Inhibition And Catalytic Cracking Of Tar During The Pyrolysis Of The Corn Cob

The source of biomass is widely and reproducible,and it is of great practical significance to clean and utilize it.Pyrolysis biomass is one of the most commonly used methods,but the tar in pyrolysis process is easy to clog and corrode the piping system and equipment,which seriously affects the heat transfer efficiency.The carbonized material obtained by pyrolysis is not only a raw material for preparing activated carbon,but also can be used as carbon source in the process of hydrogen production.The pyrolysis process of corn cob is explored mainly from pyrolysis process optimization and catalytic pyrolysis in this paper.First of all,with particle size of 3-5 mm corn cob as raw material,the experiment respectively by 1°C·min^-1,5°C·min^-1,10°C·min^-1 and 15°C·min^-1 up to850°C,the results showed that the heating rate from 1°C·min^-11 up to 15°C·min^-1,liquid production rate reduced to 67.07%from 46.36%.The solid yield decreased from 23.89%to 21.29%.The gas yield increased significantly and the composition also changed greatly.Weightlessness is the most severe temperature pyrolysis analysis showed that cod within 200-450°C,respectively in different temperature insulation continue to heat up again after 120 min,the results show that after heat preservation under 350°C have been the least liquid production rate was 43.12%,the solid phase production rate was 18.50%.While in between 150-350°C step heating way can make the liquid production rate down to 37.17%,but solid phase carbonized material production rate is only 14.05%.The effect of seven different catalysts on pyrolysis process was investigated under the condition that the heating rate was 5°C·min^-1 and the pyrolysis temperature was 850 ^℃.Results show that nickel base catalysis can effectively inhibit the tar production,among them,the load of the two kinds of additives C5（Ni/Ce-ZrO₂/γ-Al₂O₃）and C6（Ni/La₂O₃-MgO/γ-Al₂O₃）the effect of the inhibition of tar is best,adding catalyst C5 and C6 liquid output were 20.41%and21.36%respectively,after compared with the same conditions without catalyst,decreased by 56%and 53.7%respectively;At the same time,the production rate of solid phase also increased.The catalyst C5 and C6 were respectively used for cyclic experiments.The results showed that the catalyst remained highly active during the first four cycles,and the activity of the catalyst decreased sharply after repeated cycles.XRD,SEM,EDS and XPS characterization analysis shows that in the previous cycle,carbon deposition on the surface of the catalyst is mainly amorphous coke,less effect on catalyst activity,with the increase of cycling times,carbon deposition on the surface of the catalyst into shapes filamentous carbon,reduce the activity of the catalyst.Magnesium oxide is beneficial to eliminate partial carbon deposition,and C6 is better than C5.In addition,the regeneration performance of catalyst C5 and C6 is not good,and further study is needed.In the process of corn cob pyrolysis,adding alkali metal compound sodium silicate and sodium nitrate as additives,the output of gas phase increased sharply,but the solid carbon materials were exhausted.In the vertical reactor,the high temperature area increases,so that the pyrolysis product can fully occur twice in the reactor,which effectively reduces the output of tar.In addition,containing catalyst C5 and C6carbonized materials in the reaction with CO₂,showed a high reaction rate,after reaction under 900°C for 30 min,carbonized material burning loss rate of 75%,higher than without catalyst of carbonized material nearly doubled.