Catalytic Upgrading of Switchgrass Pyrolysis Bio-oil Vapors

摘要

Catalytic upgrading of bio-oil from switchgrass pyrolysis was investigated overCe_(0.5)Zr_(0.5)O_2 mixed oxides to produce higher carbon chain molecules for use as fuel additivesfrom short aldehydes and carboxylic acids found in bio-oil mixtures. The experiments werecarried out in a single two-stage process where the gaseous products from the pyrolysis reactionwere fed directly to a fixed catalyst bed in a separate reactor in series with the pyrolysis reactor.The final products were condensed to the liquid phase and collected for analysis. GC by GCanalysis of products shows evidence of catalytic activity. Acetic acid and propanoic acid foundin the bio-oil were converted to acetone and 3-pentanone, respectively, among other products,when reacted over the catalyst. This is consistent with our work on model compounds that shortaldehydes and carboxylic acids are converted to higher chain aldehydes and ketones by way ofaldol condensation and ketonization over mixed oxides catalyst. Reacting over mixed oxidescatalyst resulted in lower liquid yields from pyrolysis when compared to experiments withoutcatalyst. The char yields remained the same while the gas yields, by difference, appear to haveincreased under these conditions. The coated monolith catalysts seem to have higher activitythan the pelletized catalysts for the same amount of ceria and zirconia loading.