (subcritical and supercritical) water for hydrogen production. Issue 5 (14th August 2018)

• Record Type: Journal Article
• Authors: Nanda, Sonil; Reddy, Sivamohan N.; Vo, Dai‐Viet N.; Sahoo, Bichitra N.; Kozinski, Janusz A.
• Is Part Of: Energy science & engineering. Volume 6:Issue 5(2018)
• Page Start: 448
• Page End: 459
• Publication Date: 2018-08-14
• Subjects: catalyst -- gasification -- hydrogen -- subcritical water -- supercritical water -- wheat straw; Energy industries -- Periodicals; Energy development -- Periodicals; Power resources -- Periodicals; 621.042
• DOI: 10.1002/ese3.219
• Languages: English
• ISSNs: 2050-0505

Abstract

Abstract: To supplement the increasing energy demands and cope with the greenhouse gas emissions, biofuels generated from lignocellulosic biomass are gaining widespread attention. In this study, wheat straw was used as a candidate lignocellulosic biomass to produce hydrogen fuel through hydrothermal gasification. The fluid phases of water investigated for gasification included subcritical (300 and 370°C) and supercritical (450 and 550°C) phases. Along with the effects of temperature (300‐550°C), the influences of feed concentration (20‐35 wt%) and reaction time (40‐70 minutes) were comprehensively studied for wheat straw gasification in subcritical and supercritical water. To maximize hydrogen and total gas yields, the effects of two metal catalysts (eg, Ru/Al2 O3 and Ni/Si‐Al2 O3 ) were examined. Hydrogen and total gas yields, as well as lower heating values of the gas products, were comparatively evaluated during the subcritical and supercritical water gasification of wheat straw. Supercritical water gasification of wheat straw at 550°C with 20 wt% feed concentration for 60 minutes of reaction time resulted in higher yields of hydrogen (2.98 mmol/g) and total gases (10.6 mmol/g). When compared to noncatalytic gasification, catalytic gasification using 5 wt% loading of Ru/Al2 O3 and Ni/Si‐Al2 O3 enhanced the hydrogen yields up to 4.18 and 5.1 mmol/g, respectively, along with respective total gas yields of 15 and 18.2 mmol/g. Nonetheless, wheat straw‐derived biochar produced at high supercritical water temperatures also retained high carbon content and calorific value. Abstract : The gasification of wheat straw was performed in subcritical and supercritical water for hydrogen‐rich syngas production. The effects of process parameters that were studied include temperature (300‐550°C), feed concentration (20‐35 wt%) and reaction time (40‐70 minutes) at a pressure range of 21‐23 MPa. Hydrogen‐rich syngas production from wheat straw conversion during hydrothermal gasification was enhanced using Ru/Al2 O3 and Ni/Si‐Al2 O3 . Wheat straw‐derived biochar was also physicochemically characterized.