不同催化剂对污泥热解特性的影响及机理分析
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摘要
为提高污泥资源化,进一步实现污泥热解产物利用的多元化,探究了经机械化学预处理后,CaO、CaO-半焦和半焦3种不同催化体系对污泥快速热解产物特性的影响。结果表明:CaO催化体系下,H_2产率较原污泥提高了80%,通过TG-DTG、FTIR分析发现,添加CaO有助于热解过程中发生固碳反应和CO_2的原位释放,利于CO、H_2生成和半焦产率的降低;采用适量半焦与CaO混合作为催化剂,可以优化热解气品质,显著提高H_2占比,体积分数达到44. 21%,同时促进焦油产生,为后续焦油二次裂解产气提供新思路;完全以半焦为催化剂有利于热解后焦炭孔隙和比表面积的增加,使其具备开发为吸附材料和负载型催化材料的潜力。
In order to improve resource utilization of sludge and further diversification of sludge pyrolysis product utilization,in this study,the effect of sludge pyrolysis characteristics was explored on three different catalytic systems of CaO,CaO-semicoke and semi-coke after mechanical chemical pretreatment. The result showed that H_2 yield of CaO catalyst was 80% higher than that of the original sludge. By TG-DTG and FTIR,we also found that the addition of CaO caused carbon fixation reaction and in-situ release of CO_2 during pyrolysis,which was beneficial to the generating of CO,H_2 and reduced semi-coke yield.Mixing appropriate semi-coke and CaO could optimize the quality of pyrolysis gas,increase the proportion of H_2 significantly even up to 44. 21%. It can also promote the production of tar,which provided ideas for the subsequent secondary cracking of tar. Semi-coke,as the single catalyst,facilitated the increase of pore structure and specific surface area of the semi-coke produced in pyrolysis,gave it the potential to be developed into adsorbent materials and supported catalytic materials.
In order to improve resource utilization of sludge and further diversification of sludge pyrolysis product utilization,in this study,the effect of sludge pyrolysis characteristics was explored on three different catalytic systems of CaO,CaO-semicoke and semi-coke after mechanical chemical pretreatment. The result showed that H_2 yield of CaO catalyst was 80% higher than that of the original sludge. By TG-DTG and FTIR,we also found that the addition of CaO caused carbon fixation reaction and in-situ release of CO_2 during pyrolysis,which was beneficial to the generating of CO,H_2 and reduced semi-coke yield.Mixing appropriate semi-coke and CaO could optimize the quality of pyrolysis gas,increase the proportion of H_2 significantly even up to 44. 21%. It can also promote the production of tar,which provided ideas for the subsequent secondary cracking of tar. Semi-coke,as the single catalyst,facilitated the increase of pore structure and specific surface area of the semi-coke produced in pyrolysis,gave it the potential to be developed into adsorbent materials and supported catalytic materials.
引文
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[6] Shen L,Zhang D K. An experimental study of oil recovery from sewage sludge by low-temperature pyrolysis in a fluidized-bed[J].Fuel,2003,82(4):465-472.
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[8] Klinghoffer N B,Castaldi M J,Nzihou A. Catalyst properties and catalytic performance of char from biomass gasification[J].Industrial&Engineering Chemistry Research,2012,51(40):13113-13122.
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[13]刘龙茂，陈建林，李娣，等．城市生活污泥低温催化热解实验研究[J]．环境科学与技术，2009,32(7):156-159.
[14]张亚，金保昇，左武，等．污泥残炭对城市污泥催化热解制油影响的实验研究[J]．东南大学学报(自然科学版)，2014,44(3):605-609.
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[18]胡艳军，吴亚男，高涛，等．污泥热解中残焦表面官能团结构演化特征[J]．燃烧科学与技术，2018,24(2):126-131.
[19]陈建标．炼化废水污泥混煤热解燃烧特性及动力学研究[D]．大连:大连理工大学，2016.
[20]荣鼐．基于CaO载碳体的煤化学链气化关键过程实验研究[D]．杭州:浙江大学，2015.
[21] Ohtsuka Y,Tomita A. Calcium catalysed steam gasification of Yallourn brown coal[J]. Fuel,1986,65(12):1653-1657.
[22]刘秀如，吕清刚．流化床污泥热解实验及产物性质研究[J]．环境科学学报，2013,33(11):3068-3074.
[23]毛文静，韩融，陈贝，等．机械化学预处理干污泥快速热解产气特性研究[J]．环境科学与技术，2018,41(8):145-151.
[24] Liu X Q,Ding H S,Wang Y Y,et al. Pyrolytic temperature dependent and ash catalyzed formation of sludge char with ultrahigh adsorption to 1-naphthol[J]. Environmental Science&Technology,2016,50(5):2602-2609.
[25] Grube M,Lin J G,Lee P H,et al. Evaluation of sewage sludge based compost by FT-IR spectroscopy[J]. Geoderma,2006,130(3/4):324-333.
[26] Gai C,Chen M J,Liu T T,et al. Gasification characteristics of hydrochar and pyrochar derived from sewage sludge[J]. Energy,2016,113:957-965.
