CH_(4)-CO_(2)重整镍基催化剂抗积碳性能研究进展  

Research progress in carbon deposition resistance of nickel-based catalysts for carbon dioxide reforming of methane

作　　者：马清祥[1] 张静[1] 王毅婕 吕凌辉 范辉[1] 曾春阳 赵天生[1] MA Qingxiang;ZHANG Jing;WANG Yijie;LYU Linghui;FAN Hui;ZENG Chunyang;ZHAO Tiansheng(State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering,Ningxia University,Yinchuan 750021,China;China Petroleum and Chemical Industry Federation,Beijing 100723,China)

机构地区：[1]宁夏大学省部共建煤炭高效利用与绿色化工国家重点实验室,宁夏银川750021 [2]中国石油和化学联合会,北京100723

出　　处：《洁净煤技术》2022年第5期14-28,共15页Clean Coal Technology

基　　金：宁夏自然科学基金资助项目(2021AAC03063,2020AAC03023)。

摘　　要：温室效应引起的全球变暖对人类生存环境造成了严重威胁。CH_(4)-CO_(2)重整反应(DRM)以两大温室气体为原料,在消耗利用CH_(4)和CO_(2)的同时,产生H_(2)/CO物质的量比接近1的合成气,是费托合成生产液体燃料或高值化学品的理想原料。镍基催化剂是DRM反应应用最广泛的催化剂,但在高温反应条件下易因烧结和积碳而失活,阻碍了其工业应用。针对镍基催化剂因积碳而失活的不足,综述了DRM反应热力学和反应机理,对催化剂积碳失活机理进行分析,论述了催化剂活性组分、载体、助剂以及制备方法等。CH_(4)-CO_(2)重整热力学分析表明高温低压有利于平衡向生成合成气方向移动。逆水煤气变换反应会消耗原料中CO_(2)产生CO,因此一般情况下CO_(2)转化率高于CH_(4)转化率,H_(2)/CO物质的量比小于1。反应温度557~700℃时,积碳主要来源于CO歧化反应和CH_(4)裂解反应。反应温度超过700℃,不利于CO歧化反应的发生,积碳主要来源于CH_(4)裂解反应。积碳依据活性不同可分为无定形碳和石墨碳,无定形碳在低于573 K即可被H_(2)或含氧物种消除。而石墨碳需要在较高温度才能被气化消除,是造成催化剂失活的主要原因。增加原料气中CO_(2)/CH_(4)物质的量比、在原料气中添加水蒸气或氧气可以在一定程度上减少积碳,但解决积碳问题的核心是催化剂的研究。双金属镍基催化剂在一定比例下形成合金,在活化CH_(4)及消碳过程起协同作用。载体介孔结构的限域效应使镍颗粒尽可能存在于催化剂孔道中,有利于减小金属镍颗粒尺寸且在一定程度上增强金属-载体相互作用力,从而提高催化剂对DRM反应催化活性和抗积碳能力。具有特殊氧化还原性质和超常储氧能力(OSC)的载体可利用氧空位来促进CO_(2)活化和解离,通过将表面碳氧化为CO来减少由于碳沉积而导致的催化剂失活。使用碱性载体或助剂可适Global warming caused by the greenhouse effect poses a serious threat to the human living environment.Dry reforming of methane(DRM) reaction uses two major greenhouse gases as feedstock to produce syngas with H_(2)/CO molar ratio close to 1 while consuming methane and carbon dioxide,making it an ideal feedstock for Fischer-Tropsch synthesis to produce liquid fuels or high value chemicals.Nickel-based catalysts are the most widely used catalysts for DRM reaction,but they are prone to deactivation due to sintering and carbon accumulation under high temperature,hindering their industrial application.In view of the inactivation of nickel-based catalysts due to carbon deposition,thermodynamics and reaction mechanisms of DRM reactions were reviewed,carbon deposition inactivation mechanisms was analysed,and catalyst active components,supports,auxiliaries and preparation methods were discussed.Thermodynamic analysis of DRM reaction shows that high temperature and low pressure favor a shift in equilibrium towards syngas production.Reverse water-gas shift reaction consumes CO_(2) from the feedstock to produce CO,so in general the CO_(2) conversion rate is higher than the CH_(4) conversion rate,and the H_(2)/CO molar ratio is less than 1.At a reaction temperature of 557-700 ℃,the carbon deposition mainly comes from the carbon monoxide disproportionation reaction and the methane cracking reaction.Reaction temperature above 700 ℃ are not conducive to carbon monoxide disproportionation reactions and carbon deposition will mainly originate from methane cracking reaction.Amorphous carbon can be eliminated by hydrogen or oxygenated species at temperatures below 573 K.On the other hand,graphite carbon requires gasification at higher temperature to be eliminated and it is the main cause of catalyst deactivation.Increasing the CO_(2)/CH_(4) molar ratio in the feed gas or adding water vapour or oxygen to the feed gas can reduce carbon deposition to some extent,but to solve the problem of carbon accumulation is the study of cataly

关 键 词：CH_(4) CO_(2) 重整 镍基催化剂 失活 抗积碳 

分 类 号：TQ53[化学工程—煤化学工程]