George M. Bollas

Dr. George M. Bollas

Department of Chemical & Biomolecular Engineering, UTC Institute for Advanced Systems Engineering, University of Connecticut, 159 Discovery Dr. Unit 5183, RM 221, Storrs, CT-06269, USA

Research Focus & Metrics

Academic Career Length

25Years (2002-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 September 2013 in Green Chemistry
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Journal Article
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SDShoucheng Du
Shoucheng Du
Ioulia VallaIoulia Valla
Ioulia Valla
George M. BollasGeorge M. Bollas
George M. Bollas
Char and coke from biomass catalytic pyrolysis have different origins. They cannot be lumped as one since they occupy different locations on the catalyst surface and, thus, contribute differently to catalyst deactivation. In this study, catalyst (ZSM-5) deactivation in the perspective of comparison of char and coke from pyrolysis of different biomass types is investigated. Pine sawdust, glucose, and cellulose are used as feedstocks in the pyrolysis experiments. Biomass char and coke samples produced via slow and fast, thermal and catalytic pyrolysis are characterized with respect to their overall content, oxidation reactivity, catalyst surface area, pore size distribution changes, bonding groups and their effect on catalyst performance. In particular, it is shown that char forms as an external layer on the catalyst surface and in its macropores, whereas coke forms inside the zeolite micropores via hydrogen transfer and addition reactions. The catalyst effect on glucose and pine slow catalytic pyrolysis is minor compared with that on cellulose slow catalytic pyrolysis, due to macropore blocking by char formation. In fast catalytic pyrolysis, catalyst deactivation is mainly attributed to micropore blocking by coke formation. Char and coke are shown to coexist on the catalyst surface after fast catalytic experiments, with the char content after glucose fast catalytic pyrolysis being 30 wt% of the total solid residue. The origins of char and coke in the cellulose, hemicellulose and lignin components of pine are identified and mechanisms for their formation are proposed.

20 April 2016 in ACS Sustainable Chemistry & Engineering
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Journal Article
Closed access
SDShoucheng Du
Shoucheng Du
JVJulia A. Valla
Julia A. Valla
RPRichard S. Parnas
Richard S. Parnas
George M. BollasGeorge M. Bollas
George M. Bollas

1 September 2015 in Bioresource Technology
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Journal Article
Closed access
DGDavid P. Gamliel
David P. Gamliel
SDShoucheng Du
Shoucheng Du
George M. BollasGeorge M. Bollas
George M. Bollas
Ioulia VallaIoulia Valla
Ioulia Valla

1 May 2014 in International Journal of Hydrogen Energy
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Journal Article
Closed access
ZZZhiquan Zhou
Zhiquan Zhou
LHLu Han
Lu Han
George M. BollasGeorge M. Bollas
George M. Bollas

1 October 2014 in Bioresource Technology
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Journal Article
Closed access
SDShoucheng Du
Shoucheng Du
YSYijia Sun
Yijia Sun
DGDavid P. Gamliel
David P. Gamliel
Ioulia VallaIoulia Valla
Ioulia Valla
George M. BollasGeorge M. Bollas
George M. Bollas

1 December 2013 in Chemical Engineering Science
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Journal Article
Closed access
LHLu Han
Lu Han
ZZZhiquan Zhou
Zhiquan Zhou
George M. BollasGeorge M. Bollas
George M. Bollas