Effects of NH4H2PO4-Loading and Temperature on the Two-Stage Pyrolysis of Biomass: Analytical Pyrolysis-Gas Chromatography/Mass Spectrometry Study

The two-stage pyrolysis of rice husk impregnated with NH4H2PO4 (PA) was carried out with pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) technique. The effects of PA content and first stage pyrolysis temperature (T1) on the product distribution were investigated, with related reaction mechanisms being analyzed. During the first stage pyrolysis, the impregnation of PA could promote the formation of anhydrosugars and furans, but inhibit the generation of phenolics and other products. High selectivity on levoglucosenone (LGO) and furfural (FF) was achieved under optimum pyrolysis conditions of PA content of 8.63 wt% and T1 of 390 degrees C, with the peak area% of LGO and FF as high as 34.65% and 20.98%, respectively. Whereas, the products in the second stage pyrolysis (phenolics, furans, hydrocarbons, etc.) contained low oxygen contents, and thus, could be used for fuel application due to the high heating value.