Tire Fluidized Bed Pyrolysis Char Pore Structure Characteristics Of Study

The disposal of waste tires is an increasing environmental problem. In China, the main routes for disposal have centered on landfill, open dumping which have proven to be harmful for environment. By incineration only the thermal value of the tires is used while valuable chemical compounds are lost. On the other hand, pyrolysis is an environmentally friendly way to recover useful compounds from waste tyres.A bench-scale bubbling fluidized bed with 30mm inside diameter was used to study the pyrolysis of waste tires. The effects were examined of (l)pyrolysis temperature (450-850℃) and (2)different size of bed materials and (3)fluidization velocity(U/Umf). As the temperature is increase there is an decrease in the yield of char.The size of bed materials and fluidization velocity are important influence factor. The influence of them is similar with each other.The element nitrogen and sulfur in waste tyres are major precursors of secondary pollutions.As temperature was increased, percentage of C, H,N, S and H/C of chars decreased. It showed that the aromaticity of chars increased. Most of S, about 60-80%, remain in chars.The characteristics of pyrolytic chars prepared at various pyrolysis temperature were analyzed by Mercury Porosimeter and SEM. The experimental results showed that the chars received at 400℃ were not pyrolyzed completely. And their surface was liquation. Most of internal pores were as large as 20-200nm and 2-200 um. The distribution of pore size was similar for all the conditions studied. BET curve relative to temperature appeared "~" shape. Influence of temperature and fluidization conditions on BET is similar to pore volume and porosity. Analysis of pore features showed that pyrolysis char is fusible char and pore structure is very complicate.The pore distribution of activated carbon received at various temperature was mostly between 2~10nm. The distribution of activated carbon received at various activated time was similar to the temperature mode. The pore size was mostly between 2~10nm too. There were no macropore have been found expect the half hour activated mode at 800℃ temperature, most of the pore were mesopore and micropore.The total BET surface area of the activated carbon increased with the increasing activated temperature. When the activated temperature was reached 800℃, the totalBET surface area was 376m2/g-the highest surface area in this article. Continuing heightened the activated temperature, the total surface area decreased.The highest total BET surface area received at various activated time was 1 hour mode at 800℃. Increasing the activated time the surface area had no apparently changed. The activated process was finished in 1 hour.The distribution of pore volume was similar to the BET surface area.