摘要
采用水蒸气脱铝获得表面酸量不同的USY载体,并用离子交换法制备了金属(Pd+Pt)含量为1.15%的双金属催化剂.用NH3的程序升温脱附、X射线衍射、N2吸附-脱附和X射线光电子能谱等方法表征了载体和催化剂.以四氢萘加氢为探针反应,4,6-二甲基二苯并噻吩为硫源,在固定床反应器中考察了催化剂的活性和耐硫性.结果表明硫含量为200μg/g时,载体酸量为626和203μmol/g的两个催化剂的耐硫性最好,而载体酸量更低和更高的催化剂的耐硫性较差,表明载体的酸量太大或太小都不利于催化剂的抗硫性.X射线能量散射分析表明,酸量大时S在酸性位吸附很多,这可能导致催化剂中毒.酸量过小的催化剂抗硫性差则与金属中心缺电子效应较小有关.
USY zeolite supports with different acid amounts were obtained by steam dealumination. Dual metal catalysts with a total loading of Pd and Pt of 1.15 % were prepared by the ion-exchange method. The supports and catalysts were characterized by temperature-programmed desorption of ammonia, X-ray diffraction, nitrogen adsorption, and X-ray photoelectron spectroscopy. The catalytic activity for the hydrogenation of tetralin was examined with a fixed-bed continuous-flow reactor operating at 4.0 MPa. The sulfur tolerance was tested with a feed of 200μg/g sulfur in the form of 4,6-dimethyldibenzothiophene. The two catalysts supported on USY zeolites with surface acid amounts of 626 and 203 /μmol/g, respectively, showed excellent sulfur tolerance, while the catalysts of higher and lower acid amount showed decreased sulfur tolerance. Energy dispersive spectroscopic analysis proved that the support with a large acid amount adsorbed more sulfur, which might lead to the lower sulfur tolerance of the catalyst. The low sulfur tolerance of the catalyst with a low acid amount was attributed to the insignificance of the electron deficiency of the metal particles.
出处
《催化学报》
SCIE
CAS
CSCD
北大核心
2007年第3期274-280,共7页
基金
国家自然科学基金(20425619).
关键词
Y沸石
水蒸气
脱铝
钯
铂
四氢萘
加氢
耐硫性
溢流氢
Y zeolite
steam
dealumination
palladium
platinum
tetralin
hydrogenation
sulfur tolerance
spill-over hydrogen
