Catalytic Co-pyrolysis Of Cellulose And PP Over (Al-)MCM-41 Zeolites

Fast pyrolysis is one of the most economical and efficient technologies to convert biomass to bio-oil and valuable chemical products.Co-pyrolysis with hydrogen rich matirials such as plastics over zeolite catalysts is one of the signicant solutions to various problems of bio-oil such as high oxygen content,low heat value and high acid content.This paper studied pyrolysis of cellulose and PP seperately and co-pyrolysis of cellulose and PP with different blending ratios(3:1,1:1,1:3)over MCM-41 and Al-MCM-41.The pyrolysis over different heating rates(10 K/min,20 K/min,30 K/min)was studied by Thermogravimetry Analysis(TGA)and kinetic parametes were obtained by Coats-Redfern method.TG and DTG data shows that the two catalysts advance the pyrolysis reaction of PP significantly and reduce its peak temperature of DTG curve from 458℃ to 341℃.The activation energy of pyrolysis of PP also has a remarkable reduction over the two catalysts.Py-GC/MS method was used to obtain the product distribution of pyrolysis of cellulose and PP seperately and co-pyrolisis of cellulose and PP with different blending ratios over MCM-41 and Al-MCM-41 at different temperatures.Experiment results proved that catalyst acidity,co-pyrolysis with PP,and pyrolysis temperature brings significant changes to the product distribution of cellulose.The yield of furans increases with the catalysis of MCM-41 as for the pyrolysis of cellulose and co-pyrolysis,while the yield of olfins and aromatics both experience significant growth over Al-MCM-41,which can be explained by the abundant acid centers in Al-MCM-41.With addition of PP,oxygenated compounds such as furans are decreased,while yields of olfins and aromatics increase greatly.Olefins reach the highest yield with the highest ratio of PP,which aromatics and furans reach the highest yield with the highest ratio of cellulose.High temperature promotes to produce more aromatics and less acids,which can decrease the oxygen content and pH value of liquid product.H?gh temperature also helps to produce more light molecules.Chemical machanism of catalytic co-pyrolysis of cellulose and PP over(Al-)MCM-41 is given.The catalytic effects of(Al-)MCM-41 in chemical aspects are mainly deoxygenation reactions and cracking effects over acid centers to convert oxygenates into hydrocarbons.In physical aspects the catalytic effects are hydrocarbon pools formed inside the channels.The main route for cellulose to form aromatics is aromatization by hydrocarbon pool,while for co-pyrolysis of cellulose and PP,aromatics are mainly formed by Diels-Alder reaction.