Gasification ethylene yields

The technology of gasification is under active development in both equipment and process design to reduce capital costs, and in the chemistry of the process to improve yields and obtain more favorable gas ratios. The latter includes the use of catalysts to enhance the process and to promote the formation of specific products, such as methane or ethylene for increased thermal efficiency or for feedstocks for chemical synthesis. 

Volatile matter produced by pyrolysis of the biomass begins to participate in secondary, gas-phase reactions at temperatures exceeding 600°C. These reactions occur very rapidly and yield a hydrocarbon-rich syngas product. As recognized by Diebold (. these reactions resemble the hydrocarbon cracking reactions employed in the manufacture of ethylene and propylene by the petrochemical industry (9,10). The secondary gas-phase reactions dominate the gasification chemistry of biomass. 

It was proposed by Roh et al. [37] that the presence of partially oxidized Ce sites in Ce,cZri 02 suppresses CH4 formation by acetaldehyde decomposition, thus optimizing the hydrogen yield. In addition, Ce Zri c02 promotes noble metal and transition metals for the water-gas shift reaction (Eq. (24.3)) [38]. Moreover, in the reduced state, CexZii x02 niay reduce water to directly yield hydrogen [39]. Finally, Ce Zri, (02 improves the catalyst stability by (i) limiting the formation of ethylene and (ii) promoting carbon gasification [40]. 

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