金屬改性HZSM-5催化重整勝利褐煤熱解揮發(fā)分研究
發(fā)布時間：2018-10-24 10:27
【摘要】：熱解是褐煤等低階煤提質(zhì)利用的重要途徑之一。但褐煤熱解焦油中重質(zhì)組分占比大且含氧量高,嚴重制約其儲存和利用。褐煤焦油輕質(zhì)化制備BTEXN等輕質(zhì)芳烴是褐煤熱解加工亟待解決的關(guān)鍵技術(shù)之一。本論文在下墜式管式反應器中對勝利褐煤熱解揮發(fā)分進行原位催化重整,以在溫和條件下裂解重質(zhì)組分為目標研究焦油的輕質(zhì)化,為褐煤熱解定向制備輕質(zhì)芳烴新工藝的開發(fā)提供理論依據(jù)。本論文首先通過熱重手段采用非等溫法模型獲得了勝利褐煤熱分解的動力學參數(shù),考察了反應溫度和停留時間對熱解產(chǎn)物分布的影響,詳細分析了熱解焦油的化學族組分組成。等轉(zhuǎn)化率KAS和FWO模型擬合得到熱分解的活化能分別為292.7和277.6 kJ/mol。溫度是影響褐煤熱解的主要因素,當溫度為600 oC,停留時間為1.0 s時,焦油達到最大產(chǎn)率21.4%(daf)。焦油中氣相色譜/質(zhì)譜聯(lián)用儀可檢測的族組分有含氮有機化合物(ONSs)、含氧有機化合物(OOSs)、含硫有機化合物(OSSs)、脂肪烴和芳烴,其中OOSs和芳烴分別占族組分的50.0%和28.9%。實驗選用HZSM-5作為催化劑,通過浸漬法制備了Co、Mo和Ni改性的HZSM-5催化劑,考察了催化劑對褐煤熱解揮發(fā)分的催化作用。用X射線衍射儀、物理吸附儀、化學吸附儀、傅立葉變換紅外光譜儀和透射電子顯微鏡等對制備的催化劑進行了表征。當熱解揮發(fā)分經(jīng)HZSM-5催化裂解后,氣體產(chǎn)率增加,焦油產(chǎn)率減少,重整焦油在600 oC達到最大產(chǎn)率11.9%。在600 oC下HZSM-5催化重整焦油中芳烴含量占族組分的87.3%,而OOSs含量只占8.1%;BTEXN的產(chǎn)率達到16.1 mmol/g,相比于非催化條件下BTEXN的含量增加了3.0倍,這是由于HZSM-5分子篩具有特殊孔道和酸性位,煤熱解揮發(fā)分產(chǎn)物在經(jīng)過HZSM-5作用后發(fā)生催化裂化、烯烴烷烴的芳構(gòu)化以及酚脫羥基反應,從而生成了較多的BTEXN。由于活性金屬位和酸位的共同作用,Co、Mo和Ni改性的HZSM-5具有更高的催化性能,在600 oC下催化重整焦油中芳烴分別占族組分的90.5%、88.8%和94.2%,焦油中BTEXN等輕質(zhì)芳烴的產(chǎn)率分別達到33.0、26.6和39.7 wt.%,是HZSM-5重整焦油中產(chǎn)率的2.1、1.7和2.6倍。其中Ni/HZSM-5具有最好的催化性能,催化產(chǎn)生的輕質(zhì)芳烴產(chǎn)率最高,且催化產(chǎn)生的H2占熱解總氣體量的62.7%,說明Ni/HZSM-5催化劑可作為褐煤催化熱解揮發(fā)分重整制備輕質(zhì)芳烴及富氫氣體的潛在催化劑。
[Abstract]:Pyrolysis is one of the important ways to improve the quality of low rank coal such as lignite. However, the storage and utilization of lignite pyrolytic tar is restricted because of its large proportion of heavy components and high oxygen content. The production of light aromatic hydrocarbons such as BTEXN from brown coal tar is one of the key technologies to be solved in pyrolysis of lignite. In this paper, the pyrolysis volatilization of Shengli lignite was studied by in-situ catalytic reforming in a falling tubular reactor, and the light weight of tar was studied under mild conditions. It provides a theoretical basis for the development of a new process for the directional pyrolysis of lignite to produce light aromatics. In this paper, the kinetic parameters of pyrolysis of Shengli lignite were obtained by non-isothermal method by thermogravimetry. The effects of reaction temperature and residence time on the distribution of pyrolysis products were investigated, and the chemical composition of pyrolytic tar was analyzed in detail. The activation energies of thermal decomposition obtained by KAS and FWO models were 292.7 and 277.6 kJ/mol., respectively. Temperature is the main factor affecting pyrolysis of lignite. When the temperature is 600 oC, residence time is 1.0 s, the maximum yield of tar is 21.4% (daf). The group components that can be detected by gas chromatography-mass spectrometry in tar are nitrogen-containing organic compounds, (ONSs), oxygen-containing organic compounds, (OOSs), sulfur organic compounds, fatty hydrocarbons and aromatics, of which OOSs and aromatics account for 50.0% and 28.9% of the group components, respectively. Co,Mo and Ni modified HZSM-5 catalysts were prepared by impregnation method with HZSM-5 as catalyst. The catalytic effect of the catalyst on volatile matter of lignite pyrolysis was investigated. The catalysts were characterized by X-ray diffraction, physical adsorption, chemical adsorption, Fourier transform infrared spectroscopy and transmission electron microscope. When the pyrolysis volatiles were pyrolyzed by HZSM-5, the gas yield increased, the tar yield decreased, and the reforming tar reached the maximum yield of 11.9 at 600 oC. At 600 oC, the aromatics content in HZSM-5 catalytic reforming tar accounted for 87.3% of the group fraction, while the yield of OOSs content reached 16.1 mmol/g, which was 3.0-fold higher than that of BTEXN under non-catalytic conditions, which was due to the special pore and acidic potential of HZSM-5 molecular sieve. Catalytic cracking, aromatization of olefin alkanes and phenol dehydroxylation of the volatile products of coal pyrolysis take place after the action of HZSM-5, resulting in the formation of more BTEXN.. Because of the interaction of active metal site and acid site, Co,Mo and Ni modified HZSM-5 have higher catalytic performance. At 600 oC, the aromatics in the tar of catalytic reforming accounted for 90.588% and 94.2% of the group fraction, respectively. The yields of light aromatics such as BTEXN in tar reached 33.00.26.6 and 39.7 wt.%, respectively, which were 2.11.7,2.6 times higher than those in HZSM-5 reforming tar, respectively. Among them, Ni/HZSM-5 has the best catalytic performance and the highest yield of light aromatics. The hydrogen produced by the catalyst accounts for 62.7% of the total pyrolysis gas, which indicates that the Ni/HZSM-5 catalyst can be used as a potential catalyst for pyrolysis of lignite to prepare light aromatics and hydrogen rich body.
