非热等离子体强化Cu催化CO_(2)加氢制甲醇机理探索  

Mechanistic exploration of non-thermal plasma-enhanced Cu-catalyzed CO_(2)hydrogenation to methanol

作　　者：陈玉民[1,2] 董永恒 史承静 孙龙坤 朱丙鑫 李冰 刘洋[1,2] 周怀春[1,2] CHEN Yumin;DONG Yongheng;SHI Chengjing;SUN Longkun;ZHU Bingxin;LI Bing;LIU Yang;ZHOU Huaichun(School of Low-Carbon Energy and Power Engineering,China University of Mining and Technology,Xuzhou 221116,China;Jiangsu Smart Energy Technology and Equipment Engineering Research Center,Xuzhou 221116,China)

机构地区：[1]中国矿业大学低碳能源与动力工程学院,江苏徐州221116 [2]江苏省智慧能源技术与装备工程研究中心,江苏徐州221116

出　　处：《煤炭学报》2024年第10期4276-4294,共19页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(52376218);国家重大科研仪器研制资助项目(51827808);中央指导地方科技发展专项资金资助项目(ZYYD2024JD22)。

摘　　要：CO_(2)耦合绿氢制甲醇可同时实现CO_(2)规模转化利用和绿氢储存,甲醇可作为绿色低碳燃料或工业平台产品大规模应用,对推动碳捕集、利用与封存(CCUS)技术进一步发展具有重要意义。非热等离子体(NTP)能在温和条件下活化CO_(2)进行加氢反应,耦合催化剂后可实现甲醇等特定产物定向调控,但其反应机理亟待明确。基于此,结合介质阻挡放电(DBD)实验与连续脉冲等离子体反应动力学模拟,对NTP强化Cu/γ-Al_(2)O_(3)催化CO_(2)加氢制甲醇反应机理和过程耦合规律进行研究。实验证明,NTP与10%Cu/γ-Al_(2)O_(3)耦合可在80℃、0.1 MPa下实现18.74%CO_(2)转化率和36.28%CH_(3)OH选择性。放电参数在线监测和原位发射光谱(OES)测量结果表明,耦合Cu/γ-Al_(2)O_(3)后局部放电增强,使得平均电子能量和密度增加促进CO、H生成并参与表面反应而消耗,导致光谱强度减弱。进一步由敏感性和ROP分析发现,NTP中H、CO等活性物质通过CO_(2)(S)+H→COOH(S)、CO+H(S)→HCO(S)、CO(S)+H→HCO(S)、CH_(3)O(S)+H→CH_(3)OH(S)等E-R反应替代对应高能垒L-H反应促进甲醇高效生成。分析反应路径得出,甲酸盐(HCOO*)路径是Cu/γ-Al_(2)O_(3)表面甲醇生成主要路径,其中反应CH_(3)O(S)+H(S)→CH_(3)OH(S)+Cu(S)是最大限速步,RWGS+CO氢化路径中通过CO_(2)(S)→COOH(S)→CO(S)路线生成CO(S)并快速脱附为降低CH_(3)OH选择性重要因素。不确定性分析表明,虽然提高CO_(2)吸附速率可有效提高其转化率,但当H(S)不足时反而会增加CO选择性,最优CO_(2)和H_(2)吸附速率比为γ(H_(2))/γ(CO_(2))=7~8;提高CO(S)吸附稳定性并增强H_(2)电子碰撞解离以促进H生成,可提高CO(S)→HCO(S)、CH_(3)O(S)→CH_(3)OH(S)等速率,协同实现27.4%、51%的CO_(2)转化率和CH_(3)OH选择性。Combining CO_(2)and green hydrogen to produce methanol can simultaneously realize CO_(2)conversion and green hydrogen storage.Methanol can be used as a green low-carbon fuel or industrial platform product for large-scale application,which is of great significance to promote the further development of Carbon Capture,Utilization and Storage(CCUS)technology.Non-thermal plasma(NTP)can activate CO_(2)under mild conditions for hydrogenation reaction and obtain specific products such as methanol by combining with catalysts to tailor the reaction routes,but the underlying reaction mechanism is still unclear.Based on this,the reaction mechanism and process coupling laws of the NTP-enhanced CO_(2)hydrogenation with assistance of Cu/γ-Al_(2)O_(3) for methanol production were investigated by combining hydrogenation experiments in a dielectric barrier discharge(DBD)reactor with continuously-pulsed discharge plasma simulations.The experiments investigation showed that 18.74%CO_(2)conversion and 36.28%CH_(3)OH selectivity could be achieved by combining NTP and 10%Cu/γ-Al_(2)O_(3) at 80℃ and 0.1 MPa.The on-line discharge parameters monitoring and in-situ emission spectroscopy(OES)showed that the localized discharge was enhanced by Cu/γ-Al_(2)O_(3),which increased the average electron energy and density,thus promote the CO and H generation and their surface consumption reaction,resulting in the weakening of spectral intensity.Furthermore,the sensitivity and ROP analyses indicated that the active substances such as H and CO in NTP promoted methanol generation efficiently by alternating the corresponding L-H routes,which usually had higher energy barriers,via E-R reactions such as CO_(2)(S)+H→COOH(S),CO+H(S)→HCO(S),CO(S)+H→HCO(S),and CH_(3)O(S)+H→CH_(3)OH(S).The reaction pathways analysis revealed that the formate(HCOO*)pathway was the main pathway for methanol generation on the Cu/γ-Al_(2)O_(3) surface,where the reaction CH_(3)O(S)+H(S)→CH_(3)OH(S)+Cu(S)was the rate-limiting step.The generation of CO(S)via the CO_(

关 键 词：等离子体催化 CO_(2)加氢 绿色甲醇 动力学计算 发射光谱 

分 类 号：TQ223[化学工程—有机化工]