天然气蒸汽重整制氢技术研究现状

Technology research status of natural gas steam reforming to produce hydrogen

甲烷水蒸汽重整是目前广泛应用的制氢方法,具有工艺成熟、装置运行可靠、经济性强、环保和资源合理利用等优点,在适应大规模生产方面具有不可比拟的优势,但面临着工业设备投资大及催化剂易积炭失活的问题。国内外对甲烷水蒸汽重整的重点研究方向是制备高活性、高稳定性和强抗积炭性能的催化剂以及研制低水碳比条件下应用的催化剂,有效降低能耗。甲烷水蒸汽重整催化剂分为非贵金属催化剂、负载贵金属催化剂和过渡金属碳化物及氮化物催化剂,这些催化剂均能在高空速下使反应达到热力学平衡,甲烷转化率和CO/H2选择性均很高。金属活性组分负载量、载体、助剂及负载过程对催化剂活性、稳定性和选择性有重要的影响。同时,在甲烷水蒸汽重整反应过程中,催化剂活性组分的烧结、重新组合以及催化剂表面的积炭均可以引起催化剂失活,其中,催化剂表面积炭是最主要的影响因素,积炭反应是发生C—H和C—C键断裂后的表面碳聚反应,可引起活性中心中毒,堵塞孔道,甚至使催化剂粉化。积炭反应的影响因素包括添加稀土金属氧化物、催化剂制备工艺和催化剂的载体。

Steam reforming of methane （SRM） is the widely used method of hydrogen production, which has multiple advantages of mature technology, reliable operation, economy, environmental protection, rational use of resources and so on. Steam reforming of methane has unparalleled advantages in adapting to large -scale production, however, it is also faced with the problems of large industrial equipment investment and easy catalyst deactivation due to carbon deposition. Currently, the researches on SRM at home and abroad focus on the development of the catalysts with high activity, high stable, and strong resistance to carbon deposition, which are applied under low water to carbon ratio, effectively reducing the energy consumption. SRM catalysts included non-noble metal catalysts, supported noble metal catalysts and transition metal carbides or nitrides catalysts, which could make the reaction reach thermodynamic equilibrium under high space velocity, and CH4 conversion and CO/H2 selectivity were high. The loadings of metal active component,carriers, additives and loading process had significant influence on the activity, stability and selectivity of the catalysts. Meanwhile, in the SRM reaction, the active component sintering, recombining and coke on the catalyst surface could cause deactivation of the catalyst, and the carbon deposit on catalyst surface was the most important factor. The carbon deposit was carbon aggregating reaction on surface, which occured after C-H and C-C bond breaking, and caused active centre poisoning, pore blocking and even the catalyst pulverization. The influencing factors of carbon deposit reactions included rare earth metal oxide addition, catalyst preparation process and catalyst carrier.