晶面调控促进Pt/TiO_(2)催化剂对丙烷及苯系物的催化氧化活性

Crystal facet regulation to enhance catalytic oxidation activity of Pt/TiO_(2)catalyst for propane and benzene series

在TiO_(2)水热合成过程中,通过引入氟化铵(NH4F)和氢氟酸(HF)作为晶面调控剂,来获得高暴露(001)晶面的锐钛矿型TiO_(2),并通过浸渍法负载Pt制得相应的Pt/TiO_(2)催化剂。结果表明:NH4F和HF的介入,虽然均能提高纳米TiO_(2)的(001)晶面暴露比例,并增大其晶粒尺寸,但同时均降低了其比表面积,协同影响着催化剂的催化活性;HF的介入对TiO_(2)的(001)晶面调节功效最大,显著提高了所得Pt/TiO_(2)-HF催化剂对苯系物及丙烷的催化氧化活性;相较于空白Pt/TiO_(2)催化剂试样,在Pt/TiO_(2)-HF催化剂作用下的苯系物T_(97)由198℃降低至181℃,丙烷T50由431℃降低至363℃(T_(97),T_(50)分别表示转化率为97%,50%时的反应温度)。

In the hydrothermal synthesis of TiO_(2),the ammonium fluoride(NH4F)and hydrofluoric acid(HF)were introduced as crystal facet regulators to obtain anatase TiO_(2)with high exposure(001)facet,and the corresponding Pt/TiO_(2)catalysts were prepared by the impregnation method supported by Pt.The results showed that the introduction of NH4F and HF could both increase the exposure ratio of(001)crystal facet and the grain size of nano-TiO_(2),whereas,the specific surface area of nano-TiO_(2)reduced at the same time,which synergistically affected the catalytic activity of the corresponding obtained catalysts.The introduction of HF had the greatest effect on the(001)crystal facet of TiO_(2).The catalytic oxidation activity of the obtained Pt/TiO_(2)-HF catalyst for benzene series and propane was significantly improved.Compared with the blank Pt/TiO_(2)catalyst samples,T97 of benzene series decreased from 198℃to 181℃,and T50 of propane decreased from 431℃to 363℃in the presence of Pt/TiO_(2)-HF catalyst(T97 and T50 represented the reaction temperature when the corresponding conversion rate was at 97%,50%respectively.).