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David E.,National Research Institute of Cryogenics and Isotope Technologies
Chemical Engineering Transactions | Year: 2015

Gasification of biomass is an important process for utilization of production of chemicals and fuels. During the gasification, biomass is converted with oxygen,air or steam into a gas mixture such as CO, CO2, H2, H20 etc. Besides the gases, a number of low, volatile hydrocarbons (mostly CH4) are obtained, together with tars. The tar represents a complex mixture of components, usually polyaromatic that are difficult to deal with in the downstream processes that accompany gasification as well as in utilization technologies. The gasification technology for biomass conversion is still in the development stage and cannot be considered as proven technology for small and medium scale applications. The main technical barrier remains the efficient removal of tar from the produced gases in gasification systems. The purpose of this work is to identify an appropriate catalyst that can be used as an active in-bed material for removal of biomass tar to increase the efficiency processing. Novel nano char-supported iron catalysts were prepared, tested for the steam reforming of biomass tar and their performances were compared with ilmenite catalyst. The activity of char-supported iron catalysts toward steam tar reforming process was investigated under different operational conditions. The experimental data show that catalysts have activity in steam tar reforming process. At low temperature, the tar was mainly converted into coke using iron carbon catalyst , whereas, at high temperature, the tar was primarily reformed into gas using ilmenite. The specific reactivity of the char-supported iron catalyst changed significantly after the steam reforming at different temperatures because of the changes in the properties of the char and the iron-containing species in the catalyst. Copyright © 2015, AIDIC Servizi S.r.l.


David E.,National Research Institute of Cryogenics and Isotope Technologies
Journal of Analytical and Applied Pyrolysis | Year: 2013

The main objective pursued in this work is to investigate the hydrogen-rich gas production from residual biomass by applying the steam gasification technique. Characteristics of steam gasification of two kinds of biomass (rapeseed oil cakes and walnut shells) at different heating rate (in the order of 10-20 C s-1) and different metal oxide catalysts (CaO, MgO and a mixture 50% CaO and 50% MgO) in a gas-solid concurrent down flow free-fall reactor were investigated. The effects of steam/biomass (S/B) mass ratio (0.0-1.0 g/g) and reactor temperature (750-850 C) on the product yields and the composition of product gas were determined. The experimental results show that the gas yield and the content of H2 in the gas increase with reactor temperature, while the yields of tar, char and the content of CO and CH 4 in the product gas decrease. The presence of steam increases the gas yield and reduces the tar and char yields. It is inferred that an in situ steam reforming reaction of tar takes place even in a short gas residence time in the free-fall reactor. Water-gas shift reaction determines greatly the gas compositions and H2 production at higher temperature. The effects of different occurring catalysts, CaO, MgO and a mixture 50% CaO and 50% MgO, were also investigated in the same unit. The mixt catalyst reveals a comparably good performance in terms of catalytic activity of tar destruction and the consequential increase in the production of gases in thus a short vapor-catalyst contact time. The results verify that the presence of steam and catalyst favors the tar decomposition and lead to increasing of hydrogen content in gas yield. The results obtained with this work indicate the effectiveness of residual biomass recycling, suggest a way to conserve the natural resources and to reduce the environment pollution. © 2013 Elsevier B.V. All rights reserved.


David E.,National Research Institute of Cryogenics and Isotope Technologies | Stefanescu I.,National Research Institute of Cryogenics and Isotope Technologies | Armeanu A.,National Research Institute of Cryogenics and Isotope Technologies
UPB Scientific Bulletin, Series C: Electrical Engineering | Year: 2010

This paper presented an experimental study for CO2 capture from flue gas by pressure swing adsorption process (PSA). Capture of carbon dioxide from a binary mixture (N2/CO2) simulating flue gas was performed by PSA, using selective adsorbents (zeolite-X, carbon molecular sieve, activated carbons). One PSA process consists of three adsorption beds. The process was tested by varying the operation parameters: pressures of adsorption and vacuum evacuation steps. As a typical result, a high purity CO2 (≈99%) can be produced with recoveries of 50% and 65% from feed gases containing 15-25 vol. % CO2 respectively. By the other process of two stage PSA, CO2 can be concentrated from feed gas to product of 99% with much higher capture (>80%). The obtained results prove that the capture of CO2 from the fossil fuel industry by PSA process is to find cost-effective solutions that will reduce the release of CO2 into the atmosphere and can contribute to cleaning of environment.

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