Interaction between a bimetallic Ni-Co catalyst and micrometer-sized CaO for enhanced H_2 production during cellulose decomposition

摘要

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 H_2O. 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 H_2 generation could not be enhanced by using more of a single additive. However, the combination of both the additives dramatically promoted selective H_2 generation. The mechanism of their interaction is discussed. When the catalyst, CaO, and 1 vol.% H_2O were present, a stable sustained (interval of >150 ℃) high-rate (max >80 vol.%) H_2 output resulted. The cumulative H_2 yield (250-550 ℃) reached 688 ml/g cellulose and the H_2 selectivity during this period was nearly 70 vol.%. The char yield was also minimized, at 5.2%.