摘要
对近几十年乙炔氢氯化合成氯乙烯用非均相无汞催化剂失活的原因和再生方法进行总结。乙炔法合成氯乙烯催化机理分先吸附乙炔和先吸附氯化氢两类。催化剂活性组分锡、铋和钯流失,氧化态铂和金被乙炔分子还原至低价或金属态,活性组分分散不均和晶粒长大均容易导致催化活性下降。先通入乙炔或乙炔进料过量、表面短链类聚乙烯或聚乙炔过渡态化合物难脱附、不同的载体及其表面性质均会诱导生成积炭物质。制备复合催化剂、添加碱土或稀土金属助剂有助于协同催化和自行还原再生。表面改性能改变吸附顺序,在线通入适量NO以及时去除积炭,可提高催化剂的稳定性。离线有氧烧炭再生含碳载体效果较差,而硝酸加热处理或王水处理失活的贵金属催化剂能恢复初始或接近初始催化活性。并对乙炔氢氯化无汞催化剂的发展进行展望。
The deactivation reasons for and regenerated methods of non-mercury heterogeneous catalyst for synthesis of vinyl chloride （VCM） with acetylene hydrochlorination in recent decades were summarized in this article. The catalytic mechanisms of VCM synthesis by acetylene method were devided into two types ： pre- adsorption acetylene and hydrogen chloride. The loss of active components tin, bismuth and palladium, the reduction of oxidation state platinum and gold to low valency state or metal state by acetylene molecules, poor dispersion and grains growth of active components resulted in activity decrease of the catalyst. The factors,including previous treatment with acetylene or excess acetylene, difficult desorption of transition state compounds of short chain polyethylene or poly-acetylene, different carriers and their surface properties, could contribute to carbon deposition. Preparation of composite catalyst, and addition of alkaline earth and rare earth metal additives were beneficial to synergistic catalysis and self-regeneration. The surface modifi- cation of the carriers could change the order of absorption. In order to remove coke in time, appropriate NO gas was introduced online, and then the stability of the catalyst was enhanced. The performance of the carbon carrier was poor via off-line aerobic coke-burning regeneration. However, deactivated noble metal catalyst could be regenerated to recover its initial or near initial catalytic activity with nitric acid or aqua regia treatment. Finally, the development of mercury-free catalyst for acetylene hydrochlorination in thefuture was outlined.
出处
《工业催化》
CAS
2015年第11期860-865,共6页
Industrial Catalysis
关键词
催化剂工程
无汞催化剂
失活
再生
乙炔氢氯化
氯乙烯
catalyst engineering
non-mercury catalyst
deactivation
regeneration
acetylene hydrochlo-rination
vinyl chloride monomer
