两步法合成液化石油气催化剂的研究

摘要

制备了合成液化石油气(LPG)二段反应用系列催化剂,采用两步法合成工艺,对反应温度、反应压力、合成气GHSV等条件进行优选,并进行100 h的稳定性实验.采用XRD和TPO方法对催化剂进行表征,分析了催化剂失活原因.实验结果表明,5％(w)Ni-5％(w)Cu/β双金属催化剂为二段反应最优催化剂,该催化剂具有较高的LPG选择性,显著降低了副产物CO2和甲烷的选择性,提高了碳氢化合物收率;最适宜的反应条件为:一段初始反应温度为273℃,反应进行70 h后,温度提高为277℃;二段反应温度350℃,反应压力4 MPa,合成气GHSV=2 500 mL/(h·g);在100 h稳定性实验中CO转化率和LPG选择性均保持在70％以上.表征结果显示,铜活性组分的烧结和由此引起的芳香族烃在催化剂表面的吸附是LPG选择性下降的主要原因.%A series of catalysts for the second stage in a two-stage process for the synthesis of liquefied petroleum gas(LPG) from synthesis gas were prepared,and characterized by means of XRD and TPO.The reaction conditions,namely reaction temperature,reaction pressure and GHSV of synthesis gas,were optimized,stability test for 100 h was carried out,and the deactivation of the catalyst was analyzed.It was indicated that the bimetallic catalyst with 5％(w)Ni-5％(w)Cu/β wasthe best for the second stage process with higher selectivity to LPG.When the catalyst was used,both the selectivities to CO2 and methane as byproducts reduced significantly,and the total yield of hydrocarbons increased.Under the optimum reaction conditions of reaction temperature of the first stage from initial 273 ℃ to 277 ℃ after the reactions 70 h,the second stage temperature 350 ℃,reaction pressure 4 MPa and GHSV of the synthesis gas 2 500 mL/(h · g),both the conversion CO and the selectivity to LPG were kept above 70％ in the stability test.The characterization results showed that the sintering of copper and the adsorption of aromatic hydrocarbons on the catalyst surface led to the decrease of the selectivity to LPG.