助剂Zn对PtSn/Al2O3催化剂丙烷脱氢性能的影响  

Effects of Zn on catalytic performances of PtSn/Al2O3 in propane dehydrogenation

作　　者：马占华 李帅 姜爱晶 李军[1] 孙兰义 安长华 MA Zhanhua;LI Shuai;JIANG Aijing;LI Jun;SUN Lanyi;AN Changhua(State Key Laboratory of Heavy Oil Processing,College of Chemical Engineering,China University of Petroleum,Qingdao266580,Shandong,China;Tianjin Key Laboratory of Organic Solar Cells and Photochemical Conversion,School ofChemistry and Chemical Engineering,Tianjin University of Technology,Tianjin 300384,China)

机构地区：[1]中国石油大学化学工程学院,重质油国家重点实验室,山东青岛266580 [2]天津理工大学化学化工学院,天津市有机太阳能电池与光化学转换重点实验室,天津300384

出　　处：《化工进展》2019年第8期3670-3678,共9页Chemical Industry and Engineering Progress

基　　金：国家自然科学基金(21506255)

摘　　要：以羰基铂锡化合物为前体,采用浸渍法将其负载于Zn改性Al2O3载体上制备了PtSn/x Zn-Al2O3催化剂,考察了Zn的添加对催化剂丙烷脱氢性能的影响。采用N2吸附-脱附、X射线衍射(XRD)、吡啶红外吸附(Py-IR)、氨气程序升温脱附(NH3-TPD)、透射电子显微镜(TEM)等手段对催化剂的孔结构、表面酸性以及积炭行为进行了分析。结果表明,PtSn/x Zn-Al2O3催化剂孔道以介孔为主,孔径集中分布于8~10nm;Zn助剂的添加,在催化剂表面会形成ZnO物种,可使PtSn/Al2O3催化剂上的金属颗粒粒径减小、分散更加均匀;Zn的加入能有效降低催化剂表面酸量,主要表现为L中强/强酸中心的降低,随着Zn含量的增加,催化剂表面酸量先减少后增加。少量Zn的存在可使PtSn/Al2O3丙烯选择性和稳定性显著提高,但过量Zn的加入会降低催化剂的脱氢活性,适宜Zn的质量分数为0.75%~1.0%。反应后催化剂表面积炭主要表现为烯烃性质和芳香烃性质,Zn的添加可有效抑制积炭的形成,提高催化剂稳定性。The PtSn/x Zn-Al2O3 catalysts were prepared from platinum-tin carbonyl complexes by impregnation of the precursors on Zn-modified Al2O3 support. The effects of Zn on the catalytic performance of PtSn/Al2O3 catalysts in propane dehydrogenation were investigated. The physical structures, the surface acidities and the carbon deposition behaviors of PtSn/x Zn-Al2O3 were studied by several techniques, including N2 adsorption-desorption, X-ray diffraction(XRD), infrared spectra of pyridine adsorption(Py-IR), ammonia temperature-programmed desorption(NH3-TPD) and transmission electron microscopy(TEM). The results showed that the pore sizes in PtSn/x Zn-Al2O3 were mainly distributed between 8 nm and 10 nm. When Zn was added to PtSn/Al2O3 catalyst, ZnO species were formed,which could promote the metal particles to be smaller and more evenly dispersed on the surface of the catalysts. The acid quantity was reduced after Zn was added, especially for the acid sites with medium and strong Lewis acidity. With the increase of Zn loading, the acid quantity decreased firstly and then increased. The propylene selectivity and the stability of PtSn/Al2O3 catalysts were obviously improved by adding Zn promotor. However, the dehydrogenation activity decreased rapidly when the excess Zn was added. The optimized loading of Zn should be in the range of 0.75%-1.0%(mass fraction). The carbon deposited on the surface of the catalyst was mainly composed of olefin and aromatic hydrocarbons. The presence of Zn promoter could effectively inhibit the formation of deposited coke and improve the stability of the catalysts.

关 键 词：丙烷脱氢 锌助剂 催化剂 选择性 稳定性 

分 类 号：TQ031.4[化学工程]