Preparation Of TiN-Supported Nickel Catalyst And Its Application In Catalytic Conversion Of Dahuangshan Lignite

In this paper,using TiN as the carrier and nickel acetate as the nickel source,Ni/TiN catalysts with different nickel loadings of 0-30 mol%were prepared by the incipient wetness impregnation-calcination reduction method.First,the hydrogenation conversion of phenyl benzyl ether(BOB)catalyzed by different loadings of Ni/TiN was investigated.Based on the conversion rate of BOB and the selectivity of the product,the optimal catalyst was selected as Ni/TiN with a loading of10%.(Expressed as Ni_10%/TiN).A series of characterizations on TiN,Ni_10%/TiN and Ni_10%/TiN recycled five times were performed by X-ray diffraction,transmission electron microscopy,scanning electron microscopy,electron energy spectroscopy,X-ray photoelectron spectroscopy,physical adsorption equipment,automatic chemical adsorption and plasma mass spectrometer,etc.The results show that Ni particles are more uniformly dispersed on TiN,there is a strong interaction between Ni and TiN,and the catalyst exhibits good stability.Using BOB and 2-phenoxy-1-phenylethanol(2-BOBE)as lignite-related model compounds,the catalytic hydrogenation conversion of Ni_10%/TiN on the model compounds was investigated under different conditions,and the reaction conditions were optimized.The results showed Ni_10%/TiN can catalytically convert BOB and 2-BOBE into aromatic compounds at 250 ? and lower hydrogen pressure.According to the product distribution,the mechanism of catalytic hydrogenation of model compounds is inferred.Using the catalytic hydrogenation conversion of BOB as a probe,the stability and cycle performance of Ni_10%/TiN were investigated.The results showed that Ni_10%/TiN still maintains a good stable structure,catalytic activity and selectivity after five cycles of use.Taking Xinjiang Dahuangshan lignite(DL)as the research object,the effect of Ni_10%/TiN on the catalytic hydrogenation conversion of DL was discussed.First,the effects of solvents(methanol,ethanol,isopropanol and n-hexane)on the catalytic hydrogenation of DL were investigated under the conditions of 300 ? and 1 MPa initial hydrogen pressure.The results show that when methanol,ethanol,and n-hexane are used as solvents,the yield of solubles obtained by catalytic hydrogenation conversion(CHC)of DL is higher than that of non-catalytic hydrogenation conversion(NCHC),while the opposite result occurs when isopropanol is used as solvent.When ethanol is used as the solvent,the yield of solubles from CHC of DL is the highest,reaching 54.3%,while the yield of solubles from NCHC of DL is 31.1%.Then use n-heptane as the extractant to further separate the solubles obtained from DL hydroconversion into light components and heavy components.The yields of light components and heavy components in the solubles obtained from the catalytic hydrogenation of DL were 21.7%and 32.6%,respectively,while the light components and heavy components in the solubles obtained from the non-catalytic hydrogenation conversion of DL were 11.3%and 19.8%.GC/MS,FTIR,and Oribtrap MS analysis were used to analyze the light and heavy components in the solubles obtained from the non-catalytic and catalytic hydrogenation conversion of DL.The results confirm that compared with non-catalytic hydrogenation conversion,the content of aromatic compounds in the light components of the solubles obtained by catalytic hydrogenation conversion is significantly increased.The light components obtained from non-catalytic hydrogenation conversion contain more long-chain alkanes with larger molecular weights.Besides,the unsaturation and oxygen content of the heavy components obtained by the catalytic hydrogenation conversion of DL are lower than those obtained by the non-catalytic hydrogenation conversion,indicating that Ni/TiN can effectively break the C_alk-O bridge bonds of DL to obtain a large amount of small molecule aromatic compounds.Finally,the catalytic hydrogenation conversion mechanisms of DL were explored based on the molecular composition of the solubles obtained from the catalytic hydrogenation of DL.There are 30 figures,16 tables,and 115 references in this thesis.