| This paper selects Luan coal gangue?CG?,Huokou coal?HK?and Linfen corncob?CB?which were all from Shanxi Province in China as raw materials for experiment,and the experiments were carried out in a fiber tube furnace.The pyrolysis behavior of coal gangue,coal and corncob was studied respectively and the co-pyrolysis behavior of coal gangue,coal and corncob with medical stone based catalysts were also studied.The effects of blending ratios,temperatures and catalysts on the product yield and compositions during co-pyrolysis were also investigated.In addition,the contents of gases such as H2,CH4,CO2 and CO produced from co-pyrolysis were measured by gas chromatography.The tar was analyzed by 1HNMR,13CNMR,FTIR and GC/MS,and the chars were analyzed by SEM,FTIR,Raman and XRD.The co-pyrolysis mechanism of coal gangue,coal and corncob was also discussed.The main results are as follows:?1?When HK coal was pyrolyzed at 700?,the tar yield was 10.7%,the char yield was 76.3%and the gas yield was 13.0%.When adding Fe?NO3?3/HZSM-5 and Co/HZSM-5,the char yield increased,while when adding Mo/HZSM-5 and Mo/?-Al2O3 respectively,the char yield decreased a little,and the gas yield increased.?2?During co-pyrolysis of HK coal and coal gangue,the tar yield was higher when adding Fe?NO3?3/MS,while for Co,Mo,the tar yield is higher when HZSM-5 is used as carrier.In addition,adding Fe?NO3?3/MS and Fe?NO3?3/HZSM-5 increased the relative content of H2 and adding Co/HZSM-5 increased the relative content of CH4 during co-pyrolysis.?3?During co-pyrolysis of HK coal and corncob with different catalysts at700?,when adding Fe?NO3?3/MS,Fe?NO3?3/HZSM-5 and Fe?NO3?3/?-Al2O3,the total conversion and char yield decreased a little,the tar yield reduced,which were25.4%,27.3%,and 24.3%respectively;and the gas yield increased,which were38.0%,37.0%and 39.0%respectively.During the co-pyrolysis of HK demineralized coal and corncob?the blending ratio of the demineralized coal is 20%?,the total conversion were the highest when adding Fe?NO3?3/HZSM-5,and the gas yield was the highest when adding Fe?NO3?3/?-Al2O3;and the tar yield were increased slightly,which were 38.0%and 37.5%when adding Fe?NO3?3/HZSM-5 and Fe?NO3?3/?-Al2O3.?4?During the co-pyrolysis of coal,coal gangue and corncob at 700??HK:CG:CB=1:5:4?,after adding different catalysts,the char yield has little effect,the tar yield decreased.The tar yield was the lowest when adding Co/MS,which was 11.0%and the gas yield was the highest and it was 25.7%.In addition,the addition of Fe?NO3?3/?-Al2O3?Mo/?-Al2O3 and Co/?-Al2O3 increased the relative content of H2 at500?,which were 27.5%,29.4%and 28.4%respectively;and the addition of Fe?NO3?3/MS increased the relative content of CH4 at 600?,which was 40.2%.The addition of Fe?NO3?3/HZSM-5 increased the relative content of CH4 at 400?and500?,which were 56.4%and 75.0%respectively;and the addition of Mo/?-Al2O3decreased the relative content of CO2 obviously?except 700??.Moreover,the addition of Fe?NO3?3/MS,Co/MS and Mo/MS also increased the relative content of CO,while the addition of Co/MS increased the most at 700?,which is 23.8%.?5?From the results of analysis of tar,such as NMR,GC/MS,and FTIR etc.,it was found that the medical stone-based catalysts could increase the content of carbon in the tar,which is linked to O in carbohydrates,esters and alcohols,and improved the quality of tar.Through the results of analysis of char,such as SEM,FTIR,XRD,Raman,etc.,it was found that the catalysts with medical stone and?-Al2O3 as carriers had no significant effect on the structure and mineral compositions of the char.This study will provide the theoretical basis for the selection of catalysts during the catalytic pyrolysis of coal,coal gangue and biomass,and provide guidance for the clean and efficient utilization of them. |
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