On-line Catalytic Cracking Of Woody Biomass Fast Pyrolysis Vapors Using Mesoporous Catalysts

Fast pyrolysis is a efficient technique to transform lignocellulosic biomass mainly into liquid product. Limited to the poor utilization technology, large-scale use is not viable at present. Crude bio-oil is hard to be used as liquid fuels owing to the poor fuel properties, and also difficult for chemical recovery due to the complex chemical composition. Based on the present background, pyrolysis mechanism of biomass main components was summarized firstly, and then two parts of experimental studies were carried out:1. Comparison study on fast pyrolysis of poplar wood and pine woodThe purpose of this section is to reveal the component difference of the poplar wood (a typical hardwood) and pine wood (a typical softwood) on the distribution of their fast pyrolysis products. Analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed for fast pyrolysis of several biomass materials and on-line analysis of the pyrolysis vapors. The results indicated that pyrolytic product distribution from the two woods differed from each other. The pyrolytic products from the pine wood did not contain syringol-type phenolic compounds. Moreover, fast pyrolysis of the poplar wood produced more linear acids and carbonyls, but less anhydrosugars than the pine wood. In addition, the small amount of the ash in the two woods had no great effects on the furans and phenolic compounds, but inhibit the formation of anhydrosugars and meanwhile promote the formation of the linear carbonyls. Based on the experimental results and the pyrolytic pathways for the formation of major pyrolytic products, we revealed the main reason for the different product distribution from the two woods.2. study on the on-line catalytic cracking of poplar wood using mesoporous catalystsThe purpose of this section is to investigate the pyrolytic behavior of biomass in the presence of different mesoporous materials. Py-GC/MS was employed for fast pyrolysis of poplar and on-line analysis of the pyrolysis vapors. The results indicated that mesoporous zirconia oxide performances better catalytic activity than mesoporous titanium oxide and SBA-15; it can effectively increase the content of phenols and hydrocarbon, meanwhile decrease aldehydes. But to our regret, all kinds of materials used in this study do not show a favorable inhibitory action for acids. Further modified is needed to enhance the catalytic property.