[2] Yang K,Zhu Y,Shan R,et al. Heavy metals in sludge during anaerobic sanitary landfill:speciation transformation and phytotoxicity[J]. Journal of Environmental Management,2017,189:58-66.
[3] Meier C,Voegelin A,Elena P D R A,et al. Transformation of silver nanoparticles in sewage sludge during incineration[J].Environmental Science&Technology,2016,50(7):3502-3510.
[4] Zhen G Y,Lu X Q,Kato H,et al. Overview of pretreatment strategies for enhancing sewage sludge disintegration and subsequent anaerobic digestion:current advances, full-scale application and future perspectives[J]. Renewable and Sustainable Energy Reviews,2017,69:559-577.
[5] G. Gascó，Blanco C G,Guerrero F,et al. The influence of organic matter on sewage sludge pyrolysis[J]. Journal of Analytical&Applied Pyrolysis,2005,74(1/2):413-420.
[6] Shen L,Zhang D K. An experimental study of oil recovery from sewage sludge by low-temperature pyrolysis in a fluidized-bed[J].Fuel,2003,82(4):465-472.
[7] Tang S Q,Zheng C M,Yan F,et al. Product characteristics and kinetics of sewage sludge pyrolysis driven by alkaline earth metals[J]. Energy,2018,153:921-932.
[8] Klinghoffer N B,Castaldi M J,Nzihou A. Catalyst properties and catalytic performance of char from biomass gasification[J].Industrial&Engineering Chemistry Research,2012,51(40):13113-13122.
[9]彭海军，李志光，夏兴良，等．污泥热解残渣催化市政破膜污泥的热解作用[J]．环境化学，2014,33(3):508-514.
[10] Udomsirichakorn J,Basu P,Salam P A,et al. Effect of CaO on tar reforming to hydrogen-enriched gas with in-process CO2capture in a bubbling fluidized bed biomass steam gasifier[J]. International Journal of Hydrogen Energy,2013,38(34):14495-14504.
[11] Jordan C A,Akay G. Effect of CaO on tar production and dew point depression during gasification of fuel cane bagasse in a novel downdraft gasifier[J]. Fuel Processing Technology,2013,106(2):654-660.
[12] Chen S Y,Sun Z,Zhang Q,et al. Steam gasification of sewage sludge with CaO as CO2sorbent for hydrogen-rich syngas production[J]. Biomass and Bioenergy,2017,107:52-62.
[13]刘龙茂，陈建林，李娣，等．城市生活污泥低温催化热解实验研究[J]．环境科学与技术，2009,32(7):156-159.
[14]张亚，金保昇，左武，等．污泥残炭对城市污泥催化热解制油影响的实验研究[J]．东南大学学报(自然科学版)，2014,44(3):605-609.
[15] Adéla Hlavsová，Agnieszka Corsaro,Helena Raclavská，et al. The effects of varying CaO content and rehydration treatment on the composition,yield,and evolution of gaseous products from the pyrolysis of sewage sludge[J]. Journal of Analytical and Applied Pyrolysis,2014,108:160-169.
[16] Ellig D L,Lai C K,Mead D W,et al. Pyrolysis of volatile aromatic hydrocarbons and n-heptane over calcium oxide and quartz[J]. Industrial&Engineering Chemistry Process Design&Development,1985,24(4):1080-1087.
[17]卢艳军，胡艳军，余帆，等．基于Py-GC/MS的污泥含碳、氧官能团热解演化过程研究[J]．化工学报，2018,69(10):4378-4385.
[18]胡艳军，吴亚男，高涛，等．污泥热解中残焦表面官能团结构演化特征[J]．燃烧科学与技术，2018,24(2):126-131.
[19]陈建标．炼化废水污泥混煤热解燃烧特性及动力学研究[D]．大连:大连理工大学，2016.
[20]荣鼐．基于CaO载碳体的煤化学链气化关键过程实验研究[D]．杭州:浙江大学，2015.
[21] Ohtsuka Y,Tomita A. Calcium catalysed steam gasification of Yallourn brown coal[J]. Fuel,1986,65(12):1653-1657.
[22]刘秀如，吕清刚．流化床污泥热解实验及产物性质研究[J]．环境科学学报，2013,33(11):3068-3074.
[23]毛文静，韩融，陈贝，等．机械化学预处理干污泥快速热解产气特性研究[J]．环境科学与技术，2018,41(8):145-151.
[24] Liu X Q,Ding H S,Wang Y Y,et al. Pyrolytic temperature dependent and ash catalyzed formation of sludge char with ultrahigh adsorption to 1-naphthol[J]. Environmental Science&Technology,2016,50(5):2602-2609.
[25] Grube M,Lin J G,Lee P H,et al. Evaluation of sewage sludge based compost by FT-IR spectroscopy[J]. Geoderma,2006,130(3/4):324-333.
[26] Gai C,Chen M J,Liu T T,et al. Gasification characteristics of hydrochar and pyrochar derived from sewage sludge[J]. Energy,2016,113:957-965.