Study On Pyrolysis Characteristics Of Transition Metal Oxide Supported USY Zeolites To Shendong Coal

As a primary energy source with abundant reserves in China,coal will not change its position in energy consumption for a short period of time.Coal pyrolysis is an important link in coal conversion process such as liquefaction and gasification.The suitable catalyst in pyrolysis process can change the composition of pyrolysis products and improve the quality of the tar.The effect of metal modified USY catalyst on the catalytic pyrolysis of Shendong coal in a powder-particle fluidized bed was studied in this paper.Single-and double-metal oxide supported catalysts with different loadings were prepared by impregnation using commercial USY molecular sieves as carrier.The structure and properties of the catalysts were characterized by ICP,XRD,BET and NH₃-TPD.The characterization results showed that the impregnated metal can be effectively loaded onto the catalyst.After the metal was supported,the weak acid amount of the catalyst increased and the amount of strong acid decreased,the specific surface area and pore volume decreased,and the introduction of the metal didn't damage the structure of the carrier.The results of powder-particle fluidized bed experiments showed that the addition of catalyst mainly catalyzed the pyrolysis volatiles of Shendong coal,and the yield of semi-coke had no obvious change.The acidic sites of USY zeolite increased the yield of pyrolysis water and gas,and increased the amout of coke.The yields of phenols,aliphatic hydrocarbons,monocyclic aromatics and oxygenated compounds in tar decreased,while the yield of naphthalenes aromatics increased significantly.After loading WO₃,the tar yield was reduced.Among them,phenols content increased,and the content of naphthalenes aromatics,monocyclic aromatics,aliphatic hydrocarbons and heteroatom compounds decreased.Meanwhile the yield of oxygen-containing gases in pyrolysis gas increased significantly.When the loading amount was 6%,the gas yield reached the maximum,the yield of phenols increased by 150.7%,and the yield of naphthalenes decreased.Bimetallic catalysts with different loadings of NiO,Fe₂O₃ and Co₃O₄ were prepared by using 6W-USY as support.The results of Shendong powder-particle fluidized bed showed that the yield of pyrolysis gas increased with Ni/W-USY catalyst,and the increase of H₂was obvious.The content of monocyclic aromatics,aliphatic hydrocarbons and oxygenates in tar increased significantly,and the content of naphthalenes and polycyclic aromatics decreased.The thermal weight loss of tar at 300?under 6Ni/W-USY was less than that under W-USY,and the yield of aliphatic hydrocarbons increased significantly.The yields of CO,CH₄ and H₂ in pyrolysis gas increased obviously under the action of Fe/W-USY catalyst.After loading metal,the strong acidity of catalyst decreased,and the deoxidization ability weakened so that phenols content increased,and the content of naphthalenes aromatics decreased.The thermal loss of 6Fe/W-USY pyrolysis tar at 300?was greater than that under W-USY,and the tar had more light components.Among them,the yield of phenols increased 54.5%,and the yield of naphthalenes aromatics decreased by 18.6%.Under the action of Co/W-USY catalyst,the yields of CO and H₂ in gas products increased.When the loading of Co₃O₄ was 6%,the total gas yield reached the maximum.Co/W-USY catalyst decreased the content of naphthalenes significantly and increased the content of other oxides and aliphatic hydrocarbons.The thermal weight loss of 6Co/W-USY pyrolysis tar at 300?was less than that of W-USY,and the yield of GC-MS measurable parts in tar decreased.