【學位授予單位】：中國礦業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD849.2;TQ530.2
本文編號：2291123
[Abstract]:Pyrolysis is one of the important ways to improve the quality of low rank coal such as lignite. However, the storage and utilization of lignite pyrolytic tar is restricted because of its large proportion of heavy components and high oxygen content. The production of light aromatic hydrocarbons such as BTEXN from brown coal tar is one of the key technologies to be solved in pyrolysis of lignite. In this paper, the pyrolysis volatilization of Shengli lignite was studied by in-situ catalytic reforming in a falling tubular reactor, and the light weight of tar was studied under mild conditions. It provides a theoretical basis for the development of a new process for the directional pyrolysis of lignite to produce light aromatics. In this paper, the kinetic parameters of pyrolysis of Shengli lignite were obtained by non-isothermal method by thermogravimetry. The effects of reaction temperature and residence time on the distribution of pyrolysis products were investigated, and the chemical composition of pyrolytic tar was analyzed in detail. The activation energies of thermal decomposition obtained by KAS and FWO models were 292.7 and 277.6 kJ/mol., respectively. Temperature is the main factor affecting pyrolysis of lignite. When the temperature is 600 oC, residence time is 1.0 s, the maximum yield of tar is 21.4% (daf). The group components that can be detected by gas chromatography-mass spectrometry in tar are nitrogen-containing organic compounds, (ONSs), oxygen-containing organic compounds, (OOSs), sulfur organic compounds, fatty hydrocarbons and aromatics, of which OOSs and aromatics account for 50.0% and 28.9% of the group components, respectively. Co,Mo and Ni modified HZSM-5 catalysts were prepared by impregnation method with HZSM-5 as catalyst. The catalytic effect of the catalyst on volatile matter of lignite pyrolysis was investigated. The catalysts were characterized by X-ray diffraction, physical adsorption, chemical adsorption, Fourier transform infrared spectroscopy and transmission electron microscope. When the pyrolysis volatiles were pyrolyzed by HZSM-5, the gas yield increased, the tar yield decreased, and the reforming tar reached the maximum yield of 11.9 at 600 oC. At 600 oC, the aromatics content in HZSM-5 catalytic reforming tar accounted for 87.3% of the group fraction, while the yield of OOSs content reached 16.1 mmol/g, which was 3.0-fold higher than that of BTEXN under non-catalytic conditions, which was due to the special pore and acidic potential of HZSM-5 molecular sieve. Catalytic cracking, aromatization of olefin alkanes and phenol dehydroxylation of the volatile products of coal pyrolysis take place after the action of HZSM-5, resulting in the formation of more BTEXN.. Because of the interaction of active metal site and acid site, Co,Mo and Ni modified HZSM-5 have higher catalytic performance. At 600 oC, the aromatics in the tar of catalytic reforming accounted for 90.588% and 94.2% of the group fraction, respectively. The yields of light aromatics such as BTEXN in tar reached 33.00.26.6 and 39.7 wt.%, respectively, which were 2.11.7,2.6 times higher than those in HZSM-5 reforming tar, respectively. Among them, Ni/HZSM-5 has the best catalytic performance and the highest yield of light aromatics. The hydrogen produced by the catalyst accounts for 62.7% of the total pyrolysis gas, which indicates that the Ni/HZSM-5 catalyst can be used as a potential catalyst for pyrolysis of lignite to prepare light aromatics and hydrogen rich body.
【學位授予單位】：中國礦業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TD849.2;TQ530.2
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