Browsing by Author "Church, TL"

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    Interaction between a bimetallic Ni-Co catalyst and micrometer-sized CaO for enhanced H2 production during cellulose decomposition
    (Elsevier, 2011-01-01) Zhao, M; Yang, XS; Church, TL; Harris, AT
    An SBA-15 supported Ni–Co catalyst and micrometer-sized CaO were used as additives in cellulose decomposition in the presence and absence of injected H2O. A thermogravimetric analyser coupled to a mass spectrometer (TG-MS) was used to examine the different roles of the Ni–Co catalyst and CaO in tuning the kinetics of decomposition and the distribution of the gaseous products. There existed optimal additive/cellulose ratios beyond which H2 generation could not be enhanced by using more of a single additive. However, the combination of both the additives dramatically promoted selective H2 generation. The mechanism of their interaction is discussed. When the catalyst, CaO, and 1 vol.% H2O were present, a stable sustained (interval of >150 °C) high-rate (max >80 vol.%) H2 output resulted. The cumulative H2 yield (250–550 °C) reached 688 ml/g cellulose and the H2 selectivity during this period was nearly 70 vol.%. The char yield was also minimized, at 5.2%. © 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd.
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    Novel CaO-SiO2 sorbent and bifunctional Ni/Co-CaO/SiO2 complex for selective H-2 synthesis from cellulose
    (American Chemical Society, 2012-01-17) Zhao, MW; Yang, XS; Church, TL; Harris, AT
    Catalysis- and sorption-enhanced biomass gasification is a promising route to high-purity hydrogen (H-2); however, most CaO-based sorbents for CO2 capture have poor surface area and mechanical properties, lose carrying capacity over multiple uses, and have insufficient porosity to accommodate extra catalyst sites. We aimed to develop a high-surface-area CaO-SiO2 framework onto which catalysts could be grafted. The best CaO-SiO2 sorbent (n(Ca)/n(Si) = 2:1) maintained a Cao conversion of 65% even after 50 carbonation-decarbonation cycles, better than commercial micrometer-sized CaO or tailored CaO, because of stabilization via Ca-O-Si interactions and an ordered porous structure. Bimetallic catalyst grains (Ni/Co alloy, <20 nm) could be evenly loaded onto this structure by impregnation. The resulting bifunctional complex produced H-2 at nearly the same rate as a mixture of catalyst and commercial CaO while using less total sorbent/catalyst. Furthermore, this complex was much more durable due to its higher coking resistance and stable structure. After 25 carbonation decarbonation cycles, the new catalyst sorbent complex enhanced the H-2 yield from cellulose far more than a mixture of catalyst and commercial CaO did following the same treatment. © 2012, American Chemical Society.